Phytochemical analysis and salivary amylase inhibition activities of Carica papaya leaf and Garcinia mangostana pericarp extracts and partially purified fractions

Abstract

Plant-derived digestive enzyme inhibitors particularly those targeted to carbohydrate metabolism has been the focus of recent studies as natural supplements for weight control and diabetes. The present study explores the salivary amylase inhibition activity of Garcinia mangostana (Linn.) pericarp extracts and Carica papaya (Linn.) leaf extracts and fractions, as well as perform phytochemical screening and quantification, and thin layer – and high performance liquid chromatographic profiling. ­Results show that crude extracts and purified fractions were able to inhibit salivary amylase, with C. papaya fraction 1 being the most active at 30.89% inhibition. Phytochemical screening of all extracts tested ­positive for tannins, glycosides, phenolics, flavonoids and alkaloids. Quantification of phenolics showed that extracts contained high levels of phenolics, with C. papaya crude extract having the highest content with 219.0±12.7 mg GAE/g extract followed by G. mangostana crude extract with 247.1±18.0 mg GAE/g extract. Quantification of total flavonoids also showed C. papaya crude extract to contain the highest content with 55.12±0.679 mg QE/g extract. All extracts contained negligible alkaloid content, though. HPLC and TLC profiling showed several peaks and bands, when viewed in 210 nm and UV light, respectively. These results demonstrate in vitro the salivary amylase inhibitory activity of both plants and their potential as antidiabetic drug candidates; however, further studies need to be done, like isolation and structure elucidation of active components and toxicity assays. Keywords: Amylase inhibition, phytochemical quantification, Carica papaya, Garcinia mangostana