Browsing by Author "Karunarathne, E. D. C."

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Antibacterial activity of Flueggea leucopyrus Willd
(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Karunarathne, E. D. C.; Lokuwalpola, D. V.; Sandaruwan, K. P. A. M.; Dabarera, M. D.; Wanigasekara, D. N.
Fluggea leucopyrus Willd. (Euphorbiacea) known as ‘Katupila’ in local dialect is a plant widely used in indigenous medicinal system in Sri Lanka as a remedy for cancers and infectious diseases. Sufficient scientific investigations however are unavailable to rationalize the ethnobotanical and ethnopharmacological significance of the plant. Present study was conducted to investigate the antimicrobial potential of F. leucopyrus whole plant extract. The antimicrobial activity of the methanolic extract of F. leucopyrus was determined by agar well diffusion method. The extract was tested against five standard bacterial strains and eight clinically isolated bacterial cultures; Staphylococcus aureus (ATCC 25923), Staphylococcus aureus (ATCC 6538), Escherichiacoli (ATCC 8739), Pseudomonas aeruginosa (ATCC 9027), Pseudomonas aeruginosa (ATCC 27853), Streptococcus pyogenes, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, Salmonella typhi, Bacillus subtilis, Methicillin Resistant Staphylococcus aureus (MRSA) and Staphylococcus saprophyticus. The test was triplicated for each microorganism. Ciprofloxacin was used as the positive control while 20% Dimethyl sulfoxide (DMSO) which was used to dissolve the plant extract was used as the negative control. No inhibition of growth was observed in the negative controls and the positive control was able to inhibit the growth of all test bacterial strains used. The growth of S. pyogenes, K. pneumoniae, S. typhi, B. subtilis, E.coli (ATCC 8739) was not affected by F. leucopyrus extract, meanwhile S. aureus (ATCC 25923), S. aureus (ATCC 6538), P. mirabilis, E. faecalis, MRSA, P. aeruginosa (ATCC 9027), P. aeruginosa (ATCC 27853) and S. saprophyticus seemed to be susceptible to the extract showing inhibition zone diameters of 12.67±0.58 mm, 12.67±0.58 mm, 15.33±0.58 mm, 9.67±0.58 mm, 13.67±0.58 mm, 12.67±0.58 mm, 11.33±0.58 mm and 13.67±0.58 mm respectively. These preliminary observations suggest that F. leucopyrus plant is a potent source of antimicrobial substances. Further studies are required to determine the phytochemicals responsible for the antimicrobial action.
Antimicrobial activity of dried fruit rind extract of Garcinia zeylanica
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Sudesh, A. D. H.; Wanigasekara, D. N.; Karunarathne, E. D. C.
Emergence of antibiotic resistance among pathogenic microorganisms has become a severe threat in the medical field. Therefore, search for potential antimicrobial agents, such as substances from medicinal plants with alternative modes of action, is of major interest. Garcinia zeylanica, which is an endemic plant to Sri Lanka, is mainly used as a culinary herb. Antimicrobial activity of G. zeylanica dried fruit rind extract was evaluated against five bacterial strains and a yeast using Agar well-diffusion method. The study was aimed to investigate any potential antimicrobial effect of the fruit rind extract comparatively with conventional antibiotics. Commercially available dried rinds of G. zeylanica were collected and methanolic extract was prepared using Soxhlet method followed by solvent evaporation. Turbidity adjusted (McFarland 0.5), log phase cultures of Methicillin Resistant Staphylococcus aureus (MRSA), Methicillin Sensitive Staphylococcus aureus (MSSA), Escherichia coli (ATCC 25922), Staphylococcus pyogenes (ATCC 19615) and Pseudomonas aeruginosa (ATCC 27853) were evenly inoculated as a uniform lawn on Mueller Hinton Agar plates, while Candida albicans was swabbed to obtain an even lawn on Sabouraud Dextrose Agar . Three wells of 8 mm diameter per each plate were made for positive control, negative control and for the test extract. Amoxicillin was used as the positive control for MRSA, MSSA, E.coli and S. pyogenes and Ciprofloxacin was used so for P. aeruginosa. Fluconazole was the positive control for C. albicans. Sterile distilled water was used as the negative control. The test was triplicated for each strain. After 24 hour incubation at 37ºC, all the bacterial strains and the yeast were found to be susceptible to the dried rind extract of G. zeylanica. The mean inhibition zone diameters of the test extract for MRSA, MSSA, E.coli, S. pyogenes, P. aeruginosa and C. albicans were 29.33 mm, 28.67 mm, 20.67 mm, 31.00 mm, 24.00 mm and 25.67 mm respectively when the average inhibition zone diameters of the standard antibiotics were 11.67 mm, 39.33 mm, 29.67 mm, 37.67 mm, 38.67 mm and 27.67 mm accordingly. This study concludes that G. zeylanica dried fruit rind extract exerts a significant antimicrobial activity against the bacterial strains and the yeast strain tested
General hygienic condition of packaged lettuce samples purchased from selected supermarkets in Gampaha district, Sri Lanka
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Lokuwalpola, D. V.; Wanigasekara, D. N.; Sudesh, A. D. H.; Karunarathne, E. D. C.
