The antimicrobial activity of different extracts from roots of Aristolochia bracteata retz was tested against Staphylococcus aureus, Escherichia coli, Salmonella typhi and Salmonella typhimurium which are pathogenic bacteria that cause gastrointestinal disorders. The root of A. bracteata retz was extracted with various solvents (petroleum ether, hexane, chloroform, ethyl acetate, methanol and water). The extracts were subjected to microbiological tests. Methanol was found to show more activity than other extracts. So the methanol extract was subjected for isolation. The isolated compound was confirmed by comparing with the standard aristolochic acid I. By using the same extract, the antioxidant activity was also tested by Dpph and Nitric oxide (NO) methods against free radicals which were present. More inhibition of the free radicals was observed in the Dpph method than NO method.

In India, the use of different parts of several medicinal plants to cure specific ailments has been in vogue since ancient times. The indigenous systems of medicine, namely, ayurvedic, siddha and unani, have been in existence for several centuries. The medicinal plants constitute a group of industrially important crops which bring appreciable income to the country by way of export.

Uses of plants for curing various ailments are not only confirmed by the doctors but are also known to several households. There are many interesting and astonishing things to learn from the collectors of medicinal herbs. Spreading and preserving this knowledge of medicinal plants and their uses have become important for human existence.

Our pharmaceutical industry is fairly advanced and sophisticated. The plant-based drugs, however, shortened the life span of the source material. There is continuous search for more potent and cheaper raw material to feed the industry. With concerted research and development efforts, many medicinal plants could provide raw material in abundance to the indigenous pharmacists and local herbalists.

The work of isolation of active principles from medicinal plants and characterization can be traced to the beginning of 19^th century. The use of modern isolation technique and pharmacological testing procedure means that new plant drugs usually find their way into medicine as purified substances rather in the form of galenical preparation (Nadkarni, 1976; Achenbach and Fischer, 1997; and Chakraborty and Patil, 1997).

Life Sciences Journal, Antimicrobial Activities, Medicinal Plants, Pharmaceutical Industry, Cold Maceration Process, Phytochemical Investigations, Spectrophotometric Method, Antioxidant Activities, Extraction Methods, Aristolochic Acid, Neuronal Immune System, Methanolic Extract.