Evaluation of the underutilized Malpighia glabra L. fruits as a future functional food: nutritional composition, phenolic profile, biological activities, and synergistic effects with pharmaceutical drugs

Malpighia glabra L., commonly known as acerola or Barbados cherry, is a non-commercial tropical fruit species in Thailand that is primarily consumed fresh by local communities. Limited scientific data have restricted its potential for future food applications. In this study, we investigated the nutritional composition, phenolic profiles, and in vitro biological activity of M. glabra fruits. Results demonstrated that the ripened fruits (100 g fresh weight) provided low energy (36.9 kcal) with negligible fat content but exceptionally high vitamin C content (838 mg). The ethanolic extract exhibited strong antioxidant activities as examined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay (250.98 µmol Trolox equivalent (TE) per g dry weight (DW)), ferric ion reducing antioxidant power (FRAP) assay (642.35 µmol TE per g DW), and oxygen radical absorbance capacity (ORAC) assay (443.90 µmol TE per g DW). These activities were attributed to the phenolic composition, of which rutin was the predominant compound, as detected by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). The extract also demonstrated in vitro inhibition of α-glucosidase, with a half-maximal inhibitory concentration (IC50) of 4.81 mg mL-1, and β-secretase, with an IC50 value of 5.45 mg mL-1. Synergistic interactions were observed in vitro between the extract and acarbose (an anti-diabetic drug) and the extract and donepezil (an anti-Alzheimer's drug). These findings characterize the nutritional composition and in vitro bioactivities of ripened M. glabra fruits, supporting further investigation into their potential development as functional food ingredients.