Isolation and characterization of the chemical constituents from Plumeria rubra

•Purification and characterization of secondary metabolites (1-8) from Plumeria rubra.•These include five new (1-5) together with three known chemicals (6-8).•The structures were assigned based on spectroscopic and spectrometric analysis.

Rubranonoside (=7-O-α-l-rhamnopyranosyl-4′-O-β-d-glucopyranosylnaringenin; (1), a new flavanone glycoside, rubranin (=(2S,3S,4R)-2-{[(2R,16E)-2-hydroxyhexaeico-16-en]amino}octadecane-1,3,4-triol-1-O-β-d-glucopyranoside; (2), a new sphingolipid, rubradoid (plumieridine-1-O-β-d-galactopyranoside; (3), a new iridoid galactoside, rubrajaleelol (4) and rubrajaleelic acid (5), two new nor-terpenoids together with known iridoids: 1-α-plumieride (6), plumieride p-Z-coumarate (7) and plumieride-p-E-coumarate (8) have been isolated from the EtOAc-soluble fraction of the MeOH extract of Plumeria rubra. Their structures were assigned from 1H, 13C NMR spectra and 2D NMR analyses (COSY, NOESY, HMQC and HMBC experiments) in combination with HRMS experiments and comparison with literature data of related compounds. All the isolates (1-8) were tested for their antioxidant, antiurease, cytotoxic and phytotoxic activities and were found almost inactive.

Graphical abstractFive new compounds (1-5), together with 1-α-plumieride (6), plumieride p-Z-coumarate (7) and plumieride-p-E-coumarate (8) have been isolated from the EtOAc-soluble fraction of the MeOH extract of Plumeria rubra. Their structures were assigned from 1H, 13C NMR spectra and 2D NMR analyses (COSY, NOESY, HMQC and HMBC experiments) in combination with HRMS experiments and comparison with literature data of related compounds.Download full-size image