Abstract:
The African pumpkin (Momordica balsamina) contains bioactive phenolic compounds that
may assist in reducing oxidative stress in the human body. The leaves are mainly consumed after
boiling in water for a specific time; this hydrothermal process and conditions of the gastrointestinal
tract may affect the presence and bioactivity of phenolics either positively or negatively. In this
study, the effects of hydrothermal processing (boiling) and in vitro simulated human digestion on
the phenolic composition, bioaccessibility and bioactivity in African pumpkin were investigated in
comparison with those of spinach (Spinacia oleracea). A high-resolution ultra-performance liquid
chromatography, coupled with diode array detection, quadrupole time-of-flight and mass spectrometer
(UPLC-DAD-QTOF-MS) was used to profile phenolic metabolites. Metabolites such as
3-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and
4,5-dicaffeoylquinic acid were highly concentrated in the boiled vegetable extracts compared to the
raw undigested and all digested samples. The majority of African pumpkin and spinach extracts
(non-digested and digested) protected Deoxyribonucleic acid (DNA), (mouse fibroblast) L929 and human
epithelial colorectal adenocarcinoma (Caco-2) cells from 2,20-Azobis(2-methylpropionamidine)
dihydrochloride (AAPH)-induced oxidative damage. From these results, the consumption of boiled
African pumpkin leaves, as well as spinach, could be encouraged, as bioactive metabolites present
may reduce oxidative stress in the body.
