International conference on Frontiers in Chemical Technology 2020 (FCT 2020)

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Comparison study of the oxalate content in commonly used green leafy vegetables
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Liyanage, J. V.; Jayasundara, U. K.
Consumption of large amount of oxalate could be harmful because of the formation of calcium oxalate deposits in vital tissues or organs of the body. Patients with kidney stone problems are advised to limit dietary oxalate intake to 40-50 mg per day. In this study, commonly consumed green leafy vegetables (GLVs) such as spinach, Gotukola, cup leaves, Mukunuwanna, leeks, Kangkung, Hathawariya, Minchi, Kathurumurunga, Thebu, curry leaves, Bulath, manioc, cabbage and salad leaves were studied gravimetrically to determine the oxalate content. Edible portion of plant material was air dried, homogenized, refluxed for 12 hours, filtered, extracted with analytical grade diethyl ether, saturated with a calcium solution and then separated. The diluted and acidified solution with distilled water was titrated with standard KMnO4 assuming oxalate was the only oxidizable species. The experiments were carried out in triplicate for each species. Only a very few related studies are available in literature and the results were comparable. The results revealed that oxalate contents in GLVs ranged from (556.04 ± 1.60) mg to (3.20 ± 2.45) mg per 20 g of raw GLV portion. Also, the results confirmed that the GLVs can be divided into four categories based on the oxalate content as high (> 200 mg), medium (199 mg – 100 mg), low (99 – 10 mg) and undetectable (< 10 mg). Hathawariya, spinach, curry leaves and Kankung showed the highest amount of oxalate ranging from 556.04 ± 1.60 to 238.04 ± 1.84 mg per 20 g, while cabbage, salad leaves and leeks showed undetectable amount of oxalate ranging from 7.47 ± 1.84 to 3.20 ± 2.45 mg. It is interesting to note that commonly consumed GLVs by Sri Lankans have detectable amount of oxalate content which exceeds the minimum advisable level according to American Diabetes Association. Adding such GLVs to meal along with calcium supplements may worsen the health condition of kidney stone patients.
Antibacterial activities of peptaibols, trichocellin A-I and B-II, isolated from the endophytic fungus Trichoderma reesei
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Madhushika, D. P. H.; Jayasundara, J. M. N. M.; Ratnaweera, P. B.; Williams, D. E.; de Silva, E. D.; Andersen, R. J.
Antibiotics are highly used in chemotherapy for bacterial infections worldwide. However, due to misuse and overuse of antibiotics pathogenic bacteria have developed and continue to develop resistance to the existing antibiotics rendering them ineffective. Thus there is an urgent need to develop new types of antibiotics to counter the spread of these lethal, drug resistant infections. Endophytic fungi of Cyperaceae plants are a relatively unexplored but a significant resource for the discovery of new biologically active natural products. Therefore, the main objective of this study was to isolate bioactive secondary metabolites of the endophytic Trichoderma reesei (GenBank accession number MT476871) fungus isolated from Cyperus iria in Sri Lanka. Initial screening of T. reesei showed antibacterial activity against the Gram positive Bacillus cereus and Staphylococcus aureus at 400 μg/mL. T. reesei was grown in large scale and extracted into ethyl acetate following an incubation period of 13 days. Solvent-solvent partitioning of the crude extract (1005 mg) led to an active chloroform fraction (580 mg), which was chromatographed on Sephadex LH20 size exclusion column chromatography. The active fraction B (143 mg) from the six fractions (A-F) obtained from size exclusion chromatography was further purified via C18 reversed-phase high performance liquid chromatography (HPLC) to yield two peptaibols. The structures of the peptaibols were determined as trichocellin A-I and B-II by nuclear magnetic resonance (NMR) and mass spectral data. Both peptaibols A-I and B-II were active against the two Gram positive bacteria tested with minimum inhibitory concentrations (MICs) of 64 and 8 μg/mL for B. cereus and 32 and 16 μg/mL for S. aureus respectively. The positive control Gentamycin gave a MIC of 2 μg/mL for both bacteria. To the best of our knowledge this is the first study to isolate trichocellins from an endophytic T. reesei fungus. The study revealed that the isolated trichocellins from T. reesei are potent antibacterial compounds.
Polyethylene degradation capability of Schizophyllum commune
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, T. W. N. K.; Attanayake, R. N.; Paranagama, P. A.
Tremendous increases in the manufacture and consumption of polyethylene, over recent decades have led to numerous environmental and economic concerns. This is the first comprehensive research on determination of Endolichenic Fungi (ELF), capable of degrading polyethylene substrates. The objective of this study was to identify the ability of various ELF, for the degradation of polyethylene in liquid media. Commercially available Low Density Polyethylene (LDPE) bags were used as the test material. ELF isolates cultured on Potato Dextrose Agar, were introduced into Mineral Salt Medium Broth containing LDPE strips. The isolate, Schizophyllum commune showed a positive growth response in the broth medium. The strips treated with this isolate, were tested for the reduction in dry weight, changes in peaks of Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy, reduction in tensile strain at break and changes in Scanning Electron Microscopic analyses. Results showed that isolate, reduced the weight of LDPE strip by 10.54%, after 21 days of incubation, while control showed 0% reduction. The control LDPE strip on ATR-FTIR analysis showed prominent peaks at 2916 cm-1, 2848 cm-1, 1463 cm-1 and 720 cm-1. Changes visible in sample infrared spectra after 21 days of incubation, were the fluctuations in the percentage transmittance of above peaks and formation of new peaks at 1740 cm-1, 1215 cm-1 and 1046 cm-1. The tensile strain at break, of treated strips, reduced by 27.41%, after 21 days of incubation while control showed 0% reduction. The presence of pits and cavities, in Scanning Electron Micrographic images, suggested the penetration of fungi, into the LDPE matrix, during degradation. The occurrence of several nonuniformly scattered whitened areas and erosion zones, indicated the surface erosion of LDPE strips, in degradation. These changes were not observed in the control LDPE strips. This study provides insight into the role of Schizophyllum commune towards solving the dilemma of polyethylene wastes, through biodegradation.
