http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/72 2026-07-21T13:44:51Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12745 Title: Assessment of antioxidant potential of Poruthumaan leaf extracts Authors: Sripriya, R.D.M.; Sivakathan, S. Abstract: Abstract: Introduction & Objectives Poruthumaan is an underutilized medicinal plant growing in wild areas of Northern Province, Sri Lanka. It is traditionally consumed for relieving menstrual problems and arthritis. Despite its extensive ethnomedicinal use, its antioxidant potential remains underexplored. Methodology This study aimed to evaluate the antioxidant properties of Poruthumaan leaf extracts prepared using methanol (80% v/v), acetone (80% v/v), and water. Dried leaf powder–solvent mixture (1:10, w/v) was homogenized for 10 minutes and then shaken for 1 hour. The extracts were then separated and concentrated using rotary evaporation. The extracts were subjected to evaluation of total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis(3-ethylbenzothiazoline-6- sulfonate) (ABTS) assay, and Ferric Reducing Antioxidant Power (FRAP). All experiments were conducted in triplicate, and the data were statistically analyzed using MINITAB software. Results The acetone extract had the highest TPC (498.6 ± 4.92 mg Gallic acid equivalent/g), followed by methanol (411.06 ± 2.01 mg Gallic acid equivalent/g) and water (176.12 ± 4.18 mg Gallic acid equivalent/g) extracts. A similar trend was observed for TFC, where the acetone extract showed the highest TFC (3.33 ± 0.37 mg Quercetin equivalent/g), followed by methanol (1.98 ± 0.16 mg Quercetin equivalent/g) and water (1.087 ± 0.087 mg Quercetin equivalent/g) extracts. Antioxidant assays demonstrated strong radical-scavenging and reducing capacities, with DPPH (IC50 = 43.90 μg/mL; standard IC50 = 37.53 μg/mL), ABTS (IC50 = 28.88 μg/mL; standard IC50 = 25.44 μg/mL), and FRAP (45.39 μg/mL; standard = 42.15 μg/mL), with no statistically significant differences (p > 0.05) between sample and standard. Conclusion The findings indicate significant antioxidant activity of Poruthumaan leaves, however, further research is needed to establish its potential health benefits. 2026-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12744 Title: Effect of coriander (Coriandrum sativum L.) leaf powder incorporation on cooking characteristics, antioxidant release, and in-vitro starch digestibility of parboiled white rice Authors: Dilakshi, R.; Rudhura Premdharshan, M.; Sivakanthan, S. Abstract: Introduction & Objectives Rice (Oryza sativa L.) is a staple in Asia; its high starch content can raise blood sugar, increasing type 2 diabetes risk. This study investigated the impact of incorporating coriander (Coriandrum sativum L.) leaf powder (CLP) (2.5% (w/w)) during cooking on the antioxidants and starch digestibility of parboiled white rice (BG 360), widely consumed in Sri Lanka. Methodology Rice cooked with CLP (treated) and without CLP (control) were subjected to in vitro digestion (gastric phase: pepsin, pH 1.2, 2 hours and intestinal phase: pancreatic α-amylase, pH 6, 5 hours). Digestive supernatants were analyzed at 30 min intervals for 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging activity (RSA), 2,2-azinobis(3- ethylbenzothiazoline- 6-sulfonate) (ABTS) RSA, ferric reducing antioxidant power (FRAP), total phenolic content (TPC), total flavonoid content (TFC), and amylose content. Results The treated rice showed higher antioxidant activity than control, with a marked increase from the gastric phase. DPPH and FRAP values rose steadily in the treated sample (DPPH from 167.97±0.63 to 200.50±0.38% and FRAP from 690.40±3.36 to 1166.04±2.69 μmol ascorbic acid equivalent/100g, respectively), while the control showed only slight increases. ABTS activity peaked between the gastric and intestinal phases for both; however, the treated rice consistently outperformed the control. TPC and TFC remained slightly increased throughout digestion, with a prominent increase in TFC observed after gastric digestion in the treated sample. Amylose release was significantly lower in the treated rice, indicating slower starch digestion. Conclusion In conclusion, enrichment with CLP yielded functional rice with antioxidant properties and reduced starch digestibility. Further in vivo studies are needed to confirm these findings. 