Abstract

EVALUATION OF ANTIMICROBIAL ACTIVITIES OF VARIOUS SOLVENT EXTRACTS OF GINGER RHIZOME PEELS AND WHOLE GINGER RHIZOME WITHOUT PEELS

Shaileyee Das, Anup Kumar Das and Subhash C. Mandal*(Professor)

Abstract

The rhizome peel and rhizome of Zingiber officinale L. contain a wide range of bioactive compounds that may be accountable for their biological activities. However, little information is available about active constituents, as well as their inputs to the antioxidant properties. This study investigated the total phenolics, triterpenoids, flavonoid contents, antioxidant and antimicrobial activities of Cold maceration (CM), ultrasound (UAE) assisted and microwave assisted (MAE) ethanolic extracts from rhizome peel and rhizome ginger at maturity. The antioxidant activities and contents of total phenolic (TPC), terpenoids(TTC) and flavonoids (TFC) varied with tissue type and extraction method. Overall, the MAE Peel extracts exhibited the highest TPC (35.8 mg GAE/g DM), 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity (0.589 mg AA/g DM). The UAE extracts of Peel samples had the greatest TFC (7.45 mg RE/g DM). The greatest TTC (15.17 g/100 g DM) was observed in the cold maceration ethanolic extracts at the peel stage. All peel and rhizome extracts exhibited antimicrobial activity against Listeria monocytogenes and Staphylococcus aureus, but only the cold maceration extracts of the peel and rhizome samples showed activity against Salmonella spp. The UAE peel extracts demonstrated the maximum inhibitory potency against Escherichia coli, L. monocytogenes and S. aureus. These results highlighted the rhizome of Z. officinale as natural antimicrobial and antioxidant substances for food appliances.

Keywords: Zingiber officinale L., Triterpenoids, Antioxidant activity, Antimicrobial activity, Extraction methods, Flavonoids.