In vitro antiglycation and antioxidant activity of the aqueous extract of leaves of Solanum torvum
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Irfan, F. A.; Deraniyagala, S. A.
Protein Glycation, is a non-enzymatic process which forms Advanced Glycation End Products (AGEs). Accumulation of AGEs in the body causes health complications, especially those related to diabetes. Oxidative stress is also considered to be a contributing factor for such health complications. The present study was undertaken to look into the inhibitory potential on the formation of AGEs as well as the anti-oxidant potential of the aqueous extract of the leaves of the Sri Lankan variety of Solanum torvum (thibbatu) [AELST].The extract was prepared according to the method of Kasaya preparation in Ayurveda medicine. Fructose mediated Protein Glycation was induced by using Bovine Serum Albumin and fructose in buffer of pH 7.4 to mimic AGE formation. The assay showed that AELST has a 7.7% - 85.1% inhibitory effect on AGE formation at a concentration range of 0.25 - 2.0 mg/mL. Amino guanidine which was the positive control, known to have much side effects showed AGE inhibition from 0%- 87.5% for the same concentration range. The plant extract showed the presence of phenols and flavonoids. AELST also showed a radical scavenging activity between 19.2% - 76.7% in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay while the standard BHT showed a percentage inhibition of 13.2% - 83.5% for the concentration range of 25-200 μg/mL. In the hydroxyl radical scavenging assay AELST showed a percentage radical scavenging activity of 29.3% - 42.7% while the positive control ascorbic acid showed a percentage inhibition of 24.1% - 36.9% in a concentration range of 0.5 - 2.0 mg/mL. Hydroxyl radical is one of the potent reactive oxygen species in the biological system. The results show that AELST has the potential to be developed to suppress complications arising due to AGE formation in patients with chronic hyperglycemia and also as a remedy to prevent diseases in which radicals are implicated.
Determination of water quality and suitability in a chronic kidney disease of unknown etiology (CKDu) prevalence area, Sri Lanka
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Botheju, W. S. M.; Liyanage, Janitha A.
Chronic Kidney Disease of unknown etiology (CKDu) is a global health obstacle that is presenting as kidney disease in patients who do not show common causative factors, such as diabetes or hypertension. Although the causative factors and major causes for CKDu prevalence are still in debate, most of the external factors which affect the disease are associated with drinking water. Therefore, this study investigated the water quality and suitability of drinking water in a CKDu prevalence area to assess its suitability for human consumption. The water samples were collected from 30 dug wells in Girandurukotte Grama Niladhari Division (GND), Badulla District which reported the highest number of CKDu patients and from Buddhangala GND in Ampara District (as reference sampling site) in dry season. Dissolved Oxygen (DO), Electrical Conductivity (EC) and Fluoride (F) were analyzed as on-site measurements. Calcium (Ca), Magnesium (Mg), Cadmium (Cd), Arsenic (As) were determined using Inductive Coupled Plasma Mass Spectrometry. Sulphate, Nitrate and Chlorides were analyzed using Ion Chromatography. Each analysis was performed in triplicates. The Water Quality Index (WQI) was calculated using standards of drinking water quality recommended by the World Health Organization (WHO). According to the results, pH, DO, EC, F, Ca, Mg, Cd, Cr, Pb, As, total hardness, sulphate, nitrate and chloride values in Girandurukotte GND were 7.03±0.08, 4.8±0.8 mg/L, 396.9±9.1 μS/cm, 1.64±0.04 mg/L, 1.05±0.90 mg/L, 202.85±5.60 mg/L, 0.124±0.074 μg/L, 54.75±0.54 μg/L, 0.20±0.05 μg/L, 30.64±8.60 μg/L, 83.60±4.02, 60.28±5.62 mg/L, 20.56±8.62 mg/L and 122.65±10.36 mg/L respectively. The results obtained for WQI in Girandurukotte and Buddhangala were 71.84 (51-75 poor) and 42.67 (26-50 good) respectively. Results indicate that water samples analyzed from Girandurukotte are not safe for human consumption and other domestic purposes while the water samples in reference site are safe for human consumption. Therefore, taking all necessary precautionary measures before the consumption can be recommended to avoid adverse health impacts.
Antioxidant, anti-inflammatory and antibacterial potentials of aqueous leaf extract of Pouteria campechiana (Kunth) Baehni (Ratalawulu)
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Hettiarachchi, O. I.; Deraniyagala, S. A.; Hettiarachchi, C. M.
