PGIS Research Congress

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Antioxidant, antidiabetic, cytotoxic and phytotoxic properties of two medicinal plants, Buchanania axillaris and Curcuma longa
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Premasiri, H. A. K. D.; Siriwardhane, U.; Piyasena, N. P.; Adikaram, N. K. B.; Marikkar, N.; Jayasinghe, U. L. B.
Medicinal plants are a rich source of bioactive compounds with potential applications in pharmaceuticals, nutraceuticals, and agrochemicals. This study aimed to assess the bioactivities of extracts from Buchanania axillaris leaves and rhizomes of Curcuma longa. They were collected domestically within the Kandy District, Sri Lanka. Plant material was air-dried and ground to obtain a homogenous powder using a grinder. The powdered samples were extracted into methanol by sonicating for 30 min. This procedure was repeated twice, and the filtrates were combined and evaporated to dryness using a rotary evaporator. The crude extracts were evaluated for antioxidant activity using triplicates for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, enzyme inhibitory activity against α-amylase, α-glucosidase, and lipase, and 10 nauplii for cytotoxicity through the brine shrimp lethality assay, and 10 seeds for phytotoxicity by the lettuce seed germination assay. The results demonstrated that B. axillaris exhibited potent antioxidant activity, with an IC₅₀ value of 0.03 ± 0.07 mg/L for DPPH radical scavenging activity, than C. longa (61.49 ± 0.57 mg/L). Positive control was ascorbic acid (IC₅₀ = 3.47 ± 0.45 mg/L). Both extracts displayed α-glucosidase inhibitory activity, with 100% inhibition at 1000 mg/L, indicating their potential in managing diabetes. Curcuma longa showed moderate α-amylase inhibitory activity, with an IC₅₀ of 465.81 ± 23.31 mg/L (Positive Control-Acarbose IC₅₀ = 8.87 ± 1.21 mg/L). Neither extract exhibited significant lipase inhibitory effects within the tested concentration range. The cytotoxicity assay revealed potent brine shrimp lethality for C. longa, with a LC₅₀ of 20.01 ± 3.14 mg/L, against the positive control, atropine, LC₅₀ = 88.60 ± 8.11 mg/L. Buchanania axillaris exhibited phytotoxic potency with IC₅₀ values of 520.97 ± 15.14 mg/L and 665.14 ± 20.54 mg/L, while C. longa exhibited IC₅₀ values of 625.29 ± 12.76 mg/L and 586.53 ± 9.32 mg/L, compared to the positive control, abscisic acid (IC₅₀ = 1.46 ± 0.19 mg/L and 1.85 ± 0.31 mg/L) for root and shoot inhibition, respectively, suggesting potential applications as natural herbicides. The findings indicate promising bioactivities of B. axillaris and C. longa extracts, suggesting further exploration for potential applications in pharmaceuticals, nutraceuticals, and agriculture.
Bioactivities of methanolic leaf extracts of Adenanthera pavonina, Cynometra cauliflora and Dregea volubilis
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Bowaddeniya, U. G. W. S.; Kalinga, J.; Piyasena, N.; Marikkar, J. M. N.; Adikaram, N. K. B.; Jayasinghe, L.
This study determines the bioactivities of the leaves of three abundantly distributed plants in Sri Lanka. Healthy leaves of Cynometra cauliflora (Fabaceae: “Naminan”), Adenanthera pavonina (Fabaceae: “Madatiya”) and Dregea volubilis (Apocynaceae: “Anguna”) were collected from Kandy District. The collected leaves were shade-dried, ground and extracted into methanol by sonication. Antioxidant ability by 2-2–Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and Ferric Reducing Antioxidant Power (FRAP) assays, α-Amylase inhibitory activity, cytotoxicity against brine shrimps and phytotoxicity against lettuce seed germination were assessed for a concentration series ranging from 2000 mg/L to 31.25 mg/L. All assays were triplicated. Results of the DPPH radical scavenging assay revealed C. cauliflora has relatively strong activity (IC₅₀ 7.19 ± 0.15 mg/L) compared to the positive control: ascorbic acid (IC₅₀ 1.97 ± 0.02 mg/L), whereas A. pavonina (IC₅₀ 248.64 ± 0.02 mg/L) and D. volubilis (IC₅₀ 361.40 ± 0.09 mg/L) extracts showed moderate activities. Compared to the FRAP of positive control, Trolox (12.07 ± 0.03 μmol of FeSO₄/mg of the sample), the highest FRAP was observed in C. cauliflora (4.28 ± 0.02 μmol of FeSO₄/mg) followed by A. pavonina (0.05 ± 0.03 μmol of FeSO₄/mg) and D. volubilis (0.04 ± 0.03 μmol of FeSO₄/mg). Cynometra cauliflora (IC₅₀134.29 ± 5.24 mg/L) and A. pavonina leaves (IC₅₀ 365.03 ± 4.57 mg/L) have strong α-amylase inhibition potential compared with the IC₅₀ of positive control: acarbose (45.99 ± 3.97 mg/L) whereas, D. volubilis resulted a weak activity (> 2000 mg/L). In the brine shrimp lethality assay, C. cauliflora, A. pavonina, and D. volubilis showed LC₅₀ of 880.07 ± 0.15 mg/L, 1900.42 ± 0.08 mg/L, and 109.95 ± 0.13 mg/L respectively. K₂Cr₂O₇ (LC₅₀ 35.16 ± 0.03 mg/L) was used as the positive control. In lettuce seed germination assay, compared to the inhibition of abscisic acid (shoot inhibition IC₅₀ 0.99 ± 0.35 mg/L, root inhibition IC₅₀ 1.11 ± 0.50 mg/L), only C. cauliflora resulted a moderate root inhibition (523.22 ± 0.05 mg/L) while other two extracts showed a weak inhibition (> 2000 mg/L). None of the crude extracts resulted an inhibition in the shoot elongation. Results from all assays were significantly different from the positive controls. However, as crude leaf extracts of C. cauliflora and A. pavonina may contain potent anti-diabetic compounds due to the strong potential to inhibit α-amylase enzyme.