2026-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12742 Title: Isolation and characterization of bacteria from paddy (Oryza sativa) fields Authors: Thavarasa, M.; Shayanthan, A. Abstract: Paddy (Oryza sativa) cultivation is integral to Sri Lanka's agriculture, as rice is the staple food of the country. Wide variety of microorganisms are in the Paddy Jaffna, Sri Lanka rhizosphere which play an important role on paddy growth and soil fertility. Modern paddy cultivation heavily relies on chemical fertilizers, which degrade soil health and productivity. This study was conducted to isolate and characterize plant growth-promoting rhizobacteria from local paddy fields. Soil samples were collected from Vaddakachchi Ramanathan farm and Paranthan rice research station in Kilinochchi district. Through serial dilution and plating in nutrient agar medium, 24 distinct bacterial isolates were obtained. Purified isolates were subjected to functional characterization for nitrogen-fixing ability, phosphate-solubilization ability, and plant growth promotion using a seed germination assay. Results revealed that isolate B1 showed significantly highest nitrogen fixing ability, followed by B8, A5, and A2. The phosphorus solubilization ability is less in all the strains and ranged below 1ppm. The seed germination test revealed that bacterial inoculation positively influenced paddy seed germination and seedling growth. The bacterial isolates B1, B8, B14, A2, and A5 showed higher seed germination percentage and vigour index compared to the control. Therefore, isolates B1, B8, A2 and A5 have the potential to be used as biofertilizers to improve crop productivity. This study indicates the potential of indigenous soil bacteria in enhancing plant growth-promoting traits. Further studies are needed to explore other plant growth-promoting traits and validate their effect in field conditions. 2026-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/12738 Title: Evaluation of the effect of passion fruit (Passiflora edulis) leaf extract on the oxidative stability of palm oil during heating Authors: Jayasekara, I.R.N.D.; Sivakanthan, S. Abstract: The growing need for natural alternatives to synthetic antioxidants in edible oils has driven extensive research into plant-derived extracts for enhancing oil stability during thermal processing. This study was carried out to evaluate the effect of continuous heating on the quality of palm oil and to assess its oxidative stability during heating by adding passion fruit leaf extract as an antioxidant. Acetone was used as the solvent to extract antioxidant components from fresh leaves with a sample to solvent ratio of 1:10 (w/v). Negative control (oil samples without any added antioxidants), positive control (oil sam-ples added with 200 ppm of Butylated Hydroxytoluene (BHT) and test samples (oil samples added with 1000 ppm of leaf extract) were prepared. All oil samples were evaluated for stability under continuous heating at 170±5 °C. Continuous heating was carried out for up to 24 h (30 min heating followed by 30 min cooling), that is, 24 heating cycles. Sampling was done at 2 h intervals (after every 2 heating cycles). The levels of oxidation of the samples were determined by evaluation of peroxide value, p-anisidine value, TOTOX value, free fatty acid content, total polar compounds, fatty acid composition and conju-gated diene (CD) and conjugated triene (CT) values. All parameters measured were increased in all three samples; however, free fatty acid content, peroxide value, p-anisidine value and CD and CT values were significantly less in the test samples than in the positive control and negative control. The average rate of total polar compound formation, expressed as the percentage increase per heating cycle, was significantly lower in extract-treated (1.29% per cycle) and positive control (1.27% per cycle) samples than in the negative control (1.68% per cycle). These results indicate that the sample supplemented with passion fruit leaf extract exhibited higher thermal stability than both controls, and that fresh leaf extract (1000 ppm) more effectively controls the thermal oxidation of palm oil than BHT during continuous heating. 2026-01-01T00:00:00Z