Raimundo Braz Filho

A stilbene and two flavanones from Derris rariflora

Abstract The wood of the vine Derris rariflora (Leguminosae-Lotoideae) contains 3,5-dimethoxy-4-prenylstilbene, (2S)-5,7-dihydroxy-6-prenylflavanone and (2S)-5-hydroxy-7-methoxy-6-prenylflavanone.

Flavonoids from Iryanthera laevis

Abstract Trunk wood of Iryanthera laevis Markgr. (Myristicaceae) contains 2′,4′-dihydroxy- 4,6′dimethoxydihydrochalcone, three 2′-hydroxy-4′,5′-methylenedioxyflavans with differently substituted A-rings (7-OH-6,8-diMe; 7-OH-5,8-diMe; 5-OH-7-OMe-6,8-diMe) and 1-(2′-hydroxy-4′-methoxy-5′-methylphenyl)-3(2″-hydroxy-4″,5″-methylenedioxphenyl)- propane, as well as three additional known diarylpropanes.

Cytotoxicity of δ-tocotrienols from Kielmeyera coriacea against cancer cell lines.

In the search for new anti-cancer compounds, Brazilian Cerrado plant species have been investigated. The hexane root bark extract of Kielmeyera coriacea lead to a mixture of δ-tocotrienol (1) and its dimer (2). The structures of both compounds 1 and 2 were established based on detailed 1D and 2D NMR and EI-MS analyses. The cytotoxicity of the mixture was tested against four human tumor cell lines in the following cultures: MDA-MB-435 (melanoma), HCT-8 (colon), HL-60 (leukemia), and SF-295 (glioblastoma), and displayed IC(50) values ranging from 8.08 to 23.58μg/mL. Additional assays were performed in order to investigate the mechanism of action of the mixture (1+2) against the human leukemia cell line HL-60. The results suggested that the mixture suppressed leukemia growth and reduced cell survival, triggering both apoptosis and necrosis, depending on the concentration.

Atividades larvicida e anticolinesterásica de plantas do gênero Kalanchoe

Acetylcholine esterase inhibitors are successfully used to treat the symptoms of Alzheimers disease. Extracts of three Kalanchoe species (K. brasiliensis, K. pinnata and K. gastonis-bornieri) showed acetylcholine esterase inhibitory effects and a toxic effect on Aedes aegypti larvae. Here we describe the bioassay guided fractionation of extracts of the most active extracts (K. brasiliensis) which resulted in the isolation of an active mixture of three flavonoids: 8-methoxyquercetin, 3,7-di-O-rhamnopyranoside and 8-methoxykaempferol-3,7-di-O-rhamnopyranoside. On TLC these flavonoids showed an acetylcholine esterase inhibitory effect.

Neolignans from a Nectandra species

Abstract The trunk wood of an Amazonian Nectandra (Lauraceae) species contains one bicyclo[3.2.1]octanoid and four hydrobenzofuranoid neolignans. The latter comprise representatives of the mirandin, the rearranged burchellin and the burchellin types. The former was characterized as (1 S , 4 R , 5 S , 6 R , 7 R )-3-allyl-4-hydroxy-1-methoxy-(3′, 4′, 5′-trimethoxyphenyl)- 7-methyl-8-oxobicyclo[3.2.1]oct-2-ene macrophyllin-B), a new representative of the seemingly rare macrophyllin type.

Chemical constituents from Vellozia graminifolia (Velloziaceae)

From the hexane and ethyl acetate extracts obtained from stems, roots and leaf sheaths of Vellozia graminifolia, a mixture of linear hydrocarbons, a mixture of pentacyclic triterpenes, five monoisoprenylated flavonoids and one labdane diterpene, (-)-ent-3beta-hydroxy-8(17)-labden-15-oic acid, were isolated. The linear hydrocarbons and minor triterpenes were identified in their corresponding mixtures by High Resolution Gas Chromatography (HRGC) and HRGC coupled to mass spectrometry. The major pentacyclic triterpenes and the diterpene were characterized by spectral data, including 2D NMR experiments, and chemical transformations.

Natural abundance 13C–13C coupling constants observed via double quantum coherence: structural elucidation of velloziolide, a diterpene with a novel skeleton

A diterpene with a novel skeleton, velloziolide, has been isolated from Vellozia Candida Mikan; its structure has been established mainly by using natural abundance 13C–13C coupling constants observed via double quantum coherence.

Constituintes químicos de Zanthoxylum ekmanii (URB.) Alain

Chemical investigation of Z. ekmanii resulted in the isolation of skimmianine, dictamnine, tembamide, sesamin, lupeol and b-sitosterol. The structures were established by spectroscopic analyses. This is the first report on the phytochemical study of the roots and leaves of Z. ekmanii.

Triterpenóides pentacíclicos de Mentha villosa: identificação estrutural e atribuição dos deslocamentos químicos dos átomos de hidrogênio e carbono

The structures of seven oleanene and ursene triterpenoids (1-7) isolated from aerial parts of Mentha villosa were identified. In addition, the complete 1H and 13C resonance assignments of these triterpenoids were accomplished using 1D and 2D NMR spectroscopic experiments.

Constituintes químicos de Tovomita brasiliensis ()

The trunk wood of Tovomita brasiliensis Walp. from Belem, Para State, contains 1,5-dihydroxy-6.7-dimethoxyxanthone, betulinic acid and sitosterol. The additional presence of 8-hydroxy-3,5-dimethyl-3.4-dihydroisocoumarin, 8-hydroxy-5-methoxy-3-methyl-3,4-dihydroisocoumarin and 7-chloro-8-hydroxy-6-methoxy-3-methylisocoumarin in the benzene extract is most probably due to infestation of the plant material by fungi.