The production and antiprotozoal activity of abietane diterpenes in Salvia austriaca hairy roots grown in shake flasks and bioreactor

The biomass and concentration of bioactive quinone methide-type diterpenes in hairy roots of Salvia austriaca were determined and compared with levels of these metabolites in roots of field-grown plants. The cultures were maintained in shake flasks and a nutrient sprinkle bioreactor. Diterpene production was more efficient in the shake flask root culture than the bioreactor one. Biomass and diterpene production within the shake flask culture was evaluated using Schenk and Hildebrandt (SH), Gamborg (B5), and woody plant medium (WPM), with both full- and half-strength macro and micronutrient concentrations (1/2 SH, 1/2 B5, and 1/2 WPM). Among the tested media, SH medium proved to be most effective for biomass and diterpene production. In this medium, the transformed roots accumulated the levels of taxodone (3.89 mg g(-1) DW; equivalent to 63.3 mg L(-1)), taxodione (1.15 mg g(-1) DW; equivalent to 17.4 mg L(-1)), 15-deoxy-fuerstione (2.15 mg g(-1) DW; equivalent to 32.5 mg L(-1)), and 7-(2'-oxohexyl)-taxodione (0.076 mg g(-1) DW; equivalent to 1.1 mg L(-1)). Three diterpenes were also detected in the roots of S. austriaca intact plants, but their concentrations were lower than those in hairy root culture. No 7-(2'-oxohexyl)-taxodione was found in the roots of field-grown plants. The hairy roots were able to maintain high metabolite levels even for 6 years of cultivation. Taxodone, taxodione, 15-deoxy-fuerstione, and 7-(2'-oxohexyl)-taxodione were tested for in vitro activity against Trypanosoma brucei rhodesiense, T. cruzi, and Plasmodium falciparum and their cytotoxicity was determined using L6 cells. Among these compounds, taxodione was the most active against T. brucei rhodesiense [IC50 = 0.05 µM with high selectivity, selectivity index (SI) = 38]. Taxodione was found to inhibit the growth of P. falciparum and T. cruzi by 50% at respective concentrations of 1.9 and 7.1 µM (SI values of 1.0 and 0.27). Other diterpenoids demonstrated weaker activity against tested parasites (IC50 values ranging from 0.62 to 194.7 µM) and lower selectivity (SI value ranged from 0.4 to 5.0).