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At least 73 records · Page 4Linked to original sources
PubMed1978

A quantitative gas-liquid chromatographic method for the estimation of hecogenin and tigogenin in the leaves, juice and sapogenin concentrates of Agave sisalana.

A gas-liquid chromatographic method has been devised for the routine estimation of the hecogenin [3beta-hydroxy-(25R)-5beta-spirostan-12-one] and tigogenin [ (25R)-5beta-spirostan-3beta-ol] contents of Agave sisalana leaf and juice samples and of the crude sapogenin concentrates known as "coffee grounds". Because of partial degradation of the sapogenins in the GLC system it was found necessary to acetylate the compounds prior to their estimation. In East African samples the tigogenin proportion of the total sapogenin content is usually about 10%. At this level, the 95% inverse tolerance limits on predicted tigogenin weights are approximately +/- 7%.

Chromatography, Gas↗
PubMed1980

Ruizgenin, a new steroidal sapogenin diol from Agave lecheguilla.

From the leaves of Agave lecheguilla Torrey, two steroidal sapogenin diols have been isolated. Mass spectral, infra-red and nuclear magnetic resonance data of these two compounds showed them to be (25R)-spirost-5-ene-2 alpha, 3 beta-diol (yuccagenin) and (25R)-5 beta-spirostane-3 beta, 6 alpha-diol. The latter is a new compound to which the trivial name ruizgenin has been given.

Chromatography, Thin Layer↗
PubMed2000

A new steroidal saponin from the leaves of Agave americana.

A new bisdesmosidic spirostanol saponin, along with three known saponins, were isolated from Agave americana (Agavaceae). The structure of the new saponin was elucidated as (25R)-3 beta,6 alpha-dihydroxy-5 alpha-spirostan-12-one 3,6-di-O-beta-D-glucopyranoside. Among the isolated saponins, hecogenin tetraglycoside showed cytotoxic activity against HL-60 human promyelocytic leukemia cells with an IC50 value of 4.3 micrograms/mL.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Anti-inflammatory activity of aqueous extracts and steroidal sapogenins of Agave americana.

Lyophilized aqueous extracts obtained from Agave americana L (Agavaceae) collected in the north of Sardinia were characterized with regard to their steroidal sapogenin content. Extracts of A. americana and genins isolated from them were evaluated for anti-inflammatory properties by testing their effects on carrageenin-induced edema. The effect of orally administered genins on gastric mucous membranes was also assessed. Lyophilized extracts administered by the intraperitoneal route at doses equivalent to 200 and 300 mg/kg of fresh plant starting material, showed good anti-inflammatory activity. Doses of genins (total steroidal sapogenins, hecogenin and tigogenin) equivalent to the amount in the lyophilized extracts produced an antiedentatous effect which was much stronger and more efficacious than that obtained with an i.p. administration of 5 mg/kg of indomethacin or dexamethasone 21-phosphate at a dose equivalent to the molar content of hecogenin administered. At the doses used to evaluate the anti-inflammatory activity, the genins did not have any harmful effect on the gastric mucous membranes. Lesions occurred when significantly higher doses of hecogenin were given, but gastric damage was still less than that caused by the drugs used for comparative purposes.

Animals↗
PubMed1999

Gross histopathological effects of an extract of Agave attenuata on the epithelium of the digestive tract of Bulinus africanus.

A lethal concentration of a crude, aqueous extract of Agave attenuata was applied as a contact poison to Bulinus africanus, the intermediate host of Schistosoma haematobium, for a 24-h period. The gross histopathological effects of the extract on the epithelium of the digestive tract were then studied. A graded series of cellular injuries to the epithelial layer was observed along the length of the tract. These included the loss of cilia and brush border, disruption of the epithelial layer, cellular vacuolation, swelling and rupture, and the discharge of secretory products from mucous gland cells. The results of the microscopy show that epithelial tissue is probably a primary target of the molluscicide. The cytological injuries induced by extracts of A. attenuata indicate that the molluscicide acts by disrupting the osmoregulatory mechanisms of the epithelial cells, but further, detailed studies are required to confirm this.

