Figure 1.

(A) Chemical structures of bis(5-methylthio-3-oxo-undecyl) disulfide (1), 5-methylthio-1-(3-oxo-undecyl)disulfanylundecan-3-one (2) and 3-hexyl-4,5-dithiocycloheptanone (3) isolated from D. membranacea. (B) IC₅₀ values of 1–3; measuring compound concentration resulting in 50% inhibition of NO production in RAW 264.7 cells. (C–E) Cytostatic activity of 1–3; evaluating compound effect on the proliferation rate of RAW 264.7 cells. Proliferation rate was measured using MTT tetrazolium dye, it was normalized to initial cells plated and compared to cells treated with carbowax 400 0.1% v/v + 0.01% ethanol. Statistical analysis was carried out using a Mann–Whitney unpaired t-test in Graphpad Prism 7.0 and graphs represent mean ± SEM (* indicates p < 0.05, ** indicates p < 0.01, *** indicates p < 0.001).