Browsing by Author "Kalansuriya, P."

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Antimicrobial and Antifungal Activities of Silver Nanoparticles Biosynthesized by Pothos scandens and Kaempferia galanga Aqueous Extracts
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Samadhi, K. G. A.; Kalansuriya, P.; Wijerathna, W. M. D. G. B.; Wasana, K. G. P.
In order to alleviate the clinical challenges associated with antibiotic use, there is an immediate need for innovative solutions. Utilizing nanotechnology-based antimicrobials represents a promising approach to enhance the effectiveness of natural products. Ayurvedic medicine has long relied on the utilization of Pothos scandens(family: Araceae, common name: climbing aroid, Sinhala name: Pota Wal, Tamil name: Annaparuva) and Kaempferia galanga (family: Araceae, common name: aromatic ginger, Sinhala name: Inguru Piyali, Tamil name: Kacholum). Leaves, barks, and gums of Kaempferia galanga are used to address a variety of microbial-related ailments. The objective of this study was to biosynthesize of PS-AgNPs and KG-AgNPs and conduct in vitro screening for antimicrobial properties. Pothos scandens bark pieces (10 g) and Kaempferia galanga rhizome (100 mg) derived aqueous crude extracts (PSA and KGA) was prepared under sonication (44 kHz, 40 ºC, 30 min). PSA and KGA coated AgNPs (PS-AgNPs and KG-AgNPs) were biosynthesized under different conditions i.e., homogenization, magnetic stirring, exposure to UV or sun light with loading different concentrations (2.5, 5, 7.5 mg/mL). Antimicrobial properties of crude extracts, PS-AgNPs and KG-AgNPs and uncoated AgNPs (UAgNPs) were screened in vitro (1 mg/per well) in triplicate, using agar well-diffusion method against standard microbial and fungal strains Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853) and Candida albicans (ATCC 90028). Gentamicin (intravenous solution at 40 mg/mL diluted to 0.4 mg/mL), 10 μg per well was used as the positive control against microbes and fluconazole (intravenous solution at 2 mg/mL diluted to 1 mg/mL), 25 μg per well was used as the positive control against fungal cultures. AgNPs were characterized using size distribution data, polydispersity index (PDI), zeta potential, FTIR, AFM and SEM imaging. SEM and AFM imaging revealed the presence of spherical PSAgNPs and KG-AgNPs with size ranges 50–300 nm. Inhibition zone diameter (IZD) of PSAgNPs against S. aureus was 15±0.816 mm, while it was zero for PSA. IZD for KG-AgNPs against S. aureus was 13±0.816 mm, while it was zero for KGA. PS-AgNPs (11±0 mm) showed antimicrobial activities against P. aeruginosa and against KG-AgNPs (15±0.816 mm) while it was zero for both PSA and KGA. IZD for PS-AgNPs and KG-AgNPs against C. albicans were 14±3.741 mm and 16±1.632 mm while it was zero for both PSA and KGA. PS-AgNPs, PSA, KGAgNPs and KGA did not exert any bioactivity against E. coli and U-AgNPs did not exert any bioactivity against the three microbial strains. The present study revealed that the novel PSAgNPs and KG-AgNPs formulation is a promising antimicrobial agent against P. aeruginosa and S. aureus
Identification of plant based anti-diabetic drug leads: A computer-based drug discovery approach
(Department of Social Statistics, Faculty of Social Sciences, University of Kelaniya Sri Lanka, 2023) Katipearachchi, S. H.; Faizan, M.; Kalansuriya, P.; Attanayake, A. P.
