There is an urgent and unmet need for new antifungal therapies. Global fungal infection rates continue to rise and fungal infections pose increasing burdens on global healthcare systems. Exacerbating the situation, the available antifungal therapeutic arsenal is limited and development of new antifungals has been slow. Current antifungals are known for unwanted side effects including nephrotoxicity and hepatotoxicity. Thus, the need for new antifungals and new antifungal targets is urgent and growing. A collection of 60 commercially-available essential oils has been screened for antifungal activity against Aspergillus niger, Candida albicans, and Cryptococcus neoformans, as well as for cytotoxic activity against MCF-7 and MDA-MB-231 human breast tumor cell lines; the chemical compositions of the essential oils have been determined by gas chromatography-mass spectrometry (GC-MS). Ten essential oils showed remarkable antifungal and cytotoxic activities: Indian, Australian, and Hawaiian sandalwoods; melissa; lemongrass; cilantro; cassia; cinnamon; patchouli; and vetiver.
A pharmacological survey of flora of the Paluma rainforest including 90 species representing 19 families has been carried out. Crude plant extracts have been screened for cytotoxic, antibacterial, antifungal, and antiviral activity, as well as brine shrimp lethality. Of these, 27 extracts exhibited remarkable cytotoxic activity, 23 showed antimicrobial activity, and 7 showed promising antiviral activity. Thus, 53 of the plant species examined showed marked bioactivity in one or more bioassays; a "hit rate" of 59%. These results underscore the phytomedicinal potential of Australian tropical rainforests.
The leaf essential oils of Beilschmiedia sp. nov. "chancho blanco", Cinnamomum costaricanum, Ocotea meziana, Ocotea sp. nov. "los llanos" and Ocotea sp. nov. "small leaf" showed notable in-vitro cytotoxic activity on MCF-7 cells. In order to examine possible synergistic effects of essential oil components, cytotoxic activities of 1:1 binary mixtures of a number of volatile compounds were determined. Notable synergistic cytotoxic enhancement was observed for mixtures of various compounds with citral, citronellal, and artemisia ketone. The cytotoxic activity of α-humulene, on the other hand, was antagonized by pinenes, thujene, and camphene. Likewise, camphene and terpinen-4-ol reduced the activity of β-caryophyllene.
Many anti-tumor drugs function by intercalating into DNA. The xanthine alkaloid caffeine can also intercalate into DNA as well as form π-π molecular complexes with other planar alkaloids and anti-tumor drugs. The presence of caffeine could interfere with the intercalating anti-tumor drug by forming π-π molecular complexes with the drug, thereby blocking the planar aromatic drugs from intercalating into the DNA and ultimately lowering the toxicity of the drug to the cancer cells. The cytotoxic activities of several known DNA intercalators (berberine, camptothecin, chelerythrine, doxorubicin, ellipticine, and sanguinarine) on MCF-7 breast cancer cells, both with and without caffeine present (200 μg/mL) were determined. Significant attenuation of the cytotoxicities by caffeine was found. Computational molecular modeling studies involving the intercalating anti-tumor drugs with caffeine were also carried out using density functional theory (DFT) and the recently developed M06 functional. Relatively strong π–π interaction energies between caffeine and the intercalators were found, suggesting an “interceptor” role of caffeine protecting the DNA from intercalation.
The crude ethanol extract from the leaves of Dendropanax cf. querceti (Araliaceae) from Monteverde, Costa Rica, exhibits cytotoxic activity against Hep-G2, A-431, and H-411E tumor cell lines. The active component has been isolated by activity-directed separation and identified by 1H-and 13C-NMR spectroscopy as the triterpene lupeol. The mechanism of cytotoxic activity of lupeol has been determined to be inhibition of topoisomerase II.The Araliaceae family contains about 65 genera and more than 800 species, primarily tropical (1, 2), especially in the lndo-Malayan region and tropical America. Although members of the Araliaceae in North America, Europe, and Asia have been studied extensively and have been seen to contain a profusion of substances with marked bioactivity, there are, on the other hand, abundant woody members of the family found in the Neotropics which have been poorly studied or completely neglected. We have been interested in examining the phytochemistry and biological activity of members of the Araliaceae from the montane cloud forest of Monteverde, Costa Rica (3). Dendropanax querceti J. D. Smith in its typical form is a shade tolerant understory to small lower canopy tree, which grows in Costa Rica in the montane rain forests of the Cordillera de Talamanca at 2200-2700 m (4). Individuals from the smaller Cordillera de Tilaran grow at lower elevation (1000-1800m) in the premontane and lower montane rain forests on the Caribbean slope and crest of the range (5). Trees from the Cordillera de Tilaran differ from typical D. querceti in leaf size and shape, and may represent an undescribed species (W. Haber, personal communication). Hence we refer to the population of the Cordillera de Tilaran as Dendropanax cf. querceti. In this paper we report the isolation, purification, and activity of the cytotoxic component from leaves of Dendropanax cf. querceti. D. querceti has, to our knowledge, no current economic utility.Leaves of D. cf. querceti were collected during June, 1991, from trees growing in lower montane moist forest at ca. 1400m a.s.l. at Monteverde, Costa Rica, and were immediately extracted using a Soxhlet extractor and refluxing 95 % ethanol.Identity of the plants was determined (R. 0. Lawton) by comparison with the collections of the Museo Nacional de Costa Rica, the Field Museum, and the Missouri Botanical Garden. Vouchers have been deposited with the University of Alabama in Huntsville and the Museo Nacional de Costa Rica. The fresh leaves (120g) were cleaned of epiphylls and other debris, were chopped and were then extracted with refluxing ethanol for three hours. The crude extract was assayed for cytotoxic activity and exhibited remarkable cytotoxicity (93 % inhibition at a concentration of 0.02 5 % w/v) against human Hep G2 hepatocellular carcinoma cells (3). The cytotoxicity of the crude extract on tumor derived cell lines was measured using the MTT assay (6) for cell viability. As shown in Table 1, at a concentration of 0.02 5 % w/v, the crude extract of D. cf. querceti showed 93 % kil...
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