Lettuce (Lactuca sativa) is usually consumed in raw form or processed minimally. Therefore, consumption of contaminated raw lettuce is associated with food outbreaks due to poor hygienic condition. Lettuce leaves can be contaminated with pathogenic microorganisms during harvesting, packaging and transportation processes. This study focuses on the general hygienic condition of the packaged lettuce available in supermarkets. Ten packaged samples were purchased from ten supermarkets of Gampaha district, Sri Lanka and they were labeled as L1, L2, L3, L4 and so on. 10 g of each lettuce sample was weighed and transferred to stomacher bags containing 90 mL of sterilized peptone water aseptically. After homogenization, a dilution series was prepared for each sample up to 10-6. One-milliliter aliquot of dilutions from 10-2 to 10-6 of each sample was plated using pour plate method. The used agar medium was Plate Count Agar. The inoculated agar plates were incubated at 30°C for 24 hours. Duplicates were used for all the plated dilutions of each sample. Average Colony Forming Units per gram (CFUg-1) was calculated. The calculated CFU/g values of L1 to L10 were 2.1×106, 1.8×106, 2.8×106, 2.3×105, 2.0×106, 1.2×105, 2.5×105, 1.9×104, 1.3×105 and 2.2×106 respectively. The highest obtained CFU per gram of lettuce was for L3. The lowest value was given by sample L8. Very high microbial load in packaged lettuce samples may indicate the poor hygienic condition
Study of the growth of Malassezia furfur on mycological culture media supplemented with different lipid sources
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Wanigasekara, D. N.; Sudesh, A. D. H.; Karunarathne, E. D. C.; Senevirathne, R. D. K.
Malassezia furfur, causative agent of certain skin conditions, such as pytiriasis versicolor, dandruff and seborrheic dermatitis is a lipophilic yeast. Though it is a clinically important etiological agent, insufficient interest of the in vitro researches can be noticed due to lack of convenient culture media to isolate and subculture the organism. The aim of this study was to evaluate the growth of M. furfur on conventional, mycological culture media supplemented with eight different lipid sources. Two basal media, Sabouraud Dextrose Agar (SDA) and Potato Dextrose Agar (PDA) were separately supplemented with butter, ghee, margarine, milk powder, virgin coconut oil, castor oil, olive oil and sesame oil to the amount of 1% w/v. Chloramphenicol was added to all the prepared culture media to avoid bacterial contamination. M. furfur was inoculated on the supplemented media and on the two basal media using sterile microbiological cotton swabs. Inoculated agar plates were incubated at 32°C for 7 days. Triplicated sets of plates were used for inoculation. After the incubation, several parameters such as presence of growth, extent of growth, colony morphology and microscopic view of the yeast cells were recorded. The growth was confirmed as M. furfur by the typical “spaghetti- meatballs” shape of the microscopic view after staining with crystal violet. No growth was observed in both PDA and SDA basal media. Luxuriant growth of the yeast was observed on SDA and PDA supplemented with ghee or butter. Relatively good growth was recorded in the SDA plate supplemented with margarine while a poor growth was on PDA supplemented with margarine. The growth on olive oil added SDA was poor while no growth was observed on olive oil added PDA. Growth on milk powder added PDA was higher than that of SDA. Virgin coconut oil added Agar plates exhibited no growth and all the PDA and SDA plates supplemented with castor oil, sesame oil failed to give any growth. Therefore, the study concludes that supplementation both SDA and PDA with ghee or butter is a reliable approach for clinical isolation and sub culturing of M. furfur