Luis Astudillo

Oleanolic acid promotes healing of acetic acid-induced chronic gastric lesions in rats.

PURPOSE Previous work demonstrates that oleanolic acid (OA), a triterpene widely distributed in plants, shows gastroprotective effect in the ethanol, aspirin and pilorous ligature-induced gastric ulcer in rats as well as in the ethanol/hydrochloric acid-induced ulcer in mice. The aim of this work was to assess the healing effect of OA in the acetic acid-induced chronic gastric ulcer model in rats. METHODS Chronic gastric lesions were induced in male Sprague-Dawley rats with acetic acid. OA was administered orally during 14 days at 25, 50 and 100 mg/kg per day. Ranitidine (50 mg/kg) and the vehicle were used as controls. The ulcer area (mm2) and the curative ratio (%) were determined. Histological preparations were carried out for comparative purposes. RESULTS The effect of OA was significantly different as compared to the control reducing the lesion area (in mm2) from 39+/-7 in controls to 17.8+/-1.9 and 9.4+/-1.1 at the doses of 50 and 100 mg/kg, respectively. The curative ratio was 54.5 and 76% for the compound at 50 and 100 mg/kg, while ranitidine at 50 mg/kg reduced the lesion area to 6.9+/-0.8 with a curative ratio of 84%. Mucosal thickness increased from 342 microm in controls to 540 microm in oleanolic acid- (100 mg/kg) and 945 microm in ranitidine-treated animals. Histological examination of the stomach showed regeneration of the lesions. CONCLUSIONS OA improves healing of chronic gastric lesions in rats. The low toxicity and widespread occurrence of OA in plants suggest a potential for the development of the triterpene or their derivatives as a new antiulcer drug.

Gastroprotective activity of the diterpene solidagenone and its derivatives on experimentally induced gastric lesions in mice

The labdane diterpene solidagenone 1 and its semisynthetic and biotransformations products 2-7 were assessed for gastroprotective effect in the HCl.EtOH-induced lesions in mice. At 100 mg/kg, solidagenone presented a statistically significant gastroprotective effect (P<0.05) comparable to lansoprazole at 20 mg/kg. The presence of the furan ring was required for the activity of solidagenone while hydroxylation at C-3 or C-6 afforded products with different activity associated with the stereochemistry. Solidagen-6beta-ol 7 and 3alpha-hydroxysolidagenone 2 presented higher activity than solidagenone itself, while its epimers were inactive.

Gastroprotective activity of oleanolic acid derivatives on experimentally induced gastric lesions in rats and mice

The gastroprotective effect of the triterpene oleanolic acid (OA) was assessed on gastric ulceration in rats. The effect of a single oral dose of OA was evaluated at 50, 100 and 200 mg kg−1 in the following models: pylorus ligature (Shay), and aspirin‐ and ethanol‐induced gastric ulcers. A single oral administration of OA at doses of 50, 100 and 200 mg kg−1 inhibited the appearance of gastric lesions induced by ethanol, aspirin and pylorus ligature. In the pylorus ligature and aspirin models, the effect of OA at the selected concentrations was comparable with that of ranitidine at 50 mg kg−1. In the ethanol‐induced gastric lesion model, OA showed a dose‐dependent activity, and at 100 and 200 mg kg−1 was as active as omeprazole at 20 mg kg−1. The effect of OA, its acetylated and methoxylated derivatives, oleanonic acid and its methyl ester were assessed on HCl/ethanol‐induced ulcers in mice at 200 mg kg−1. OA and its methoxylated (OAM) and acetylated (OAAM, OAA) derivatives proved to be active in this animal model. The semisynthetic derivatives OAM and OAAM had the greatest gastroprotective activity, but their effect was not significantly greater than OA. In an acute toxicity test on mice, intraperitoneal administration of OA showed no toxicity at doses up to 600 mg kg−1.