Antioxidants are of dietary importance in preventing oxidative stress due to the production of excess free radicals in our body leading to many diseases including cancer, atherosclerosis and diabetes as well in aging. Despite the advances in modern medicine, plant -based remedies play an important role in healthcare due to less side effects. Due to the side effects of NSAIDS and antibiotics, plant -based remedies would be beneficial. This study was conducted to assess the potential use of P. campechiana (Ratalawulu) as an antioxidant, anti-inflammatory and antibacterial agent. The aqueous leaf extract of Ratalawulu was prepared according to the method of decoction preparation in ayurvedic medicine. All assays were carried out according to previously published procedures. Aqueous leaf extract of P. Baehni showed a Total Phenolic Content of 230.71±7.62 mg (PGE)/g in the Folin-Ciocalteu method. Total flavonoid content was 140.98 ± 98.46 mg (QE)/g according to AlCl3 colorimetric assay [PGE- Pyrogallol equivalence, QE- Quercetin equivalence]. 2,2-Diphenyl-1-picrylhydrazyl radical scavenging activity of aqueous leaf extract of P. Baehni ranged between 1.4%-17.8% for concentration between 0.01-0.1 mg/ml whereas ascorbic acid showed 2.46%-43.93% for the same concentration range. Ferric ion reducing assay for aqueous leaf extract of P. Baehni showed gradual increase in reducing property relating to antioxidant action by donating a hydrogen atom to break free radical chains. Hydroxyl scavenging activity showed 5.73%-44.03% for concentration series of 20-100 mg/ ml whereas, Ascorbic acid ranged from 9.40%-47.06%. Hydroxyl radical is one of the potent reactive oxygen species in the biological system. Nitric oxide scavenging anti-inflammatory assay showed 58.06%-75.36% whereas ascorbic acid showed 80.73%-91.76% for concentration series of 0.4-6.4 mg/ ml. In the human red blood cell assay, percentage protection by aqueous leaf extract of P. Baehni was 15.0%-62.4% and that of ascorbic acid was 12.1%-72.8% for 6.0-300 μg/ml. Aqueous leaf extract of P. Baehni also showed antibacterial activity against Staphylococcus aureus. Taken together, these results suggest the potential use of aqueous leaf extract of P. Baehni as an antioxidant, anti-inflammatory and antibacterial agent, and merit further related investigation.
Effect of fertilizer application to the agricultural soil and the determination of soil to plant transfer coefficients of selected elements
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, W. P. R. T.; Dayananda, M. D. N. R.; Botheju, W. S. M.; Liyanage, Janitha A.
Transfer of metals from soil to plant depends on the availability of particular elements in soil and the fertilizer which are applied to the agricultural fields. This study aims to determine the effect of fertilizer application to the agricultural soil and to determine the soil to plant transfer coefficients of selected elements in Eppawala Grama Niladhari Division (GND), Anuradhapura, Sri Lanka. Fifteen soil and rice root samples were randomly collected from paddy fields and composite fertilizer samples were prepared by adding Urea, Muriate of Potash and Rock Phosphate in the ratios which were used by farmers in sampled area. Metals were analyzed by Inductive Coupled Plasma Mass Spectrometry (ICP-MS-Agilent 7800). Mean concentrations of Cr, Fe, Cu, As, Cd, Pb and Zn in fertilizer composites were 445.00±171.00, 114638.00±46722.00, 92.90±38.40, 178.00±109.00, 5.56±3.41, 912.00±534.00 and 2553.00±1452.00 in mg/kg respectively. Mean concentrations of Cr, Fe, Cu, As, Cd, Pb and Zn in soil samples were 0.22±0.03, 135.10±38.90, 1.37±0.16, 0.25±0.30, 0.01±0.00, 0.32±0.07 and 40±10.3 in mg/kg respectively. The transfer coefficients (TC) of different metals were quantified to indicate the lability of metals in soils. Greater TC value indicates relatively poor retention of metal in soil or greater efficiency of plant roots to absorb metal, and low TC is attributed to strong sorption of metal to the soil colloid. TCs from soil to roots for Cr, Fe, Cu, As, Cd, Pb and Zn were 62.14, 260.04, 46.93, 6.94, 21.26, 14.14 and 3.37 respectively. It indicates that rice roots absorb higher amounts of metals in soil colloids which are resulting mostly from the fertilizer applications. It can be concluded that considerable amount of metals coming from the fertilizers are remaining in the soil and the efficiency of absorbing metals from plant roots is higher than the retention of metals in soil as having greater Transfer Coefficients.
Antibacterial activity of entomopathogenic fungi isolated from Vespa affinis and Apis dorsata in Sri Lanka
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Sandeepani, H. P.; Ratnaweera, P. B.
