Bioactives from Psidium guajava leaf decoction: LC-HRMS-MS-Qtof identification, bioactivities and bioavailability evaluation

Abstract

Psidium guajava leaf decoction has been used in ethnomedicine due to its positive health effects. This study aimed to evaluate the chemical composition, antioxidant activity, enzyme inhibition, and permeation of phenolic compounds from a guava leaf aqueous extract and ethanolic precipitation supernatant. The aqueous extract showed higher content of total phenolics (89.58 ± 7.92 µg GAE/mg extract) and flavonoids (749.42 ± 10.16 µg RE/mg extract). Catechin, quercetin, epigallocatechin, protocatechuic acid, gallic acid, chlorogenic acid, hyperoside, quercitrin, guaijaverin, and jacoumaric acid were identified through high-resolution liquid chromatography - high-resolution tandem mass spectrometry interfaced with a quadrupole time-of-flight. The antioxidant activity was evaluated through the DPPH method and both samples had strong antioxidant activity (EC50 7.26 ± 0.41 and 11.93 ± 0.57 µg/mL), inhibited acetylcholinesterase (IC50 48.66 ± 1.39 and 63.44 ± 1.13 µg/mL), and the aqueous extract inhibited 3-hydroxy-3-methyl-glutaryl-CoA reductase (IC50 8.40 ± 0.51 µg/mL). The samples were not cytotoxic towards Caco-2 cells, according to the MTT assay. Gallic acid, catechin, chlorogenic acid, hyperoside, and quercitrin permeated a simulated intestinal barrier between 0.21% and 9.95% and chlorogenic acid, hyperoside, and quercitrin from the supernatant between 0.10% and 0.68%. These results help explain some observations and uses in ethnomedicine.