Characteristics of extracts from Prunella vulgaris on the immune response of monocytes/macrophages
Abstract of thesis entitled
CHARACTERISTICS OF EXTRACTS FROM
PRUNELLA VULGARIS ON THE IMMUNE RESPONSE OF
for the degree of Master of Philosophy
at The University of Hong Kong
in August 2004
Prunella vulgaris L. (JCtt^) has earned its name as anti-viral, anti-bacterial and anti-tumoral, and some anti-viral mechanisms of this herb have been reported. However, there is little information available on the anti-bacterial and anti-tumoral mechanisms of this herb. It is well known that innate immunity is the first line of host defense against various infectious diseases and tumors. Hence, we hypothesized that certain immune stimulatory factor(s) may be present in Prunella vulgaris which could enhance immune responses in human body, thereby contributing to the therapeutic effects. As anti-microbial and anti-tumoral functions of the immune system of the human body are largely related to
monocyte/macrophage activities, the aim of this study is to examine how extracts isolated from Prunella vulgaris can modulate directly or indirectly the immune responses of monocytes/macrophages.
We employed two cell lines, namely murine macrophage RAW 264.7 cells and brain macrophage BV2 cells to investigate the immune modulatory effects of Prunella vulgaris. Four fractions, referred to as PV1, PV2, PV3 and PV4, were first isolated from the herb. Then PV2 was further fractionated to yield four additional fractions: PV21, PV22, PV23 and PV24. All these fractions were evaluated for their modulatory effects on the activities of monocytes/macrophages. PV24 markedly stimulated the production of nitric oxide (NO), superoxide, tumor necrosis factor (TNF)-a and the expression of inducible nitric oxide synthase (iNOS) & TNF-a gene in the macrophage cell lines. PV24 can at the same time effectively regulate the immune stimulatory effect by decreasing the number of viable macrophages, which can be regarded as a type of activation induced cell death (AICD), to prevent the harmful overloading of cytotoxic factors. The results clearly indicated that PV24 could exert a more potent immune stimulatory effect than the other fractions.
The evidence provided in this study showed for the first time that the extracts from Prunella vulgaris, especially fraction PV24, not only could effectively stimulate immune responses but also prevent monocytes/macrophages from harmful over-activation. We believe that this is also one of the important effects of Prunella vulgaris responsible for the anti-microbial and anti-tumoral activities.
School:The University of Hong Kong
School Location:China - Hong Kong SAR
Source Type:Master's Thesis
Keywords:prunella vulgaris monocytes macrophages
Date of Publication:01/01/2005