Antioxidant and antigenotoxic properties of compounds isolated from Marrubium

In our continual course toward the valorization of traditionally used endemic flora through the analysis of its chemobiodiversity, the phytochemical analysis of aerial parts of Marrubium deserti de Noe was undertaken. Dichloromethane and methanol extracts led to the isolation of terpenoid derivatives among which two were new labdane diterpenes named marrulibacetal A and desertine, respectively. Six of them were known compounds (a mixture of the isomers cyllenin A and 15-epi-cyllenin A, marrubiin, marrulactone, marrulibacetal and b-stigmasterol) and seven known phenolic compounds were also isolated: apigenin and several 7-O-substituted derivatives (apigenin-7-O-b-neohesperidoside, apigenin-7-O-glucoside, terniflorin and apigenin-7-O-glucuronide) together with two phenylethanoid glucosides (acteoside and forsythoside B). The structures and relative configurations of the new compounds were elucidated by MS and a series of 1D and 2D NMR analyses. Some pure compounds have been evaluated for their antioxidant activities through different methods: DPPH and ABTS assays as well as CUPRAC assay. Genotoxic and antigenotoxic activities of extracts and pure compounds were also evaluated in vitro on Escherichia coli PQ37 cells by the SOS Chromotest. Some of the isolated compounds like phenylethanoid derivatives showed stronger antioxidant capacity than trolox and were also able to significantly inhibit b-galactosidase induction caused by the mutagen agent nitrofurantoin. 2011 Published by Elsevier Ltd.