Phytochemical investigation and in vitro antioxidant activity of an indigenous medicinal plant Alpinia nigra B.L. Burtt

Objective

To investigate antioxidant potential of methanol extract of Alpinia nigra leaves.

Methods

The study was done by using various in vitro methods such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), nitric oxide and hydrogen peroxide radical scavenging assays. Phytochemical constituents, total phenolic content and total flavonoid content of the extract at different concentrations (10-500 µg/mL) were determined.

Results

Alpinia nigra leaves showed high free radical scavenging activity as evidenced by the low IC₅₀ values in DPPH (64.51 µg/mL), in ABTS (28.32 µg/mL), in nitric oxide (80.02 µg/mL) and in H₂O₂ (77.45 µg/mL) scavenging assays. Furthermore the TPC and TFC of the extract were found to be 69.25 mg gallic acid equivalent per gram of extract and 78.84 mg quercetin equivalent per gram of extract respectively.

Conclusions

The results of present comprehensive analysis demonstrated that Alpinia nigra leaves possess high phenolic, flavonoid contents and potential antioxidant activity, and could be used as a viable source of natural antioxidants and might be exploited for functional foods and neutraceutical applications.