Agave americana L.

Nota de alcance

PARTE UTILIZADA=Used part: Hojas, raíz.

ACCIÓN FARMACOLÓGICA= Pharmacological action: Pectoral y depurativo.

COMPOSICIÓN QUÍMICA= Chemical composition: La cabuya ha sido objeto de numerosas investigaciones fitoquímicas. Toda la planta y en especial el parénquima de las hojas constituye una fuente de saponinas. Se aislaron nueve glucósidos esteroidales, habiéndose identificado como única aglicona la hecogenina. Posteriormente se han identificado otras agliconas en especial la rocogenina, tigogenina y la gitogenina. Se han identificado diferentes azúcares como componentes de los glucósidos e igualmente se han aislado varias enzimas, especialmente proteasas. En las flores se han identificado también clorogenina y glucósidos del kaempferol. El zumo de las hojas, en ensayos in vitro tiene actividad antibacteriana sobre varios microrganismos Gran-positivos y Gran-negativos. Las propiedades antiinflamatorias, antiartríticas y otras atribuidas, no han sido sometidas a los necesarios ensayos farmacológicos. El hecho que las saponinas de la cabuya han servido de base para la producción de hormonas esteroidales, podría dar alguna base a los usos populares de esta especie vegetal. En dosis mayores a las terapéuticas puede provocar gastritis y efectos laxantes y en dosis mayores aún provoca diarrea. Se han reportado además las siguientes actividades: actividad moluscicida (Australorbis glabratus) LC50 = 1000ppm, efecto efecto sobre las membranas por la fracción saponínica, actividad antimicótica, actividad antituberculosa, actividad antiviral (Herpes Tipo I) y efecto promotor de tumores (Sarcoma HSI).

ZONA GEOGRÁFICA= Geografical zone: Uruguay.

Nota de alcance

DIVERSIDAD GENÉTICA Y MEJORAMIENTO DE PLANTAS MEDICINALES=Medicinal plants and improvement of medicinal herbs:

GDSL and SGNH hydrolases are lipases involved in a wide range of functions, behaving in many cases as bifunctional enzymes. In this work, the isolation and characterization of AgaSGNH, a cDNA encoding a member of the SGNH-hydrolase superfamily from young leaf epidermis of the monocot Agave americana L., is reported. The protein possesses a typical signal peptide at its N-terminus that allows its secretion to the epidermis cell wall, as verified by immunolocalization expts. In addn., the AgaSGNH sequence contains a His-Leu-Gly-Ala-Glu (HLGAE) motif which is similar to that obsd. in other plant acyltransferases. Expression levels by northern blot and in situ localization of the corresponding mRNA, as well as the immunolocalization of the protein in Agave young leaves indicate that the protein is specifically present in the epidermal cells. The detailed study performed in different parts of the Agave leaf confirms two aspects: first, the expression of AgaSGNH is limited to the epidermis, and second, the max. mRNA levels are found in the epidermis of the youngest zones of the leaf which are esp. active in cutin biosynthesis. These levels dramatically decrease in the oldest zone of the leaf, where the presence of AgaSGNH mRNA is undetectable, and the biosynthesis of different cuticle components is severely reduced. These data could be compatible with the hypothesis that AgaSGNH could carry out both the hydrolysis and the transfer, from an activated acyl-CoA to a crescent cutin in Agave americana leaves and, therefore, be involved in the still unknown mechanism of plant cutin biosynthesis.

Nota de alcance

ÚLTIMOS AVANCES EN LA QUÍMICA Y ACTIVIDADES BACTERIOLÓGICAS EN LAS PLANTAS MEDICINALES=Medicinal plants, last advances on chemistry and bacteria activities on the medicinal herbs:

1) In this paper, the physico-chem. and mech. properties of Agave americana L. fiber are studied to explore the possibilities of using this fiber in textile industry. Three different processings for extg. fibers from the leaf of Agave americana L. plant were investigated: (i) raw fibers manually extd., (ii) fibers extd. by retting leaves in seawater and (iii) fibers extd. after hydrolysis treatment of the leaves in distd. water. Chem. compn. (cellulose, lignin and hemicellulose contents), phys. properties (d., fineness and crystallinity) as well as mech. properties of the resultant fibers were measured. The chem. compn. reveals that the Agave americana L. fiber has a cellulose content at the order of 62% which is similar to that of other lignocellulosic fibers. The distd. water extd. fibers developed the highest cellulose content. Lignin content of Agave americana L. fiber is low compared to other natural fibers (2.4%) and seawater-extd. fibers generated the lowest lignin content (2.12%). Fourier transform IR spectra (FTIR) and x-ray diffractometry of all extd. fibers revealed the same chain conformation. X-ray diffractograms showed that cellulose I is the main cryst. constituent. Concerning phys. and mech. properties, raw fibers were characterised by the lowest d. (0.9) and the highest crystallinity (51.2%), they are also stronger and less extensible than the other two fibers. In this paper, we attempt to study the effect of extn. in water on the mech. and phys. properties of Agave americana L. fibers.

