Wide Range of Molecular Weight Distribution of Mitogenic Substance(s) in the Hot Water Extract of a Chinese Herbal Medicine, Bupleurum chinense

Abstract

In this study, we examined the contribution of lignin-like materials in lower molecular weight (MW) fractions from the hot water extract of Bupleuri Radix (Bupleurum chinense) (HWE-BR) for their immunopharmacological activities. Mitogenic activity was detected in all the fractions of MW ranges : lower than 1.0 kDa, 1.0-3.5 kDa, 3.5-10 kDa, and 10-50 kDa. After NaClO₂ treatment of these subfractions, UV spectra, ESR spectra, mitogenic activities on murine B-cells, and the activity of inducing nitric oxide in RAW 264.7 cells were significantly reduced, suggesting that lignin-like polyphenolic substance(s) of various MW might take part in these activityes. The intensity of ESR spectra and mitogenic activities were stronger in higher MW subfractions, thus the content of stable radical species and/or the degrees of polymerization would be important for their immunopharmacological activities.