Antibiotic resistance of bacteria throughout the world has caused serious health issues. Thus, there is a crucial need for the discovery and development of new antibiotics. Entomopathogenic fungi infect and eventually kill their host insects. However, entomopathogenic fungi are known to be a rich source of bioactive secondary metabolites. The main aim of the current study was to isolate and investigate the antibacterial activities of entomopathogenic fungi of two insect species Apis dorsata and Vespa affinis collected from Uva Wellassa University library premises, Badulla, Sri Lanka (810 4’ E, 60 58’N). Freshly dead insect cadavers were collected, surface sterilized, crushed and spread on antibiotic (Amoxicillin, 10 mg/mL) enriched potato dextrose agar media plates. The emerging fungi were isolated, pure cultures were obtained and extracted into ethyl acetate. The fungal crude extracts were tested for antibacterial activity against Staphylococcus aureus (ATCC 25928), Bacillus cereus (ATCC 11718), Escherichia coli (ATCC 35218) and Pseudomonas aeruginosa (ATCC 9027) using agar disc diffusion method (400 μg/disc) and bioautography. The experiments were carried out in triplicate. For the identification of fungi, genomic DNA were isolated, the ITS region of the ribosomal RNA gene was amplified using ITS1 and ITS4 primers, the obtained PCR products were sequenced and BLAST analyzed. Nine morphologically different entomopathogenic fungal strains were isolated from A. dorsata while eight were isolated from V. affinis. Thirteen fungal extracts showed antibacterial activity against at least one bacterial species tested while four extracts were inactive to all bacteria. Ten, eight and nine fungal extracts showed some activity against S. aureus, B. cereus and E. coli respectively while none of the extracts showed any activity against P. aeruginosa. Talaromyces versatilis fungal extract from A. dorsata showed the best inhibition with a mean diameter of 13.00 ± 1.00 mm against E. coli with an activity similar to the positive control (Gentamycin, 1000 ppm). The bioautography assays revealed that T. versatilis and an Aspergillus extracts were active against S. aureus while A. nomius extract was active against B. cereus. The FTIR analysis and thin layer chromatography studies exhibited the presence of many secondary metabolites in all fungal crude extracts. This study shows that entomopathogenic fungi of V. affinis and A. dorsata are potential sources for the discovery of novel antibacterial drug leads.
Development of a face and body cleanser using Cocos nucifera (coconut) oil, coconut shell charcoal and rice husk charcoal
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Jayasooriya, J. A. C. T.; Udawatte, C. S.
Air pollutants and toxic elements can directly affect the skin as it is the outermost barrier protecting the body. In this study, a cleanser was formulated using charcoal, virgin coconut oil, and other local ingredients. An artificial sweat solution including NaCl, NH4Cl, acetic acid, lactic acid was treated with coconut shell charcoal (CSC) and rice husk charcoal (RHC) varying the particle size, dosage, and the contact time with the solution, in triplicates. The remaining organic acids, NH4 +, and Na+ were determined by formalin titrimetric method and flame photometry. CSC having the particle size of 0.25-0.50 mm exhibited higher adsorption towards the two main components in human perspiration; NaCl and NH4Cl than RHC, at an average contact time of 30 minutes. Therefore, CSC was used as the adsorbent. Virgin coconut oil was used as a moisturizer, an antioxidant, an emulsifying agent, sodium lauryl ether sulfate as the foaming agent and bee’s honey as the binding agent, a thickener, an antimicrobial and a humectant. Other ingredients used were kaolinite, sesame oil, and sweet orange essential oil. The pH of the product was 6; therefore, pH balanced. The product showed significant antibacterial activity against Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa when subjected to agar well diffusion method. The highest result was observed against Staphylococcus aureus, giving an inhibition zone of 2.5 cm for 100 mg of the product, while 5 μg of Ciprofloxacin showed an inhibition zone of 3.0 cm. The product was easily spreadable, washable, and had a thick consistency. Patch test was done by applying 400 mg of the product on the dorsal forearm of 10 volunteers with a diameter of 1 inch, for 30 minutes, then rinsed off with water. No adverse effects were exhibited. Therefore, this product can be considered safe, and it achieves the desired attribute as a cleanser.
Bioaccumulation of nephrotoxic metals in rice grains (Oryza sativa) in a CKDu hotspot in Sri Lanka via soil analysis
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Dayananda, M. D. N. R.; Liyanage, Janitha A.
Accumulation of nephrotoxic metals in edible crops and associated soil is a major international concerns today which results food safety issues and adverse health risks like CKDu. Soils are considered to be an excellent media to monitor and assess chemical pollution where the application, deposition and absorption of chemicals are taken place. Therefore, this study attempts to investigate the bioaccumulation of nephrotoxic metals in soil and rice grains (Oryza sativa) and to interpolate the spatial distribution of selected chemical elements using Inverse Distance Weighted (IDW) and Spatial Autocorrelation tools in ArcMap 10.2.2 software in a CKDu hotspot; Girandurukotte Grama Niladhari Division (GND), Badulla, Sri Lanka via soil analysis. Dambethalawa GND in Ampara district was selected as the reference site. 30 soil samples were collected according to random stratified design including 10 paddy cultivated sites and 10 composite rice grain samples were collected from those paddy fields separately. Microwave digested soil and rice samples were analyzed by inductively coupled plasma mass spectrophotometry. The average concentrations of Cd, Pb, As, Cr, Ca and Mg in soil were 0.45±0.02, 0.20±0.02, 0.65±0.25, 0.29±0.04, 4812.00±692.00, and 15157.00±1275 mg/kg respectively. According to the lower Moran’s indices given by the Spatial Autocorrelation, the selected metals were evenly distributed throughout the sampling area and Cd, Pb, Ca and Mg contents in CKDu prevailed area was significantly higher (p<0.05) than the reference. The higher bioaccumulation factors (from soil to rice grain) (BCF>1) indicated that rice grains tend to accumulate the nephrotoxic metals including Cd;2.35, Pb;7.48, As;2.60 and Cr;5.80. The calculated Enrichment factors (EF) which derives the degree of soil contamination by nephrotoxic metals were Cd;6.49, Pb;6.01, As;1.30 and Cr;1.48 and greater EFs (EF>1) indicates higher availability and distribution of metals in contaminated soil when compared to the reference. It can be concluded that the degree of soil contamination by nephrotoxic metals was higher in the selected CKDu hotspot than the reference. Hence, human renal dysfunctions can be related with consumption of contaminated rice with those metals.
