Essential oils from Schinus terebinthifolius leaves - chemical composition and in vitro cytotoxicity evaluation

Context: In folk medicine, Schinus terebinthifolius Raddi (Anacardiaceae), has been used as a remedy for ulcers, respiratory problems, wounds, rheumatism, gout, diarrhea, skin ailments and arthritis, as well as to treat tumors and leprosy. Objective: To investigate the chemical composition and cytotoxicity of essential oil from leaves of S. terebinthifolius as well as the identification of active compounds from this oil. Material and methods: Essential oil from S. terebinthifolius leaves, obtained by hydrodistillation using a Clevenger-type apparatus, was characterized in terms of its chemical composition. Also, the crude oil was subjected to chromatographic separation procedures to afford an active fraction composed of alpha- and beta-pinenes. These compounds, including hydrogenation (pinane) and epoxydation (alpha-pinene oxide) derivatives from alpha-pinene, were tested in vitro against murine melanoma cell line (B16F10-Nex2) and human melanoma (A2058), breast adenocarcinoma (MCF7), leukemia (human leukemia (HL-60) and cervical carcinoma (HeLa) cell lines. Results: Forty-nine constituents were identified in the oil (97.9% of the total), with germacrene D (23.7%), bicyclogermacrene (15.0%), beta-pinene (9.1%) and beta-longipinene (8.1%) as the main compounds. The crude essential oil showed cytotoxic effects in several cell lines, mainly on leukemia and human cervical carcinoma. Fractions composed mainly of alpha- and beta-pinenes as well as those composed of individually pinenes showed effective activities against all tested cell lines. Aiming to determinate preliminary structure/activity relationships, alpha-pinene was subjected to epoxydation and hydrogenation procedures whose obtained alpha-pinene oxide showed an expressive depression in its cytotoxicity effect, similar as observed to pinane derivative. Discussion and conclusion: The obtained results indicated that the monoterpenes alpha- and beta-pinenes could be responsible to the cytotoxic activity detected in the crude oil from leaves of S. terebinthifolius. In addition, it was possibly inferred that the presence of double bond in their structures, mainly at endocyclic position, is crucial to cytotoxic potential detected in these derivatives.