Densitometric Determination of Hecogenin from Agave americana Leaf Using HPTLC

We report a simple TLC densitometric method for the quantification of hecogenin from the leaves of Agave americana using HPTLC. The method was validated for precision, repeatability and accuracy. The method was found to be precise with RSD of 0.78 (intraday) and 0.82 (interday) for different concentrations of hecogenin. Instrumental precision was 0.42 (% RSD) for hecogenin. The content of hecogenin in different samples was estimated by the proposed method and was found to be in the range of 0.05−0.14% w/w in the samples analysed. Accuracy of the method was checked by conducting recovery study at three different levels for hecogenin and the average percentage recovery was 98.98%, 101.92% and 103.33%, respectively. The TLC densitometric method developed for the quantification of hecogenin was found to be simple, precise, specific, sensitive, accurate and can be used in routine quality control. Revised: 7 and 25 April 2006     

Two New Steroidal Glycosides from Fermented Leaves of Agave americana

Two new spirostanol glycosides named agamenoside A and B, ere isolated from the fermented leaves of Agave americana. Their structures were elucidated as (23S,25R)-5α-spirostan-3β,6α，23－triol 3-O-α-L-rhamnopyranosyl-(1→3)-β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside(1) and (25R)-5α-spiro-stan-3β,6α-diol 3-O-β-D-glucopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyra-nosyl-(1→4)-β-D-galactopyranoside(2) by a combination of chemical and spectral methods.     

Aqueous extracts of Agave sisalana boles have prebiotic potential

Abstract

This work aimed at evaluating the prebiotic potential of the aqueous extract and crude polysaccharides from Agave sisalana boles by an in vitro screening. Crude polysaccharides were obtained from the aqueous bole extract by precipitation with acetone and resuspension in water. The liquid extract and the polysaccharide solution were then spray dried and submitted to thermal analysis and quantification of metabolites. Prebiotic activity was checked on probiotic strains belonging to the Lactobacillus genus using inulin, fructo-oligosaccharides, fructose and glucose as positive controls. The powder of A. sisalana bole extract, which has recently been identified as a rich source of inulin, exhibited higher potential of fermentation compared with crude polysaccharides.     

Characterization of three saponins from a fraction using 1D DOSY as a solvent signal suppression tool. Agabrittonosides E–F. Furostane Saponins from Agave brittoniana Trel. spp. Brachypus

A careful NMR analysis, especially by 1D TOCSY and 1D ROESY, of a refined saponin fraction allowed us to determine the structure of three saponins from a polar extract of Agave brittoniana Trel. spp. Brachypus leaves. The use of 1D DOSY for the suppression of the solvent signal was useful to obtain the chemical shifts of anomeric signals. A full assignment of the ¹H and ¹³C spectral data for the new saponins, agabrittonosides E–F (1–2) and the well‐known Karatavioside C (3) and their methoxyl derivatives, is reported. The structures were established using a combination of 1D and 2D (¹H, ¹H‐COSY, TOCSY, ROESY, g‐HSQC, g‐HMBC and g‐HSQC‐TOCSY) NMR techniques and ESI–MS. In addition, the methoxylation of these furostane saponins in the presence of MeOH was studied. Copyright © 2010 John Wiley & Sons, Ltd.     

Two New Steroidal Saponins from the Fresh Leaves of Agave sisalana

A new furostanol saponin, sisalasaponin C ( 1 ), and a new spirostanol saponin, sisalasaponin D ( 2 ), were isolated from the fresh leaves of Agave sisalana, along with three other known steroidal saponins and two stilbenes. Their structures were identified as (3β,5α,6α,22α,25R)‐3,26‐bis[(β‐D ‐glucopyrano‐ syl)oxy]‐22‐hydroxyfurostan‐6‐yl β‐D ‐glucopyranoside ( 1 ), (3β,5α,25R)‐12‐oxospirostan‐3‐yl 6‐deoxy‐α‐L ‐mannopyranosyl‐(1→4)‐β‐D ‐glucopyranosyl‐(1→3)‐[β‐D ‐xylopyranosyl‐(1→3)‐β‐D ‐glucopyranosyl‐(1→2)]‐β‐D ‐glucopyranosyl‐(1→4)‐β‐D ‐galactopyranoside ( 2 ), (3β,5α,6α,22α,25R)‐22‐methoxyfurostane‐3,6,26‐triyl tris‐β‐D ‐glucopyranoside, cantalasaponin‐1, polianthoside D, (E)‐ and (Z)‐2,3,4′,5‐tetrahydroxystilbene 2‐O‐β‐D ‐glucopyranosides. The last three known compounds were isolated from the fresh leaves of Agavaceae for the first time. The structures of the new compounds were elucidated by detailed spectroscopic analysis, including 1D‐ and 2D‐NMR experiments, and chemical techniques.     

