Globularia alypum L. is a wild plant belonging to Globulariaceae family. It is a perennial shrub which is found throughout the mediterranean area. The plant is known for its uses in the indigenous system of medicine for a variety of purposes.1) In the Moroccan Traditional Pharmacopoeia, G. alypum locally named "Ain Larneb" is one of the most traditional plant remedies.2) Its leaves are traditionally used as hypoglycaemic agent, laxative, cholagogue, stomachic, purgative and sudorific.3) It is also used in the treatment of cardiovascular and renal diseases as demonstrated by a recent ethnobotanical surveys, which showed that G. alypum is one of the most used medicinal plant in Morocco.2,4) The infusion of G. alypum, exhibiting no toxicological effects, was thus shown to produce a significant hypoglycaemic in rats both by oral and intraperitoneal administration.5) A significant antileukemic activity of an aqueous extract of G. alypum was also reported. 6) Recently, methanol and dichloromethane extracts of G. alypum were also shown to reduce histamine and serotonin contraction in vitro.
7)As part of our continuing search of bioactive natural products, we investigated the iridoids of G. alypum grown in Morocco. The wide use of this plant for the treatment of many diseases in addition to the fact that no phytochemical study is reported on the Moroccan G. alypum strain prompted us to explore its chemical composition related to its antioxidative activity. So far, the only chemical investigations of G. alypum are those of Bernard et al.,8,9) Chaudhuri and Sticher [10][11][12] and Ben Hassine et al. 13) where the presence of some glycosidic iridoids, flavonoids and a lignan diglucoside was reported. Our preliminary investigations on the biological activity of this plant showed that the hydro-methanolic extract of its aerial parts exhibited significant antioxidant effect, based on the scavenging activity of the stable 2,2-dipenyl-1-picrylhydrazyl (DPPH) free radical. We report here the isolation and the structure elucidation of a new chlorinated iridoid named globularioside along with 5 known iridoids by ESI/MS, MS-MS, 1D and 2D NMR analysis.
ExperimentalGeneral Experimental Procedures UV-visible spectra were recorded using a Kontron Uvikon 930 spectrophotometer fitted with a quartz cell. Optical rotations were measured on a Perkin-Elmer 141 polarimeter. FT-IR spectra were recorded with a Nicolet Avatar 320 FT-IR spectrophotometer. 1 H-and 13 C-NMR spectra were recorded in CD 3 OD with a Varian Mercury plus 300 spectrometer at 300 and 75 MHz, respectively for 1 H and 13 C (broad band proton decoupling mode for carbon). Analytical TLC was performed on Merck silica gel 60 F254 plates. Column chromatography was performed on SPE column using mixtures of MeOH/Water. Analytical HPLC analysis was performed on a Varian apparatus including a 9012 solvent delivery system, a 9100 autosampler and a 9065 polychrom diode array detector. Analysis were performed on a Kromasil reversed phase C18 5 mm column (250ϫ4.6 mm) eluting with a m...