Gumersindo Mirón-López

Tyrianthinic Acids from Ipomoea tyrianthina and Their Antimycobacterial Activity, Cytotoxicity, and Effects on the Central Nervous System #

Four new partially acylated tetrasaccharides of 11-hydroxyhexadecanoic acid (1-4) were isolated from a methanolic extract of Ipomoea tyrianthina. The structures of these compounds were elucidated by spectroscopic and chemical methods. The resin glycoside composition of I. tyrianthina varied with the location of growth in Mexico. Compounds 1-4 showed antimycobacterial activity, were cytotoxic against the KB cell line, and, in a mouse model, exhibited potentiation of hypnosis induced by pentobarbital, protected against seizures induced by pentylenetetrazole, and released GABA and glutamic acid.

Glycolipid ester-type heterodimers from Ipomoea tyrianthina and their pharmacological activity

Tyrianthins A (1) and B (2), two new partially acylated glycolipid ester-type heterodimers were isolated from Ipomoea tyrianthina. Scammonic acid A was determined as the glycosidic acid in both monomeric units. Tyrianthin A (1) (IC(50) 0.24+/-0.09 microM and E(max) 81.80+/-0.98%), and tyrianthin B (2) (IC(50) 0.14+/-0.08 microM and E(max) 87.68+/-0.72%) showed significant in vitro relaxant effect on aortic rat rings, in endothelium- and concentration-dependent manners. Also, these compounds were able to increase the release of GABA and glutamic acid in brain cortex, and displayed weak antimycobacterial activity.

Cytotoxic diterpenes from roots of Crossopetalum gaumeri, a Celastraceae species from Yucatan Peninsula

Four new diterpenes, crossogumerins A-D (1-4) along with six known ones (5-10) were isolated from the root bark of Crossopetalum gaumeri, an endemic medicinal plant from the Yucatan Peninsula. Their structures were elucidated on the basis of 1D and 2D NMR techniques, including HMQC, HMBC, and ROESY experiments. Compounds 1-5, 8-10 were evaluated for cytotoxicity against HeLa (carcinoma of the cervix) and Hep-2 (lung carcinoma) human tumor cells lines and against normal Vero cells (African green monkey kidney) in lag and log phase of growth. Podocarpane diterpenes, crossogumerin B (2) and nimbiol (10), exhibited the highest activity against HeLa cells (IC50 values of 3.1 and 8.1 μM, respectively), but also selectivity on Vero cells (SI 22.6 and 7.5, respectively). The preliminary SAR studies suggest that an epoxy moiety in ring B and a hydrogen bond-donor group strategically positioned in the diterpene core are important requirements for cytotoxicity and selectivity.

Resin glycosides from Ipomoea tyrianthina and their sedative and vasorelaxant effects

The methanol-soluble extract from the root of Ipomoea tyrianthina was studied in order to isolate compounds with activity on the central nervous system and vasorelaxant effects. Chromatographic methods were used to isolate and purify seven new glycolipids (2–8). The structures of compounds 1–8 were elucidated by a combination of NMR spectroscopy and mass spectrometry. Tyrianthinoic acid (1) is a glycosidic acid composed of a linear pentasaccharide core bonded to a 11-hydroxyhexadecanoic acid. The structure of tyrianthinic acids III (2), IV (3), and V (4) consists of a partially acylated tyrianthinoic acid. Tyrianthinic acid VI (8) is a tetrasaccharide core bonded to a jalapinolic acid, acylated by a 2-methyl-3-hydroxybutanoic acid. Tyrianthins C (5), D (6), and E (7) are ester-type heterodimers of scammonic acid A with different acylating residues in the two monomeric units. The macrolactonization site was located at C-3 of the rhamnose unit. The position of the ester linkage for monomeric unit B on the macrocyclic unit A was established at C-4 of the terminal quinovose. Compounds 5–7 increased the sleeping time induced by pentobarbital and the release of gamma-aminobutyric acid in brain cortex. In addition, compounds 5–7 showed significant in vitro relaxant effects on aortic rat rings, in endothelium- and concentration-dependent manners.

Isolation and antitrichomonal activity of the chemical constituents of the leaves of Maytenus phyllanthoides Benth. (Celastraceae)

Cyclolignan (+)-lyoniresinol (1), veratric acid (2), vanillic acid (3), lupeol, oleanolic acid, 3β-hydroxy-urs-11-en-28,13β-lactone (4), the mixture of α- and β-amyrin, trans-polyisoprene, and β-sitosterol were isolated from the leaves of Maytenus phyllanthoides. The structures of the isolated compounds were established based on spectroscopic data, mainly 1H and 13C nuclear magnetic resonance (NMR). Compound 1, its acetate analog 1a, and compounds 2, 3, and 4 were tested against Trichomonas vaginalis. (+)-Lyoniresinol showed activity corresponding to IC50 17.57 µM. This is the first report on the occurrence of 3β-hydroxy-urs-11-en-28,13β-lactone (4) in the Celastraceous family and lyoniresinol in the Maytenus genus, and on the antitrichomonal activity of lyoniresinol.

