Constituents of Leonotis leonurus Flowering Tops

Leonotis leonurus L., also known as Lion's Tail or Wild Dagga, is a member of the Mint family (Lamiaceae). The plant is reported to have anticonvulsant [1], antinociceptive, anti-inflammatory and hypoglycemic activities [2]. Several labdane diterpenoids were reported in the leaves and aerial parts. However, no work has been reported on the flowers of this plant. A phytochemical study of the flowering tops of L. leonurus yielded a new diterpene ester 1,2,3-trihydroxy-3,7,11,15-tetramethylhexadecan-1-palmitate (1) along with providing new source for five known compounds identified as succinic acid (2), uracil (3), luteolin 7-O-glucoside (4), acteoside (5), and geniposidic acid (6). The structures of 1–6 were determined by spectroscopic methods including 1D- and 2D-NMR, IR, UV, MS etc. All six compounds were evaluated for their antimalarial and cytotoxic activities. Antimalarial activity was observed only for compound 4 (IC₅₀ s = 2.2 µg/mL for D6 clone, and 2.6 µg/mL for W2 clone) [3]. Cytotoxicity was not observed for any of these compounds up to a concentration of 4.76 µg/mL. Acknowledgements: This work was supported in part by the United States Department of Agriculture, Agricultural Research Service, Specific Cooperative Agreement No 58-6408-2-0009 and Grant Number P20RR021929 from the National Center For Research Resources. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health. References: [1] Bienvenu E, et al. (2002) Phytomedicine, 9: 217–223. [2] Ojewole JAO (2005) Methods and findings in experimental and clinical pharmacology, 27: 257–64. [3] Kirmizibekmez H, et al. (2004) Planta Medica 70(8): 711–717.