Animals↗
PubMed1998

Phloem Transport of Fructans in the Crassulacean Acid Metabolism Species Agave deserti

Four oligofructans (neokestose, 1-kestose, nystose, and an un-identified pentofructan) occurred in the vascular tissues and phloem sap of mature leaves of Agave deserti. Fructosyltransferases (responsible for fructan biosynthesis) also occurred in the vascular tissues. In contrast, oligofructans and fructosyltransferases were virtually absent from the chlorenchyma, suggesting that fructan biosynthesis was restricted to the vascular tissues. On a molar basis, these oligofructans accounted for 46% of the total soluble sugars in the vascular tissues (sucrose [Suc] for 26%) and for 19% in the phloem sap (fructose for 24% and Suc for 53%). The Suc concentration was 1.8 times higher in the cytosol of the chlorenchyma cells than in the phloem sap; the nystose concentration was 4.9 times higher and that of pentofructan was 3.2 times higher in the vascular tissues than in the phloem sap. To our knowledge, these results provide the first evidence that oligofructans are synthesized and transported in the phloem of higher plants. The polymer-trapping mechanism proposed for dicotyledonous C3 species may also be valid for oligofructan transport in monocotyledonous species, such as A. deserti, which may use a symplastic pathway for phloem loading of photosynthates in its mature leaves.

Journal Article↗
PubMed1976

Water Relations and Photosynthesis of a Desert CAM Plant, Agave deserti.

The water relations and photosynthesis of Agave deserti Engelm., a plant exhibiting Crassulacean acid metabolism, were measured in the Colorado desert. Although no natural stomatal opening of A. deserti occurred in the summer of 1975, it could be induced by watering. The resistance for water vapor diffusion from a leaf (R(WV)) became less than 20 sec cm(-1) when the soil water potential at 10 cm became greater than -3 bars, as would occur after a 7-mm rainfall. As a consequence of its shallow root system (mean depth of 8 cm), A. deserti responded rapidly to the infrequent rains, and the succulent nature of its leaves allowed stomatal opening to continue for up to 8 days after the soil became drier than the plant. When the leaf temperature at night was increased from 5 to 20 C, R(WV) increased 5-fold, emphasizing the importance of cool nighttime temperatures for gas exchange by this plant. Although most CO(2) uptake occurred at night, a secondary light-dependent rise in CO(2) influx generally occurred after dawn. The transpiration ratio (mass of water transpired/mass of CO(2) fixed) had extremely low values of 18 for a winter day, and approximately 25 for an entire year.

Journal Article↗
PubMed1978

Resistance Analysis of Nocturnal Carbon Dioxide Uptake by a Crassulacean Acid Metabolism Succulent, Agave deserti.

Nocturnal CO(2) uptake by a Crassulacean acid metabolism succulent, Agave deserti Engelm. (Agavaceae), was measured so that the resistance properties of the mesophyll chlorenchyma cells and their CO(2) concentrations could be determined. Two equivalents of acidity were produced at night per mole of CO(2) taken up. The nocturnal CO(2) uptake became light-saturated at 3.5 mEinsteins cm(-2) of photosynthetically active radiation (400-700 nm) incident during the preceding day; at least 46 Einsteins were required per mole of CO(2) fixed. Variations in the daytime leaf temperature between 20 and 37 C had little effect on nocturnal CO(2) uptake. After the first few hours in the dark, the leaf liquid phase CO(2) resistance (r(liq) (CO(2) )) and the CO(2) concentration in the chlorenchyma cells (c(i) (CO(2) )) both increased, the latter usually reaching the ambient external CO(2) level at the end of the dark period. Increasing the leaf surface temperature above 15 C at night markedly increased the stomatal resistance, r(liq) (CO(2) ), and c(i) (CO(2) ).The minimum r(liq) (CO(2) ) at night was about 1.6 seconds cm(-1). Based on the ratio of chlorenchyma surface area to total leaf surface area of 82, this r(liq) (CO(2) ) corresponded to a minimum cellular resistance of approximately 130 seconds cm(-1), comparable to values for mesophyll cells of C(3) plants. The contribution of the carboxylation reaction and/or other biochemical steps to r(liq) (CO(2) ) may increase appreciably as the nighttime temperature shifts a few degrees from the optimum or after a few hours in the dark, both of which caused large increases in r(liq) (CO(2) ). This necessitates a large internal leaf area for CO(2) diffusion into the chlorenchyma to support moderate nocturnal CO(2) uptake rates by these succulent leaves.