Development of newly sanguinarine biosynthetic capacity in in vitro rootless shoots of Argemone mexicana L. Mexican prickly poppy.

ObjectiveTo analyze berberine and sanguinarine biosynthetic capacities of both in vitro shoot and root cultures of Argemone mexicana and tissues from entire plants at different developmental stages.ResultsBerberine and sanguinarine were equally distributed in roots and aerial tissues of developing plantlet whereas, in juvenile plants, sanguinarine was only detected in roots. This alkaloid distribution was consistent with that of biosynthetic transcripts in juvenile plants. However, lower transcript abundance in plantlets´ leaves suggests that alkaloids were mainly formed in roots and then mobilized to this tissue. In vitro root cultures maintained similar alkaloid profiles to those from intact seedlings and plantlets. However, in addition to berberine, rootless shoot cultures accumulated high levels of sanguinarine and biosynthetic transcripts.ConclusionIn vitro shoot cultures of A. mexicana can synthesize sanguinarine in addition to berberine. This represent a convenient system for the production of both alkaloids.

HPLC-DAD DETERMINATION OF BERBERINE, CHELERYTHRINE AND SANGUINARINE IN THE MEXICAN PRICKLY POPPY (Argemone mexicana L. PAPAVERACEAE), A MEDICINAL PLANT

Jorge F. Xool-Tamayoa,b, Manlio Graniel-Sabidoa, Gumersindo Mirón-Lópeza, Gonzalo J. Mena-Rejóna, Miriam MonforteGonzálezb and Felipe Vázquez Flotab,* Facultad de Química, Universidad Autónoma de Yucatán, Calle 43 No. 613 x Calle 90 Col. Inalámbrica, Mérida Yucatán 97069 México Unidad de Bioquímica y Biología Molecular de Plantas, Centro de investigación Científica de Yucatán, Calle 43 No. 130 Chuburná de Hidalgo, Mérida Yucatán 97205, México

Crystal structure of ochraceolide A isolated from Elaeodendron trichotomum (Turcz.) Lundell

The crystal structure of the triterpene lactone ochraceolide A (3-oxolup-20 (29)-en-30,21α-olide) isolated from Elaeodendron trichotomum (Turcz.) Lundell is reported.

Chrysophanol anthrone: a theoretical study on the potential energy surface

Abstract The potential energy surface (PES) of chrysophanol anthrone, the active component of Goa Powder, was systematically explored and thoroughly scrutinised via density functional theory, in order to gain an understanding of its physicochemical properties. In particular, we focused on the rotations of the two hydroxyl-phenyl dihedral angles. A picture with a four stable rotamers emerged where only the most stable conformer has a planar structure and the less stable conformer has the maximum deviation from planarity. The computed PES shows that the energy barriers for the conformer interconversion are less than 15 kcal/mol. From the analysis of the calculated intramolecular hydrogen bond enthalpy, we conclude that the number of the intramolecular hydrogen bonds governs the conformer stability. Additionally, the conformational equilibrium was pursued by means of an analysis of the energy of OH internal rotation barriers. The total energy changes were decomposed in an electrostatic decomposition scheme in order to gain an insight into the effects governing the torsional barrier and preferred conformations. This analysis shows that the interplay between the repulsive and attractive potentials causes the conformer stability, where the attractive term dominates the conformer stabilisation.

ANTIPROTOZOAL ACTIVITY OF EXTRACTS OF ELAEODENDRON TRICHOTOMUM (CELASTRACEAE)

Background: Chagas disease, amebiasis, giardiasis and trichomoniasis represent a serious health problem in Latin America. The drugs employed to treat these illnesses produce important side effects and resistant strains have appeared. The present study was aimed to evaluate the antiprotozoal activity of leaves, stem bark and root bark of Elaeodendron trichotomum, a celastraceus, that is used in Mexico as an anti-infective in febrile-type diseases. Materials and methods: Dichloromethane and methanol extracts of leaves, bark and roots of Elaeodendron trichotomum were tested against Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis, and Trypanosoma cruzi. A quantitative HPLC analysis of pristimerin and tingenone was performed. Results: The dichloromethane extract of roots was active against E. histolytica, G. lamblia, T. vaginalis, and T. cruzi, at IC50’s of 0.80, 0.44, 0.46, and 2.68 μg/mL, respectively. The HPLC analysis revealed the presence of tingenone (3.84%) and pristimerin (0.14%). Conclusions: The dichloromethane extract of the roots bark showed significant activity against all screened protozoa.