HPTLC quantification of garcinol in three endemic Garcinia species of Assam, estimation of secondary metabolites and evaluation of in vitro antioxidant activity

Abstract Garcinol, the main polyisoprenylated benzophenone present in Garcinia species. A simple, rapid, reliable high-performance thin-layer chromatography (HPTLC) technique has been developed for simultaneous detection and quantification of garcinol in three endemic Garcinia sp. of Assam, India. While G. mangostana and G. indica have garnered extensive recognition, these lesser-known species have not received proportionate level of scientific exploration, therefore has served as the subject of investigation. Chromatographic separation was achieved using pre-coated silica gel 60 F 254 plates. The optimized mobile phase (Toluene-Ethyl acetate-Formic acid, 5:4:1 V/V ) at 276 nm produced well-defined and sharp peaks of garcinol, maintaining a constant R F value of 0.75. The regression equation demonstrated a linear relationship with a correlation coefficient of 0.9955. The method was validated in accordance with International Conference of Harmonization guidelines (ICH), encompassing assessments for precision, accuracy, repeatability and robustness, all of which yielded low percentage of relative standard deviation values, attesting to its excellent performance. The content of garcinol found in the extracts were in the range of 0.58–0.98 % w/w . In secondary metabolite analysis, significant amount of phenols (26.06 ± 1.65–57.51 ± 2.62 gallic acid equivalent mg g −1 ), flavonoids (11.27 ± 1.06–21.09 ± 1.34 quercetin equivalent mg g −1 ) and ascorbic acid (3.56 ± 0.12–3.65 ± 0.11 mg/10 g) contents were detected in the extracts. Further, the extracts exhibited good anti-radical activity, which may be attributed to the presence of important secondary metabolites. Therefore, this research establishes the three endemic Garcinia sp. as promising source of garcinol. Additionally, the developed method can be applied for routine quality control analysis of herbal formulations containing garcinol.