Microbial ß-mannosidases and their industrial applications.

Heteropolymers of mannan are polysaccharide components of the plant cell wall of gymnosperms and some angiosperms, including palm trees (Arecales and Monocot). Degradation of the complex structure of these polysaccharides requires the synergistic action of enzymes that disrupt the internal carbon skeleton of mannan and accessory enzymes that remove side chain substituents. However, complete degradation of these polysaccharides is carried out by an exo-hydrolase termed ß-mannosidase. Microbial ß-mannosidases belong to families 1, 2, and 5 of glycosyl hydrolases, and catalyze the hydrolysis of non-reducing ends of mannose oligomers. Besides, these enzymes are also involved in transglycosylation reactions. Because of their activity at different temperatures and pH values, these enzymes are used in a variety of industrial applications and the pharmaceutical, food, and biofuel industries.

Bioassay-guided isolation and identification of cytotoxic compounds from Gymnosperma glutinosum leaves.

Bioassay-guided fractionation of hexane extracts of Gymnosperma glutinosum (Asteraceae) leaves, collected in North Mexico, afforded the known compounds hentriacontane (1) and (+)-13S,14R,15-trihydroxy-ent-labd-7-ene (2), as well as the new ent-labdane diterpene (-)-13S,14R,15-trihydroxy-7-oxo-ent-labd-8(9)-ene (3). In addition, D-glycero-D-galactoheptitol (4) was isolated from the methanolic extract of this plant. Their structures were established on the basis of high-field 1D- and 2D NMR methods supported by HR-MS data. The cytotoxic activity was determined by using the in vitro L5178Y-R lymphoma murine model. Hentriacontane (1) and the new ent-labdane 3 showed weak cytotoxicity, whereas the ent-labdane 2 showed significant (p < 0.05) and concentration dependent cytotoxicity (up to 78%) against L5178Y-R cells at concentrations ranging from 7.8 to 250 µg/mL.

Gastroprotective effect and cytotoxicity of labdeneamides with amino acids.

Semisynthetic aromatic amides from ARAUCARIA ARAUCANA diterpene acids have been shown to display a relevant gastroprotective effect with low cytotoxicity. The aim of this work was to assess the gastroprotective effect of amino acid amides from imbricatolic acid and its 8(9)-en isomer in the ethanol/HCl-induced gastric lesions model in mice as well as to determine the cytotoxicity of the obtained compounds on the following human cell lines: normal lung fibroblasts (MRC-5), gastric adenocarcinoma (AGS), and liver hepatocellular carcinoma (Hep G2). The diterpenes 15-acetoxyimbricatolic acid, its 8(9)-en isomer, 15-hydroxyimbricatolic acid, and the 8(9)-en derivative, bearing a COOH function at C-19, were used as starting compounds. New amides with C-protected amino acids were prepared. The study reports the effect of a single oral administration of either compound 50 min before the induction of gastric lesions by ethanol/HCl. Some 20 amino acid monoamides were obtained. Dose-response experiments on the glycyl derivatives showed that at a single oral dose of 100 mg/kg, the compounds presented an effect comparable to the reference drug lansoprazole at 20 mg/kg and at 50 mg/kg reduced gastric lesions by about 50%. All derivatives obtained in amounts > 30 mg were compared at a single oral dose of 50 mg/kg. The best gastroprotective effect was observed for the exomethylene derivatives bearing a valine residue at C-19 either with an acetoxy or free hydroxy group at C-15. The tryptophanyl derivative from the acetate belonging to the 8,9-en series presented selective cytotoxicity against hepatocytes. The glycyl amide of 15-acetoxyimbricatolic acid was the most cytotoxic and less selective compound with IC50 values between 47 and 103 µM for the studied cell lines. This is the first report on the obtention of semisynthetic amino acid amides from labdane diterpenes.

New gastroprotective ferruginol derivatives with selective cytotoxicity against gastric cancer cells.

