Chemistry
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Item Potential of Inhibiting the Receptor Binding Mechanism of SARS-COV-2 using Phytochemicals contained in Paspanguwa Water Extract: Molecular Docking and Dynamic Studies(Asian Journal of Chemistry, 2024-11-30) JAYAWARDENA, P.A.S.N.P.; SOORIYAWANSHA, A.M.S.C.; KUMARATHUNGA, P.G.J.D.; DANANJAYA, P.D.H.; KADIGAMUWA, C.C.; DAHANAYAKE, J.N.This study is focused on the SARS-CoV-2 virus by in silico screening of phytochemicals contained in ‘Paspanguwa’ water extract, targeting ACE2 receptors using molecular docking. Phytochemicals of the five herbal ingredients contained in ‘Paspanguwa’ were extracted into water and were identified based on the literature reviews. Ligands geometries were optimized using Avogadro software and transformed to PDBQT format files by detecting torsion root using AutoDock Tools 1.5.6. SWISS-MODEL server was used to model the structure of the ACE2 receptor based on the UniProt ID Q9BYF1. The stereochemical quality of the protein model was assessed using SAVES v 6.0 and ProSA servers. Finally, potential ligands were docked to the ACE2 receptor protein by considering all variants of this virus and their interactions with the ACE2 receptor. The highest binding energy (BE) (-10.42 kcal/mol) was given by carpesterol phytochemical with allosteric site-2 and allosteric site-3 in the ACE2 receptor and this complex was subjected to molecular dynamic (MD) analysis using a CHARMM36 force field. According to the radius of gyration (Rg), root mean square deviation (RMSD) and root mean square fluctuation (RMSF) results, the studied protein-ligand complex was stable throughout the simulation time.Item Influence of pumpkin seed powder on the characteristic properties of whole wheat cake(Elsevier eBooks, 2024) De, Suprakash; Bharti, D.; Pradhan, B. K.; Behera, H.; Kim, N. M.; Wickramarachchi, S.; Sarkar, P.; Pal, K.Pumpkin seeds are a good source of unsaturated fatty acids, dietary fibers, and minerals. It can be used as a food supplement as the nutritional value of the seeds is relatively high. This study incorporates PSP (pumpkin seed powder) in varying amounts (0%, 5%, 10%, 15%, and 20%) in cake samples. Afterward, their effects on physicochemical, thermal, mechanical, and electrical characteristics were observed. Adding PSP to the cake recipe significantly increased the porosity of the cake by only up to 10% PSP incorporation. The PSP improved the hardness and other textural properties of the cake samples. Also, we can deduce that the water retention capacity of the cake samples increased with the addition of PSP, which increased the moisture content of the cake samples. From the results, we can observe that the browning of the cake increased with the incorporation of PSP in the cake samples. From all the characteristics, we can conclude that the cake sample with 10% PSP had the best texture. This means that PSP can be incorporated into cake samples only up to 10% without compromising the texture and taste.Item Effect of pumpkin seed powder on the properties of cake batter prepared with whole wheat flour(Elsevier eBooks, 2024) De, Suprakash; Bharti, D.; Pradhan, B. K.; Behera, H.; Kim, N. M.; Wickramarachchi, S.; Pal, K.; Sarkar, P.Nutrition plays a crucial role in overall health. Recently, different fruit and vegetable seeds have been incorporated into various food products to increase their nutritional values. Due to its higher nutritional content, the research community has recently explored pumpkin seed powder (PSP) as an ingredient in different bakery products. In the current study the batter composition prepared by whole wheat flour at varying PSP concentrations (5%, 10%, 15%, and 20% w/w) has been studied. The obtained results from the current study suggested that incorporating PSP significantly alters the color, texture, and microstructure of the prepared batter samples. Also, the water retention and air incorporation capacity of the batter samples showed a significant increase after the PSP incorporation. From the 2,2-diphenyl-1-picryl-hydrazyl-hydrate scavenging assay, the antioxidant properties of the prepared batter samples were analyzed. The results suggested an increased antioxidant activity after PSP addition. Though PSP adds to the nutritional value, adding PSP greater than 10% adversely affects the texture of the batters. With 10% of PSP replacement the prepared batter showed a balanced textural property in our study.Item Chemometric assessment of bioaccumulation and contamination pathways for toxic metals in diet and environment: implications for chronic kidney disease of unknown etiology (CKDu) in Sri Lankan agricultural regions(Environmental Monitoring and Assessment, 2024) Perera, R.A.; Perera, R.T.; Liyanage, U.P.; Premaratne, J.; Liyanage, J. A.Prolonged consumption of foods containing toxic metals can elevate the risk of