In vitro antidiabetic, antioxidant activities and GC-MS analysis of and leaf extracts.

This study aimed to assess the antidiabetic, and antioxidant potential of and , well known for traditional ethnomedicinal uses in North-east India. Leaf extracts prepared in water, methanol and petroleum ether were evaluated for in vitro antidiabetic and antioxidant assay using α-amylase inhibition, glucose diffusion method and DPPH radical scavenging activity. The α-amylase inhibition with methanolic extract at 400 μg/ml (66.67%) and aqueous extract at 300 μg/ml (58.15%) were stronger than in equivalent concentrations of acarbose, , 62.17, and 51.52%, respectively. Aqueous extract showed a maximum 67.65% inhibition of glucose diffusion at 180 min in comparison to control without leaf extract. The DPPH radical scavenging activity of extract in methanol was significantly better than equivalent aqueous or ether extract. However, the solvent choice had little impact on antioxidant activity in . GC-MS analysis revealed the presence of a large number of phytochemicals in methanol fraction of aqueous extracts in comparison to . Though the in vitro α-amylase inhibition or glucose diffusion retardation implied potential medicinal use of endangered orchid and , further investigation may be warranted for identification of relevant bio-active compounds and in vivo validation of their pharmacological properties.