Plants are promising sources of new bioactive compounds. The aim of this study was to investigate the cytotoxic potential of nine plants found in Brazil. The species studied were: Annona pickelii Diels (Annonaceae), Annona salzmannii A. DC. (Annonaceae), Guatteria blepharophylla Mart. (Annonaceae), Guatteria hispida (R. E. Fr.) Erkens & Maas (Annonaceae), Hancornia speciosa Gomes (Apocynaceae), Jatropha curcas L. (Euphorbiaceae), Kielmeyera rugosa Choisy (Clusiaceae), Lippia gracilis Schauer (Verbenaceae), and Hyptis calida Mart. Ex Benth (Lamiaceae). Different types of extractions from several parts of plants resulted in 43 extracts. Their cytotoxicity was tested against HCT-8 (colon carcinoma), MDA-MB-435 (melanoma), SF-295 (glioblastoma), and HL-60 (promielocitic leukemia) human tumor cell lines, using the thiazolyl blue test (MTT) assay. The active extracts were those obtained from G. blepharophylla, G. hispida, J. curcas, K. rugosa, and L. gracilis. In addition, seven compounds isolated from the active extracts were tested; among them, β-pinene found in G. hispida and one coumarin isolated from K. rugora showed weak cytotoxic activity. In summary, this manuscript contributes to the understanding of the potentialities of Brazilian plants as sources of new anticancer drugs.

Medicinal plants are one of the most important sources of drugs used in the pharmaceutical industry. Among traditional medicinal plants, Lippia gracilis Schauer (Verbenaceae) had been used for several medicinal purposes in Brazilian northeastern. In this study, leaf essential oil (EO) of L. gracilis was prepared using hydrodistillation. Followed by GC-MS analysis, its composition was characterized by the presence of thymol (55.50%), as major constituent. The effects of EO on cell proliferation and apoptosis induction were investigated in HepG2 cells. Furthermore, mice bearing Sarcoma 180 tumor cells were used to confirm its in vivo effectiveness. EO and its constituents (thymol, p-cymene, γ-terpinene and myrcene) displayed cytotoxicity to different tumor cell lines. EO treatment caused G1 arrest in HepG2 cells accompanied by the induction of DNA fragmentation without affecting cell membrane integrity. Cell morphology consistent with apoptosis and a remarkable activation of caspase-3 were also observed, suggesting induction of caspase-dependent apoptotic cell death. In vivo antitumor study showed tumor growth inhibition rates of 38.5-41.9%. In conclusion, the tested essential oil of L. gracilis leaves, which has thymol as its major constituent, possesses significant in vitro and in vivo antitumor activity. These data suggest that leaf essential oil of L. gracilis is a potential medicinal resource.

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Lippia gracilis Schauer is an aromatic plant widely found in Northeastern Brazil. The leaf infusions or decoctions and alcoholic macerate are used for some inflammatory diseases and headache. This paper reports the isolation of naringenin by semi-preparative liquid chromatography from the methanolic extract of L. gracilis (ELg) and the evaluation of the analgesic and anti-inflammatory activities of this extract by measuring nociception through acetic acid, formalin, and hot-plate tests in carrageenan-induced inflammation in mice. Following oral administration, ELg (100, 200, and 400 mg/kg) significantly reduced the number of writhes in the writhing test and the time of paw licks in both phases of the formalin test when compared to the control group animals. Mice treated with ELg did not exhibit any behavioral alteration during the hot plate and rota-rod tests, suggesting non-participation of the supraspinal components in the modulation of pain by ELg and no motor abnormality. The oral administration of 400 mg/kg of ELg produced an anti-inflammatory effect on peritonitis induced by carrageenan. These effects can be associated with a decrease of inflammatory mediator synthesis by compounds of ELg, such as naringenin, which has anti-inflammatory action as already described.

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