Maria Amélia D. Boaventura

Biological screening of Annonaceous Brazilian Medicinal Plants using Artemia salina (Brine Shrimp Test)

Eighteen different extracts from five Annona species collected in Minas Gerais state, Brazil, were submitted to the brine shrimp lethality test in order to detect potential sources of novel cytotoxic, antitumor, pesticidal and anti-Trypanosoma cruzi compounds. All of the Annonaceous species tested showed good larvicidal activity as compared to a reference compounds and literature data.

Trypanocidal Sesquiterpenes from Lychnophora Species

The bioguided fractionation of the crude extracts of Lychnophora passerina (Mart. ex DC) Gardn., L. pinaster Mart. and L. trichocarpha Spreng. led to the isolation of four compounds active against the trypomastigote forms of Trypanosoma cruzi: the sesquiterpene lactones goyazensolide (1), eremantholide C (2), and lychnopholide (3) and a new caryophyllene derivative, which was named lychnophoic acid (4).

Antibacterial activity of eight Brazilian annonaceae plants

Sixteen extracts, obtained from eight Brazilian plants of Annonaceae family, were screened for their antibacterial activity: Xylopia frutescens, X. aromatica, X. amazonica, X. benthamii, Annona ambotay, A. crassiflora, A. muricata and A. cherimolia. Amongst the investigated extracts, six showed antibacterial activity against at least one of the tested organisms at the concentration of 100 µg/mL. The most active extracts were those prepared from X. frutescens, X. amazonica, and A. ambotay. A phytochemical screening showed the presence of anonaceus acetogenins in some active extracts. Eleven diterpenoids were also tested for comparison purposes. Six were natural products, previously isolated from Xylopia sp. (kaurenoic, frutoic, xylopic, 15β-hydroxy-kaurenoic and trachylobanic acids plus kaurenol) and five were derivatives of such compounds, obtained by esterification or reduction reactions. Trachylobanic acid showed antibacterial activity against B. subtilis and S. aureus.

Estudo fitoquímico de Unonopsis lindmanii - Annonaceae, biomonitorado pelo ensaio de toxicidade sobre a Artemia salina leach

Extracts obtained from leaves, seeds and bark of Unonopsis lindmanii were evaluated by means of Brine Shrimp Lethality test (BSL). Through bioassay-guided chromatographic fractionation, liriodenine, an oxoaporphine alkaloid, was isolated from the bark extracts as the bioactive compound. Two additional inactive known alkaloids, unonopsine and lysicamine were also isolated from the bark extracts.

Frutoic acid, a dimeric kaurane diterpene from Xylopia frutescens

Sitosterol and six diterpenes were isolated from green fruit, stem bark and leaves of Xylopia frutescens and characterized as ent-15α-acetoxy-kaur-16-en-19-oic acid (xylopic acid), ent-kaur-16-en-19-oic acid (kaurenoic acid), ent-16β-hydroxy-kaurane, ent-kaur-16-en-19-ol, ent-16β-hydroxy-kauran-19-oic acid and ent-16β,17-dihydroxy-kauran-19-oic acid. Acutifloric acid, a diterpenic dimer, and its 7β-hydroxy-derivative, a novel compound named frutoic acid, were also isolated.

Novel Derivatives of Kaurenoic Acid

Kaurenoic acid, a kauranic diterpenoid, presents in vitro activity against trypomastigote forms of Trypanosoma cruzi, showing, however, lytic activity on blood erythrocytes, as a side effect. The syntheses of twelve new derivatives of kaurenoic acid, four amides, four amines (and three hydroclorides) and four oximes, was carried out aiming at the improvement of the therapeutic activity and without the side effect. Among the derivatives prepared, one compound showed enhanced trypanocidal activity in vitro towards Trypanosoma cruzi trypomastigote erythrocytic forms, when compared to kaurenoic acid, but continued to show discrete lytic activity on erythrocytes; another compound showed a level of activity similar to that of kaurenoic acid, but without lysis.

Araticulin, a bis-tetrahydrofuran polyketide from Annona itcrassiflora seeds

A new tetrahydroxy adjacent bis-tetrahydrofuran polyketide, araticulin, has been isolated from the cytotoxic ethanolic extract of Annona crassiflora seeds. Its structure was established by NMR and mass spectrometry as a threo-trans-threo-trans-threo isomer of purpureacin-2, the only previously known bis-tetrahydrofuran polyketide bearing an OH group at C-12.

The biotransformation of ent-kaur-16-en-19-oic acid by Rhizopus stolonifer.

Microbial transformation of ent-kaur-16-en-19-oic acid was carried out with R. stolonifer. After seven days of incubation, two metabolites, ent-7 alpha-hydroxy-kaur-16-en-19-oic acid and ent-12 beta-hydroxy-kaur-9(11),16-dien-19-oic acid, were isolated as a result of hydroxylation and hydroxylation/dehydrogenation, respectively. Incubation for 15 days also afforded ent-16 beta,17-dihydroxy-kauran-19-oic acid. The metabolites were identified by spectroscopic methods.

Constituents from aerial parts of Wedelia paludosa.

Tetrachyrin (1), 3alpha-tigloyloxykaur-16-en-19-oic acid (2) and 3alpha-cinnamoyloxykaur-16-en-19-oic acid (3) have been isolated from the ethanol extract of Wedelia paludosa aerial parts.

Acetogeninas de anonáceas isoladas de folhas de Rollinia laurifolia

Phytochemical investigation of hexanic extract of leaves of Rollinia laurifolia afforded three known acetogenins, uvariamicin-I (1), solamin(2) and gonionenin(3), for the first time isolated from Rollinia genus. The structures of 1, 2 and 3 were elucidated by spectroscopic methods.