Composition, antioxidant capacity and cytotoxic activity of Eugenia uniflora L. chemotype-oils from the Amazon.

ETHNOPHARMACOLOGICAL RELEVANCE: Oils and extracts of Eugenia uniflora have been reported as antimicrobial, antifungal, antinociceptive, antiprotozoal, antioxidant and cytotoxic.

AIM OF THE STUDY: The oils of five specimens (E1 to E5) that occur in the Brazilian Amazon were extracted, analyzed for their chemical composition, and submitted to antioxidant and cytotoxic assays.

MATERIAL AND METHODS: Oils were hydrodistilled, analyzed by GC and GC-MS, and submitted to PCA and HCA analyses. The antioxidant activity of the oils was evaluated by the DPPH radical scavenging and the β-carotene/linoleic acid assays. Antiproliferative effects of the oils and curzerene were tested against colon (HCT-116), gastric (AGP-01), and melanoma (SKMEL-19) human cancer cell lines and a normal human fibroblast cell line (MRC-5), using MTT assay.

RESULTS: Oxygenated sesquiterpenes and sesquiterpene hydrocarbons such as curzerene, selina-1,3,7(11)-trien-2-one, selina-1,3,7(11)-trien-2-one epoxide, germacrene B, caryophyllene oxide, and (E)-caryophyllene were predominant in the oils. PCA and HCA analyses classified the oils samples into four chemotypes. TEAC values of chemotype II (E3 oil, 228.3±19.2mg TE/mL) and chemotype III (E4 oil, 217.0±23.3mg TE/mL) displayed significant antioxidant activities. The oils E2 and E4 showed cytotoxic activity against all cell lines tested HCT-116 (IC50 E2: 16.26μg/mL; IC50 E4: 9.28μg/mL), AGP-01, (IC50 E2: 12.60μg/mL; IC50 E4: 8.73μg/mL), SKMEL-19 (IC50 E2: 12.20μg/mL; IC50 E4: 15.42μg/mL), and MRC-5 (IC50 E2: 10.27μg/mL; IC50 E4: 14.95μg/mL). Curzerene showed the more significant activity against melanoma cells (SKMEL-19, IC50 : 5.17μM), induced apoptosis at 5.0μM and 10.0μM compared to DMSO, exhibiting a decrease in the cell migration at 5.0μM and 10.0μM, after 30h of treatment.

CONCLUSION: The curzerene chemotype oil and E. uniflora oils can be indicated as drug candidates for anticancer activity of the lung, colon, stomach, and melanoma, with a real prospect to their subsequent phytotherapeutic development.