Comparative bioactivity assessment of Garcinia mangostana pericarp and Gymnema sylvestre leaves: antioxidant potential, enzyme inhibition and cytotoxicity
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Bandara, Y. G. A. D. K.; Kalinga, J.; Siriwardhane, U.; Piyasena, N.; Marikkar, J. M. N.; Adikaram, N. K. B.; Jayasinghe, L.
Plants are a rich source of bioactive compounds that can help prevent non-communicable diseases by neutralizing free radicals in the body and acting as enzyme inhibitors. This study evaluated the bioactivity of methanolic extracts from Garcinia mangostana pericarp, and Gymnema sylvestre leaves. Crude extracts were investigated for antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and ferric reducing antioxidant power (FRAP) assay. In addition, α-amylase inhibitory assay, brine shrimp lethality assay, and lettuce seed germination assay were performed to assess their potency as pharmaceuticals. The DPPH assay demonstrated higher free radical scavenging activity for G. mangostana with a lower IC₅₀ value of 8.76 ± 0.06 mg/L, and G. sylvestre had a lower activity with an IC₅₀ value of 264.97 ± 3.51 mg/L, compared to ascorbic acid as the positive control (IC₅₀ = 1.90 ± 0.01 mg/L). Garcinia mangostana showed higher antioxidant activity by the FRAP assay with a value of 2290.91 ± 3.67 μmol FeSO₄/g, while G. sylvestre showed a lower antioxidant capacity (393.91 ± 8.15 μmol FeSO₄/g) compared to Trolox as the positive control (12070.12 ± 0.30 μmol FeSO₄/g). Furthermore, G. mangostana showed high amylase inhibitory activity, with an IC₅₀ value of 61.46 ± 2.55 mg/L while G. sylvestre showed comparable activity with an IC₅₀ value of 75.40 ± 2.00 mg/L compared to acarbose as the positive control (IC₅₀ =15.97 ± 0.58 mg/L). A higher brine shrimp lethality was observed for G. mangostana extracts with an LC₅₀ of 38.32 ± 1.53 mg/L, whereas G. sylvestre showed lower lethality with an LC₅₀ of 583.25 ± 23.33 mg/L against K₂Cr₂O₇ as the positive control (34.40 ± 0.30 mg/L). Only G. mangostana showed phytotoxicity by the lettuce seed germination assay with an IC₅₀ of 462.22 ± 4.84 mg/L and 221.41 ± 23.09 mg/L for root and shoot, respectively. These results highlight a higher antioxidant potential and effective enzymatic inhibition of G. mangostana compared to G. sylvestre. However, the higher brine shrimp lethality of G. mangostana necessitates consideration of its dosage and application in pharmaceutical formulations.
Determination of antioxidant and enzyme inhibitory activities of Osbeckia octandra L., Cissus quadrangularis, and Vitex negundo in Sri Lanka
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya ,Sri Lanka, 2024-11-01) Mallawa Arachchi, M. A. K. H.; Mendis, B. E. P.; Siriwardhane, U.; Kalinga, J.; Piyasena, N. P.; Marikkar, J. M. N.; Adikaram, N. K. B.; Jayasinghe, L.
