Estudo espectroscópico em elucidação estrutural de flavonoides de Solanum jabrense Agra & Nee e S. paludosum Moric

The NMR (RMN¹H, 13C, COSY, HMQC, HMBC, NOE-DIFF, NOESY) and mass spectra data analysis of sixteen flavonoids, including nine natural, 7-O-methylkanferol (ramnocitrin), 3,7-di-O-methylkanferol (kumatakenin), 3-O-methylquercetin, 3,7,3',4'-tetra-O-methylquercetin (retusin), 3,7,8,4'-tetra-O-methylgossipetin, 3,7,8,3',4'-penta-O-methylgossipetin, 7-O-methylapigenin (genkwanin), 3,7,8-tri-O-methylherbacetin, 7,4'- di-O-methylquercetin (ombuine), isolated from Solanum paludosum and S. jabrense, and seven prepared methyl and acetyl derivatives, are discussed according the substitution on the rings A, B and C.

Phenolic compounds from Sidastrum micranthum (A. St.-Hil.) fryxell and evaluation of acacetin and 7,4'-Di-O-methylisoscutellarein as motulator of bacterial drug resistence

From the aerial parts of Sidastrum micranthum (A. St.-Hil.) Fryxell (Malvaceae) were isolated m-methoxy-p-hydroxy-benzaldehyde, o-hydroxy-benzoic acid, acacetin, quercetin, 7,4′-Di-O-methylisoscutellarein, genkwanin and tiliroside. These compounds were identified by data analyses of spectroscopic methods. Although acacetin and 7,4′-Di-O-methylisoscutellarein did not display relevant antibacterial activity (MIC = 256 µg/mL), they modulated the activity of antibiotics, i.e. in combination with antibiotics at 64 µg/mL (¼ MIC), a two-fold reduction in the MIC was observed for norfloxacin and ethidium bromide; regarding tetracycline and erythromycin a two-fold reduction in the MIC was observed only with 7,4′-Di-O-methylisoscutellarein.

Antibacterial and anti-inflammatory activities of an extract, fractions, and compounds isolated from Gochnatia pulchra aerial parts

This paper reports on the in vitro antibacterial and in vivo anti-inflammatory properties of a hydroethanolic extract of the aerial parts of Gochnatia pulchra (HEGP). It also describes the antibacterial activity of HEGP fractions and of the isolated compounds genkwanin, scutellarin, apigenin, and 3,5-O-dicaffeoylquinic acid, as evaluated by a broth microdilution method. While HEGP and its fractions did not provide promising results, the isolated compounds exhibited pronounced antibacterial activity. The most sensitive microorganism was Streptococcus pyogenes, with minimum inhibitory concentration (MIC) values of 100, 50 and 25 µg/mL for genkwanin and the flavonoids apigenin and scutellarin, respectively. Genkwanin produced an MIC value of 25 µg/mL against Enterococcus faecalis. A paw edema model in rats and a pleurisy inflammation model in mice aided investigation of the anti-inflammatory effects of HEGP. This study also evaluated the ability of HEGP to modulate carrageenan-induced interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and monocyte chemoattractant protein-1 (MCP-1) production. Orally administered HEGP (250 and 500 mg/kg) inhibited carrageenan-induced paw edema. Regarding carrageenan-induced pleurisy, HEGP at 50, 100, and 250 mg/kg diminished leukocyte migration by 71.43%, 69.24%, and 73.34% (P<0.05), respectively. HEGP suppressed IL-1β and MCP-1 production by 55% and 50% at 50 mg/kg (P<0.05) and 60% and 25% at 100 mg/kg (P<0.05), respectively. HEGP abated TNF-α production by macrophages by 6.6%, 33.3%, and 53.3% at 100, 250, and 500 mg/kg (P<0.05), respectively. HEGP probably exerts anti-inflammatory effects by inhibiting production of the pro-inflammatory cytokines TNF-α, IL-1β, and MCP-1.

In vitro allelopathic potential of Leonurus sibiricus L. leaves

The chemical interaction between plants is known as allelopathy and it is related to the release of substances into the environment. The present study aimed at the evaluation of the allelopathic activity of the leaves of Leonurus sibiricus against the germination and initial growth of Raphanus sativus, Lactuca sativa, and Lepidium sativum. Chemical analyses showed the presence in the leaves of four major flavonoids (quercetin-3-O-alpha-L-rhamnopyranosyl-(1 > 6)-beta-D-galactopyranoside; rutin; hyperin, and isoquercetrin) and of three minor flavonoidic compounds (genkwanin, 3'-hydroxy genkwanin, and quercetin). Extracts, their chromatographic fractions and pure isolated flavonoids showed different biological activities. A methanol extract of leaves of Leonurus sibiricus caused significant reduction only in the germination of Lactuca sativa, with no effects on the germinative processes of Raphanus sativus and Lepidium sativum. Some chromatographic fractions, containing the flavonoids, showed inhibitory activity on the initial stages of root growth of all tested seeds. The isolated flavonoids, at the higher concentration tested (10(-4) M) seemed to be responsible for the inhibition of the germination, as well as the radical elongation. Among pure compounds, 3'-OH-genkwanin and quercetin showed the stronger antigerminative activity at the concentration of 10(-4) M, whereas the radical elongation was reduced by rutin, isoquercetrin and 3'-OH-genkwanin. All compounds, tested at concentrations ranging between 10(-5) and 10(-7) M, showed stimulatory activities.

Gastroprotective mechanisms of the chloroform and ethyl acetate phases of Praxelis clematidea (Griseb.) R.M.King & H.Robinson (Asteraceae)

Flavonoid-rich Praxelis clematidea (Griseb.) R.M.King & H.Robinson (Asteraceae) is a native plant of South America. This study evaluates the gastroprotective activity and possible mechanisms for both the chloroform (CHCl3P) and ethyl acetate phases (AcOEtP) obtained from aerial parts of the plant. The activity was investigated using acute models of gastric ulcer. Gastric secretion biochemical parameters were determined after pylorus ligature. The participation of cytoprotective factors such as mucus, nitric oxide (NO), sulfhydryl (SH) groups, prostaglandin E2 (PGE 2), reduced glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), reduction of lipid peroxidation (malondialdehyde level), and polymorphonuclear infiltration (myeloperoxidase activity), was also investigated. CHCl3P (125, 250, and 500 mg/kg) and AcOEtP (62.5, 125, and 250 mg/kg) showed significant gastroprotective activity, reducing the ulcerative index by 75, 83, 88 % and 66, 66, 81 % for ethanol; 67, 67, 56 % and 56, 53, 58 % for a non-steroidal anti-inflammatory drug (NSAID); and 74, 58, 59 % and 64, 65, 61 % for stress-induced gastric ulcer, respectively. CHCl3P (125 mg/kg) and AcOEtP (62.5 mg/kg) significantly reduced the ulcerative area by 78 and 83 %, respectively, for the ischemia-reperfusion model. They also did not alter the biochemical parameters of gastric secretion, the GSH level or the activities of SOD, GPx or GR. They increased the quantity of gastric mucus, not dependent on NO, yet dependent on SH groups, and maintained PGE2 levels. The P. clematidea phases demonstrated gastroprotective activity related to cytoprotective factors. © 2012 The Japanese Society of Pharmacognosy and Springer.