Antiplatelet, anticoagulant, and fibrinolytic activity in vitro of extracts from selected fruits and vegetables

A diet rich in fruits and vegetables is known to decrease the risk of cardiovascular disease. However, the information regarding the antithrombotic activity (antiplatelet, anticoagulant, and fibrinolytic) of fruits and vegetables is scarce. The aim of this study was to assess the antithrombotic activity of extracts from fruits and vegetables widely consumed in central Chile. The study included samples of 19 fruits and 26 vegetables, representative of the local diet. The extracts prepared from each sample included an aqueous (juice or pressed solubles) and/or methanol-soluble fraction. The extracts were evaluated for antiplatelet, anticoagulant, and fibrinolytic activity in vitro at a final concentration of 1 mg/ml. The antiplatelet activity was assessed by platelet aggregation inhibition; anticoagulant activity was measured by the prothrombin time (PT), diluted prothrombin time (dPT), activated partial thromboplastin time (APTT), kaolin clotting time (KCT), and thrombin time. The fibrinolytic effect was determined with the euglobin clot lysis time and fibrin plate methods. Extracts of green beans and tomatoes inhibited platelet aggregation induced by ADP and arachidonic acid, in a concentration-dependent manner. The methanolic extracts of grapes prolonged the PT and dPT. Finally, extracts of raspberry prolonged the APTT and also presented fibrinolytic activity. In conclusion, from a screening that included a variety of fruits and vegetables, we found antiplatelet activity in green beans and tomatoes, anticoagulant activities in grapes and raspberries, whereas fibrinolytic activity was observed only in raspberries. Further investigations are necessary to advance in knowledge of the active compounds of these fruits and vegetables and their mechanisms of action.

Cryptofolione derivatives from Cryptocarya alba fruits

Cryptofolione (1) and the new cryptofolione derivative 6‐(4,6‐dimethoxy‐8‐phenyl‐octa‐1,7‐dienyl)‐4‐hydroxy‐tetrahydro‐pyran‐2‐one (2) were isolated from the fruits of Cryptocarya alba. The structures were elucidated by spectroscopic methods. Cryptofolione showed activity towards Trypanosoma cruzi trypomastigotes, reducing their number by 77% at 250 μg mL−1. Cryptofolione showed moderate cytotoxicity in both macrophages and T. cruzi amastigotes. It also displayed a mild inhibitory effect on the promastigote form of Leishmania spp. As both cytotoxic and trypanocidal effects are similar, the compound presented little selectivity in our assay models.

Fractions of aqueous and methanolic extracts from tomato (Solanum lycopersicum L.) present platelet antiaggregant activity.

Cardiovascular disease (CVD) is the leading cause of death worldwide. Its prevention emphasizes three aspects: not smoking, physical activity and a healthy diet. Recently, we screened the antithrombotic activity of a selected group of fruits and vegetables. Among them, tomato showed an important effect. The aim of this study was to evaluate and characterize the platelet antiaggregatory activity of tomato (Solanum lycopersicum L.). For this, we obtained aqueous and methanolic tomato extracts and evaluated the effect of pH (2 and 10) and temperature (22, 60 and 100°C) on this activity. Furthermore, in order to isolate the antiaggregant principle, we separated tomato extracts into several fractions (A–D) by size exclusion chromatography. In addition, we evaluated the platelet antiaggregating activity ex vivo in Wistar rats. Aqueous and methanolic extracts of tomato treated at 22, 60 and 100°C and pH 2 and 10 still inhibited platelet aggregation (in vitro). Moreover, it was noted that one of the fractions (fraction C), from both aqueous and methanolic extracts, presented the highest activity (∼70% inhibition of platelet aggregation) and concentration dependently inhibited platelet aggregation significantly compared with control (P < 0.05). These fractions did not contain lycopene but presented two peaks of absorption, at 210 and 261 nm, compatible with the presence of nucleosides. In rats treated with tomato macerates, a mild platelet antiaggregating effect ex vivo was observed. Further studies are required to identify the molecules with platelet antiaggregating activity and antiplatelet mechanisms of action.

Gastroprotective activity of solidagenone on experimentally-induced gastric lesions in rats

The gastroprotective effect of the labdane diterpene solidagenone was assessed on gastric ulcer in rats. The effect of a single oral dose of the compound was evaluated at 50, 100 and 200 mg kg−1 in the following test systems: pylorus ligature (Shay), aspirin‐ and ethanol‐induced gastric ulcers. In pylorus‐ligated rats (Shay model), the ulcerative index decreased by 37% with solidagenone pre‐treatment at the three assayed doses. The effect of a single oral dose of 50 mg kg−1 solidagenone was comparable with ranitidine at the same concentration and similar to higher doses of the compound. A significant effect (P< 0.001) at 100 and 200 mg kg−1 was observed in the aspirin‐induced ulcer model. At both doses, reduction in the number of lesions was approximately 50% compared with controls. The effect was comparable with the reference compound ranitidine (50 mg kg−1). With the ethanol‐induced gastric ulcers, the effect of solidagen one at 100 and 200 mg kg−1 was similar to a single oral dose of 20 mg kg−1 omeprazole with a 50% reduction of the mean number of lesions compared with controls. In acute toxicity tests on mice, intraperitoneal administration of solidagenone showed no toxicity at doses up to 600 mg kg−1. This is the first report on the gastroprotective activity of a labdane diterpene.

