In vitro hypoglycaemic and ACE inhibitory activities of Marrubium radiatum Devile ex Benth and Salvia acetabulosa L.: two traditional medicinal plants from Lebanon

Marrubium radiatum Devile ex Benth and Salvia acetabulosa L. (Lamiaceae) were used for treatment of hypertension and diabetes in Lebanon traditional medicine. In order to find a scientific validation of their traditional use, in vitro assays for alpha-amylase and alpha-glucosidase inhibition were performed while the antihypertensive action was analysed by the inhibition of Angiotensin Converting Enzyme (ACE) [1-3]. Plant material was extracted using methanol or n-hexane as solvent [4]. The ACE inhibitory activity was measured trough the cleavage of the chromophore-fluorophore labelled substrate dansyltriglycine by ACE preparation from rabbit lung (EC 3.4.15.1) into dansylglycine, which is quantitatively measured by HPLC. M. radiatum showed a IC50 of 72.79 and 75.42 microg/mL while S. acetabulosa exhibited a IC50 of 52.71 and 105.22 microg/mL for MeOH and n-hexane, respectively. The glucose absorption, from the intestine to the blood is elated to the alpha-amylase and alpha-glucosidase activity. Both M. radiatum and S. acetabulosa are able to inhibit alpha-amylase. In particular the MeOH extract exert highest activity with a IC50 of 61.12 and 91.16 microg/mL. The ability of M. radiatum and S. acetabulosa MeOH extract to inhibit alpha-glucosidase was weak (IC50 of 365.95 and 315.89 microg/mL). In conclusion, this study supports the traditional use of these species and further work is necessary in order to identify active principles responsible for the found activities.