Diabetes mellitus is known to be one of the fastest-rising chronic metabolic diseases with multiple etiologies. The disease is characterized by chronic hyperglycemia resulting from defects in insulin secretion, insulin action or both. Available therapeutic agents, come with their fair share of side effects. Plant-derived medications that have been used for centuries in the treatment of diabetes in ayurveda and folk medicine have gained a lot of attention in recent years. Studies have shown that plants consist of many bioactive compounds with anti-diabetic properties. Computer-aided drug discovery is slowly gaining popularity with molecular docking accelerating drug discovery by providing structure-based interactions between ligand and receptor proteins. This study was designed to use computational methods to identify the best anti-diabetic compounds devised from ten selected plants. A total of ten plants and three target receptor proteins were selected for in silico screening based on the literature. The selected plants were Nigella sativa L., Coccinia grandis (L.) Voigt, Cheilocostus speciosus (J.Koenig) C.D.Specht, Momordica charantia L., Strychnos potatorum L.f, Gymnema sylvestre (Retz.) R.Br., Aloe vera (L.) Burm.f., Scoparia dulcis L., Abutilon indicum (L.) Sweet, and Trigonella foenum-graceum L. A phytochemical compound library with a total of 952 ligands was prepared using IMPPAT database. The main target receptor proteins, include 􀁄-glucosidase, 􀁄-amylase and dipeptidyl peptidase-IV (DPP-IV), based on their key roles in the maintenance of glucose homeostasis. The 3D protein structures were downloaded from the RCSB Protein Data Bank. Miglitol, sitagliptin and acarbose were selected as reference drugs for each target protein to conduct a comparative study. Biovia Discovery Studio was used to visualize the target protein and prepare the protein for virtual screening. UCSF Chimera and PyRx Autodock were used for the energy minimization of the proteins and the virtual screening respectively. Schrodinger Maestro was used for the dynamic simulation studies with the OPLS- 2005 force field and TIP3P Solvent model. The compound library was screened by carrying out flexible docking against each target protein. The search space for virtual screening was defined to include all the critical inhibitor-binding sites based on the literature. All the compounds having binding affinity less than -6 kcal/mol were selected.. Only the compounds with promising binding energy values, depending on each target, were subjected to the target-ligand interaction analysis conducted using Biovia Discovery Studio. The binding affinity and interaction patterns of phytochemical ligands were evaluated against three receptor proteins. The best three molecules for each protein were selected based on the best hydrogen bond interactions since they determine the specific, energetically favorable ligand binding at the target sites. The selected 12 molecules were further analyzed for the best target-ligand binding conformation and subjected to molecular dynamics simulation. Compound 27 and compound 85 in T. foenum-graceum with RMSD less than 3Å and hydrogen bond retention above 75% in 100NS simulation were identified as promising therapeutic drug leads for the treatment of diabetes. In vitro screening for the antidiabetic activities would be conducted using 􀁄-glucosidase, 􀁄-amylase and DPP-IV assays to further assess their effectiveness as anti-diabetic drug leads.
In vitro antidiabetic activity of Spondias pinnata aqueous extract and encapsulated chitosan-TPP nanoparticles
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Wadasinghe, R. R.; Attanayake, A. P.; Kalansuriya, P.
Spondias pinnata (L. f.) Kurz is a medicinal plant used in complementary medicine. Decoctions prepared using stem-bark of S. pinnata find applications in treating diabetes mellitus. However, low bioavailability of bioactive metabolites (polyphenols and flavonoids) and lack of appropriate release of metabolites delimit the antidiabetic activity of S. pinnata aqueous extract (SAE). Encapsulation of SAE with chitosan-tripolyphosphate (CS-TPP) could enhance its therapeutic potential and provide controlled release. The objective of this work to determine in vitro antidiabetic activity of S. pinnata stem-bark extracts and SAE-encapsulated CS-TPP nanoparticles using α-amylase inhibitory, α-glucosidase inhibitory, glucose uptake and glucose adsorption assay. The extracts were prepared by extracting dried and powdered stem-bark of S. pinnata into distilled water, acetone, ethyl acetate, dichloromethane under ultrasonication (40 kHz, 37 °C, 30 min) separately. The total phenol content (TPC) and flavonoid content (TFC) of the extracts were determined using Folin-Ciocalteu and aluminium chloride methods, respectively. Based on the results of α-amylase inhibitory assay, SAE was selected for the encapsulation with CS-TPP. The SAE had TPC of 4.18±0.02 mg gallic acid equivalents per gram of dry weight (GAE/g DW) and TFC of 0.37±0.01 mg quercetin equivalents per gram of dry weight (QE/g DW) and showed the highest α-amylase inhibitory activity (IC50 53.34±7.43 µg/mL). The acetone extract had TPC of 34.43±0.35 mg GAE/g DW and TFC of 4.06±0.05 mg QE/g DW and showed the highest α-glucosidase inhibitory activity (IC50 8.82±1.42 µg/mL). The highest glucose uptake and glucose adsorption were shown by acetone extract and aqueous extract, respectively. SAE-encapsulated nanoparticles were prepared from CS-TPP at varying concentrations (0.250, 0.375, 0.500 and 0.625% w/v) of SAE using ionic gelation method under magnetic stirring; the highest encapsulation efficiency (68.21% ± 0.66%) and loading capacity (0.79% ± 0.17%) were obtained at 0.625% w/v of SAE. Loaded nanoparticles were separated by centrifugation and free polyphenols were determined by Folin-Ciocalteu method. The Z-average particle diameter of SAE-encapsulated CS-TPP nanoformulations was 417±86 nm with polydispersity index of 0.574 and zeta potential of +20.63 mV. The IC50 values corresponding to α-amylase inhibitory activity and α-glucosidase inhibitory activity of SAE-encapsulated CS-TPP nanoparticles were 1.10±0.03 mg/mL and 3.16±0.15 mg/mL, respectively. Although the percentage of glucose uptake and adsorption in SAE encapsulated CS-TPP nanoparticles is lower than the crude extract, it had shown 11.59±1.03 % glucose uptake at 5 mM glucose concentration and 1.47 mmol/g glucose adsorption at 100 mM glucose concentration. The SAE, acetone extract and SAE-encapsulated CS-TPP nanoparticles showed higher antidiabetic activity than the positive control, acarbose. Further investigations on the releasing profiles of SAE-encapsulated CS-TPP nanoparticles would reveal the rates at which the active metabolites are released to the media during the timeframes of the conducted assays.
