Antidiabetic, Antibacterial and Antioxidant Activities of Different Extracts from Brucea javanica (L.) Merr Seeds

Introduction: The seeds of B. javanica are known as herbal material for anticancer, antimalaria and antiamoeba. Limited report is available on their antidiabetic and antibacterial properties. Methods: Methanol (ME) and Ethyl acetate extracts (EAE) were studied for their inhibition activities on α-glucosidase in vitro, including combination of ME with acarbose and inhibition mechanism. Antibacterial activity was tested by well diffusion and microdilution methods. The extracts were evaluated for their in vitro antioxidant property by DPPH assay, as well as their phenolic and flavonoid contents. Results: ME exhibited a strong α-glucosidase inhibition activity (IC₅₀ 271.97 μg/ml) compared to EAE and acarbose (IC₅₀ of 1745.05 and 823.99 μg/ml, respectively). A low dose of ME gave an additive inhibition on α-glucosidase when combined with acarbose. By a kinetic analysis, ME was found to inhibit α-glucosidase in a mixed-type inhibition. Both ME and EAE showed strong antibacterial activities against gram negative and positive bacteria. The strongest inhibition was observed against C. violaceum and S. mutans for ME (MIC of both 0.387 mg/ml) and P. aeruginosa for EAE (MIC 2.938 mg/ml). Both extracts showed weaker antioxidant activities than standards; IC₅₀ 664.73 and 4225.40 μg/ml, respectively. ME was rich in phenolics (277.54 mg GAE/100 g DW), unlike EAE (1.86 mg GAE/100 g DW). Conclusion: This study can recommend B. javanica seeds as a source for antidiabetic and antibacterial agents. Combination with acarbose may have important role for the treatment of diabetes mellitus.