Flavonóides das flores de Stiffitia chrysantha Mikan

The flowers of Stiffitia chrysantha Mikam(Asteraceae) contain eriodictiol, quercetin, luteolin and b-D-glycopyranosil-sitosterol. These compounds and its derivatives were identified by their 1H and 13C NMR, infra-red and mass spectra data. The heteronuclear 2D NMR were used to confirm the assignments of the proton and carbon chemical shifts, it was used to eliminate definitively the ambiguous correlation reported in the literature for C-5 and C-9 of quercetin and C-23 and C-25 of b-D-glycopyranosil-sitosterol.

Flavonóides e triterpenos de Baccharis pseudotenuifolia: bioatividade sobre Artemia salina

The phytochemical investigation of the chloroformic and methanolic extracts of the Baccharis pseudotenuifolia led to the isolation of triterpenes, steroids and flavonoids. From chloroformic extract were isolated oleanolic acid and alpha-spinasterol while from methanolic extract were isolated the flavonoids: hispidulin, naringenin, 3'-methoxy-luteolin, apigenin, kaempferol, eriodyctiol, aromadendrin, quercetin, 3'-methoxy-quercetin, quercetin-3-O-rhamnoside and quercetin-3-O-glucoside. The structure of these compounds were identified by IR, CG/MS, ¹H and 13C NMR spectral analysis and comparison with literature. In addition, the extracts were evaluated by means of Brine Shrimp Lethality test and the highier activity was observed in the chloroformic extract.

Flavonóide e triterpenos de Stigmaphyllom paralias

Stigmaphyllom paralias is a herb belonging to the family Malpighiaceae that occurs in sand soil of brazilian " restinga". This is the first report regarding phytochemical study with this species. The hexane extract of the aerial parts of plant afforded the triterpenes friedelin, lupenone, 3-oxo-alpha-amirin and 3-oxo-beta-amirin, the mixture of alpha-amirinyl palmitate and stearate, lupeol and 3,4-seco-friedelan-3-oic acid. The AcOEt extract yielded the flavonoid luteolin-7-rutinoside. All compounds were characterized by analysis of spectrometric data and the fatty acids esterified with alpha-amirine were identified by GC/MS of methyl derivatives of transesterified products . This is the first natural occurence of 3,4-seco-friedelan-3-oic acid and the 13C NMR spectral data were inequivocally assigned by two-dimensional techniques. This work also permitted to correct the 13C NMR resonances attributed to methyl groups C-26 and C-27 of fridelin.

Constituintes químicos e atividade antioxidante de Sida galheirensiS Ulbr. (Malvaceae)

The phytochemical investigation of Sida galheirensis led to the isolation of 5,4'-dihydroxy-3,7,3´-trimethoxyflavone, 17³-ethoxyphaeoforbide, a rare natural product, 6,7-dimethoxycoumarin, ortho-hydroxybenzoic acid, sitosterol-3-O-beta-D-glucopyranoside, stigmasterol-3-O-beta-D-glucopyranoside, 5,7,4'-trihydroxyflavone, 5,7,3',4'-tetrahydroxyflavone, kaempferol-3-O-beta-D-(6"-E-p-coumaroyl) glucopyranoside and luteolin 7-O-beta-D-glucopyranoside. Their structures were assigned based on spectroscopic analyses, including two-dimensional NMR techniques. Antioxidant activities of hexane, CHCl3, EtOAc, BuOH and EtOH extracts of Sida galheirensis were measured using the 1,2-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. This is also the first work reporting the chemical investigation of Sida galheirensis.

Otimização de método para determinação de flavonóis e flavonas em frutas por cromatografia líquida de alta eficiência utilizando delineamento estatístico e análise de superfície de resposta

This work optimized the HPLC conditions for the simultaneous determination of luteolin, apigenin, myricetin, quercetin and kaempferol in aglycone form, as well defined the best conditions for hydrolysis/extraction of these flavonoids in fruits, using the statistical central composite design and response surface analysis. A reverse phase method was developed using a gradient of methanol/water acidified with 0.3% formic acid as mobile phase and a photodiode array detector. The samples were extracted with methanol/water (50:50 v/v) at 90 ºC. The optimum time and HCl concentration varied for the different fruits investigated, demonstrating the necessity of optimizing these conditions for each fruit analyzed. Good recovery (87.1 to 96.3%), repeatability and linearity were obtained.

