Phytoconstituents Analysis and Bioactivity Study of Alpinia nigra (Gaertn.) Burtt

Abstract

The antioxidant and antimicrobial activities of the essential oil and extract of Alpinia nigra (Gaertn.) Burtt (Zingiberaceae) were assessed in vitro. Besides total phenolic and flavonoid content of leaf extract, the composition of essential oil was also investigated. Essential oil extracted from the leaves by hydro-distillation was analysed by GC-MS. Ten components, representing 99.3% of the leaf oil, were identified, of which the major constituents were β-pinene (56.27%), α-caryo-phyllene (13.70%), α-farnesene (7.92%) and caryophyllene (6.46%). Total phenolic, total flavonoid contents in the extract were 69.25 mg gallic acid equivalent/ g of extract and 78.84 mg quercetin equivalent/g of extract respectively. Antioxidant activities of the oil and extract were determined in terms of scavenging of DPPH, ABTS and H₂O₂ radicals. The essential oil and extract were also evaluated for antimicrobial activity using inhibition zone diameter and minimum inhibitory concentration. Oil and extract exhibited moderate to strong antioxidant activity. Alpinia nigra leaf oil exhibited stronger antimicrobial activity than the extract against the tested pathogens. These results show that Alpinia nigra leaf essential oil and extract could be considered as natural alternative to traditional food preservatives and be used to enhance food safety and shelf life.

Keywords:

• Alpinia nigra
• essential oil
• antioxidant activity
• antimicrobial activity
• β-pinene