2) Leaf ext. of Agave americana was evaluated for antifungal activity against Alternaria brassicae, the causal agent of Alternaria blight of Indian mustard [Brassica juncea (L.) Czern. & Coss]. Methanolic leaf ext. (crude ext.) of A. americana showed antifungal activity against A. brassicae. The green mass obtained by vacuum drying of the crude ext. was used for further sequential fractionation using Et acetate, n-butanol and methanol. Among the three fractions, the methanolic fraction showed the strongest antifungal activity by its inhibition of conidial germination of A. brassicae. The methanolic fraction of A. americana leaves was fractionated further using open column liq. chromatog. into six sub-fractions (I - VI). Among the six sub-fractions tested, sub-fraction II showed a strong inhibitory effect on conidial germination of A. brassicae and thereby inhibited lesion development of Alternaria blight of Indian mustard at a concn. of 40 mg/mL or higher. Qual. sepn. of mols. present in sub-fraction II by thin layer chromatog. followed by diagnosis with Libermann - Burchard reagent indicated that sub-fraction II contained a mixt. of saponins. The potential of using A. americana for the management of fungal pathogens of crop plants is discussed.

3) This study was carried out to examine the potential of Agave americana fibers (AAF) for the treatment of wastewater contaminated with dyes. The batch mode adsorption of two dyes, viz. Sumfixe Supra Red (SSR) and Alpacelle Lumiere Brown (ALB), by AAF was investigated at different pH values, temps., and initial dye concns. The highest dye adsorption capacities at 30° were attained at pH 2.0 for SSR and at pH 2.5 for ALB. In both cases, an increase in temp. increased the velocity of the reaction. The max. amts. of dyes desorbed were at basic pH values. To compare the results with studies on other biomaterials, the adsorption isotherms and kinetic data were analyzed employing the usual models (Freundlich, Langmuir and Temkin isotherms and first- and second-order kinetics). Conventional anal. indicated that the kinetics of the processes were closer to pseudo-second order rather than first order. The data were also modeled with a new method of anal. based on the statistical theory of complex systems and the heterogeneity of the sorption energy (energy landscape). This enabled the adsorption process to be characterized in terms of a greater no. of phys. parameters.

4) Agave americana contains inulin as storage carbohydrate. Therefore, agave is interesting to be used for the extn. of inulin by pressing. The yield of the process is low due to the high hardness of the core. The objective of this work was to evaluate pretreatments to reduce the hardness in the process of obtaining insulin by pressing. Treatments with water, sulfuric acid 1 % (by mass) or sodium hydroxide 1 % (by mass) were tested and optimized. The pretreatment of the core of A. americana with sulfuric acid 1 % allowed the redn. of hardness from 30 000 g to 2000 g of breaking force. The math. model obtained predicts an optimum processing at 84 °C during 75 min. The treatment with sulfuric acid 1 % also allows white core of A. americana to be obtained, while the other treatments provide yellow core. These results open a good alternative to obtain value added products from this resource.

Nota de alcance (en)

Root: Sudorific and antisyphilitic. Roots are steeped in water, and the water ingested for various ailments such as stomach pain, painful and difficult urination, scurvy, swollen and bleeding pulp of teeth, swollen bones, constipation, and poor appetite or loss of appetite.

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Origin:
Native to America; grown in gardens for ornamentation.

Action:
Leaf juice—used for warts, cancerous ulcers and putrid tumours. Leaves are also used as a resolvant in syphilis and scrofula.

Nota bibliográfica

1) GONZALEZ, Matías ; LOMBARDO, Atilio ; VALLARINO, Aida. Plantas de la medicina vulgar del Uruguay. Montevideo : Talleres Gráficos, 1937, p.104.

2) 270 (doscientos setenta) plantas medicinales iberoamericanas. Santiago de Bogotá : CYTED-SECAB, 1995, p.7.

3) REINA, Jose J.; GUERRERO, Consuelo; HEREDIA, Antonio. Isolation, characterization, and localization of AgaSGNH cDNA: a new SGNH-motif plant hydrolase specific to Agave americana L. leaf epidermis. Journal of Experimental Botany. 2007, vol.58 , nº11 , p.2717-2731.

4) EL OUDIANI, A., et al. Physico-chemical characterisation and tensile mechanical properties of Agave americana L. fibres. Journal of the Textile Institute. 2009, vol.100, nº5 , p.430-439.

5) GULERIA, Sanjay; KUMAR, Ashok. Antifungal activity of Agave americana leaf extract against Alternaria brassicae, causal agent of Alternaria blight of Indian mustard (Brassica juncea). Archives of Phytopathology and Plant Protection. 2009, vol.42 nª4, 370-375.

6) BEN HAMISSA, Aicha Menyar; BROUERS, Francois; MAHJOUB, Borhane; SEFFEN, Mongi. Adsorption of textile dyes using Agave americana (L.) fibers: equilibrium and kinetics modelling. Adsorption Science & Technology. 2007, vol.25, nº5, p.311-325.

7) RAMIREZ, Jose A.; et al. Manuel. Evaluation of treatments to reduce hardness of Agave americana core. Food Technology and Biotechnology. 2006, vol.44 , nº4 , p.545-551.