Phytochemical profile, in vitro antioxidant, and anti-protein denaturation activities of Curcuma longa L. rhizome and leaves

Curcuma longa L. is a famous spice cultivated in many countries with significant variations reported in its phytochemical contents and biological potential. For the first time, the present work is aimed to identify the major phytochemicals present in methanol:chloroform (MC) and petroleum ether (PE) extracts of Curcuma longa rhizome and leaves (by determining polyphenols and GC/MS analysis), and their in-vitro antioxidant and anti-protein denaturation potential. Results showed that the highest value (P < 0.05) of polyphenolic content was in MC extract of rhizome (51.46 +/- 0.46 mg GAE/g) followed by 31.20 +/- 0.53 mg GAE/g in MC leaves extract. The strong antiradical activity was evaluated in MC extract of rhizome with IC50 value of 92 +/- 0.02 mu g/mL. MC extracts of both the rhizome and leaves exerted a potent inhibitory effect against protein denaturation with IC50 values of 106.21 +/- 0.53 and 108.06 +/- 4.67 mu g/mL (P > 0.5), respectively. GC/MS analysis showed that alpha-tumerone was the main component in the rhizome oil (32.44%), whereas in the leaf oil, palmitic acid was the prominent constituent (28.33%) and alpha-phellandrene recorded a comparable percentage (7.29). In conclusion, C. longa is a valuable source of natural antioxidants and anti-inflammatory constituents, as indicated by its high polyphenolic content and by its considerable in vitro antiradical and anti-protein denaturation potential.