Total phenolic and flavonoid contents and antioxidant activity of ginger (Zingiber officinale Rosc.) rhizome, callus and callus treated with some elicitors

The present study was aimed at determining total phenolic and flavonoid contents and studying the antioxidant activity of ginger (Zingiber officinale Rosc.) rhizome and callus, 6-gingerol and 6-shogaol and callus treated with elicitors. Petroleum ether (PE) and chloroform: methanol (1:1, v/v) (CM) extracts were prepared by maceration. Highest total phenolic content was obtained from the CM extract (60.34 ± 0.43 mg gallic acid/g) of rhizome while callus showed lower content detected in the CM extract (33.6 ± 0.07 mg gallic acid/g). Flavonoids were only detected in rhizome (CM extract 40.25 ± 0.21 mg quercetin/g). Both rhizome extracts exhibited good antioxidant activity with higher activity recorded in PE extract (IC50 value 8.29 ± 1.73 μg/mL). Callus extracts revealed lower antioxidant activity (IC50 value 1265.49 ± 59.9 μg/mL obtained from CM extract). 6-gingerol and 6-shogaol displayed high antioxidant activity in both assays with IC50 4.85 + 0.58DPPH and 5.35 ± 0.33ABTS μg/mL for the former and IC50 7.61 ± 0.81DPPH and IC50 7.05 ± 0.23ABTS μg/mL for the latter. Treatment of callus with elicitors showed significant (p