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Dive into the research topics where Alejandra Rojas is active.

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Featured researches published by Alejandra Rojas.


Journal of Ethnopharmacology | 1992

Screening for antimicrobial activity of crude drug extracts and pure natural products from Mexican medicinal plants

Alejandra Rojas; Lourdes Hernández; Rogelio Pereda-Miranda; Rachel Mata

Preliminary antimicrobial screening against Candida albicans and selected Gram-positive and Gram-negative bacteria of methanol extracts prepared from eight Mexican medicinal plants, noted for their antiseptic properties, was conducted. The significant activity exhibited for extracts of Ratibida latipalearis, Teloxys graveolens, Dodonaea viscosa, Hyptis albida, H. pectinata, H. Suaveolens and H. verticillata tends to support their traditional use as anti-infective agents. Only the extract of Hintonia latiflora was inactive. The antimicrobial activities of 44 pure natural compounds and two derivatives were determined. Of these, only 23 compounds were effective in inhibiting the growth of the tested organisms (MIC less than or equal to 100 micrograms/ml).


Pharmaceutical Biology | 2010

Vasoactive and antioxidant activities of plants used in Mexican traditional medicine for the treatment of cardiovascular diseases

C. Ibarra-Alvarado; Alejandra Rojas; Sandra Mendoza; Moustapha Bah; Dora M. Gutiérrez; L. Hernández-Sandoval; M. Martínez

This study demonstrated that the aqueous extracts of plants employed in Mexican traditional medicine for the treatment of cardiovascular diseases are able to modify the tone of arterial smooth muscle. Agastache mexicana (Kunth) Lint & Epling (Labiatae), Chenopodium murale L. (Chenopodiaceae), Chirantodendron pentadactylon Larreat (Sterculiaceae), Dracocephalum moldavica L. (Labiatae), Psittacanthus calyculatus G. Don (Loranthaceae), Prunus serotina ssp. capuli (Cav. ex Spreng) McVaugh (Rosaceae), and Sechium edule Sw. (Cucurbitaceae) contain secondary metabolites that promote vascular relaxation and display antioxidant activities. As expected, their antioxidant effects showed a significant correlation with the polyphenolics content. However, a lower correlation was found between the antioxidant activity and the maximum vasodilatory effect, suggesting that the vasodilatation elicited by the plant extracts could be only partly attributed to their antioxidant properties. The extract of P. calyculatus, which displayed a maximum vasorelaxant effect that was higher than that of acetylcholine, induced endothelium-dependent vasodilatation. Futhermore, the vasorelaxant response to the P. calyculatus extract was reduced after adding an inhibitor of soluble guanylate cyclase activity, providing evidence that the NO/cGMP pathway is involved. On the other hand, the extracts of Bocconia frutescens L. (Papaveraceae), Magnolia grandiflora L. (Magnoliaceae), and Solanum rostratum Dunal (Solanaceae) induced concentration-dependent contraction of rat aortic rings, suggesting that these plants have potential health benefits for the treatment of ailments such as venous insufficiency. The pharmacological activities of the extracts studied provide scientific support for their ethnomedical use.


Toxicon | 2002

Calcium-dependent smooth muscle excitatory effect elicited by the venom of the hydrocoral Millepora complanata.

Alejandra Rojas; Mónica Torres; J. Isela Rojas; Angélica Feregrino; Edgar P. Heimer de la Cotera

In the present paper, we describe the results obtained from a preliminary pharmacological and biochemical study of the fire coral Millepora complanata, a regular component of coral reefs in the Mexican Caribbean. The protein-containing crude extract obtained from M. complanata (tested from 0.001 to 1000 microg protein/ml) caused a concentration-dependent stimulation of spontaneous contractions of the guinea pig ileum. The extract (EC(50)=11.55+/-2.36 microg/ml) was approximately 12-fold less potent than ionomycin (EC(50)=0.876+/-0.25 microg/ml) and its maximum induced contraction (1mg protein/ml) was equivalent to 68% of the response to 60mM KCl. FPLC size exclusion chromatography of the M. complanta extract afforded 12 primary fractions, of which only FV (containing proteins with molecular weights ranging from 17 to 44 kDa) and FVIII (consisting of peptides with molecular weights lesser than 1.8k Da) elicited an excitatory effect when tested at the EC(50) of the original extract. After incubation in Ca(2+)-free medium, the ileal response to FV and FVIII was significantly reduced. Blockage of L-type Ca(2+) channels with nifedipine (1 microM) inhibited FV and FVIII-evoked contractions. Cd(2+) (10 microM), an unspecific blocker of voltage-activated calcium channels, also antagonized FV and FVIII-induced effects, whereas the Na(+) channel blocker tetrodotoxin (10nM) did not significantly affect FV and FVIII responses. These results suggest that the contractions induced by the bioactive fractions obtained from the crude extract of M. complanata are caused mainly by a direct action on smooth muscle cells, via an increase in Ca(2+) permeability that occurs, at least partly, through L-type voltage-dependent Ca(2+) channels found in the cell membrane of smooth muscle.


