BHAVANA (WET TRITURATION) AS MECHANOCHEMISTRY: A REVIEW OF ITS EFFECTS ON PARTICLE SIZE, PHYTOCHEMICAL TRANSFER AND BIOACTIVITY
Background: Bhavana is the repeated wet grinding of a powder with a liquid medium until dryness. It is used in almost every branch of Ayurvedic pharmaceutics, from herbal churna and vati to kajjali and bhasma preparation. Classical texts attribute to it the transfer of the liquid's properties to the drug and an increase in potency. Objective: To review the experimental evidence on what bhavana does physically and chemically, and to interpret it using the concepts of mechanochemistry. Methods: A critical narrative review of classical rules for bhavana, experimental studies comparing preparations with different numbers or types of bhavana, and relevant literature on mechanochemistry. Results: Classical texts prescribe from one to a thousand bhavanas, using 39 different liquid media, with seven days as the default duration. In Gandhaka Rasayana, 88 bhavanas gave a D90 particle size of 26.9 µm, compared with 40.8 µm after 11 bhavanas and 93.7 µm without bhavana, together with higher water- and methanol-soluble extractives and a more uniform surface. In kajjali, longer trituration narrowed particle size from 185–661 nm at 22 hours to 100–171 nm at 120 hours and reduced free mercury, consistent with a mechanochemical reaction between mercury and sulphur. Bhavana also influenced pharmacognostical parameters of Amalaki and Haritaki preparations. Conclusion: Bhavana is a combined process of comminution, impregnation and mechanochemical reaction. Defined energy input, number of cycles and instrumental end-points would allow it to be standardised and scaled up.