Author
Humberto Cervantes-Cuevas
Other affiliations: Instituto Politécnico Nacional
Bio: Humberto Cervantes-Cuevas is an academic researcher from Universidad Autónoma Metropolitana. The author has contributed to research in topics: Carbon-13 NMR & Materials science. The author has an hindex of 4, co-authored 8 publications receiving 66 citations. Previous affiliations of Humberto Cervantes-Cuevas include Instituto Politécnico Nacional.
Papers
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TL;DR: The results show that E. aschenbornianum had gastroProtective activity, that the hexane extract had the highest protective activity, and that encecanescin isolated from this extract was the main active gastroprotective agent.
38 citations
TL;DR: A series of C-8 mono-and disubstituted isatylidenes were prepared in order to examine the influence of the substituent on the polarization of the ethylenic carbons as mentioned in this paper.
Abstract: A series of C-8 mono- and disubstituted isatylidenes were prepared in order to examine the influence of the substituent on the polarization of the ethylenic carbons C-3 C-8. Donor-acceptor C-8 substitution resulted in an inversion of the polarization of the ethylenic carbons, as evidenced by the 13 C NMR spectra, and because these compounds can exist in solution as equilibrium mixtures of the E -a nd Z-isomers. The dual donor-acceptor character of the heterocycle is controlled by the cross-conjugated C-3 C-8 double bond, in which the C-3 carbon atom has the possibility of conjugating with either the donor or the attracting portion of the heterocyclic system, consistent with contributions from isatylidene resonance forms which induce the C-8 carbon atom to be charged either positively or negatively, thus allowing an opposite sense of the push-pull effect. Copyright © 2000 John Wiley & Sons, Ltd. KEYWORDS: NMR; 13 CN MR; 1 H NMR; isatylidenes; push-pull effects; isotope effects
17 citations
TL;DR: In this paper, 2-methyl-1,2-hexanediols were obtained from 2-hexanone using an 1,3-trans-oxathiane as the chiral chromatographic auxiliar.
5 citations
TL;DR: Four of these imidazolidinones were analyzed by X-ray diffraction to corroborate the configuration determined by NMR, and revealed the existence of intramolecular hydrogen bonds capable to control the conformation of the phenethyl and acyl groups in the solution state.
5 citations
TL;DR: The deuterium-induced 13C isotope shifts of 21 nitrogen-containing benzoheterocyclic systems labelled at the NH position were measured in this article, including bridged diphenylamines, ben- DMSO-d 6.
Abstract: The deuterium-induced 13C isotope shifts of 21 nitrogen-containing benzoheterocyclic systems labelled at the NH position were measured in The compounds included bridged diphenylamines, ben- DMSO-d 6 . zolactams, 4-quinolinone, acridinones, carbazoles and indoles. The variations of two-bond isotope eUects are dis- cussed as a function of cross-conjugation of the NH(D) group and acidity of the NH proton. Copyright 1999 (
4 citations
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TL;DR: Of the various levels of theory tried, MP2 calculations with a triple-zeta-valence basis set were found to be the most effective for providing reliable results.
Abstract: The 1H and 13C NMR spectra of a number of push−pull alkenes were recorded and the 13C chemical shifts calculated employing the GIAO perturbation method. Of the various levels of theory tried, MP2 calculations with a triple-ζ-valence basis set were found to be the most effective for providing reliable results. The effect of the solvent was also considered but only by single-point calculations. Generally, the agreement between the experimental and theoretically calculated 13C chemical shifts was good with only the carbons of the carbonyl, thiocarbonyl, and cyano groups deviating significantly. The substituents on the different sides of the central CC partial double bond were classified qualitatively with respect to their donor (S,S < S,N < N,N) and acceptor properties (C≡N < CO < CS) and according to the ring size on the donor side (6 < 7 < 5). The geometries of both the ground (GS) and transition states (TS) of the restricted rotation about the central CC partial double bond were also calculated at the HF ...
131 citations
TL;DR: It is revealed that zerumbone promotes ulcer protection, which might be attributed to the maintenance of mucus integrity, antioxidant activity, and HSP-70 induction.
Abstract: Background Zingiber zerumbet Smith is a perennial herb, broadly distributed in many tropical areas. In Malaysia, it’s locally known among the Malay people as “lempoyang” and its rhizomes, particularly, is widely used in traditional medicine for the treatment of peptic ulcer disease beyond other gastric disorders.
81 citations
TL;DR: In this paper, a general protocol for the oxidation of indole and oxindole derivatives with dimethyldioxirane to give 3-hydroxyoxindoles present in many natural products was described.
59 citations
TL;DR: The present study showed that zingerone has a protective effect on the ethanol-induced gastric ulcer, which may be due to its free radical scavenging activity.
Abstract: Background and objectives: Zingerone is an ingredient of ginger (Zingiber officinale) with different pharmacological activities. Several studies have investigated the effect of zingerone on various gastrointestinal diseases, including irritable bowel syndrome and diarrhea. This study is aimed to evaluate the effect of zingerone on ethanol-induced gastric ulcers in rats. Materials and Methods: Gastric ulcers were induced by ethanol (96%, 5 mL/kg, po) in male wistar rats and zingerone (50, 100, and 200 mg/kg) was administrated orally. Normal saline and ranitidine were used as negative and positive control, respectively. In this study, the number and length of ulcers, and malondialdehyde (MDA) and nitric oxide (NO) levels in stomach tissues were determined. Results: The findings showed that the mean number and length of gastric ulcers were significantly lower in zingerone-received groups than ethanol group (P < 0.05). The level of malondialdehyde was decreased in the stomach of zingerone groups (P < 0.05) compared to the ethanol group. In addition, zingerone treatment prevented the decrease of nitric oxide level by ethanol in the stomach tissue. Conclusions: The present study showed that zingerone has a protective effect on the ethanol-induced gastric ulcer, which may be due to its free radical scavenging activity.
55 citations
TL;DR: More than 300 monomeric compounds or active parts have been screened for pharmacological activities from Eupatorium in vivo and in vitro, and increasing amount of data supports application and exploitation for new drug development.
Abstract: Eupatorium (family: Compositae), which comprises nearly 1200 species, is distributed throughout tropical America, Europe, Africa, and Asia. Up to now, the reported constituents from the genus Eupatorium involve flavonoids, terpenoids, pyrrolizidine alkaloids, phenylpropanoids, quinonoids, essential oils, and some others, altogether more than 300 compounds. Studies have shown that Eupatorium and its active principles possess a wide range of pharmacological activities, such as cytotoxic, antifungal, insecticidal, antibacterial, anti-inflammatory, and antinociceptive activities. Currently, effective monomeric compounds or active parts have been screened for pharmacological activities from Eupatorium in vivo and in vitro. Increasing amount of data supports application and exploitation for new drug development.
53 citations