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.

New control methods are necessary for stored grain pest management programs due to both the widespread problems of insecticide-resistance populations and the increasing concerns of consumers regarding pesticide residues in food products. Thus, this study evaluated the bioactivity of extracts and fractions obtained from different structures (leaves, branches, and seeds) of Annona mucosa (Annonaceae) against Sitophilus zeamais (Coleoptera: Curculionidae), which is a primary insect pest of stored cereals in tropical conditions. In the screening assay, the most promising treatments were extracts prepared from the seeds of Annona mucosa in hexane and dichloromethane (LC 90 values of 259.31 and 425.15 mg kg À1 , respectively) and, to a lesser extent, an extract prepared from the leaves in hexane (LC 90 of 1047.15 mg kg À1). Based on these results and the chromatographic profile of the bioactive crude extracts, the extract prepared from the seeds in hexane was fractionated by liquideliquid partitioning. The dichloromethane and hydroalcoholic fractions exhibited insecticidal activity against S. zeamais, and no significant difference was observed between these two fractions. The chemical analyses (1 H NMR, HPLC, and TLC) showed the presence of alkaloids and acetogenins in the bioactive fractions, which are likely related to the observed bioactivity. Thus, A. mucosa, particularly its seeds, is a promising source of compounds that can be used as a prototype model and/or a biorational insecticide for the control of S. zeamais in stored cereals.

Huanglongbing (HLB) is the most devastating disease of citrus worldwide. It is caused by bacteria of the genus 'Candidatus Liberibacter' and transmitted by two psyllid species, the Asian citrus psyllid (ACP) Diaphorina citri, and the African citrus psyllid Trioza erytreae. Considerable research has been conducted toward developing and implementing HLB and ACP management strategies. With respect to ACP control, of interest is that reports indicate guava, Psidium guajava, can be repellent to ACP. We conducted research to further evaluate repellency of guava to ACP. In one set of experiments, guava oil from five Brazilian guava cultivars ('J3', 'Pedro Sato', 'Século XXI', 'Thailand' and 'Paluma') was extracted from leaves (immature and mature) by hydrodistillation in a Clevenger-type apparatus and evaluated for psyllid repellency. In a second set of experiments, repellency of guava leaves to ACP was investigated using leaves (immature and mature) from two guava cultivars in Florida, 'Pink' and 'Thai White'. In each set of experiments, repellency was evaluated by releasing ACP adults into a cage with two large vials, one containing a young flush shoot (= immature leaves) of Murraya exotica (a favored host plant of the psyllid, the flush of which is highly attractive to ACP) and one with M. exotica flush and the test material of interest (guava oil, immature guava leaf or mature guava leaf). The adults were free to move throughout the cage and into the vials, and the number of psyllids in each vial was counted after 24 h. The results showed that all guava materials tested had at least some repellency to ACP. Mature leaves tended to have a greater repellent effect than immature leaves. Each of the five oils exhibited repellency. A report in the literature suggested that sulfur compounds associated with guava may be responsible for ACP repellency. Interestingly, the five guava oil extracts we studied were repellent to ACP but none contained any sulfur compounds. Identification of the constituents responsible for repellency could lead to new ACP management tactics.

No abstract

The toxicity of organic plant extracts to Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) was assessed for three tropical plant species: branches, leaves, and seeds of Annona montana (Annonaceae), branches of Aristolochia paulistana (Aristolochiaceae), and leaves and branches of Casearia sylvestris (Salicaceae). The screening assay resulted that the extracts of A. montana seeds obtained with hexane (LC50 = 534.75 mg kg(-1) and LT50 = 6.10 days) and with dichloromethane (LC50 = 424.67 mg kg(-1) and LT50 = 5.03 days) were the most promising treatments, followed by the extract prepared from A. montana leaves with hexane (LC50 = 837.70 mg kg(-1) and LT50 = 4.90 days). Moreover, extracts (at 1,500 mg kg(-1)) prepared from C. sylvestris branches with dichloromethane and A. paulistana with hexane caused significant mortality (37% and 41.5%, respectively) beyond sublethal effects on S. zeamais. Therefore, based on the biological assays, extraction yield, and evaluation of the chromatographic profile of the crude extracts by TLC, the hexane extract of A. montana seeds was selected and fractioned using liquid-liquid partitioning. The hydroalcoholic fraction caused mortality of 55.5%, significantly superior to dichloromethane fraction, which caused 35.5% of mortality. Chemical analyses ((1)H NMR, HPLC, and TLC) were performed, and the results showed the presence of alkaloids and acetogenins in both active fractions, which have been associated with bioactivity. Therefore, extracts prepared from A. montana seeds (especially) is an interesting source of new compounds with promising grain-protectant properties.