Effect of Water Stress Induced by Polyethylene Glycol on Growth, Proline Accumulation in Agave americana L.

The effect of water deficit was determined on both in vitro and soil seedling as well as in cells in suspension of Agave americana L.In order to do the establishment of cells,the formation of callus was induced;for it two auxins were evaluated:2,4-dichlorophenoxyacetic acid(2,4-D)and 4-mino-3,5,6-trichloropicolinic acid(picloram)at three concentrations(0.25,0.5 and 0.75 mg L−1)in three explants(leaf,root and meristems)cultured in MS semisolid medium.The callogenesis response was related to the type and section of the explant,as well as the regulator used,and a cell suspension was established using 0.5 mg L−1 naphthaleneacetic acid(NAA)+0.5 mg L−1 Benzylaminopurine(BAP).Seedlings were exposed to polyethyleneglycol(15%and 30%w/v)with a water potential of−0.87 and−2.67 MPa,respectively,under soil conditions.Water stress was applied through restricted irrigation.Fresh weight,root system growth,and chlorophyll concentration were some of the parameters that were affected by the effect of water deficit on A.americana L.Chlorophyll concentration values were significantly decreased by 15 at 30%PEG(19.6 SPAD units)compared to the control treatment.In in vitro plants,the highest concentration of proline was found in the roots,being the treatment with 30%polyethylene glycol where the highest concentration of this osmoregulator was obtained(62.5 mg g−1 DW).Under restricted irrigation conditions,an increase in proline concentration was observed both in the aerial part(2.2μg 100 g−1 DW)and in the root system(1.8μg 100 g−1 DW).However,the concentrations found were approximately ten times greater,less than those found under in vitro conditions.Therefore,the accumulation of proline can be considered an indicator of stress in Agave Americana L.growth in vitro.

Two New Steroidal Glycosides from Fermented Leaves of Agave americana

Two new spirostanol glycosides named agamenoside A and B, were isolated from the fermented leaves of Agave americana. Their structures were elucidated as (23S, 25R)-5a -spirostan-3b, 6a, 23-triol 3-O-a-L-rhamnopyranosyl-(13)- b-D-glucopyranosyl-(12)-[b-D- xylopyranosyl-(13)]-b-D-glucopyranosyl-(14)-b-D-galactopyranoside (1) and (25R)-5a-spiro- stan-3b, 6a-diol 3-O-b-D-glucopyranosyl-(12)-[ b-D-xylopyranosyl-(13)]- b-D-glucopyra- nosyl-(14)- b-D-galactopyranoside (2) by a combination of chemical and spectral methods.

A New Pregnane Glycoside from Fermented Leaves of Agave americana

A new minor pregnane glycoside was isolated from the fermented leaves of Agave americana. Its structure was elucidated as (20S)-5a-pregnane-3? 20-diol 20-O--D-glucopyrano- side (1) by spectral methods.

Two New Spirostanol Steroidal Sapogenins from Fermented Leaves of Agave americana

Two new spirostanol sapogenins named agavegenin A and B were isolated from the fermented leaves of Agave americana L. Their structures were elucidated as (23S, 25R)-5a- spirostan-3b, 6a, 11a, 23-tetraol (1) and (23S, 25S)-5a-spirostan-3b, 23, 27-triol (2) by spectral methods.

Cytocompatible cellulose nanofibers from invasive plant species Agave americana L.and Ricinus communis L.:a renewable green source of highly crystalline nanocellulose

In this study,the fibers of invasive species Agave americana L.and Ricinus communis L.were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers.Cellulose nanofibers were obtained by two methods,based on either alkaline or acid hydrolysis.The morphology,chemical composition,and crystallinity of the obtained materials were characterized by scanning electron microscopy(SEM)together with energy-dispersive X-ray spectroscopy(EDX),dynamic light scattering(DLS),X-ray diffraction(XRD),and Fourier transform infrared(FTIR)spectroscopy.The crystallinity indexes(CIs)of the cellulose nanofibers extracted from A.americana and R.communis were very high(94.1%and 92.7%,respectively).Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293 T(HEK293 T)cells were also performed.The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed(i.e.,0-500μg/mL).Our results showed that the nanocellulose extracted from A.americana and R.communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications.