Browsing by Author "Dahanayaka, L. W."

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Open Access
Correlation between molecular diversity and biochemical traits of edible aerial parts of Basella alba L. from different geographical locations of Sri Lanka
(BioMed Central Ltd, 2025-12-29) Dahanayaka, L. W.; Mapa, M. M. S. T; Kadigamuwa, C.C; Udayanga, D
Background: Basella alba L. a widely consumed green leafy vegetable, exhibits considerable nutritional and therapeutic potential attributed to its bioactive constituents. Prior investigations revealed significant variation in phytochemical and antioxidant activity across agro-climatic zones in Sri Lanka, suggesting potential genetic influence. This study is designed to explore underlying genetic variation using RAPD markers to investigate the correlations and contributions of genotype on previously reported bioactivity variation. Results: From a screening of 15 RAPD primers, four primers (OPA 9, OPA 10, OPA 16, and OPB 10) produced, polymorphic, consistent and clearly scorable banding profiles (under optimized PCR conditions) in B. alba L. collected from 15 Sri Lankan locations. These primers collectively yielded 36 bands, 35 of which were polymorphic, resulting in a high polymorphism rate of 97.2%, confirming the informativeness of the selected primers for genetic diversity analysis. Genetic similarity was assessed using Jaccard’s coefficient in NTSYSpc.v2·10e, revealing values ranging from 0.44 to 0.97, with the highest similarity from the samples from Ratnapura and Kandy and the lowest similarity in Ratnapura and Kalutara. A dendrogram constructed via UPGMA grouped the samples into two major clusters and five sub-clusters, demonstrating substantial genetic differentiation influenced by geographic origin. Cluster I included Ratnapura and Kandy, while the remaining samples formed Cluster II and its subgroups, each representing different ecological zones. When compared to the phytochemical and antioxidant clustering data of the previous study, partial correspondence was observed. A Mantel test comparing genetic diversity and biochemical/antioxidant potential revealed a weak negative correlation which was not significantly different. Some of the locations within similar genetic cluster shared similar biochemical traits, while others diverged significantly, indicating that environmental conditions also influence bioactive compound synthesis. Notably, Cluster I (Ratnapura and Kandy) showed both genetic similarity and lower antioxidant traits. Samples from Ella and Polonnaruwa showed similar bioactive traits even though they were grouped into different genetic clusters. Conclusion: These findings suggest that both genetic makeup and environmental adaptation contribute to observed biochemical diversity in B. alba L. with a clear geographical correlation. This study highlights the value of integrating molecular and biochemical analyses to develop regionally adapted B. alba L. cultivars with enhanced nutritional traits, supporting sustainable agriculture in Sri Lanka and beyond.
Open Access
Impact of geographical variation on nutritional and antioxidant properties of Basella alba L. from Sri Lanka
(BioMed Central Ltd, 2025-01-27) Dahanayaka, L. W.; Mapa, M. M. S.T; Kadigamuwa, C.C; Udayanga, D
Background: Basella alba L. (Malabar spinach) is a widely consumed leafy vegetable, well known for its nutritional and therapeutic properties. These properties arise from the availability of essential nutrients, phytochemicals, and antioxidant potential, which may vary depending on environmental factors induced by the geographical location. In this study our aim is to investigate the correlation between the geographical location and proximate composition, phytochemical content, and antioxidant activity of B. alba harvested from fifteen locations in Sri Lanka. Results: According to the statistical analysis by ANOVA and Tukey test, the results of proximate analysis confirmed that samples from different locations showed statistically significant variance in nutritional content. Furthermore, phytochemical content and antioxidant potential varied showing a significant difference between locations in total chlorophyll (27.53 to 6.69 µg/g dry weight), carotene (4.54 to 1.15 µg/g dry weight), total flavonoid content (10.54 to 3.94 mg/g dry weight in Quercetin equivalents), total phenolic content (8.33 to 0.46 mg/g dry weight in gallic acid equivalents), 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity (38.03–11.4% inhibition), and ferric ion-reducing antioxidant power (1.23 to 3.76 mg/g dry weight in ascorbic acid equivalents) (p < 0.05). The Pearson correlation showed a strong positive correlation between total phenolic content and antioxidant activity. Principal component analysis indicates the role of antioxidant activity and chlorophyll content in location differentiation, forming distinct clusters. Cluster analysis categorized samples into four groups, linking biochemical traits to agro-climatic zones. The principal component analysis and cluster analysis showed a close relationship between some locations due to their high antioxidant and phytochemical accumulation. Conclusion: This study exhibits the importance of geographical location on the phytochemical profile and antioxidant properties of B. alba. These findings can be used to refine optimal cultivation sites for B. alba to enhance the efficacy of its nutraceutical and pharmaceutical potential.
Open Access
Impact of geographical variation on proximate composition of Sesbania grandiflora L. in Sri Lanka
(Department of Applied Sciences. Faculty of Humanities and Sciences,SLIIT, 2025-10-10) Dahanayaka, L. W.; Mapa, M. S. T.; Kadigamuwa,C. C.; Udayanga, D.
Sesbania grandiflora L. is a widely consumed green leafy vegetable in Sri Lanka, valued for its nutritional and therapeutic benefits. The nutrient composition can vary depending on many factors, including the geographical location. This study investigated the variation in proximate composition of S. grandiflora L. leaves collected from 16 locations across diverse agro-climatic zones in Sri Lanka, focusing on moisture,ash, protein, fat, carbohydrate, and fibre content. Samples were collected, cultivated under organic farming practices, and analysed using standard AOAC methods, methods of analysis established by the AOAC International (formerly the Association of Official Analytical Chemists). One-way ANOVA followed by Tukey post hoc test revealed significant differences (p < 0.05) in nutrient composition among the locations. Moisture content ranged from 64.13% to 82.79%, with both extremes recorded within the low-country wet zone, indicating substantial micro-environmental influence. Ash content varied from 1.89% to 5.68%, reflecting differences in mineral availability across soils. The highest protein content was recorded in the low-country dry zone (16.38%). Carbohydrate and fibre content were notably high in the low-country wet zone, with values reaching 18.33% and 11.79%, respectively. The findings highlight the influence of geographical location on the nutritional quality of S. grandiflora L. This study provides valuable insights for optimising the cultivation of S. grandiflora, contributing to improved dietary planning and region-specific agricultural practices in Sri Lanka.