Nitric oxide radical scavenging potential of selected widely used spices and in a mixture of spices
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Wickramaratna, H. D. P.; Amarasiri, A. M. S. S.; Attanayake, A. P.
A remarkable research interest has been shown on phytochemicals in spices and their bioactivities during the last decade. Nitric oxide (NO) radical scavenging potential is one of the assays used in the determination of in vitro antioxidant activity. The study aims to determine NO radical scavenging potential of the aqueous extracts of ten selected Sri Lankan spices and a mixture of spices made from five selected spices with high NO scavenging potential. The spices were randomly collected within the areas of Sabaragamuwa and Southern provinces from their natural habitats. L-ascorbic acid was used as the reference compound in the assay. The NO radical scavenging potential were estimated following the standard protocol using a spectrophotometric assay. The half maximal inhibitory concentration (IC50) was calculated using regression analysis and the values were expressed as mean ± standard deviation (SD) of the three analytical triplicates. IC50 values of the selected spices were 269.33 ± 2.21 μg/mL (Piper nigrum), 270.24 ± 4.23 μg/mL (Curcuma domestica), 279.85 ± 1.62 μg/ mL (Elettaria repens), 288.88 ± 0.87 μg/mL (Myristica fragrans), 292.59 ± 11.83 μg/mL (Zingiber officinale), 322.05 ± 2.13 μg/mL (Eugenia caryophyllata), 341.11 ± 1.39 μg/mL (Cinnamomum verum), 355.94 ± 2.98 μg/mL (Cymbopogon citratus), 356.32 ± 1.31 μg/mL (Brassica integrifolia) and 394.19 ± 3.87 μg/mL (Capsicum frutescens). There was a statistically significant difference in between ten spices (p<0.05). The spices which showed the highest NO radical scavenging potential (lowest IC50) were selected for the mixture. Accordingly, P. nigrum, C. domestica, E. repens, M. fragrans and Z. officinale were selected. The mixture showed the highest NO radical scavenging potential with the lowest value of IC50 (256.42 ± 0.22 μg/mL) compared to the individual spices. Based on the results, all selected extracts of spices possess NO scavenging potential and the mixture showed the highest activity.
Insight into the mechanism of the catalysis of urethane formation by organotin(IV) dicarboxylate using experimental and computational methods
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Devendra, Ransi; Edmonds, Neil R.; Söhnel, Tilo
Polyurethane is made by reacting a polyisocyanate with a polyol. Organotin dicarboxylates are used as catalysts for this reaction. However, a deeper understanding of the mechanism in catalysis is essential in the polyurethane product manufacture. Although catalysis of aromatic and aliphatic isocyanates using organotin dicarboxylate in urethane formation was claimed to have the same mechanism for both, our work showed that they were different. In this work, we investigated urethane formation for both aliphatic and aromatic isocyanates in the presence of different organotin carboxylate compounds as catalysts using experimental and computational methods. In experimental methods, kinetic studies and FTIR analysis were used. As the computational method, the DFT/B3LYP-D3 functional with the LANL2DZ basis set for tin and the 6-31G* basis set for light elements was used. The results from the experimental and theoretical studies showed that an alkoxide complex was formed initially by the interaction between organotin di-carboxylate catalyst and alcohol. Then the interaction between alkoxide complex and isocyanate molecule was modelled using a computational method. This interaction resulted in the formation of organotin carbamate and carboxylic acid. Then the newly formed organotin carbamate was computationally modelled to interact with alcohol or carboxylic acid to form the urethane and to regenerate the active catalyst. By using thermochemical data from the computational investigation, it was possible to show that aliphatic isocyanates can be more sensitive to the carboxylic ligand content of the organotin carboxylate catalyst compared to aromatic isocyanates in urethane formation. Based on these findings, different mechanisms for aromatic and aliphatic isocyanates in urethane formation can be proposed when an organotin dicarboxylate is used as a catalyst. The new knowledge from our studies was essential to minimize the viscosity increase in storage of urethane pre-polymer when synthesised using organotin dicarboxylate as the catalyst.
Isolation of cysteine-rich peptides from the deep-sea marine sponge Stryphnus fortis and determination of its antimicrobial effect
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Kosgahakumbura, K. N. M. L. N; Hettiarachchi, C. M; Jayasinghe, R. P. P. K.; Cárdenas, P.; Gunasekera, S.
