Danzhixiaoyao Wan (DW) is a common 10 herbs formulation in China for regulating several clinical conditions affecting women. This research tried to explain one of DW's functions, purging heat, using in vitro pharmacological analyses. The whole formulation and each single herb of DW were compared based on antioxidant activity with the oxygen radical absorbance capacity (ORAC) assay, and for their inhibitory effect (IE) on nitric oxide (NO) production by lipopolysaccharide (LPS)-activated RAW 264.7 macrophages with the Griess assay. The results showed that DW as a whole formulation had both antioxidant activity and an IE on NO production, while the individual herb component of DW varied in their ORAC values and inhibition of NO production. The ORAC value of the whole DW was 450 mumol TE g(-1). The order of antioxidant (ORAC) activity of the single herbs was: Mentha haplocalyx (1352 mumol TE g(-1)) > Glycyrrhiza uralensis (1184 mumol TE g(-1)) > Gardenia jasminoides (1129 mumol TE g(-1)) > Paeonia suffruticosa (465 mumol TE g(-1)), with the contributions being additive rather than synergistic. The production of nitrite by stimulated RAW 264.7 murine macrophages (unstimulated: 0.5 +/- 0.1 muM versus LPS: 38.9 +/- 2.3 muM) was significantly inhibited (P < 0.05) by M. haplocalyx, G. jasminoides, Bupleurum chinense and Paeonia lactiflora. DW as a whole had an IE on NO production, but this was not significant. The single herb M. haplocalyx had the highest ORAC value and the highest IE on NO production, followed by G. jasminoides. Both of these herbs have the 'purging heat' property in the theory of traditional Chinese medicine and this property of the samples may be correlated with the antioxidant activity and IE on NO production.
Keywords: Danzhixiaoyao Wan; antioxidant activity; individual herbs; inhibitory effect on nitric oxide production; purging heat property.