Search

The vasorelaxing effect of the methanol extract of the flowers of Crataegus gracilior , a Mexican medicinal plant used to treat some cardiovascular diseases, was assessed, and its possible chemical markers identified. The extract produced a potent vasodilator effect on isolated rat aortic rings (EC 50 = 1.83 ± 1.39 µg/mL; E max = 100 ± 3.4%). Vitexin, the most commonly identified flavonoid in the flowers and used to standardise some Crataegus species, was not found at all in this plant sample. Instead, daucosterol, and corosolic and euscapic acids were purified. The two triterpene acids have been reported to possess beneficial effects on cardiovascular diseases. These results indicate that the vasodilator effect might induce the hypotensive effect claimed by users, and that euscapic and corosolic acids may be the main vasodilator compounds, and can then be employed as the chemical markers towards the future standardisation of the extract.

Krameria pauciflora is a species belonging to the Krameriaceae family. It has been used to treat inflammatory disorders in folkloric Mexican medicine; however, chemistry and pharmacological studies have not been carried out on this species. In this work, from the dichloromethane root extract of K. pauciflora, five cycloartane-type triterpenoids were isolated: cyclomargenyl-3-O-β-caffeoyl ester (1), cyclomargenyl-3-O-β-feruloyl ester (2), cyclomargenyl-3-O-β-coumaroyl ester (3), cyclomargenol (4, polysthicol), and cyclomargenone (5). Additionally, the lignane 6'-methoxyrataniaphenol was isolated. To the best of our knowledge, compounds 1-3 are new natural products, whereas compounds 4 and 5 are isolated for the first time in the Krameria genus and the Krameriaceae family. The structures of all of these compounds were established by 1D and 2D NMR spectroscopy including ¹H, ¹³C, DEPT, COSY, HSQC, and HMBC experiments, as well as by EI mass spectrometry. There is an incomplete previous report about the spectroscopic data of compounds 4 and 5. However, in this work, a complete and unambiguous assignation has been realized. Due to the traditional use of this plant and other species from this genus, such as K. lappacea, cycloartanes isolated herein were evaluated by their inhibition of phospholipase A₂, cyclooxygenase-1, and cyclooxygenase-2 enzymes. Cyclomargenyl-3-O-β-caffeoyl ester (1) showed inhibition of phospholipase A₂, cyclooxygenase-1, and cyclooxygenase-2 target enzymes for nonsteroidal anti-inflammatory drugs. Both cyclooxygenases were inhibited by cyclomargenol (4); however, cyclomargenyl-3-O-β-feruloyl ester (2) showed inhibition only on cyclooxygenase-1., (Georg Thieme Verlag KG Stuttgart · New York.)

Three new friedelane-type triterpenes, 1,2-dehydro-2,3-secofriedelan-3-oic acid (1), 1β-hydroxyfriedelin (2), and 3β-hydroxyfriedelan-23-oic acid (3), and the known compounds friedelin-3,4-lactone (4), acetyl aleuritolic acid (5), 4-hydroxy-5-propionyl-1,3-di-O-methylpyrogallol, elemicin, and (-)-syringaresinol were isolated from the leaves of Garcia parviflora. The structures of 1-3 were elucidated by spectroscopic methods, including 1D and 2D NMR, HREIMS, X-ray, and CD analysis. Some derivatives of 2 (6-14) were prepared via oxidation, reduction, and esterification. The natural triterpenes and the semisynthetic friedelane derivatives were tested for cytotoxic activity against human cancer cell lines U251, PC-3, K562, HCT-15, MCF-7, and SKLU-1. Compound 5 was cytotoxic against U251 cells.

Amphipterygium adstringens (Schltdl.) Standl. (Anacardiaceae) is widely used in traditional Mexican medicine for the treatment of gastritis and ulcers. In this work, we studied the anti-Helicobacter pylori activity of its bark, this Gram-negative bacterium is considered the major etiological agent of chronic active gastritis and peptic ulcer disease, and it is linked to gastric carcinoma. From a bio-guided assay of the fractions obtained form a continuous Soxhlet extraction of the bark, we identified that petroleum ether fraction had significant antimicrobial activity against Helicobacter pylori. From this fraction, we isolated an anacardic acids mixture and three known triterpenes: masticadienonic acid; 3alpha-hydroxymasticadienonic acid; 3-epi-oleanolic; as well as the sterol beta-sitosterol. Only the anacardic acids mixture exhibits a potent dose-dependent antibacterial activity (MIC=10 microg/ml in broth cultures). It is enriched in saturated alkyl phenolic acids (C15:0, C16:0, C17:0 C19:0) which represents a novel source of these compounds with potent anti-Helicobacter pylori activity. The promising use of anacardic acids and Amphipterygium adstringens bark in the development of an integral treatment of Helicobacter pylori diseases is discussed.

