Diterpenes from Coleus forskohlii (WILLD.) BRIQ. (Labiatae).
Three new minor labdane diterpene glycosides, forskoditerpenoside C, D, and E (1-3), and a novel labdane diterpene forskoditerpene A (4) were isolated from the ethanol extract of the whole plant of Coleus forskohlii. Their structures and relative stereochemistry were elucidated on the basis of extensive spectroscopic analyses including 1D-, 2D-NMR, and HR-ESI-MS experiments. Compounds 1-3 showed an unusual 8,13-epoxy-labd-14-en-11-one glycoside pattern. They showed relaxative effects on isolated guinea pig tracheal spirals in vitro. Compound 4 with a cyclopropyl, confirmed by a single-crystal X-ray diffraction determination, is the first known labdane derivative with a spiro element.
A New Configurational Analysis of 1,6,7-triacetoxy-8,13-epoxy-14-labden- 11-one Isolated from Plectranthus ornatus Based on NMR and Theoretical Calculations
This work describes the configurational and conformational analyses of 1,6,7-triacetoxy-8,13-epoxy-14-labden- 11-one, a labdane diterpenoid isolated from Plectranthus ornatus. Its relative stereochemistry was previously proposed by comparison with 1 H and 13 C NMR data of forskolin (2); however, the configurations of C-8 and C-13 have not been con- firmed. Correlations between 13 C NMR experimental data and HF/6-31G* calculated values of carbon chemical shifts were performed for configurational and conformational analyses. This procedure was formerly applied to the configura- tional analysis of 2. Among the seven different forskolin-type structures investigated, the 13 C NMR data of 2 correlated best with those with the same stereochemistry of 2 described in the literature. Thus, the same procedure was considered valid for configurational analysis of the labdane diterpenoid isolated from P. ornatus. The relative stereochemistry of this compound based on theoretical calculations was similar to the structure previously proposed, but the best results were ob- tained considering configurational inversion at C-13.
HPLC determination of chlorhexidine gluconate and p-chloroaniline in topical ointment.
A novel fast isocratic reversed-phase HPLC method for simultaneous determination of chlorhexidine and its degradation product p-chloroaniline was developed. Zorbax SB Phenyl column (75 mm x 4.6 mm, 3.5 microm) was used for the separation. Mobile phase composed of acetonitrile and buffer solution of 0.08 M sodium phosphate monobasic containing 5 ml of triethylamine (0.5%) and adjust with 85% phosphoric acid to pH 3.0 in ratio 35:65 (v/v) pumped isocratically at flow rate 0.6 ml min(-1) was used. UV detection was performed at 239 nm, the total analysis time was about 10 min. The method is suitable for practical routine analysis of topical ointment in the quality control laboratory.