Bioassay-guided isolation in Salvia abrotanoides Karel. stem based on its anti-fungal and anti-trichomonas activity

Background and purpose:

 Salvia abrotanoides is considered a medicinal plant and has a broad distribution in Iran. In Iran's traditional medicine, it is also used to treat leishmaniasis, malaria, atherosclerosis, cardiovascular disease, and as a disinfectant. This research aimed to determine the anti-Candida component from S. abratonoides and anti-Trichomonas natural compounds from the stems of this plant. 

Experimental approach:

 The plant shoots were collected, dried, and after removing the leaves, grounded. Dried plant material was extracted in a maceration tank, concentrated by a Rotavap, degreased, and fractionated by normal column chromatography. Based on anti-fungal screening against Candida species, Fr. 4, with more anti-fungal activity, was selected for phytochemical analysis, by different chromatographic methods on the silica gel column and Sephadex LH-20. Isolated compounds were elucidated by NMR analysis, mass spectrum, and ultraviolet spectroscopy. Anti-fungal effects were investigated using the fungal suspension, incubation, and parasite-counting methods on purified compounds. Antibacterial effects were assessed using the Broth dilution test and reported according to the MIC parameter.

Two diterpenoid compounds named carnosol (compound 1), 11-hydroxy-12-methoxy-20- norabiata-8, 11, 13-trien (compound 2), and a flavonoid: 6,7-dimethoxy-5, 4'-dihydroxyflavone (compound 3) were isolated and identified. Compound 1 had selective anti-fungal effects against C. albicans, C. glabrata, and C. parapsilosis, but weak toxicity against Trichomonas vaginalis with IC50 of 675.8 μg/mL, less than metronidazole with an IC50 of 13.2 μg/mL. 

Conclusion and implications:

Carnosol as the main component was assayed against Candida, Aspergillus, Rhizopus, and Trichomanas species. The results confirmed its effect on Candida compared to standard drugs.