Interactions of herbal extract combinations against free radical scavenging activity

Abstract

Herbal medicines are often combinations of herbal extracts that are assumed to have additive or synergistic effects. This investigation compared the effect of individual herbal extracts with combinations of extracts on antioxidant activity by 1,1-diphenyl picryl hydrazyl (DPPH) method and showed the additive or synergistic effects by studying interactions between herbal extracts in combination. Curcuma longa Linn. (Zingiberaceae), Bacopa monneira Linn. Penn. (Scrophulariaceae), Zingiber officinale Rosc. (Zingiberaceae) and Emblica officinalis Gaertn. (Euphorbiaceae) were collected and used to prepare the extracts. Effects of the extracts on DPPH scavenging activity were estimated quantitatively by a UV-spectrophotometeric method. Combinations of two herbal extracts of the four active extracts and their interactions were tested by the DPPH method. Each extract significantly scavenges the free radical activity in a dose-dependent manner. The active extracts of Curcuma longa, Bacopa monneira, Zingiber officinale and Emblica officinalis were tested as two-extract combinations. Curcuma longa and Bacopa monneiera, when combined, showed additive effect with a trend towards synergistic effect, whereas Curcuma longa and Emblica officinalis together were additive. The four extracts together were significantly (p ≤ 0.01) more effective than the two-by-two combinations and the individual extracts alone. The less predictable nature of the two-way combinations suggests a need for careful characterization of the effects of each individual herb based on their intended use.