Chiral amide derivatives of ricinoleic acid and 3-hydroxynonanoic acid synthesis and cytotoxic activity

A series of chiral ricinoleic and 3-hydroxynonanoic acid derivatives were synthesized in this study using various chemical and biochemical procedures. An effective method for preparation of methyl esters of 3-hydroxynonanoic acid from castor oil or methyl ricinoleate by ozonolysis and oxidation was developed. Simple, fast, and efficient procedures were applied to obtain different primary and secondary, cyclic and acyclic amides, including hydroxamic acids. Among 24 synthesized derivatives of ricinoleic and 3-hydroxynonanoic acids, i.e., methyl esters, amides, and hydroxamic acids, 16 compounds were obtained and described for the first time. The synthesized compounds showed activity against the tested cancer cells, but the best cytotoxic effect was observed for hydroxamic acid derived from 3-hydroxynonanoic acid (11) against HeLa cells. In general, most of the tested compounds were more toxic against HT29 than HeLa cancer cells. The results also showed that there was no significant difference between activities of (R)- and (S)-enantiomer of particular derivatives.