A study of flavonoid composition and antimicrobial activity of Scutellaria altissima L. from different floristic regions of Bulgaria.

INTRODUCTION: Scutellaria extracts and its constituents, especially the characteristic flavonoids such as baicalein and its glycoside baicalin, exhibit significant antimicrobial activity. AIM: To perform a comparative analysis of flavonoid composition and antimicrobial activity of extracts obtained from aerial parts and roots of Scutellaria altissima from the regions of Mezek and Bachkovo, Bulgaria. MATERIALS AND METHODS: 70% ethanol and aqueous extracts of aerial parts and roots of S. altissima were used. HPLC analysis of S. altissima extracts was performed. Microbiological tests were done on clinical isolates of Streptococcus mitis, Staphylococcus aureus, Escherichia coli, and Candida albicans. Minimal bactericidal and minimal bacteriostatic concentrations of S. altissima extracts were determined by the agar method. RESULTS: The ethanol extracts contain flavonoids approximately twice as much in comparison with the aqueous extracts. The baicalin content in the aerial parts of S. altissima from the region of Mezek is 5 times higher than that in the roots. S. altissima extracts have effective antimicrobial activity against S. mitis only. The minimal bactericidal concentration of ethanol extracts of S. altissima aerial parts and S. altissima roots is 2000 µg/ml and 8000 µg/ml at 24 hours, respectively. The bactericidal effect of aqueous extracts occurs at 48 hours at minimal bactericidal concentration of S. altissima aerial parts - 2000 µg/ml and of S. altissima roots - 6000 µg/ml. CONCLUSIONS: The finding that extracts of Bulgarian S. altissima possess effective antimicrobial properties against S. mitis suggests that it can be used as a potential source for the development of natural antimicrobial agents to suppress oral pathogens and prevent some oral infections.

Antifeedant Activity of Neo-clerodane Diterpenoids from Scutellaria altissima against Colorado Potato Beetle Larvae.

Fourteen neo-clerodane diterpenoids isolated from Scutellaria altissima (Lamiaceae) were tested for insect antifeedant activity against Leptinotarsa decemlineata Say. Potato leaf disks treated with small amounts of the compounds (concentration 1000, 100, 10 ppm) resulted in good to very good antifeedant activity. Clerodin (1), scutecyprin (11) and 11-epi-scutecolumnin C (12) showed strong feeding inhibition at 1000 ppm and exhibited significant antifeedant activity at a concentration of 100 ppm. Activity was established by calculating the feeding ratio (FR) between the consumed areas of treated disks (CTD) and control disks (CCD). For comparison, FR50 values were determined as the FR at a CCD of 50%. Structural features of the compounds associated with the changes in activity and structure-antifeedant activity relationships are discussed. For the first time the anti-feedant activity has been evaluated of neo-clerodane diterpenoids with an unusual R-configuration of the carbon atom C-I 1.