Factors Affecting Radioprotective Efficacy of Ocimum sanctum (Tulsi) Extract in Mice

Abstract

Background: Oscimum sanctum (Tulsi) is well reported for its medicinal values in Ayurveda. Although several chemical radioprotectors have shown excellent protection under in vitro conditions, lack of acceptable efficacy under in vivo conditions and/or undesirable toxicity has limited their applications in humans. Tulsi leave extract have shown significant normal tissue radioprotection in cell culture and animal models in preclinical studies. Aim: This study intends developing a standardized extraction procedure so as to minimize variations in bioefficacy of extracts. Methods: In the present study, a number of factors related to the extract preparation were found to influence the total yield and orientin (a potential bioactive component responsible for radioprotection) level  that included the season of raw material collection, geographical location of plant material, extraction method used. Results: Although the plasma levels of orientin and radioprotective efficacy varied with the orientin levels in the extract, orientin does not appear to be the sole determinant of radioprotection afforded by the tulsi extract. Conclusion: These results imply that careful extraction of plant material is a prerequisite for maintaining its bioefficacy and identifying at least one bioactive marker (like orientin here) may help in achieving this to a large extent.