Two new triterpenoids, 21 beta-hydroxyolean-12-en-3-one (1) and a seco-dinor derivative of pristimerine named dzununcanone (2), were isolated from the root bark of Hippocratea excelsa. Their structures were assigned on the basis of spectroscopic evidence, mainly 1H and 13C 1D and 2D NMR including DEPT, COSY, ROESY, HSQC, and HMBC experiments, as well as EIMS and HREIMS. The known 21alpha-hydroxy-3-oxofriedelane (3), a compound new to the species, and the known methide quinones pristimerine (4) tingenone (5), and xuxuarine Ebeta (7) were also isolated. The antiprotozoal activities were determined against Giardia intestinalis. Pristimerine and tingenone were the most active antigiardial compounds, with IC50 values of 0.11 and 0.74 microM, respectively, compared with metronidazole, the current drug of choice (IC50 1.23 microM).

The anxiolytic effects of galphimine B (1), galphimine A (2), and galphimine E (3), natural nor-secofriedelanes isolated from Galphimia glauca, as well as derivatives obtained by acetylation (4), hydrogenation of the C-1/C-2 double bond (5), basic hydrolysis followed by hydrogenation of the C-1/C-2 double bond (6), and deacetylation (7) of galphimine E (3), were evaluated on ICR mice exposed to the elevated plus-maze test. This study also included the evaluation of a galphimines-rich fraction (GRF) with a known concentration of 1-3, obtained from the dry leaves of G. glauca. Intraperitoneal administration of 15 mg/kg of 1, 2, 6, and GRF (1 h before testing) caused an anxiolytic-like effect in the animals, increasing significantly (p <0.001) the percentage of time of permanence and the number of crossings toward the open arms of the plus-maze. No activity was detected after administration of compounds 3, 4, 5, and 7. These results showed that GRF had activity similar to the most active pure galphimines (1 and 2) and that, like for the spasmolytic activity previously reported, the main determining factor responsible for the anxiolytic activity of the compounds was the presence of free hydroxyl groups at C-4, C-6, and C-7 and the presence of the double bond in the A ring.

Hexane extract from the bark of Amphipterygium adstringens, as well as its principal constituents, masticadienonic acid and 3alpha-hydroxymasticadienolic acid, inhibited the growth of five human cancer cell lines. Derivatives of, namely 24,25 S-dihydromasticadienonic acid and masticadienolic acid, were also evaluated. The results showed that both and had greater activity than on colon cancer cell lines. The effects of on the production of nitric oxide (NO) from both resting and lipopolysaccharide-activated macrophages were determined. It was found that and caused an increase in NO release from resting macrophages; in lipopolysaccharide-activated macrophages, only and caused an increase in NO production.

Preparative-scale recycling HPLC was used for the complete resolution of a complex mixture of nor-secofriedelanes into five major peaks (I-V) from the sedative methanolic extracts prepared from the aerial parts of Galphimia glauca. Argentation chromatography was used to show peaks I, II, IV, and V to be mixtures of isomers around the E-ring double bond, represented by the endocyclic C-20, C-21 double-bond isomers, galphimines A (3), B (1), D (4), and E (2), and the C-20, C-29 exocyclic forms, galphimines F-I (5-8). Galphimine C (9), isolated from peak III, corresponded to the C-19, C-20 double-bond isomer of the previously known major sedative constituent galphimine B. The characterization of all the new triterpenes (3-9) was performed primarily by high-field NMR spectroscopy. Comparison between experimental and calculated (1)H-(1)H vicinal coupling constants and the analysis of molecular mechanics structures revealed that the ring B of these compounds exists in a boatlike conformation. The absolute configuration for the stereogenic carbinol center at C-4 was established by the application of the Mosher ester derivatization technique carried out in NMR tubes.

Bioassay-directed fractionation of a n-hexane extract of Couepia polyandra using an assay to detect inhibitors of the lyase activity of DNA polymerase beta resulted in the isolation of the new triterpene 3beta,16beta,23-triacetoxyolean-12-en-28-oic acid (1) and four known compounds, oleanolic acid, betulinic acid, stigmasterol, and beta-sitosterol. The structure of the new compound was established on the basis of extensive 1D and 2D NMR spectroscopic interpretation. All five compounds inhibited DNA polymerase beta lyase activity.

Six new triterpenoidal saponins, called calliandra saponins G(1), H(2), I(3), J(4), K(5) and L(6), were isolated from the branches of Calliandra anomala (Kunth) Macbr. The structures of these compounds were established on the basis of NMR spectra, FAB-MS, and chemical evidence. These saponins, interestingly, have an N-acetyl glucosamine at the 3 position of the genin, and one or two monoterpene glycosides at the position of the sugar chain.

A new quassinoid, 11-O-trans-p-coumaroyl amarolide (1) was isolated from Castela texana, and the structure was elucidated by spectroscopic analysis. Compound 1 is the first coumaroyl quassinoid derivative to have been isolated from nature. The known compounds amarolide (2), chaparrinone, chaparrin, glaucarubolone, holacanthone, and 15-O-beta-D-glucopyranosyl glaucarubol were also isolated. All isolated compounds were tested for their cytotoxicity and antiprotozoal activities.