The diterpene ferruginol has shown a strong protective effect in animal gastric ulcer models. In the present work, we report the gastroprotective effect and cytotoxicity of 16 new semisynthetic ester derivatives of ferruginol. The gastroprotective effect of these compounds was assessed with the HCl/EtOH-induced gastric lesions model in mice and the cytotoxicity was measured using MRC-5 fibroblasts, gastric adenocarcinoma (AGS) and liver hepatoma Hep G2 cells. The compounds were tested for a gastroprotective effect at a single oral dose of 20 mg/kg. The best gastroprotective effect was elicited by ferruginyl nicotinate ( 13), reducing the lesion index by 71 %, while the derivatives ferruginyl chloroacetate ( 2), ferruginyl palmitate ( 6), ferruginyl oleate ( 7), ferruginyl 3,5-dinitrobenzoate ( 11), ferruginyl 3-methylbenzofuran-2-carbonyl ester ( 12), ferruginyl indoleacetate ( 14), ferruginyl indolebutyrate ( 15) and ferruginyl pthalate ( 16) reduced the lesions by 49 - 66 %. The most promising compounds were 11, 13 and 14, presenting a gastroprotective effect higher or similar to that of ferruginol but with a high selectivity towards the tumor AGS cells. Among the three products, the most selective towards AGS cells was 14, followed by 13, and 11 (IC (50) values of 12, 22 and 29 microM, respectively). The isobutyrate 4, inactive as a gastroprotective agent, showed selective cytotoxicity against AGS and Hep G2 cells (IC (50) values of 60 and 39.2 microM, respectively). The cytotoxicity of the above cited compounds towards fibroblasts was >1000 microM. Considering the aliphatic esters of ferruginol, the best gastroprotective activity was found in the C (16) and C (18) derivatives but tended to decrease with increasing aliphatic chain unsaturation. For short-chain esters, the gastroprotective effect could be observed when the chain contained a chlorine atom. For aromatic esters, the presence of nitro groups or a nitrogen atom in the aromatic ring enhanced the gastroprotective activity. The compounds with the best gastroprotective effect and the highest selectivity against tumor cells bear an amino group (indoleacetate and nicotinate) or nitro group (3,5-dinitrobenzoate).

Gastroprotective effect of the Mapuche crude drug Araucaria araucana resin and its main constituents.

The resin from the tree Araucaria araucana (Araucariaceae) has been used since pre-columbian times by the Mapuche amerindians to treat ulcers. The gastroprotective effect of the resin was assessed in the ethanol-HCl-induced gastric ulcer in mice showing a dose-dependent gastroprotective activity at 100, 200 and 300 mg/kg per os. The main three diterpene constituents of the resin, namely imbricatolic acid, 15-hydroxyimbricatolal and 15-acetoxyimbricatolic acid were isolated and evaluated for gastroprotective effect at doses of 50, 100 and 200 mg/kg. A dose-related gastroprotective effect with highly significant activity (P<0.01) was observed at doses up to 200 mg/kg. At 100 mg/kg, the highest gastroprotective activity was provided by 15-hydroxyimbricatolal and 15-acetoxyimbricatolic acid, all of them being as active as the reference drug lansoprazole at 20 mg/kg. The cytotoxicity of the main diterpenes as well as lansoprazole was studied towards human lung fibroblasts (MRC-5) and determined by the MTT reduction assay. A concentration-dependent cell viability inhibition was found with IC50 values ranging from 125 up to 290 microM. Our results support the traditional use of the Araucaria araucana resin by the Mapuche culture.

Chemical constituents from the infusion of Zollernia ilicifolia Vog. and comparison with Maytenus species.

The new flavonoid glycoside kaempferol-3-O-alpha-L-rhamnopyranosyl(1-->2)-O-[alpha-L-rhamnopyranosyl(1-->6)]-O-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranoside was isolated together with (S)-zierin from the leaves of Zollernia ilicifolia (Fabaceae), a medicinal plant used as analgesic and antiulcerogenic effects in Brazilian Tropical Atlantic Rain Forest. The structures were established on the basis of 1H, 13C NMR and 2D NMR (COSY, HMBC, HMQC), UV, MS and IV spectra. The infusion of Zollernia ilicifolia was qualitatively compared to the infusion of the espinheiras-santas (Maytenus aquifolium and Maytenus ilicifolia) by HPLC-DAD.

The repellence of Aristolochia aff. orbicularis roots against the corn borer Sitophilus zeamais.

The repellence of Aristolochia aff. orbicularis root, a native of Xochipala, Guerrero, Mexico, to the corn borer Sitophilus zeamais (Coleoptera) was investigated. The essential oil was isolated from the aromatic root and its repellent effect was assessed. About 40 components of the oil were identified using gas chromatography-mass spectrometry and other spectroscopic methods. The repellence of the roots, the oil and the chromatography fractions were also evaluated. Some fractions had a higher repellence than the total oil.

Phenylpropanoid derivatives and biflavones at different stages of differentiation and development of Araucaria angustifolia.

Chemical investigations carried out with tissues at different developmental stages of Araucaria angustifolia established the presence of E and Z isomers of octadecyl p-coumarate and octadecyl ferulate in undifferentiated callus; in the seedling stems, the source of explants, three biflavones of the amentoflavone-type were isolated, whereas the diterpene, trans-communic acid, was obtained from the seedling roots. Adult stems accumulated the benzaldehydes, vanillin, p-hydroxybenzaldehyde and coniferaldehyde; the lignans, pinoresinol, eudesmin and lariciresinol; and the isoflavones, cabreuvine and irisolidone.