noncommunicable diseases, including chronic kidney disease of uncertain etiology (CKDu). Despite the increasing number of CKDu cases in Maradankulama and Mahakanadrawa Grama Niladhari Divisions (GN) in Sri Lanka, no prior studies have examined the accumulation of heavy metal(loid)s and their potential association with CKDu prevalence. Furthermore, there is an absence of comprehensive analyses using chemometric techniques such as PCA and hierarchical studies regarding CKDu and heavy metal contamination in Sri Lanka. This study aims to provide initial insights into the accumulation and potential pathways of toxic metals in staple foods within local diets and their subsequent presence in the agricultural environment of examined GNs. Cr, Cd, As, and Ni concentrations in analyzed foods were within permissible limits (MPLs), whereas Pb levels exceeded MPLs in rice (Oryza sativa), gotukola (Centella asiatica), lime (Citrus crenatifolia), and inland fish (Etroplus suratensis). High target hazard quotient (THQt) values in polished rice suggest possible health risks with prolonged intake. Hierarchical analysis suggested a common source of Pb accumulation. PCA and hierarchical clustering revealed the intricate connection between As and Cd, with their concurrent clustering in samples suggesting a potential common origin. This indicates that while individual concentrations comply with acceptable standards, the potential synergistic effects of Cd and As accumulation might pose elevated health risks. Further, the gut tissues of inland fish exhibited pronounced metal concentrations and significant (p < 0.05) positive correlations with toxic metals in the tank sediments suggesting a diet-based bioaccumulation pathway through sediments.Item Pervasive Microplastic Ingestion by Commercial Fish Species from a Natural Lagoon Environment(Water, 2024) Athukorala, A.; Amarathunga, A. A. D.; De Silva, D. S. M.; Bakir, A.; McGoran, A. R.; Sivyer, D. B.; Dias, B. C. G.; Kanishka, W. S.; Reeve, C.Microplastics have emerged as a significant global environmental concern in the recent decade. The aim of this study was to elucidate microplastic contamination of commercial fish species in a natural lagoon environment. Microplastic contamination was examined in the gastrointestinal tracts and gills of 157 commercial fish from 18 species with varying feeding habits in a vital and sensitive lagoon ecosystem, which connects to the Indian ocean. Microplastics were extracted using digestion, followed by stereomicroscopic inspection using Nile Red stain, and identified via μ-FTIR analysis. Over half of studied fishes ingested microplastics (54.14%). Filaments (50%) and blue items (43%) were the most commonly ingested. Of all the fish species, Eubleekeria splendens had the highest average concentration of microplastics in GIT (1.41 ± 2.52 items/g w.w. tissues), although no statistically significant difference in amount of ingested microplastics (items/g w.w. tissues) was observed among species. The highest concentrations of inhaled microplastics were recorded in Sillago vincenti (1.38 ± 1.30 items/g w.w. tissues). The majority of the extracted microplastics (33%) belonged in the size class 500–1500 μm with rayon, polyethylene terephthalate, and polypropylene as the primary polymers. This study found no correlation between microplastic ingestion and fish species and feeding habits, but a positive correlation with fish size was observed. These findings reveal widespread microplastic contamination in edible fish, posing potential risks to commercially important species due to increasing pollution in lagoon ecosystems.Item Identification of Major Interfering Substances for Heavy Metal Determination in Northern Sea Areas of Sri Lanka(2024) Anoja, N.; De Silva, R. C. L.; Prabagar, J.This study investigated the physicochemical characteristics of seawater from five locations along the northern Sri Lankan coast, encompassing areas with varying degrees of anthropogenic activity. The analysis revealed significant variations in several parameters, potentially influenced by human influences. The results reveal significant variations in several parameters. For instance, turbidity levels varied from 1.88 NTU in Thalaiyadi to 13.3 NTU in Pannai, with Pannai, Myliddy, and Kakkaithivu exceeding the recommended limit of 5 NTU. Total suspended solids (TSS) ranged from 3 mg/L in Thalaiyadi to 83 mg/L in Pannai, surpassing the recommended limit of 30 mg/L. Electrical conductivity (EC) ranged from 45,700 µS/cm in Nainathivu to 49,500 µS/cm in Pannai, exceeding the typical seawater range. Nitrate levels ranged from 10.4 mg/L in Thalaiyadi to 19.1 mg/L in Myliddy. Major cations such as calcium (361 mg/L to 417 mg/L), magnesium (1,222 mg/L to 1,327 mg/L), and sodium (10,140 mg/L to 10,530 mg/L) also showed significant differences across locations. These findings highlight the need for continuous