Cysteine-rich peptides are a promising resource for a wide range of pharmacological applications such as development of drug leads and as scaffolds for potential oral drug delivery due to their stable disulfide framework. A handful of these compounds have been isolated from marine sponges and it is speculated that plenty of them remain unexplored. In the present study, four peptides A, B, C and D containing three disulfides were isolated from the aqueous extract of the deep-sea marine sponge Stryphnus fortis (Demospongiae, Tetractinellida, Ancorinidae) from Norway, and were further purified using RP-HPLC (Reverse Phase High Performance Liquid Chromatography). The mass spectroscopic analysis using MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization- Time Of Flight) revealed monoisotopic masses of 3331.809 Da [M+H]+, 3349.731 Da [M+H]+, 3517.973 Da [M+H]+, 3917.61 Da [M+H]+respectively for the four peptides A, B, C and D. The antimicrobial activity was screened using a peptide adapted Micro dilution assay against E. coli (ATCC 25922), S. aureus (ATCC 29213) and C. albicans (ATCC 90028) up to a concentration of 50 μM. The average concentration derived from triplicates that exhibited a growth inhibition on visual inspection was considered as the Minimum Inhibitory Concentration (MIC). Moderate antimicrobial activity for peptide C was observed against S. aureus (MIC = 36.14 μM) and C. albicans (MIC = 18.07 μM). However, no inhibition was observed against E. coli up to the highest concentration tested. The human antimicrobial peptide LL 37 was used as the control (MIC value around 1-2 μM). The sequence analysis of the four peptides, their structural characterization and investigation of their potential applications are currently underway.
Qualitative analysis of heavy metal adsorption by the green synthesized silver nanoparticles
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Ramanayake, R. A. D. J.; Wickramarachchi, P. A. S. R.
Silver nanoparticles (AgNPs) have attracted high research interest because of their important applications in antimicrobial, catalysis, and water treatment plants. They display totally new and enhanced properties compared to larger bulk material particles and these novel properties are due to the difference in specific characteristics such as particle size, distribution, morphology and higher surface area-to-volume ratio. The aim of this research was to determine the Pb(II) and Cu(II) adsorption of synthesized AgNPs using natural polymer, chitosan as both reducing and capping agent. AgNPs were formed in an autoclave at 15 psi and 131 0C by varying the AgNO3 and chitosan concentrations and autoclaving time. AgNPs solution thus obtained was mixed with Pb(II) and Cu(II) (0.05, 10, 100, 200, 500 ppm) solution separately and kept overnight. The removal of metal ions from the solution was monitored by the shift and intensity variation of the surface plasmon resonance (SPR) band of the AgNPs. The green synthesized silver nanoparticles were characterized using ultra violet visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM) and particle size analyzer. UV-Vis peak at the 430 nm confirmed the formation of chitosan stabilized silver nanoparticles. The dynamic light scattering (DLS) measures confirmed that the average size of synthesized AgNPs was 818.4 nm with the polydispersity index of 0.243 revealing the uniform size and good dispersion of the nanoparticles. The optimum concentrations of AgNO3 and chitosan were recorded as 50 mM and 2% respectively. The maximum yield of nanoparticles was obtained at 60 minutes of autoclaving, which was decided as the optimum time of autoclaving. After addition of metal ions, AgNPs solutions showed a color change and a shift and variation in intensity of the SPR band at lower metal ion concentrations while at higher metal concentrations SPR band disappeared indicating the adsorption of metal ions onto the AgNPs. Hence this has the potential to be developed as a heavy metal removal technique in water.
Development of a herbal fairness cream using four medicinal plants
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Wimalasekera, H. N.; Paranagama, P. A.; Harapathdeniya, S.
There are reports in the public domain which state that artificially synthesized fairness creams have shown side effects on humans. The purpose of a fairness cream is to get a fairer skin by blocking harmful Ultraviolet (UV) rays which can activate the melanin biosynthesis in the body. When there is an excess production of melanin, it can lead to several hyperpigmentation diseases and finally result in a darker or tanned skin. This excess melanin formation can be inhibited by avoiding exposure to UV light, using tyrosinase inhibitors and anti-oxidants, which can reduce melanin proliferation. In this research study, a herbal fairness cream was prepared using four traditional medicinal plants found in Sri Lanka to inhibit excess melanin production in the body. The four plants chosen for this study were, Hemidesmus indicus (Heen Iramusu), Ixora coccinea (Rathmal), Hibiscus rosa sinensis (Pokuru Wadamal) and Citrus reticulata (Heen Naran). The plant extracts and the cream were separately subjected to anti-oxidant (DPPH and ABTS) assays and anti-tyrosinase assay. In addition, the anti-bacterial activity of this cream was studied. The methanol extracts of these four plant species displayed a high antioxidant activity and a significant tyrosinase inhibitory activity. The herbal cream was formulated using equal proportions of these extracts. Anti-tyrosinase studies of the cream revealed that it has a good anti-tyrosinase activity compared to the positive standard, Kojic acid. In addition, anti-bacterial studies revealed that the cream can inhibit bacteria Staphylococcus aureus and Bacillus subtilis. The ABTS assay showed that this polyherbal cream can act as an excellent antioxidant (IC50: 0.54±3.86) with respect to the control BHT (IC50:9.99±1.76). The cream was prepared using 100% natural ingredients which helped to enhance the therapeutic benefits of this cream. Thus, this cream can be used as a substitute for the synthetic fairness creams already available in the market.
