Comprehensive metabolomics and chemometrics unravel potential anti-diabetic metabolites of pumpkin (Cucurbita pepo L.) fruits through UPLC-QqQ-MS and GC–MS analyses

This comprehensive study explores the phytoconstituents of different parts of pumpkin (Cucurbita pepo) including flesh, peel, seeds, pumpkin juice, and pumpkin seed oil. Utilizing advanced analytical techniques including UPLC-QqQ-MS and GC-TSQ-MS combined with multivariate statistical analysis, 94 distinct chromatographic peaks from various chemical classes were annotated. Predominant classes included phenolic acids, flavonoids, cucurbitacins, amino acids, triterpenoids, fatty acids, sterols, carotenoids, and other compounds. For more comprehensive chemical profiling of the tested samples, fractionation of the different parts of the fruit was attempted through successive solvent extraction. The unsaponifiable part of the oils, analyzed by GC, showed that the phytosterols, namely ß-sitosterol, and stigmasterol are in the majority. All pumpkin extracts showed significant inhibition of carbohydrase enzymes and glucose uptake promotion by cells. Pumpkin flesh butanol fraction exhibited potent α-glucosidase inhibition, while pumpkin defatted seed methylene chloride fraction showed strong α-amylase inhibition. Additionally, pumpkin seed oil and defatted seed petroleum ether fraction demonstrated high glucose uptake activity. Bioactive metabolites including vaccenic acid, sinapic acid, kuguacin G, luteolin hexoside, delta-7-avenasterol, cucurbitosides and others were unveiled through OPLS multivariate models elucidating the anti-diabetic potential of pumpkin. These findings support the use of pumpkin as a functional food, offering insights into its mechanisms of action in diabetes management.