Adjuvant effects and antiserum action potentiation by a (herbal) compound 2-hydroxy-4-methoxy benzoic acid isolated from the root extract of the Indian medicinal plant `sarsaparilla' (Hemidesmus indicus R. Br.)

Abstract

The adjuvant effect and antiserum potentiation of a compound 2-hydroxy-4-methoxy benzoic acid were explored in the present investigation. This compound, isolated and purified from the Indian medicinal plant Hemidesmus indicus R. Br, possessed antisnake venom activity. Rabbits immunized with Vipera russellii venom in the presence and absence of the compound along with Freund's complete adjuvant, produced a precipitating band in immunogel diffusion and immunogel electrophoresis. The venom neutralizing capacity of this antiserum showed positive adjuvant effects as evident by the higher neutralization capacity (lethal and hemorrhage) when compared with the antiserum raised with venom alone. The pure compound potentiated the lethal action neutralization of venom by commercial equine polyvalent snake venom antiserum in experimental models. These observations raised the possibility of the use of chemical antagonists (from herbs) against snake bite, which may provide a better protection in presence of antiserum, especially in the rural parts of India.

Introduction

Despite continuing efforts to develop new therapeutic strategies against snake envenomation, antiserum remains the only agent which is widely used in snake bite treatment. Antiserum, which was developed in 1894 by Calmette (1894), sometimes does not provide enough protection against venom induced hemorrhage, necrosis and nephrotoxicity and often produces serum reaction (Sutherland, 1977; Corrigan et al., 1978; Stahelet al., 1985). Antiserum development in animals needs a long schedule, is expensive and requires ideal storage conditions. In recent times several attempts have been made to produce antiserum in sheep which showed greater protection and less side effects (Sjostrom et al., 1994; Sells et al., 1994). Over the years many attempts have been made for the development of chemical antagonists which may provide protection against snake bite. Not many compounds are known, even today, which prove to be effective to counter venom action, except for a few observations (Okonogi et al., 1970; Alcaraj and Hoult, 1985; Akunyili and Akubue, 1986; Crossland, 1988). The present investigation was one of the first of its kind to evaluate adjuvant effect and antiserum potentiation action of 2-hydroxy-4-methoxy benzoic acid, isolated and purified from the Indian medicinal plant Hemidesmus indicus.