Radio protective effects of the Ayurvedic medicinal plant Ocimum sanctum Linn. (Holy Basil): A memoir.

The use of compounds which can selectively protect normal tissues against radiation injury is of immense use because in addition to it protecting the normal tissue, will also permits use of higher doses of radiation to obtain better cancer control and possible cure. However, most of the radio protective compounds investigated possess inadequate clinical application principally due to their inherent systemic toxicity at their optimal protective concentrations. Plants commonly used as medicinal and dietary agents have recently been the focus of attention and studies have shown that Ocimum sanctum Linn. commonly known as the Holy Basil and its water soluble flavonoids, orientin and vicenin protects experimental animals against the radiation-induced sickness and mortality at nontoxic concentrations. Studies with tumor bearing mice have also shown that both Tulsi extract and its flavonoids selectively protect the normal tissues against the tumoricidal effects of radiation. Preclinical studies have also shown that the aqueous extract of the Tulsi leaves; its flavanoids orientin and vicenin, and eugenol, the principal nonpolar constituent present in Tulsi prevent radiation-induced clastogenesis. Mechanistic studies have indicated that free radical scavenging, antioxidant, metal chelating and anti-inflammatory effects may contribute toward the observed protection. In addition, clinical studies with a small number of patients have shown that Tulsi was effective as a radio protective agent. This review summarizes the results related to the radio protective properties of Tulsi and its phytochemicals and also emphasizes the aspects that warrant future research to establish its use as a radio protective agent.