Pharmacokinetics of gallic acid from the topical ointments of standardized extracts of Chrysophyllum cainito and Mimusops elengi in rats

Introduction: The wound healing activity of leaves of Chrysophyllum cainito and flowers of Mimusops elengi has been reported through our previous studies. Therefore, the aim of this study was to evaluate pharmacokinetics of gallic acid from the ethanolic extracts of these plants and to support the findings of the preclinical study. Methods: A simple HPLC method was developed for detection of gallic acid in rat plasma post topical application of the ointments containing 20% ethanolic extracts of both the plants and validated as per USFDA guidelines. Clonidine hydrochloride was used as an internal standard (IS). Chromatographic separation of gallic acid and IS was achieved on Cosmosil C₁₈-column using mobile phase [10 mM KH₂PO₄ in water: acetonitrile: orthophosphoric acid (95: 5: 0.05, v/v/v)] delivered at a flow rate of 1.0 mL/min. The ultraviolet detection wavelength was set at 215 nm. Results: The calibration curve was linear over a concentration range of 0.05-5.0 μg/mL. The method was found to be accurate, precise and stable for gallic acid from spiked plasma at QC levels. The average method recoveries for gallic acid were over 85% and extraction recoveries between 78 and 87%. Conclusion: The HPLC method was applied successfully to the pharmacokinetic study of gallic acid. The detection of gallic acid in rat plasma post topical application of ethanolic extracts of both the plants proves its absorption which probably facilitates the biochemical changes and thus exhibits wound healing activity of the plant extracts.