HIV-1-Inhibiting Activity of the Essential Oil of Ridolfia segetum and Oenanthe crocata

The essential oils of Ridolfia segetum (L.) Moris and Oenanthe crocata L. (Apiaceae), collected in Sardinia (Italy), have been assayed for two enzyme-associated activities of the HIV-1 reverse transcriptase (RT): RNA-dependent DNA polymerase (RDDP) activity and ribonuclease H (RNase H) activity. In biochemical assays, the essential oils inhibited HIV-1 RT RDDP activity in a dose-dependent manner, while they were inactive towards RNase H activity. Furthermore, the oils were cytotoxic towards K562 cell replication. GC‐MS analysis of the essential oils obtained by steam distillation of the aerial parts showed that the main components of R. segetum were alpha-phellandrene, alpha-terpinolene, beta-phellandrene, and dillapiol and those of O. crocata were sabinene, trans-beta-ocimene, cis-beta-ocimene, and beta-pinene.