Immunostimulatory activity of Rhus verniciflua stokes in vitro

Rhus verniciflua stokes (RVS) have been used as a traditional food and medicine to enhance immune response against infectious agents and to treat cancers [1]. Unfortunately, there is little scientific evidence to support efficacy of this widely used botanical, and little information about potential mechanism of action. In this study, the methanol extract of RVS and its successive n-butanol, ethyl acetate and aqueous extracts have been screened on immune response of goat neutrophils and murine RAW 264.7 cells. Freshly isolated neutrophils from healthy goats were incubated fractions of the RVS, and then they were tested for migration and superoxide production induced opsonized zymosan. And also the immunostimulatory effects of its fractions assessed by in vitro spleen lymphocyte proliferation and nitric oxide (NO) production. The n-butanol fraction stimulated spleen lymphocyte proliferation, NO production, goat neutrohphil migration and superoxide production and also ethyl acetate fraction exhibited some immnostimulatory activity (p<0.05).

Dose µg/ml	Spleen lymphocyte proliferation (OD value/1×104cell ml-1)
	Methanolic extracts	Aqueous extracts	Ethyl acetate extracts	n-butanol extracts
1 10 100 Control	0.513±0.056 0.565±0.007 0.449±0.020 0.661±0.027	0.555±0.015 0.604±0.064 0.523±0.013	1.094±0.026* 1.184±0.002* 1.189±0.026*	1.108±0.050* 1.222±0.103* 0.806±0.106

These results suggest that RVS n-butanol extracts examined here, exhibit immunostimulatory activity, which implicates that RVS n-butanol extract may serve as a potential source of natural immunostimulants for treatment of some animal diseases.

References: [1] Lee, J.H. et al. (2009) Phytomedicine 16:188–197.