Structure and Absolute Configuration of Abietane Diterpenoids from Salvia clinopodioides: Antioxidant, Antiprotozoal, and Antipropulsive Activities

The aerial parts of Salvia clinopodioides afforded abietanes 1a, 2a, and 3 (clinopodiolides A–C), two of which possess an unusual lactol moiety at C-19–C-20, together with an icetexane named clinopodiolide D (4a). Their structures were established by spectroscopic means, mainly 1H and 13C NMR, including 1D and 2D homo- and heteronuclear experiments. The antioxidant, antiprotozoal, and antidiarrheal effects of the isolates were evaluated. Compounds 2a and 3 showed better effects than α-tocopherol in the inhibition of lipid peroxidation with IC50 (μM) = 5.9 ± 0.1 and 2.7 ± 0.2, respectively, and moderate activity in the DPPH assay. All tested compounds showed moderate antiamoebic and antigiardial activity, as well as a good antipropulsive effect.