monitoring and effective management strategies to mitigate the negative impacts of anthropogenic activities on these coastal ecosystems. Furthermore, the complex seawater matrix presents challenges for heavy metal determination using Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) due to spectral interferences from major cations, non-specific matrix effects, and interferences from organic matter, turbidity, and suspended solids. Careful consideration of these factors through background correction techniques, matrix modifiers, sample pre-treatment, and optimization of analysis parameters is crucial for accurate heavy metal determination in these environments. This study contributes to a better understanding of the environmental conditions and emphasizes the need for further research on heavy metal contamination and the development of robust analytical methods tailored to address the challenges posed by the complex seawater matrix in northern Sri Lanka.Item Monitoring of Rainwater Quality in Kandy and Peradeniya, Sri Lanka(2023) Wijewantha, H.L.S.S.; Dharaka, B.D.P.; Priyantha, N.; Deeyamulla, M.P.The composition of atmospheric deposition is a measure of air quality, an important aspect of the health of the ecosystem. Consequently, continuous monitoring of atmospheric deposition is crucial to obtain remedial measures to avoid undesirable aspects that would affect living things. In this context, the objective of this study was to determine the rainwater quality at selected locations in Kandy and Peradeniya area of Sri Lanka, namely, Kandy city, Polgolla and University of Peradeniya (UOP), and to identify possible correlations between quality parameters through statistical means. Forty (40) rainwater samples from the UOP site and seven (07) samples each from the Kandy city and Polgolla sites were collected from the 18th May 2020 to 28th April 2021. The volume weighted average (VWA) pH values of UOP, Kandy and Polgolla sites were determined to be 7.44, 7.19 and 7.19, respectively, and moreover, acid rain (pH < 5.6) occurrences were not detected during the sampling period. The VWA values of rainfall, conductivity, salinity, TDS and hardness at the UOP site were 40.12 mm, 51.93 µS cm− 1, 0.0300 ppt, 26.59 mg L− 1 and 13.55 mg L− 1, respectively. The corresponding values of the Kandy city site were 16.52 mm, 64.04 µS cm− 1, 0.0361 ppt, 30.80 mg L− 1 and 19.49 mg L− 1, respectively; and those of the Polgolla site were 33.10 mm, 53.90 µS cm− 1, 0.0310 ppt, 25.76 mg L− 1 and 19.31 mg L− 1, respectively. The VWA values of conductivity, salinity, TDS were the highest at the Kandy city site. Further, the VWA values of hardness at Kandy and Polgolla were approximately equal, probably due to spring of Ca2+ and Mg2+ particulates from the dolomite quarry located in Digana area. The most prominent anion was identified as Cl− in bulk deposition at all three sites, while NO3− showed the lowest concentration of all sites. Moreover, very strong significant positive correlations were identified between conductivity-TDS, conductivity-salinity, conductivity-hardness, TDS-hardness, TDS-salinity, salinity-hardness, SO42− - Cl−, and NO3− - Cl− according to relevant Pearson correlation coefficients. It is thus concluded that the pollutants come from the same sources, either natural or anthropogenic.Item Chemical composition of rainwater at three sites in Kandy/Peradeniya, Sri Lanka, and its effect on air pollution(2023) Madhushani, L.S.; Dharmapriya, T.N.; Dharaka, B.D.P.; Deeyamulla, M.P.; Priyantha, N.The composition of atmospheric precipitation, an important criterion considered to account for air pollution, is usually determined with respect to wet precipitation and dry precipitation, or as bulk deposition in combined form. Although rainwater quality should be continuously monitored in order to understand the extent of air pollution, such investigation lacks attention in Sri Lanka. This study was thus aimed to determine the composition of bulk deposition collected weekly for a period of eleven months from February to December 2019, in three sampling locations; namely the University of Peradeniya (UOP), Kandy City Central (KCC) and Polgolla. Parameters quantitatively determined, rainfall, pH, conductivity, salinity, total dissolved solids (TDS), hardness, anions: Cl−, NO3−, SO42−, F−, PO43− and trace metals: Zn, Fe, Al, Mn, Cu, Pb, Cr, using standard analytical methods indicated that the KCC site showed the overall highest degree of air pollution followed by UOP and Polgolla sites. Nevertheless, no acid rain occurrences were observed during the sampling period in any of the three sites according to pH measurements. Anions of bulk deposition showed the sequence Cl−> SO42− > NO3−in all three sites with Cl−and SO42- being dominant anions. Furthermore, trace metals of bulk deposition showed the sequence, Zn > Fe > Al > Mn > Cu > Pb, in all