Natural anti-HIV agents. Part 3: Litseaverticillols A–H, novel sesquiterpenes from Litsea verticillata

Bioassay directed-fractionation led to the identification of litseaverticillols A–H () from the leaves and twigs of Litsea verticillata Hance. These new sesquiterpenes possess a unique skeleton that was recently designated as ‘litseane’. The structures of these compounds were determined by spectroscopic means including 1D and 2D NMR data. Structural configurations were determined by ROESY experiments. Mosher ester reactions and optical rotation measurements established the sesquiterpenes as racemates. Isolates inhibited HIV-1 replication in HOG.R5 cells with IC50 values ranging from 2 to 15 μg/ml (8–58 μM) while affecting the growth of HOG.R5 at concentrations 2–3-fold higher. Based on this data, structure–activity relationships can be discerned, suggesting compounds of this class are good candidates for analog production.