Metabolites from Microsphaeropsis olivacea, an Endophytic Fungus of Pilgerodendron uviferum

Seven compounds belonging to different structural skeletons were isolated from Microsphaeropsis olivacea grown in liquid and solid media. The enalin derivative 7-hydroxy-2,4- dimethyl-3(2H)-benzofuranone is reported for the first time, while additional spectroscopic information is provided for the acetates of botrallin and ulocladol. The activity of the isolated compounds was assessed towards the enzyme acetylcholinesterase (AChE) and their cytotoxicity against human lung fibroblasts. Graphislactone A and botrallin presented a moderate activity towards AChE, with IC50 of 8.1 and 6.1 μg/ml (27 and 19 μᴍ, respectively). Under the same experimental conditions, the IC50 of the standard inhibitor galanthamine was 3 μg/ml. The cytotoxicity of both compounds was > 1000 and 330 μᴍ, respectively. None of the compounds was promising as antibacterial or antifungic against phytopathogenic fungi and bacteria. Botrallin and graphislactone A were detected in the liquid potato-dextrose and yeast extract/ malt extract/dextrose as well as on a solid substrate (rice). Butyrolactone I was obtained from the fungus growing on solid medium.

Proximate composition and biological activity of chilean Prosopis species

The proximate and amino acid compositions of the leaves and pods of Prosopis chilensis and P tamarugo and the leaves of P alba have been assessed. The biological activity of the leaves and pods of the first two species as well as the leaves and exudate of P alba has been determined for free radical scavenging activity, xanthine oxidase inhibition and DNA binding. The best protein source among the forage trees was the leaves of P chilensis; P alba and P tamarugo leaves showed higher crude protein, fat and nitrogen-free extract values than reported in previous studies. According to their amino acid profiles, all species surveyed are deficient in essential amino acids. The alkaloids β-phenethylamine and tryptamine were isolated from P chilensis, and phenethylamine was detected in P tamarugo. At 0.50 mg ml−1, both compounds showed DNA binding activity, with values of 18.5 and 11% respectively. The exudate of P alba showed a strong free radical scavenging effect. The activity was related with the total phenolics content, consisting mainly of catechin. © 2000 Society of Chemical Industry

Bioassay-Guided Isolation and HPLC Determination of Bioactive Compound That Relate to the Antiplatelet Activity (Adhesion, Secretion, and Aggregation) from Solanum lycopersicum

In seeking the functionality of foodstuff applicable to medicine, ripe tomato fruits were found to show an antiplatelet activity. Therefore, the bioactive compound was isolated, structurally identified, and studied for an inhibitory effects on platelet adhesion, secretion, and aggregation. The concentration of adenosine in ripe tomato fruits (pulp and skin extracts) and its processing by-products (paste and pomace) was determined by reversed-phase high-performance liquid chromatography (HPLC). According to platelet aggregation inhibition induced by ADP, the total extract residual was fractionated by liquid-liquid separation, obtaining aqueous, ethyl acetate and petroleum ether extracts. The aqueous extract was subjected to repeated permeation over sephadex LH-20 and semipreparative TLC. The isolate finally obtained was identified as adenosine on the basis of ESI-MS, 1H NMR, HPLC, and UV spectra. Adenosine concentration dependently (2.3–457 μM) platelet aggregation inhibited induced by ADP. Also, adenosine present inhibition of platelet secretion and thrombus formation under flow conditions. The quantitative HPLC analysis revealed significant amounts of adenosine in ripe tomato fruits and its processing by-products. From these results, extracts/fractions of ripe tomato fruits and their processing by-products may be referred to as functional food and functional ingredients containing a compound that inhibits platelet function with a potent preventive effect on thrombus formation, as those that occur in stroke.