Journal of Venomous Animals and Toxins Including Tropical Diseases | 2012

Structure of nematocysts isolated from the fire corals Millepora alcicornis and Millepora complanata (Cnidaria: Hydrozoa)

A García-Arredondo; Alejandra Rojas; Roberto Iglesias-Prieto; A Zepeda-Rodriguez; L Palma-Tirado

Structural characteristics of discharged and undischarged nematocysts from the hydrozoans Millepora alcicornis and Millepora complanata, two fire corals collected in the Mexican Caribbean, were examined using transmission electron, scanning and light microscopy. In this study, we report for the first time images of the nematocysts found in these Mexican Caribbean venomous species. Two types of nematocysts were observed in both species, the more abundant identified as macrobasic mastigophore and the other a stenotele type. Macrobasic mastigophores were present in medium and large size classes while stenoteles appeared in only one size.


Journal of Venomous Animals and Toxins Including Tropical Diseases | 2008

Pharmacological characterization of venoms obtained from Mexican toxoglossate gastropods on isolated guinea pig ileum

Alejandra Rojas; A Feregrino; César Ibarra-Alvarado; Manuel B. Aguilar; Andrés Falcón; E. Heimer de la Cotera

The protein-containing extracts prepared from the venom ducts of Conus austini, Conus spurius and Polystira albida caused a concentration-dependent inhibition of spontaneous contractions in guinea pig ileum. The most potent extract was obtained from P. albida venom ducts (IC50 = 0.11 ± 0.02 µg protein/mL). The three extracts produced a moderate inhibition of contractions elicited by acetylcholine (ACh 1 µM), suggesting the presence of anticholinergic compounds. The contractile response elicited by nicotine (10 µM) was significantly reduced by the extracts prepared from the ducts of C. austini and P. albida, which indicates that the venom produced by these species contains toxins that target neuronal nicotinic receptors. All three extracts significantly inhibited contractions evoked by histamine (0.5 µM), particularly those from C. spurius and P. albida. These findings reveal the presence of antihistaminergic compounds not previously described in any conoidean venom. Finally, we found that only the extract prepared from C. spurius ducts decreased KCl (60 mM)-induced contractions, indicating that the venom of this snail contains compounds that block voltage-dependent Ca2+ or Na+ channels.


Heterocycles | 1990

Ratibinolide, a New Sesquiterpene Lactone from Ratibida latipalearis

Rachel Mata; Alejandra Rojas; Manuel Soriano; Rene Villena; Robert Bye; Edelmira Linares

Ratibinolide 1, a new sesquiterpene lactone has been isolated, using brine shrimp lethality for activity guided fractionation from Ratibida latipalearis. Its structure was established through spectral and X ray crystallographic analyses


Planta Medica | 1997

Smooth Muscle Relaxing Flavonoids and Terpenoids from Conyza filaginoides

Rachel Mata; Alejandra Rojas; Laura Acevedo; S. Estrada; F. Calzada; I. Rojas; Robert Bye; Edelmira Linares


Planta Medica | 2000

Smooth Muscle Relaxing Activity of Gentiopicroside Isolated from Gentiana spathacea

Alejandra Rojas; Moustapha Bah; J. Isela Rojas; Dora M. Gutiérrez


Planta Medica | 1999

Nitric oxide/cGMP mediates the spasmolytic action of 3,4'-dihydroxy-5,5'-dimethoxybibenzyl from Scaphyglottis livida.

Samuel Estrada; Alejandra Rojas; Yaira Mathison; Anita Israel; Rachel Mata


Comparative Biochemistry and Physiology C-toxicology & Pharmacology | 2007

Biochemical and pharmacological characterization of toxins obtained from the fire coral Millepora complanata.

César Ibarra-Alvarado; J. Alejandro García; Manuel B. Aguilar; Alejandra Rojas; Andrés Falcón; Edgar P. Heimer de la Cotera

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Rachel Mata

National Autonomous University of Mexico

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César Ibarra-Alvarado

Autonomous University of Queretaro

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Moustapha Bah

Autonomous University of Queretaro

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Alejandro García-Arredondo

Autonomous University of Queretaro

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Dora M. Gutiérrez

Autonomous University of Queretaro

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J. Isela Rojas

Autonomous University of Queretaro

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Andrés Falcón

National Autonomous University of Mexico

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Edelmira Linares

National Autonomous University of Mexico

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Edgar P. Heimer de la Cotera

National Autonomous University of Mexico

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Manuel B. Aguilar

National Autonomous University of Mexico

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