Medicinal plants have gained much attention for their therapeutic properties and diverse pharmacological effects. They are widely used in herbal healthcare practices for treating diseases. This study investigated three selected medicinal plants in Sri Lanka, traditionally used for digestive issues, bone ailments, and inflammatory conditions, to assess their in vitro bioactive potential: antioxidative, anti-hyperglycaemic, anti-obesity, and cytotoxic properties. Dried powdered samples of leaves from three medicinal plants, namely Osbeckia octandra L. (“Heen bovitiya”), Cissus quadrangularis L. (“Heeressa”), and Vitex negundo L. (“Nika”) was extracted with methanol (MeOH) via ultrasonication, followed by rotary evaporation to obtain crude extracts. The extracts were evaluated for total phenolic content (TPC) and total flavonoid content (TFC), which were separately quantified using the Folin Ciocalteu method [pyrogallol equivalent (PE)] and AlCl₃ colorimetric method [quercetin equivalent (QE)] respectively. Among the extracts, O. octandra possessed the highest TPC (291.69 ± 11.41 mg of GAE/g) and TFC (2.48 ± 0.17 mg of CE/g) values. Further, O. octandra exhibited the highest antioxidant activity in both FRAP assay (7268.00 ± 95.6 mmol FeSO4/g), positive control Trolox (13447.00 ± 19.80 mmol FeSO₄/g) and the DPPH radical scavenging assay (IC₅₀ = 11.43 ± 0.79 mg/L; positive control ascorbic acid; IC₅₀ = 3.46 ± 0.45 mg/L). Furthermore, of the three plants, only O. octandra exhibited minor inhibitory activity against α-amylase (IC₅₀ = 1129.8 ± 140.2 mg/L, positive control acarbose, IC₅₀ = 8.51 ± 0.67 mg/L). All three extracts showed significant α-glucosidase inhibitory activity at a concentration of 1000 mg/L, in which the O. octandra extract showed the highest inhibition of 99%. However, none of the extracts showed lipase inhibitory activity or brine shrimp lethality. Based on the findings, Osbeckia octandra L. demonstrated the most promising antioxidant potential among the three medicinal plants studied, which has the potential to be developed as an ingredient in functional foods and as an alternative remedy for managing non-communicable diseases.
In vitro antioxidant, cytotoxic, phytotoxic and α-amylase inhibitory potential of four Sri Lankan medicinal plants
(Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya ,Sri Lanka, 2024-11-01) Wekadapola, W. W. M. T. R.; Kalinga, J.; Siriwardhane, U.; Piyasena, N. P.; Adikaram, N. K. B.; Marikkar, J. M. N.; Jayasinghe, L.
Plants are rich in secondary metabolites that have many physiological effects. This study determined the bioactivities of four widely distributed plants in Sri Lanka. Leaves of Canna indica (Cannaceae/ Buthsarana), Muntingia calabura (Muntingiaceae/ Jam), Piper betle (Piperaceae/ Nagawalli) and Pongamia pinnata (Leguminosae/ Karada) were collected from Kandy, Sri Lanka. They were shade-dried, ground and extracted into methanol by sonication. The antioxidant potential of crude extracts was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays, antidiabetic activity by α-amylase inhibitory assay, cytotoxicity by brine shrimp lethality assay and phytotoxicity by the lettuce seed germination assay. The results revealed that M. calabura has a strong antioxidant potential (IC₅₀ 6.84 ± 0.12 mg/L) compared to the positive control, ascorbic acid (IC₅₀ 1.97 ± 0.06 mg/L). The IC₅₀ values of C. indica, P. betle and P. pinnata were 1085.72 ± 100.5 mg/L, 49.86 ± 3.15 mg/L and 182.92 ± 21.34 mg/L respectively. When compared to the positive control, Trolox (12.07 ± 0.30 μmol/dm³ FeSO₄/g), none of the crude extracts resulted in high FRAP values ranging between 0.2 – 1.8 μmol/dm³ FeSO₄/g. In α-amylase inhibitory assay, leaves of M. calabura resulted in an IC₅₀ of 84.43 ± 2.32 mg/L with no significant difference with positive control, acarbose (IC₅₀ 45.99 ± 3.97 mg/L). The IC₅₀ values of P. betle and P. pinnata were 796.00 ± 43.67 mg/L and 1394.94 ± 101.23 mg/L, while no activity was detected for C. indica. In the brine shrimp lethality assay, M. calabura, P. betle, and P. pinnata showed LC₅₀ of 540.01 ± 6.76 mg/L, 856 ± 14.72 mg/L and 771.04 ± 8.55 mg/L, respectively, while C. indica resulted in 0% lethality. Whereas the positive control, K₂Cr₂O7, resulted in LC₅₀ 35.16 ± 4.22 mg/L. In the phytotoxicity assay, the IC₅₀ for root inhibition of M. calabura, C. indica, P. betle and P. pinnata were 319.21 ± 10.35 mg/L, 63.9 ± 4.30 mg/L, 70.98 ± 1.42 mg/L and 297.59 ± 8.97 mg/L respectively. The IC₅₀ of shoot inhibitions were 704.72 ± 9.92 mg/L, 265.09 ± 12.57 mg/L, 178.13 ± 8.87 mg/L and 470.78 ± 14.62 mg/L respectively. The positive control, abscisic acid, had a root inhibition of 0.29 ± 0.03 mg/L and shoot inhibition of 0.25 ± 0.01 mg/L. These results revealed that M. calabura crude extract has strong antioxidant and antidiabetic activity, and C. indica leaves have strong root inhibition potential.

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