Metabolic profile of Psidium guajava L. fruits and their inhibitory properties on α-amylase and α-glucosidase.

Psidium guajava L. (guava) is a plant that has been utilized in traditional medicine for the treatment of type 2 diabetes mellitus (T2DM). Our research group has demonstrated that an aqueous extract from the fruits (PGE) exhibits antihyperglycemic properties. This research aimed to determine the chemical composition of PGE and to evaluate its inhibitory mechanisms against α-amylase (α-AMY) and α-glucosidase (α-GLU). The metabolic profile of PGE was determined by metabolomic analyses using ultrahigh-performance liquid chromatography coupled to mass spectrometry (UPLC-ESI-MS). Enzymatic inhibition assays were employed to evaluate the antihyperglycemic effects of PGE, and kinetic assays were used to determine the inhibition mechanisms. Non-targeted metabolomics tentatively identified 48 molecules, with the predominant metabolites being phenolic compounds. Targeted metabolomics facilitated the identification and quantification of 19 phenolic metabolites and their precursor phenylalanine. The most abundant compounds were (-)-epigallocatechin, (+)-catechin, ellagic acid, gallic acid, and quercetin 3-D-galactoside (21.07, 9.70, 7.90, 6.58, and 5.54 μg/g DW, respectively). The pathway analysis indicated that phenylalanine metabolism and phenylpropanoid, flavonoid, flavone, and flavonol biosynthesis could be involved in the generation of the phenolic metabolites. PGE exhibited inhibitory effects on α-AMY and α-GLU, whereas kinetic assays indicated that the extract exerts its inhibitory effects through competitive (α-AMY) and mixed (α-GLU) mechanisms. The evidence suggests that the inhibitory activity of PGE may be associated with its phenolic content. These findings provide insights into the potential of P. guajava fruit as a promising natural food for the future management of T2DM.