In vitro cultivation of Vismia japurensis: Isolation of the new anthrone 1,8,10-trihydroxy-3,10-dimethyl-9(10H)-anthracenone.

Vismia japurensis Reichardt is a plant of ecological and chemical importance from which a variety of bioactive substances have been isolated. The current study aimed to establish in vitro cultures of this species as a source of secondary metabolites. Appropriate decontamination treatments and germination tests were performed and, after in vitro culture establishment, the propagated plants were multiplied in a sterile environment to increase the biomass of available experimental material. Seeds showed low contamination and a high germination percentage on Woody Plant Medium (WPM) supplemented with gibberellic acid (both at concentrations of 5 and 10 mg/L). V. japurensis nodal segments rapidly regenerated when first grown in WPM and then transplanted to Murashige and Skoog medium (MS). After 60 days in MS medium, the propagated plants were removed, lyophilized, and extracted with hexane and methanol. The hexane extract was fractionated via open column chromatography, and the substance isolated was purified by high performance liquid chromatography. Structural determination of the isolated substance was carried out using one and two-dimensional nuclear magnetic resonance and mass spectrometry. The isolated substance was identified as 1,8,10-trihydroxy-3,10-dimethyl-9(10H)-anthracenone, which, based on the conducted literature search, is reported for the first time.

Antifungal activity of extracts and phenolic compounds from Deguelia duckeana

ABSTRACT Candida spp. is associated with almost 80% of all nosocomial fungal infections and is considered a major cause of blood stream infections. In humans, Cryptococcosis is a disease of the lungs caused by the fungi Cryptococcus gattii and Cryptococcus neoformans. It can be potentially fatal, especially in immune-compromised patients. In a search for antifungal drugs, Deguelia duckeana extracts were assayed against these two fungi and also against Candida albicans, which causes candidiasis. Hexane branches and CH2Cl2 root extracts as well as the substances 4-hydroxylonchocarpine, 3,5,4′-trimethoxy-4-prenylstilbene and 3′,4′-methylenedioxy-7-methoxyflavone were assayed to determine the minimal inhibitory concentration. Phytochemical study of CH2Cl2 root and hexane branch extracts from D. duckeana A.M.G. Azevedo, Fabaceae, resulted in the isolation and characterization of nine phenolic compounds: 4-hydroxyderricine, 4-hydroxylonchocarpine, 3′,4′,7-trimethoxy-flavonol, 5,4′-dihydroxy-isolonchocarpine, 4-hydroxyderricidine, derricidine, 3,5,4′-trimethoxy-stilbene, 3′,4′,7-trimethoxyflavone and yangambin. The only active extract was a CH2Cl2 root showing minimal inhibitory concentration 800 µg/ml against C. gattii, and the investigation of compounds obtained from this extract showed that 4-hydroxylonchocarpine was active against all three fungi (C. neoformans, C. gattii and C. albicans). These results suggest that D. duckeana extracts have potential therapeutic value for the treatment of pathogenic fungi.

Isolation of Flavonoids from Deguelia duckeana and Their Effect on Cellular Viability, AMPK, eEF2, eIF2 and eIF4E.

Preparations of Deguelia duckeana, known in Brazil as timbó, are used by indigenous people to kill fish. Reinvestigation of its extracts resulted in the isolation and identification of 11 known flavonoids identified as 3,5,4'-trimethoxy-4-prenylstilbene (1), 4-methoxyderricidine (2), lonchocarpine (3), 4-hydroxylonchocarpine (4), 4-methoxylonchocarpine (5), 5-hydroxy-4',7-dimethoxy-6-prenylflavanone (6), 4'-hydroxyisolonchocarpine (7), 4'-methoxyisolonchocarpine (8), 3',4',7-trimethoxyflavone (9), 3',4'-methylenedioxy-7-methoxyflavone (10), and 2,2-dimethyl-chromone-5,4'-hydroxy-5'-methoxyflavone (11). Except for 1, 3, and 4 all of these flavonoids have been described for the first time in D. duckeana and the flavanone 6 for the first time in nature. Compounds 2, 3, 4, 7, 9, and 10 were studied for their potential to induce cell death in neuronal SK-N-SH cells. Only the chalcone 4 and the flavanone 7 significantly induced lactate dehydrogenase (LDH) release, which was accompanied by activation of caspase-3 and impairment of energy homeostasis in the MTT assay and may explain the killing effect on fish. Interestingly, the flavone 10 reduced cell metabolism in the MTT assay without inducing cytotoxicity in the LDH assay. Furthermore, the flavonoids 2, 3, 4, 7, and 10 induced phosphorylation of the AMP-activated protein kinase (AMPK) and the eukaryotic elongation factor 2 (eEF2). The initiation factor eIF4E was dephosphorylated in the presence of these compounds. The initiation factor eIF2alpha was not affected. Further studies are needed to elucidate the importance of the observed effects on protein synthesis and potential therapeutic perspectives.

Chemical profile and biological activities of Deguelia duckeana A.M.G. Azevedo (Fabaceae).

Deguelia duckeana is popularly known as timbó and used by indigenous people as ictiotoxic. On account of there being no literature pertaining to the chemical profile or biological activity of this plant, the hexane, methanol and aqueous crude extracts from leaves, stems and roots were assayed that presented very high cytotoxic potential against Artemia salina, achieving 100% mortality in up to 5.0 µg mL(-1) concentration, but lower antioxidant potential on 2,2-diphenyl-1-picryl-hydrazyl and Fe(3+)/Phenanthroline assays. The phytochemical analysis of crude extracts showed the presence of flavonoids and related compounds as major constituents as well as steroids in all of them, and tannins in polar extracts. All the extracts were assayed for antibacterial activity but only the hexane extract of stems showed moderate activity on Staphylococcus aureus, which was fractionated and yielded a mixture of 3,5,4'-trimethoxy-4-prenylstilbene, lonchocarpine, 4-hydroxylonchocarpine and derricidine, reported for the first time in D. duckeana and other fraction with ß-sitosterol and stigmasterol mixture.

Challenges and rewards of research in marine natural products chemistry in Brazil.

Brazil is blessed with a great biodiversity, which constitutes one of the most important sources of biologically active compounds, even if it has been largely underexplored. As is the case of the Amazon and Atlantic rainforests, the Brazilian marine fauna remains practically unexplored in the search for new biologically active natural products. Considering that marine organisms have been shown to be one of the most promising sources of new bioactive compounds for the treatment of different human diseases, the 8000 km of the Brazilian coastline represents a great potential for finding new pharmacologically active secondary metabolites. This review presents the status of marine natural products chemistry in Brazil, including results reported by different research groups with emphasis on the isolation, structure elucidation, and evaluation of biological activities of natural products isolated from sponges, ascidians, octocorals, and Opistobranch mollusks. A brief overview of the first Brazilian program on the isolation of marine bacteria and fungi, directed toward the production of biologically active compounds, is also discussed. The current multidisciplinary collaborative program under development at the Universidade de São Paulo proposes to establish a new paradigm toward the management of the Brazilian marine biodiversity, integrating research on the species diversity, ecology, taxonomy, and biogeography of marine invertebrates and microorganisms. This program also includes a broad screening program of Brazilian marine bioresources, to search for active compounds that may be of interest for the development of new drug leads.