three sites. Bulk precipitation data analyzed using Pearson correlation showed high positive significant correlations between conductivity and salinity, conductivity and TDS, and salinity and TDS, among all water quality parameters. Among trace metals, the highest positive significant correlation was found to be between Fe and Mn at the UOP Site. The highest positive significant correlation was between Al and Zn at the KCC site. No correlation between trace metals was found at the Polgolla Site.Item Antimicrobial Properties of Seaweeds(Bentham Science, 2024) Weerasinghe, Lakshanee; Kadigamuwa, Chamila Chathuranga; Mapa, Mapa Mudiyanselage Sumudu TharanganiAntimicrobial activity is defined as the ability to destroy or inhibit the growth of microorganisms. Antimicrobial compounds are naturally occurring or synthetic organic compounds having antimicrobial activity. Recently, scientists have discovered many pharmaceutically active compounds that have antibacterial, antifungal, antiviral and antiprotozoal activities in seaweeds. To thrive in various environmental stresses, seaweed produces different metabolites such as polyphenols, polysaccharides, proteins, fatty acids, and pigments. These bioactive compounds are responsible for the antimicrobial activity exerted by seaweed. The antimicrobial activity of seaweed is influenced by various factors, such as the type of seaweed extract used, the target microorganisms, and the environmental conditions. The composition of the bioactive compounds from seaweed may depend on the extraction method and the solvent. It also depends on the seaweed sample, such as fresh or dried sample. Different mechanisms are followed by seaweed extract to acquire antimicrobial activities. Seaweed extracts exhibit various inhibition mechanisms, including disruption of the cell membrane, inhibition of target microorganism enzymes, and prevention of microorganism association with cellular receptors of the host cell. The location, salinity, temperature, etc. of the marine environment may affect the chemical composition of the bioactive compounds present in the seaweeds. The antimicrobial activity of seaweed can be evaluated in both in vitro and in vivo assays. Antimicrobial susceptibility tests and antimicrobial resistance tests are carried out by in vitro methods. The antimicrobial activity of seaweed can be a promising source in many applications, such as therapeutic applications, food industries, aquaculture, and biofouling.Item Exploring the toxic metal contamination and unveiling the risks in staple grains grown in a CKDu hotspot in Sri Lanka(Faculty of Graduate Studies - University of Kelaniya, Sri Lanka, 2023) Perera, M. A. S. N.; Perera, W. P. R. T.; Perera, P. L. R. A.; Kadigamuwa, C.C.; Liyanage, J. A.; Premaratne, W. A. P. J.Toxic metals in dietary grains could pose health risks from direct ingestion. This investigation aims to analyze the concentrations of toxic metals in selected dietary grains and conduct a comparative risk assessment in a region endemic to Chronic Kidney Disease of Unknown etiology(CKDu) in a non-endemic region. Six household fields in the CKDu endemic region in Nikawewa Grama Niladhari Division(GND) and three in the reference region; Wewagedara GND were selected for sampling. Inductively Coupled Plasma-Mass Spectrometry(ICP-MS) was used to determine Arsenic (As), Cadmium (Cd), Lead (Pb), Chromium (Cr), Copper (Cu), and Zinc (Zn) in composite samples collected from both GND areas (pulses; [(Vigna radiata; n=20), (Vigna unguiculata; n=20), (Vigna unguiculata subsp.; n=20)] cereal; [(Oryza sativa; n=30)]. Descriptive statistics revealed average As concentrations in samples as follows; Oryza sativa (38.60±13.84 g/kg,) Vigna unguiculata (3.25±1.96 g/kg), As was undetectable in samples of Vigna radiate, and Vigna unguiculata subsp. in CKDu endemic area. The average As concentrations of Oryza sativa in the reference area was 5.56±1.87g/kg and As was not detected in other grain species. All values complied with FAO/WHO & Codex permissible limits (As-100-200 g/kg). The estimated Daily Intake (EDI) value of As (0.257 g/kg/day) in Oryza sativa in the endemic area did not exceed the Tolerable Daily Intake (TDI) (As-0.3 g/kg/day). The average concentrations of Cd and Pb were reported in the CKDu endemic area; Oryza sativa (Cd-1276.92±234.42 g/kg, Pb-419.31±98.78 g/kg), Vigna radiata(Cd-571.31±60.71 g/kg, Pb-344.15±93.75 g/kg), Vigna unguiculata (Cd-1354.33±265.34 g/kg, Pb-408.56±22.20 g/kg), and Vigna unguiculata subsp.(Cd-1546.23±355.23 g/kg, Pb-408.63±115.14 g/kg) and exceeded FAO/WHO permissible limit(Cd-400 g/kg, Pb-300 g/kg). But those values were within the limits in the reference areas. However, Cu, Cr, and Zn remained within FAO/WHO safe limits in both regions. A health risk can be generated owing to long-term consumption of staple grains grown in Nikawewa GND; CKDu endemic area.