Abstract:
Background: Sri Lanka is home to numerous endemic plant species with potential therapeutic
benefits. These plants are sources for novel chemical compounds with biological activity. This
study investigates the biological properties of resins from three endemic plants, an area that has
received limited scientific attention.
Objectives: To evaluate antimicrobial, antioxidant, and anticancer activities of Canarium
zeynalicum (Kekuna), Pterocarpus marsupium (Gammalu), and Dipterocarpus zeylanicus (Hora)
resins
Methods: Crude extract of resins from Canarium zeylanicum, Dipterocarpus zeylanicus and
Pterocarpus marsupium were prepared via sequential extraction using hexane, ethyl acetate, and
methanol separately. Antimicrobial assays were done by agar disk diffusion method against Gram-
positive Staphylococcus aureus, Bacillus subtilis, Gram-negative Pseudomonas aeruginosa,
Escherichia coli, and fungal species Candida albicans, Candida tropicalis. Gentamicin and
fluconazole were used as positive controls for antibacterial and antifungal assays, respectively;
solvent-only discs served as negative controls. Antioxidant activity was evaluated by 2,2-
diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method with ascorbic acid as a reference
over a concentration range of 10 - 0.08 mg/mL. The anticancer potency of crude extracts (50-0.4
mg/mL) was assessed on BT-474 breast cancer cells, with cell viability assessed by
dimethylthiazol-carboxymethoxyphenyl-sulfophenyl-tetrazolium assay.
Results: All extracts showed antimicrobial activity against at least one of the microbes tested.
Methanol extract of P. marsupium displayed the strongest inhibition against Gram-positives, S.
aureus (17.2±0.2 mm) and fungi C. albicans (15.1±0.1 mm), while ethyl acetate extract of C.
zeylanicum was most effective against Gram-negatives, P. aeruginosa (14.2±0.2 mm). The
methanol extract of P. marsupium showed an excellent DPPH radical scavenging activity (IC50:
0.011 mg/mL). All extracts showed anticancer activity. The highest anticancer activity was in the
D. zeylanicus hexane extract, even at 0.4 mg/mL level.
Conclusions: The crude resin extracts showed antimicrobial, antioxidant, and anticancer
properties. These results highlight the importance of further research to isolate and characterize
novel bioactive compounds.