Journal Article↗
PubMed1979

Environmental Influences on Open Stomates of a Crassulacean Acid Metabolism Plant, Agave deserti.

The major short term stomatal response of Agave deserti was to temperature; increases in leaf temperature led to decreases in water vapor conductance for stomatal opening during the daytime (C(3) mode) as well as at night (Crassulacean acid metabolism or CAM mode). Hourly changes in the water vapor concentration drop from leaf to air had no significant stomatal effect in either mode. Stomatal responses to external CO(2) levels up to 800 microliters per liter were not significant after 15 minutes and only moderate after a few hours, suggesting that CO(2) effects on open stomates of this succulent were indirect in both CAM and C(3) modes.

Journal Article↗
PubMed1986

Growth Response of a Succulent Plant, Agave vilmoriniana, to Elevated CO(2).

Large (about 200 grams dry weight) and small (about 5 grams dry weight) specimens of the leaf succulent Agave vilmoriniana Berger were grown outdoors at Phoenix, Arizona. Potted plants were maintained in open-top chambers constructed with clear, plastic wall material. Four CO(2) concentrations of 350, 560, 675, and 885 microliters per liter were used during two growth periods and two water treatments. Small and large plants were grown for 6 months, while a few large plants were grown for 1 year. Wet-treatment plants received water twice weekly, whereas dry-treatment plants received slightly more water than they would under natural conditions. Plant growth rates in all treatments were significantly different between small and large specimens, but not between 6 month and 1 year large plants. Only the dry-treatment plants exhibited statistically different growth rates between the CO(2) treatments. This productivity response was equivalent to a 28% and 3-fold increase when mathematically interpolated between CO(2) concentrations of 300 and 600 microliters per liter for large and small plants, respectively.

Journal Article↗
PubMed1987

Minor Physiological Response to Elevated CO(2) by the CAM Plant Agave vilmoriniana.

One-year-old plants of the CAM leaf succulent Agave vilmoriniana Berger were grown outdoors at Riverside, California. Potted plants were acclimated to CO(2)-enrichment (about 750 microliters per liter) by growth for 2 weeks in an open-top polyethylene chamber. Control plants were grown nearby where the ambient CO(2) concentration was about 370 microliters per liter. When the plants were well watered, CO(2)-induced differences in stomatal conductances and CO(2) assimilation rates over the entire 24-hour period were not large. There was a large nocturnal acidification in both CO(2) treatments and insignificant differences in leaf chlorophyll content. Well watered plants maintained water potentials of -0.3 to -0.4 megapascals. When other plants were allowed to dry to water potentials of -1.2 to -1.7 megapascals, stomatal conductances and CO(2) uptake rates were reduced in magnitude, with the biggest difference in Phase IV photosynthesis. The minor nocturnal response to CO(2) by this species is interpreted to indicate saturated, or nearly saturated, phosphoenolpyruvate carboxylase activity at current atmospheric CO(2) concentrations. CO(2)-enhanced diurnal activity of ribulose bisphosphate carboxylase activity remains a possibility.

Journal Article↗
PubMed1998

Contact dermatitis with systemic symptoms from Agave americana.

BACKGROUND: Twelve cases of contact dermatitis provoked by Agave americana are described, 10 with systemic signs and symptoms and 8 with abnormal laboratory results. RESULTS: Patient history revealed a background of intentional exposure among soldiers seeking sick leave. Treatment with oral antihistamines and topical saline compresses resulted in subsidence of the systemic symptoms within 24 h of hospitalization and regression of cutaneous manifestations in 7-10 days. CONCLUSION: The importance that dermatologists be alert to the possibility of self-inflicted contact dermatitis induced by exposure to plants is stressed, especially to A. americana. Systemic signs are not rare accompanying findings with this plant.