Antifungal iridoids, triterpenes and phenol compounds from Alibertia myrciifolia Sprunge Ex. Schum

The new iridoid glucoside 10-O-vanilloyl-geniposidic acid has been isolated from the aerial parts of Alibertia myrciifolia along with hydroxyhopanone, 3α,22-dihydroxyhopane, ursolic acid, luteolin-3´,4´-dimethyl ether, caffeic acid and geniposidic acid. The structures of the isolated compounds were determined by means of mass spectrometry and nuclear magnetic resonance spectral analyses. The antifungal activities of the iridoids 10-O-vanilloyl-geniposidic acid and geniposidic acid were evaluated against the phytopathogenic fungi strains Colletotrichum gloeosporioides, Fusarium solani and Aspergillus niger.

Blainvillea rhomboidea: constituintes químicos e atividade citotóxica

The phytochemical investigation of the ethanol extract from the aerial parts of Blainvillea rhomboidea (Asteraceae) resulted in the isolation and characterization of 8β-tigloyloxy-grazielia acid, together with the flavonoids derrone, acacetin, luteolin and luteolin 7-methyl ether, and p-(1-methyl-ethan-1-ol)-phenol. The structures of all compounds were determined by spectroscopic methods (¹H and 13C NMR and HREIMS) and comparison with published spectral data. The flavonoids luteolin and 7-O-metyl-luteolin, isolated from the active dichloromethane fraction, showed moderate cytotoxic activity.

Chemical profiling of six samples of Brazilian propolis

Six samples of Brazilian propolis from Minas Gerais and Paraná states were analyzed to identify the constituents (GC/MS and HPLC/MS) and to determine their contents (HPLC and external standardization). All samples contained characteristic constituents of green propolis, but the samples from Minas Gerais had higher contents of prenylated phenylpropanoids and caffeoylquinic acids. Kaempferide and two other flavonoids were among the major constituents of the samples from Minas Gerais. Luteolin 5-O-methyl ether was detected only in samples from Paraná. Baccharis dracunculifolia was a source of resins for all samples analyzed, but the samples from Paraná had more complex plant origin.

Constituintes químicos de Vernonia scorpioides (Lam) Pers. (Asteraceae)

The chemical investigation of hexane and ethanol extracts from the aerial parts of Vernonia scorpioides resulted in the isolation and characterization of a new polyacetylene lactone, rel-4-dihydro-4β-hydroxy-5a-octa-2,4,6-triynyl-furan-2-(5H)-one, along with the new ethyl 3,4-dihydroxy-6,8,10-triynyl-dodecanoate, and seven known compounds: taraxasteryl acetate, lupeyl acetate, lupeol, lupenone, β-sitosterol, stigmasterol and luteolin. The structure of all compounds was determined by spectrometric techniques (HR-ESI-MS, ¹H and 13C NMR and IV) and comparison with published spectral data.

Preparative separation of polyphenols from artichoke by polyamide column chromatography and high-speed counter-current chromatography

An efficient method for the rapid separation and purification of polyphenols from artichoke by polyamide column chromatography in combination with high-speed counter-current chromatography (HSCCC) was successfully built. The crude ethanol extracts from dry artichoke were first pre-separated by polyamide column chromatography and divided in two parts as sample 1 and sample 2. Then, the samples were further separated by HSCCC and yielded 7.8 mg of chlorogenic acid (compound I), 24.5 mg of luteolin-7-O-β-D-rutinoside (compound II), 18.4 mg of luteolin-7-O-β-D-glucoside (compound III), and 33.4 mg of cynarin (compound IV) with purity levels of 92.0%, 98.2%, 98.5%, and 98.0%, respectively, as determined by high-performance liquid chromatography (HPLC) method. The chemical structures of these compounds were identified by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR).