Phenolic and flavonoid contents and antioxidant activity of methanolic extract of Durio zibethinus Murr. Peels
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, M. P. J.; Rajapakse, C. S. K.
Durio zibethinus (durian), known as the King of fruits is one of the most important seasonal fruits in tropical Asia. Even though the edible parts of durian are known to be rich in bioactive compounds, less research has been conducted to investigate the potential bioactivity of durian peels and seeds which are of less commercial value and being disposed leading to environmental pollution. Therefore, this research was mainly focused on exploration of bioactive properties in methanolic extract of durian peels. Firstly, the dried durian peels were soxhlet extracted using methanol and then the crude extract was sequentially partitioned in hexane, dichloromethane and methanol (30%). The antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) of each fraction were evaluated using DPPH (α, α-diphenyl- β- picrylhydrazyl) assay, Folin-Ciocalteu assay and aluminium chloride spectrophotometric assay respectively. Antioxidant activity (IC50) and its correlation to TPC and TFC were analyzed by the Pearson’s method. The dichloromethane fraction showed the highest antioxidant activity (IC50 179.9 ± 6.6 μg/ml) with high TPC and TFC (85.82 ± 12.11 mg gallic acid equivalent/g dried weight and 12.66 ± 1.94 mg of quercetin equivalent/g of dried weight, respectively). According to the Pearson’s correlation, a strong positive correlation was observed between the antioxidant activity and the TPC of fractions of methanol extracts of durian peels with a Pearson coefficient of 0.9904 and a moderate positive correlation was noticed between the antioxidant activity and TFC of the fractions with a Pearson coefficient of 0.6553 indicating that phenolic compounds in durian peels may contribute to their strong antioxidant activities with somewhat contribution from the flavonoid compounds. As the dichloromethane fraction had constituents with the highest antioxidant activity, it was further separated by column chromatography and analyzed by GC-MS to identify its volatile compounds. The results revealed that the dichloromethane fraction of durian peels was rich in [1,2-Benzenedicarboxylic acid, bis (2-ethylhexyl) ester], [2,3-Diphenylquinoxaline], [2-Coumaranone], [4-((1E)-3-Hydroxy-1- propenyl)-2-methoxyphenol], [7,9-Di-tert-butyl-1-oxaspiro (4,5) deca-6,9-diene-2,8-dione] and [Phenol, 2,4-bis(1,1-dimethylethyl)] which are known to exhibit antioxidant activity.
The development of novel photodegradable linear low-density polyethylene (LLDPE) and investigation of the antibacterial properties
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Kandambi, D. P. H.; Mudiyanselage, T. Kuruwita; Udawatte, C. S.
Plastic does not decompose easily under natural conditions and the need for degradable polyethylene has become an important area of research. In this study, the suitability of using cinnamaldehyde, in its natural and synthetic forms, and benzophenone, as photo oxidative sensitizers were evaluated. The results showed that oxidative degradation of linear low density polyethylene (LLDPE) increased significantly with the incorporation of these materials. Oxidative sensitization increased significantly with incorporation of natural cinnamaldehyde, Best results for oxidative sensitization were obtained by incorporation of 20% by mass natural cinnamaldehyde. The polymer composite films were prepared using a polymer solution in toluene and 2 cm x 2 cm films were caste between glass slides. 10 samples of each type were analyzed. The extent and nature of degradation was evaluated using FTIR spectroscopy, percentage weight loss and surface analysis techniques. The auto oxidative degradation of the composite films was carried out by accelerated UV initiated degradation, and also under natural rooftop conditions. Embrittlement and color development with aging in the photosensitizer incorporated polymer films were noticeably evident, when compared with the nonincorporated polymer films under similar conditions. Since polymer films are used for food and drug packing applications, antibacterial properties of the composite films were evaluated for four bacterial strains, Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853) and Bacillus cereus (ATCC 11778) using agar disc-diffusion method. Cinnamaldehyde containing composite films displayed significant antibacterial properties against all four bacterial strains, whereas benzophenone containing films did not show antibacterial properties against these strains.
Association between high sensitivity C-reactive protein and body compositions among community dwelling healthy adults; a cross-sectional study among South East Asians
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Silva, Eranga Harshani; Wickramatilake, Chandima Madhu; Lekamwasam, Sarath; Mudduwa, L. K. V.; Ubayasiri, Ranjuka Arushana
High sensitivity C-reactive protein (Hs-CRP) is a predictor of future vascular events. Although studies have shown that Hs-CRP is linked with body fat content, data among South East Asians are inconsistent and sparse. Objective of this study was to determine the association between Hs- CRP and body composition indices among community dwelling healthy adults. Seventy (women=9) healthy adults, free of medications and excessive use of alcohol (more than one unit of alcohol per day) and smoking (more than one cigarette per day) were recruited as community controls of an ongoing study. Hs-CRP was measured by an ELISA method on fasting state and they underwent Dual-energy X-ray absorptiometry (DEXA) to measure body compositions (total body fat mass (TBFM), truncal fat mass (TRFM), total body lean mass (TBLM), total body bone mineral content (TBBMC), total body bone mineral density (TBBMD)). Mean (SD) age of the group was 47(9) years with a mean (SD) body mass index of 23.4(3.6) kgm-2. Median (IQR) Hs-CRP was 0.8 (0.4-1.9) mg/L. A significant positive correlation (Spearman rho) was observed between Hs-CRP and TBFM (r=0.52) TRFM (r=0.54) and fat percentage (r=0.55) (p<0.001 for all). No significant correlations were observed between Hs-CRP and TBLM or TBBMC/TBBMD. Among healthy adults’ Hs-CRP is linked with both total and truncal fat masses and not with lean or bone masses. This information supports the view that chronic inflammation is linked with body fat content than other body compartments.
