Mimonoside D: a new triterpenoid saponin from Mimosa diplotricha Sauvalle (Fabaceae)

A new triterpenoid saponin (Mimonoside D: 3-O-alpha-L-arabinopyranosyl-3 beta-hydroxyolean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl-(1 -> 2)-beta-D- glucopyranoside ester (1)) was isolated from the aerial parts of Mimosa diplotricha Sauvalle together with nine known compounds: 7,4 '-dihydroxyflavone (2), kaempferol (3), lupeol (4), betulinic acid (5), beta-sitosterol (6), beta-sitosterol-3-O-beta-D-glucopyranoside (7), lutein (8), 5,2 '-dihydroxy-7,4 ',5 '-trimethoxyflavone (9) and vitexin (10). Their structures were elucidated on the basis of spectroscopic (1 D and 2 D nuclear magnetic resonance) and high-resolution mass spectrometric data as well as by comparison of their spectral data with those of related compounds. Compounds 2, 7 and 8 had already been isolated from M. diplotricha, while compounds 3, 4, 5 and 6 have been isolated from other Mimosa species. Compound 2 moderately inhibited Proteus mirabilis (MIC = 32 mu g/mL), weakly inhibited Pseudomonas aeruginosa (MIC = 64 mu g/mL) and very weakly inhibited Staphylococcus aureus (MIC = 128 mu g/mL) and Enterococus faecalis (MIC = 128 mu g/mL).

Automated summary

A new triterpenoid saponin and nine known compounds were isolated from Mimosa diplotricha. The structure of the new compound was elucidated through spectroscopic and mass spectrometric data. One of the compounds showed inhibitory activity against Proteus mirabilis and Pseudomonas aeruginosa.