HPLC-PDA Polyphenolic Quantification, UHPLC-MS Secondary Metabolite Composition, and In Vitro Enzyme Inhibition Potential of Bougainvillea glabra

The plants of the Bougainvillea genus are widely explored regarding nutritive and medicinal purposes. In this study, dichloromethane (DCM) and methanol (MeOH) extracts of Bougainvillea glabra (Choisy.) aerial and flower parts were analyzed for high-performance liquid chromatography with photodiode array detection (HPLC-PDA), ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) phytochemical composition, and enzyme inhibition potential against key enzymes involved in diabetes (α-amylase), skin problems (tyrosinase), and inflammatory disorders (lipoxygenase (LOX)). HPLC-PDA quantification revealed the identification of nine different polyphenolics, amongst which both flower extracts were richest. The flower MeOH extract contained the highest amount of catechin (6.31 μg/g), gallic acid (2.39 μg/g), and rutin (1.26 μg/g). However, none of the quantified compounds were detected in the aerial DCM extract. UHPLC-MS analysis of DCM extracts revealed the tentative identification of 27 secondary metabolites, where the most common belonged to terpenoid, alkaloid, and phenolic derivatives. Similarly, for enzyme inhibition, all the extracts presented moderate activity against tyrosinase and α-amylases, whereas, for LOX, both methanolic extracts showed higher percentage inhibition compared with DCM extracts. Based on our findings, B. glabra could be regarded as a perspective starting material for designing novel pharmaceuticals.