From tradition to therapeutics: antioxidant, anti-inflammatory, and antidiabetic activities of Garcinia cowa Roxb. leaf extracts

This study scientifically evaluated the antioxidant, anti-inflammatory, and antidiabetic potential of Garcinia cowa Roxb. leaf extracts, a plant widely used in Assamese traditional medicine but lacking strong pharmacological validation. Successive extracts were prepared using solvents of increasing polarity, and their total phenolic and flavonoid contents were quantified. The methanol extract showed the highest phenolic (0.317 ± 0.02 mg/mL) and flavonoid (0.208 ± 0.01 mg/mL) concentrations, which correlated with potent antioxidant activity in DPPH (IC₅₀ = 70.25 µg/mL), hydrogen peroxide (IC₅₀ = 24.80 µg/mL), and nitric oxide (IC₅₀ = 89.12 µg/mL) radical scavenging assays. In vivo evaluation using carrageenan-induced paw edema revealed notable anti-inflammatory activity. Antidiabetic assessment through α-glucosidase inhibition demonstrated significant enzyme inhibition by the methanol extract (IC₅₀ = 42.00 µg/mL), while studies in streptozotocin-induced diabetic rats showed a marked reduction in blood glucose levels over 21 days (131.5 mg/dL on Day 21), approaching the efficacy of the standard drug Miglitol (110.32 mg/dL). Histopathological examination indicated preservation of pancreatic islet architecture in extract-treated groups, supporting its therapeutic potential. Acute toxicity studies established safety up to 5000 mg/kg, suggesting a wide margin of safety. Overall, the methanol extract of Garcinia cowa leaves exhibited strong antioxidant, anti-inflammatory, and antidiabetic activities, scientifically supporting its ethnomedicinal use and indicating promise as a natural source for developing safe, effective plant-based therapeutics. Further work is required to isolate and characterize the responsible bioactive compounds.