Biological activities of iridoids from Scutellaria rupestris ssp. adenotricha
In continuation of our phytochemical research into Scutellaria (Lamiaceae) species of the Greek flora [1,2] we report the phytochemical analysis of S. rupestris Boiss. & Heldr. ssp. adenotricha (Boiss. & Heldr.) Greuter & Burdet., an endemic taxon of NW Greece and Albania . Several species of the genus Scutellaria present antispasmodic, diaphoretic and febrifuge properties and are used in folk medicine . The main products of the plant are scutellarioside I (globularin), albidoside and catalpol with catalpol being a useful taxonomic marker for the genus Scutellaria . The structures of the isolated compounds were established by means of NMR (1H-1H-COSY, 1H-13C-HSQC, HMBC, NOESY). The main constituents of the plant were examined for their antibacterial activity against Escherichia coli, Bacillus subtilis, Bacillus megaterium and Staphylococcus aureus. DNA mobility shift assays were performed for the determination of the in vitro effect of the compounds on the integrity and the electrophoretic mobility of pDNA. In addition, the compounds were examined for their ability to inhibit DNA polymerase in a PCR amplification of a target gene. Although the compounds under study did not show any antibacterial activity they demonstrated a remarkable ability to inhibit DNA polymerase. The DNA mobility shift assays also revealed that catalpol and albidoside interact with pDNA resulting in the retardation of the pDNA mobility.
Acknowledgement: The authors are grateful to Ass. Prof. Theophanis Constantinidis (Institute of Systematic Botany, Agricultural University of Athens) for the identification of the plant material.
References: 1. Skaltsa H.D., Lazari D.M. et. al. (2000). Planta Med 66: 672–674. 2. Skaltsa, H.D., Lazari, D.M., et. al. (2005). JEOR 17: 232–235. 3. Bothmer, R. (1987) Plant Syst Evol: 155: 219–249. 4. Duke, J.A. Handbook of Medicinal Herbs, CRC Press. Inc., Boca Raton, 1986: 440. 5. Cole, M.D., et al. (1991) Biochem. Syst. Ecol. 19: 333–335.