Optimization of high-fat diet fed streptozotocin induced Wistar rat model for screening antidiabetic agents
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Wickramasinghe, A. S. D.; Attanayake, A. P.; Kalansuriya, P.
High-fat diet (HFD) fed streptozotocin (STZ) induced Wistar rats are frequently used as animal models of type 2 diabetes mellitus for screening novel antidiabetic agents. As the composition of HFD, age and strain of rats, dose of STZ and the intended degree of pathophysiological changes vary among studies, the development of a model that best fits to a particular research setting is pivotal. Furthermore, ensuring the long-term stability and establishment of an adequate biochemical profile of the model are necessities which have been addressed by limited studies to date. This study attempted the development of a model which mimics type 2 diabetes mellitus for screening of novel antidiabetic drugs. Wistar rats were fed with a HFD (60% calories from fat) for four weeks, followed by STZ intraperitoneal injection (30, 40 and 50 mg/kg). Rats with fasting serum glucose >11.1 mmol/L were enrolled for the study. There were five groups (n=10/group); healthy rats, HFD fed rats, HFD+STZ (30 mg/kg) rats, HFD+STZ (40 mg/kg) rats, HFD+STZ (50 mg/kg) rats. The glycemic status of the rats was monitored weekly by the routine conduct of oral glucose tolerance tests. Experimental rats were euthanized after 28 days and blood samples were collected for biochemical investigations. Glycemic status of the model was assessed by determining fasting serum glucose, insulin, glycated hemoglobin (HbA1c) and homeostatic model assessment-insulin resistance (HOMA-IR). Lipid profiles were assessed by determining total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and very low-density lipoprotein cholesterol (VLDL-C) levels. STZ induced rats (30, 40 and 50 mg/kg) showed a significant dose dependent increase in fasting serum glucose (by 67, 61 and 136%) and insulin (by 19, 15 and 13%) concentrations (p<0.05). HOMA-IR was above 2.5 and increased in a dose dependent manner by 98, 108 and 176% in STZ induced rats (30, 40 and 50 mg/kg). However, only the STZ (50 mg/kg) induced group of rats showed fasting serum glucose concentration of 13.71 ± 1.01 (>11.1 mmol/L) and a significant increase in HbA1c by 66% compared to the healthy rats (p<0.05). Further, the STZ 50 mg/kg rats showed stable hyperglycemia throughout the study period. STZ induced rats (30, 40 and 50 mg/kg) also showed a significant dose dependent increase in TC (by 6, 7 and 9%), and TG (by 16, 15 and 23%) respectively (p<0.05). However, only the STZ induced (50 mg/kg) group of rats showed significant increase in serum concentrations of LDL-C (by 12%) and VLDL-C (by 16%) compared to the healthy rats (p<0.05). Only slight changes in HDL-C levels were observed in the STZ induced groups of rats however, the values were not significant (p>0.05). The results revealed that the Wistar rats fed with HFD rich in saturated fat for four weeks followed by a single intraperitoneal dose of STZ (50 mg/kg) would produce stable diabetic model which closely mimic pathophysiological features of type 2 DM characterized by insulin resistance and dyslipidemia.