Sesquiterpenos e outros constituintes das folhas de Pterodon pubescens Benth (Leguminosae)

In addition to β-sitosterol, stigmasterol, phaeophitin A, luteolin, kaempferol, quercetin, (+)-catechin, quercetin-3-O-α-L-rhamnopyranoside, rutin, and p-hydroxy-benzoic acid, six known sesquiterpenes, namely (rel)-2β,6β-epoxy-5β-hydroxy-isodaucane, oplopanone, 1β,6α-dihydroxy-4(15)-eudesmene, caryophyllene oxide, α-cadinol, and spathulenol, were isolated from the leaves of Pterodon pubescens (Leguminosae) growing in the Cerrado of Mato Grosso do Sul, Brazil. The (rel)-2β,6β-epoxy-5β-hydroxy-isodaucane corresponds to the correct structure of homalomenol D. The sesquiterpene oplopanone, which bears a modified cadinane skeleton, is being reported for the first time in this genus. The structures of the compounds were determined on the basis of spectral data (MS, IR, and NMR-1D and 2D) and subsequent comparison with data reported in the literature.

Determination of flavonoids in stamen, gynoecium, and petals of Magnolia grandiflora L. and their associated antioxidant and hepatoprotection activities

Chromatographic analysis of flavonoids in ethyl acetate fractions of the stamen, gynoecium, and petal of Magnolia grandiflora L. by HPLC-PDA-MS/MS-ESI in the negative ionization mode was performed in this study. The results revealed the presence of eight flavonoids: apigenin 8-C-glucoside, luteolin 8-C-glucoside, quercetin 3-O-rutinoside, quercetin 3-O-galactoside, quercetin, 3-O-glucoside, kaempferol 3-O-rutinoside, isorhamnetin 3-O-glucoside, and isorhamnetin. Their quantification revealed that luteolin 8-C-glucoside is the major flavonoid and that the total phenolic content is concentrated primarily in the stamen. The antioxidant and hepatoprotective effects of ethanolic extract of the flower organs were evaluated against hepatotoxicity induced by CCl4, compared with the effects of silymarin.

NOVOS FLAVONOIDES DE Margaritopsis carrascoana COM ATIVIDADE ANTIOXIDANTE

EtOH extracts of the stems and leaves of Margaritopsis carrascoana were found to contain new flavonoids luteolin 7-O-{β-D-apiofuranosil-(1→6)-[β-Lrhamnopyranosyl-( 1→2)]-β-D-glucopyranosyl} (5) and luteolin 7-O-{α-L-rhamnopyranosyl-(1→6)-[β-L-rhamnopyranosyl- (1→2)]-β-D-glucopyranosyl} (6), in addition to the known dihydrodehydrodiconiferyl alcohol 4-O-b-D-glucopyranoside (1), luteolin 7-O-b-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl (2), luteolin 7-O-[b-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside (3), and chrysoeriol 7-O-[b-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside (4). All isolated compounds presented higher antioxidant activities than the controls, BHT and quercetin, while the extract of the stems showed strong AChE inhibition.

Neuroprotection by flavonoids

The high morbidity, high socioeconomic costs and lack of specific treatments are key factors that define the relevance of brain pathology for human health and the importance of research on neuronal protective agents. Epidemiological studies have shown beneficial effects of flavonoids on arteriosclerosis-related pathology in general and neurodegeneration in particular. Flavonoids can protect the brain by their ability to modulate intracellular signals promoting cellular survival. Quercetin and structurally related flavonoids (myricetin, fisetin, luteolin) showed a marked cytoprotective capacity in in vitro experimental conditions in models of predominantly apoptotic death such as that induced by medium concentrations (200 µM) of H2O2 added to PC12 cells in culture. Nevertheless, quercetin did not protect substantia nigra neurons in vivo from an oxidative insult (6-hydroxydopamine), probably due to difficulties in crossing the blood-brain barrier. On the other hand, treatment of permanent focal ischemia with a lecithin/quercetin preparation decreased lesion volume, showing that preparations that help to cross the blood-brain barrier may be critical for the expression of the effects of flavonoids on the brain. The hypothesis is advanced that a group of quercetin-related flavonoids could become lead molecules for the development of neuroprotective compounds with multitarget anti-ischemic effects.