Browsing by Author "Samaraweera, G. A."

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Antimicrobial activity of poly-herbal formula “Dasapanguwa” against several Gram positive bacteria and Gram negative bacteria
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Samaraweera, G. A.; Gunathilaka, V. H. N. M.; Perera, M. A. S. N.; Perera, P. D. V. M.; Wageesha, N. D. A.; Kadigamuwa, C. C.
The resistance of bacteria against available antibiotics has become a rising problem worldwide. Therefore, the discovery of alternatives using medicinal plants is widely studied. Although medicinal plants have been studied individually, the impact of herbal formulas was studied rarely. “Dasapanguwa” is a poly-herbal formula prepared as a decoction of 10 different plant parts to use in Ayurvedic medicine in Sri Lanka for colds, fever, and infectious diseases. Although the formula is used as a treatment for infectious diseases in Ayurvedic medicine in Sri Lanka, the antimicrobial action of this preparation was not scientifically assessed. The objective of the research was the determination of the antibacterial activity of the Dasapanguwa formula against Gram positive and Gram negative bacteria. Plant parts of Mollugo cerviana (L.) Ser., Solanum virginianum L., Solanum melongena L., Justicia adhatoda L., Rotheca serrata (L.) Steane & Mabb., Glycyrrhiza glabra L., Zingiber Officinale, Coscinium fenestratum (Gaertn.) Colebr., Piper nigrum L., and Coriandrum sativum L. were collected in dried form. Water extracts of decoction 1 (D1) (plant part: 5.0 g) and Decoction 2 (D2) (plants parts: 5.0 g ground into fine powder) were prepared by refluxing in 500.0 ml of water for two hours at 100 °C followed by freeze-drying. The antibacterial susceptibility test was performed by the Kirby-Bauer disc diffusion method against Gram positive bacteria (Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis), and Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae). Antibiotic discs were prepared for each concentration of two decoctions (1.0 to 15.0 mg ml-1). Commercially available tetracycline (30 μg) and ceftriaxone (30 μg) were used as positive controls against Gram’s positive and Gram’s negative bacteria respectively according to the CLSI guideline. The diameter of the clear zones was measured. There were no inhibition zones against all the bacteria for tested concentrations of both decoctions compared to positive controls. Previous studies showed that the antibacterial activity of an herbal extract could depend on the plant, solvent, test pathogens, and concentrations. Furthermore, the activity could depend on the plant itself or the formula of poly-herbal. Therefore, it is recommended to further study the antibacterial activity of both decoctions for higher concentrations from 15 mg ml-1 against selected bacteria. Furthermore, the antibacterial activity could be studied for extracts prepared by different solvents including methanol and ethanol.
Assessment of contaminant levels of hazardous toxic metals and subsequent risk analysis in agricultural soil and selected comestibles within a region afflicted by CKDu in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Perera, M. A. S. N.; Kadigamuwa, C. C.; Gunathilaka, V. H. N. M.; Samaraweera, G. A.; Perera, W. P. R. T.; Perera, P. L. R. A.; Liyanage, J. A.; Premaratne, W. A. P. J.
Agricultural commodities constitute a pivotal component of the human daily sustenance, yet they are susceptible to contamination by pernicious heavy metals, notably Hg, Cd, Pb, and As. Consequently, agricultural products represent a substantive source of apprehension for human well-being and health. This study aims to evaluate related risk indices of agricultural soils (n=25) and selected comestible grains, namely Oryza sativa (n=25), Vigna radiata (n=25), Vigna unguiculata (n=25), and Vigna unguiculata subsp. (n=25), within the endemic region of Nikawewa Grama Niladhari Division (GND) in North Western Province (NWP) and the reference region, Wewagedara GND in NWP where no evidence for Chronic Kidney Disease of unknown etiology (CKDu). The concentrations of metals in the collected samples were determined by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and based on that risk indices were calculated. The mean geo-accumulation index (Igeo) for four metals in soil was As - 0.82, Cd - 1.47, Cu - 0.91, and Pb 1.31. That indicates no anthropogenic activities related to As, Cd and Cu while Pb is responsible for moderate pollution in endemic area. Estimated Daily Intake (EDI) values for these heavy metals were calculated with respect to the all grains. EDI means of As and Pb in the endemic and the reference areas for all grain samples were within the Tolerable Daily Intake (TDI) set by United States Environmental Protection Agency (USEPA) (As-0.300 􀁐g/kg/day) and World Health Organization (WHO) (Pb-3.600 􀁐g/kg/day) while Cd (EDI in endemic area; Oryza sativa-6.385 􀁐g/kg/day, Vigna unguiculata-3.386 􀁐g/kg/day and Vigna unguiculata subsp.-3.866 􀁐g/kg/day) highly exceeded the tolerable weekly intake (TWI) of European Food Safety Authority (EFSA) (Cd-2.5 􀁐g/kg/week) in both areas. EDI of Cr in rice samples (1.138 􀁐g/kg/day) in endemic area exceeded the TDI set by EFSA (1.0 􀁐g/kg/day) and all other values of Cr were below the TDI in both areas. According to the USEPA (intolerable cancer risk (CR) - > 1 x 10-4) cancer risk exist for all these staple grains. Igeo of Pb in the soil, raising concerns about their bioavailability and uptake by the food crops and EDI were indicated the long-term consumption of these foods especially Oryza sativa poses a serious threat to human health. Implementing proper soil management practices, monitoring heavy metal levels in crops, and raising public awareness about safe consumption practices are crucial steps towards mitigating the risk of CKDu.