Cucumin S, a new phenylethyl chromone from Cucumis melo var. reticulatus seeds

ABSTRACT

ABSTRACTA new phenylethyl chromenone, cucumin S [(R)-5,7-dihydroxy-2-[1-hydroxy-2-(4-hydroxy-3-methoxyphenyl)ethyl]chromone] (1), along with five known compounds 5,7-dihydroxy-2-[2-(4-hydroxyphenyl)ethyl]chromone (2), 5,7-dihydroxy-2-[2-(3,4-dihydroxyphenyl)ethyl]chromone (3), luteolin (4), quercetin (5), and 7-glucosyloxy-5-hydroxy-2-[2-(4-hydroxyphenyl)ethyl]chromone (6) were isolated from the EtOAc fraction of Cucumis melo var. reticulatus Ser., Cucurbitaceae, seeds. Their structures were determined by spectroscopic means (1D and 2D NMR), as well as HRESIMS, optical rotation measurement, and comparison with literature data. The isolated compounds 1–6 were assessed for their antioxidant activity using DPPH assay. Compounds 3, 4, and 5 showed potent activities compared to propyl gallate at concentration 100 µM.