DITERPENOIDS FROM THE AERIAL PARTS OF ISODON EXCISUS (MAXIM.) KUDÔ

Isodon excisus (Maxim.) Kudô (synonyms: Amethystanthus excisus (Maxim.), Rabdosia excisa (Maxim.), Plectranthus excisus Maxim.) is a perennial plant of the Lamiaceae family, the aerial part of which is used in traditional Chinese medicine to treat various diseases. Pharmacological studies of I. excisus have shown that diterpenoids are the main biologically active compounds of this plant and have antitumor, antibacterial, anti-inflammatory and antioxidant properties. To further study the pharmacological properties of I. excisus, it is necessary to continue research on the composition of diterpenoid compounds in this plant. Using extraction methods, preparative column chromatography and reverse-phase high-performance liquid chromatography (RP-HPLC) from the aerial part of the I. excisus plant growing in the Far East of Russia, 6 diterpenoids were isolated: rabdokunmin C (1), excisanin A (2), kamebakaurin (3), weisiensin C (4), wikstroemioidin T (5), excisanin E (6). Diterpenoids weisiensin C and wikstroemioidin T were isolated from I. excisus for the first time. The structure of the isolated compounds was confirmed by 13C NMR spectroscopy. Quantitative determination of diterpenoids in extracts of the aerial parts of I. excisus was conducted by RP-HPLC using the calibration curve method. The dominant diterpenoid in the aerial part of I. excisus is kamebakaurin (0.72±0.07)%, the content of wikstroemioidin T and weisiensin C in the plant is (0.011±0.002)% and (0.010±0.002)%, respectively. Excisanin A is present in trace amounts in I. excisus.