Cytotoxic effect of a resorcinolic lipid isolated from Mangifera zeylanica in a human cancer cell panel
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Rathnayaka, Rajitha K.; Samarakoon, Sameera R.; Ediriweera, M. K.; Tennekoon, K. H.; Adhikari, A.; Gunasekara, Dinara S.
Cancer remains a leading cause of death worldwide. Surgery, chemotherapy, radiotherapy, hormonal therapy and immunotherapy are considered as treatment options for cancer. Plants have played a vital role as a source of effective anti-cancer agents, and 60% of anti-cancer agents derived from natural sources. Mangifera zeylanica is a plant endemic to Sri Lanka and its bark has been use in traditional medicine to treat some cancers. Cytotoxic compounds such as quercetin, chatecin, mangiferin and bromomangiferic acids have been reported in the bark extracts previously. Cytotoxic effect of a resorcinolic lipid (RL) in estrogen receptor-positive breast cancer (MCF-7), triple-negative breast cancer (MDA-MB-231) and epithelial ovarian cancer (SKOV-3) cells has evaluated in a previous study conducted in our laboratory. This study was performed to evaluate cytotoxic effects of RL [5-((8Z, 11Z, 14Z)-hexatriaconta-8, 11, 14-trienyl) benzene-1, 3-diol], a compound isolated from hexane extract of the bark of M. zeylanica, in small cancer cell panel containing human hepatocellular carcinoma (HepG2), colorectal adenocarcinoma (Caco-2), malignant mucoepidermoid pluripotent carcinoma (NTERA-2), renal cell adenocarcinoma (ACHN), mucoepidermoid pulmonary carcinoma (NCI-H292), epidermoid carcinoma (A-431), endometrium adenocarcinoma (AN3CA) and triplenegative breast cancer cells (Hs578t) and normal embryonic kidney cells (HEK-293). Sulforhodamine B (SRB) assay was carried out to evaluate the cytotoxic effects of the RL on the cancer cell panel. Prior to the SRB assays, cancer cells were treated with RL at concentrations ranging from 1.5625 to 25μg/ mL and incubated for 48 h. Results of the SRB assay demonstrated that RL excreted a potent in vitro cytotoxicity on all cancer cell lines tested (IC50 in μg/mL; HepG2: 2.31, Caco-2: 1.59, AN3CA: 1.28, Hs578t: <1.00, NTERA-2: <1.00, ACHN: 1.42, NCI-H292: 2.84 and A-431: 1.63) with less cytotoxicity to normal embryonic kidney cells (HEK-293: 4.44). Ethidium bromide/ Acridine orange staining revealed morphological evidence of apoptosis (including chromatin condensation, nuclear fragmentation and changes in the size and shape) in cancer cells. Overall results of the current study provide preliminary evidence to prove that RL can be develop as a potential drug to treats several types of human cancers.
Synthesis of DPA based NNN donor ligands having piperidinyl groups and their platinum complexes towards potent anti-cancer applications
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Peiris, P. A. L.; Perera, N. T.
Dipicolylamine (dpa) moiety has received much attention due to its coordination versatility. Our objective is to incorporate piperidinyl groups into the dpa system due to possibility of the piperidinyl group to target sigma receptors as it shows high affinity to sigma receptors, which are expressed in high densities in breast cancer cells. In this study, two novel ligands; N((CH2)2piperidine)dpa (L1) and N((CH2)3piperidine)dpa (L2) (Figure 1) were synthesized by utilizing pendant piperidinyl groups having different chain lengths. The platinum complexes of novel ligands; [PtClN((CH2)2piperidine) dpa]Cl (C1) and [PtClN((CH2)3piperidine)dpa]Cl (C2) were also synthesized during the study. Structural data obtained from single crystal X ray diffraction for C1 confirms that L1 serves as a tridentate donor ligand. UV visible spectra of both ligands and complexes were recorded in methanol. Absorption peaks in 200-300 nm range in UV visible spectra of ligands are due to intra ligand π→π* transitions and peaks above 300 nm range are due to n→π* transitions in the ligands. As expected, no absorption peaks corresponding to n→π* transitions were observed in UV visible spectra of complexes due to lack of lone pairs in the coordination complexes. Methylene protons observed as a singlet (3.87 ppm) in 1H NMR spectrum of L1. The N-H bond of secondary amine group present in dpa gives an IR band in 3310-3350 cm-1 region. However, IR spectra of both ligands and complexes gave no transmittance peaks in region 3310-3350 cm-1 confirming the absence of the N-H group which also confirms the formation of ligands and complexes. Both ligands displayed intense fluorescence in methanol. However, fluorescence spectra of platinum complexes showed lower intensities than the respective ligands, possibly indicating static quenching of fluorescence upon coordination to metal. These ligands and complexes can be explored towards treatment of breast cancer due to incorporation of piperidinyl group.