Isolation and structural elucidation of biological active metabolites from Cleome Arabica L.

Isolation and Structural Elucidation of Biological Active Metabolites from Cleome arabica L. Marina DellaGreca, Afel Ladhari Dipartimento di Scienze Chimiche, Università di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cintia 21, I-80126 Napoli, Italy E-mail: dellagre@unina.it Secondary metabolites produced by plants and having biological activity have been broadly described in literature but only a small subset has been studied in connection with allelopathy, and their action mechanism is still far from being understood. Thus there is still a wide array of natural compounds to be investigated for more complete view of allelopathy. Our research in the bioactive natural products isolated from Mediterranean plants and their use as natural herbicide models started some years ago. Chemical studies of plants such as Sambucus nigra, Cestrum parqui, Juncus acutus, and Aptenia cordifolia etc., furnished many new phytotoxic compounds showing interesting effects on the germination and development of standard test species. Very recently, we also addressed our attention on the Capparidaceae, widespread plants in the North Africa. Cleome L. is a large genus with 150 species in the tropical and subtropical countries both in the Old and New World. Investigation of the plant extracts of Cleome arabica L. led to the isolation of compounds belonging to different classes: triterpenoids with dammarane and cucurbitane skeleton, flavonoids, flavonol glycosides and lignans. The structures of these phytoconstituents have been elucidated through extensive spectroscopic techniques, including UV, IR, 1D and 2D NMR, ESI-MS and HRESI-MS spectra.