Antibacterial activity of agave fructans against salmonella typhimurium

Abstract

The objective of this study was to evaluate the antimicrobial effect of Agave fructans against the Salmonella Typhimurium in “in vitro” experiments. The result of the antimicrobial activity was 263.89?±?0, 414.95?±?12.83, 494.54?±?13.88, 522.29?±?0, 580.41?±?14.92?AU for 10, 20, 30, 40 and 50% of Agave fructans (AF) respectively. In addition, there is a significant effect on the growth of the bacteria with all the percentages of AF evaluated (p?<?0.001, R2?=?0.859) with respect to the control. The growth rate of Salmonella with 25% AF was statistically significant compared to the control (?0.7353?±?0.586, 0.0079?±?0.002?D.O./h, respectively; p?>?0.01). Agave fructans could be an alternative to prevent the infections caused by Salmonella.     

红光皂甙元及其两个甾体皂甙的NMR研究

从番麻(Agave americana L.)发酵的叶汁中分离得到红光皂甙元(hongguanggenin)、Cantalasaponin-1及一个新的甾体皂苷Agameroside-1. 运用2D NMR技术,包括DQF ¹H-¹H COS Y,HSQC,HMBC,HSQC-TOCSY,ROESY等技术,首次全归属了3个甾体化合物的氢和碳的化学位移,并总结了红光皂甙元的甙化位移效应,从而修正了文献中部分碳信号归属以及甙元的甙化位移效应.     

Cellulose derivatives from cellulosic material isolated from Agave lechuguilla and fourcroydes

Fibers isolated from Agave lechuguilla(lechuguilla) and fourcroydes (henequen) contain about 80%cellulose, 5% hemicellulose and 15% lignin. They are a renewable resource,interesting as feedstock for new products obtained by chemicalfunctionalization. In the present paper the reactivity of such fibrousmaterialsunder typical conditions for modification of cellulose was studied. Treatmentwith n-octanol/aqueous NaOH of the fibers leads to an activated expandedgel-like material with enhanced accessibility. Carboxymethylation, sulfation,acetylation and tritylation reactions as well as subsequent carboxymethylationof the trityl derivative and selective oxidation of the primary hydroxylfunction of carboxymethylated products with TEMPO/NaBr/NaClO were successfullycarried out under conditions typical for cellulose reactions. The products werecharacterized by means of ¹³C-NMR and ¹H-NMR spectroscopyandHPLC after complete depolymerization, by GPC, and by the determination ofsolubility.     

Saponin-rich fraction from Agave sisalana: effect against malignant astrocytic cells and its chemical characterisation by ESI-MS/MS

Astrocytic tumour cells derived from human (GL-15) and rat (C6) gliomas, as well as non-tumoural astrocytic cells, were exposed to the saponin-rich fraction (SF) from Agave sisalana waste and the cytotoxic effects were evaluated. Cytotoxicity assays revealed a reduction of cell viability that was more intensive in glioma than in non-tumoural cells. The SF induced morphological changes in C6 cells. They were characterised by cytoplasmic vacuole formation associated with increase in the formation of acidic lysosomes. The SF was subjected to purification on Sephadex LH-20, which characterised three probable steroidal saponins (sisalins) by electrospray ionisation mass spectrometry multistage (ESI-MSⁿ). Sisalins from sisal may be responsible for the cytotoxicity, which involves cytoplasmatic vacuole formation and selective action for glioma cells.     

Partial purification and characterization of two proteases fromAgave fourcroydes

Large amounts of wastes are produced by the henequen industry from which it may be possible to obtain products of commercial importance. Our laboratory has detected proteolytic activity inAgave fourcroydes (henequen) juice. The proteolytic activity is a result of two proteases of 14,500 and 12,000 daltons, respectively. Both enzymes are very stable at -20°C., when freeze-dried and in the presence of EDTA and cysteine. They differ in pH optimum and thermal stability.