Adolescent↗
PubMed1993

Two new steroidal saponins from dried fermented residues of leaf-juices of Agave sisalana forma Dong No. 1.

In a previous paper, we reported the isolation and structure determination of three new steroidal saponins, dongnosides C (3), D (2) and E (1) from the dried fermented residues of leaf-juices of Agave sisalana forma Dong No. 1. In a continuing study on this plant, two additional new major steroidal saponins, named dongnosides B (4) and A (5), were obtained. Their structures were characterized respectively as tigogenin 3-O-alpha-L-rhamonpyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->2)- [beta-D- glucopyranosyl-(1-->3)]-beta-D-glucopyranosyl-(1-->4)-beta-D-galactop yranoside and 3-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->2)-[beta- D- xylopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->3)]-beta-D- glucopyranosyl-(1-->4)-beta-D-galactopyranoside on the basis of chemical and physicochemical evidence.

Carbohydrate Sequence↗
PubMed1999

Genetic diversity of the endangered endemic Agave victoriae-reginae (Agavaceae) in the Chihuahuan Desert.

Long-lived perennials are a species-rich, ecologically important component of the North American deserts, yet we know little about their genetic structure, information important for their conservation. Agave victoriae-reginae is an endemic of the Chihuahuan Desert of northern Mexico that is endangered by collection for the ornamental trade. We examined levels and patterns of variation at ten polymorphic allozyme loci in ten populations representing the range of the species. Levels of genetic variation (mean H(e)= 0.335) and differentiation (mean F(ST) = 0.236) were high. Phenetic clustering suggested the existence of at least three distinct groups of populations. If this pattern of variation is representative of other long-lived desert perennials, it may explain the species richness of this group and will pose a real challenge to gene conservation efforts.

Journal Article↗
PubMed2000

[Dermatitis from contact with Agave americana].

Various plants induce dermatitis in man. There have been only a few published cases of contact dermatitis caused by Agave americana (AA). We report intentional exposure to AA in a soldier seeking sick leave, and review our previously reported cases. Treatment with oral antihistamines and topical saline compresses resulted in subsidence of the systemic symptoms within 24 h and regression of cutaneous manifestations in 7-10 days. Physicians should be alert to the possibility of self-inflicted contact dermatitis induced by exposure to plants, especially to A. americana. Systemic signs may accompany the cutaneous lesions.

Adult↗
PubMed2000

Purpuric irritant contact dermatitis induced by Agave americana.

The sap of Agave americana, a popular ornamental plant, may cause irritant contact dermatitis. This rare eruption is typically vesiculopapular; however, a new purpuric variant with evidence of leukocytoclastic vasculitis has recently been reported. We report an additional case of a purpuric eruption associated with severe constitutional symptoms further supporting a possible vasculitic component. Both cases resulted from direct exposure to sap propelled by a chainsaw. We speculate that oxalic acid crystals, which are recognized systemic toxins, are embedded in the skin with resulting oxalism, which may result in vascular damage.

Acute Disease↗
PubMed1989

Isolation and characterization of an utero-active compound from Agave americana.

Crude extracts of Agave americana contain two utero-active compounds. One of these, tentatively named "Fraction B", has been purified to chromatographic homogeneity. Its pharmacological actions are similar to those of acetylcholine. However its chromatographic and electrophoretic mobilities are different. Some chemical properties of fraction B are compatible with the structure of an acyl derivative of choline different from acetylcholine.

Animals↗
PubMed1985

Phytobezoar from the stem ("quiote") of the cactus Agave americana: report of case.

Agave americana is a cactus growing abundantly in Mexico. Its cooked stem ("quiote") yields by mastication a sweet juice which is swallowed, while the fibers ("bagazo") are spit out. That is the way Mexicans are taught to chew quiote since their early childhood, and it accounts for the rarity of bezoars from this origin. One of such cases is reported herein.

Bezoars↗