Eduardo Madrigal-Bujaidar

Review of natural products with hepatoprotective effects

The liver is one of the most important organs in the body, performing a fundamental role in the regulation of diverse processes, among which the metabolism, secretion, storage, and detoxification of endogenous and exogenous substances are prominent. Due to these functions, hepatic diseases continue to be among the main threats to public health, and they remain problems throughout the world. Despite enormous advances in modern medicine, there are no completely effective drugs that stimulate hepatic function, that offer complete protection of the organ, or that help to regenerate hepatic cells. Thus, it is necessary to identify pharmaceutical alternatives for the treatment of liver diseases, with the aim of these alternatives being more effective and less toxic. The use of some plants and the consumption of different fruits have played basic roles in human health care, and diverse scientific investigations have indicated that, in those plants and fruits so identified, their beneficial effects can be attributed to the presence of chemical compounds that are called phytochemicals. The present review had as its objective the collecting of data based on research conducted into some fruits (grapefruit, cranberries, and grapes) and plants [cactus pear (nopal) and cactus pear fruit, chamomile, silymarin, and spirulina], which are consumed frequently by humans and which have demonstrated hepatoprotective capacity, as well as an analysis of a resin (propolis) and some phytochemicals extracted from fruits, plants, yeasts, and algae, which have been evaluated in different models of hepatotoxicity.

Induction of sister chromatid exchanges by 2,4-dichlorophenoxyacetic acid in somatic and germ cells of mice exposed in vivo.

2,4-dichlorophenoxyacetic acid (2,4-D) is one of the most widely used selective herbicides throughout the world; however, the studies that have been conducted to establish its genotoxic potential have given conflicting results. The aim of this investigation was to determine whether the herbicide increases the frequency of sister chromatid exchanges (SCEs) in bone marrow and spermatogonial cells of mice exposed in vivo. The experiment included an oral administration of 2,4-D to three groups of mice (50,100 and 200 mg/kg), as well as to a control group of animals administered with distilled water, pH 10.5 and another group injected with cyclophosphamide (50 mg/kg). In somatic cells, the results showed a significant SCE increase with the two high doses tested, a response that was manifested in a dose-dependent manner. With regard to the mitotic index and the cell proliferation kinetics, there were no modifications exerted by 2,4-D; however, cyclophosphamide induced cytotoxic damage and a cell-cycle delay. With respect to the germ cells, the genotoxic results were similar to those described earlier; that is, there was a significant SCE increase induced by the two high 2,4-D doses tested and a higher genotoxic damage was observed in the animals treated with cyclophosphamide. Our investigation established that 2,4-D is a moderate genotoxicant in mice treated in vivo with high doses, and suggests a minor hazard for humans in the present conditions of its use.

Nutrient and Nonnutrient Components of Legumes, and Its Chemopreventive Activity: A Review

Legumes in combination with other products are the staple food for a large part of the world population, especially the low-income fragment, because their seeds provide valuable amounts of carbohydrates, fiber, and proteins, and have an important composition of essential amino acids, the sulphured amino acids being the limiting ones. Furthermore, legumes also have nonnutritional compounds that may decrease the absorption of nutrients or produce toxic effects; however, it has been reported that depending on the dose, these nonnutritional compounds also have different bioactivities as antioxidant, hypolipidemic, hypoglycemic, and anticarcinogenic agents, which have been proven in scientific studies. It has been observed that in countries with a high consumption of legumes, the incidence of colorectal cancer is lower. Some studies have shown that legume seeds are an alternative chemopreventive therapy against various cancers especially colon; this was verified in various animal models of induced by azoxymethane, a colon specific carcinogenic compound, in which a diet was supplemented with different concentrations of beans, lentils, chickpeas, or soybeans, mostly. These studies have proven the anticancer activity of legumes in early stages of carcinogenesis. Therefore, it is important to review the information available to elucidate the chemopreventive mechanisms of action of legume compounds.

Genotoxic effects produced by capsaicin in mouse during subchronic treatment.

Capsaicin is the chemical responsible for the pungent, hot properties of Capsicum, a vegetable widely consumed in the diet of many countries in the world. In this work, the genotoxic capacity of capsaicin was studied in mouse during a 32-day treatment. We used the dosages of 1.46 and 1.94 mg/kg given by the i.p. route. Each week, the frequency of micronucleated normochromatic erythrocytes (MN-NE) and the ratio polychromatic/normochromatic erythrocytes (PE/NE) were scored. At the end of the experiment we also scored the frequency of sister chromatid exchanges (SCE). The results in the MN-NE analysis showed a genotoxic response with 1.94 mg/kg starting from day 16, while the 1.46 mg/kg dose produced a significant increase of MN-NE only at the 32nd day. The ratio PE/NE was only affected at the 32nd day with the high dose. Concerning the SCE frequency, the genotoxic effect was only observed with the highest dose. These results indicated that capsaicin is a genotoxicant, and due to the probable relation between an excessive consumption of Capsacum and an increase in gastric cancer, it is suggested that its consumption could be moderated until a definitive risk for humans is established.

Genotoxic and cytotoxic effects induced by aluminum in the lymphocytes of the common carp (Cyprinus carpio)

Few studies have been made in regard to the effect of aluminum on the molecular and cellular structure and function of aquatic organisms; therefore, in the present report we determined the genotoxic and cytotoxic effects induced by the metal on the lymphocytes of carp (Cyprinus carpio). Three groups of fish were exposed to 0.05, 120, and 239 mg/L of aluminum (Al), respectively, by using Al₂ (SO₄)₃·7H₂O, and another group was included as control. The cells obtained were studied with the comet assay, flow cytometry, and the TUNEL method. With the first method we found a concentration and time dependent, significant increase in the amount of DNA damage induced by Al, and a higher damage when we evaluated the level of oxidized DNA. By applying flow cytometry we established that the metal induced a DNA content increase and ploidy modifications as well as apoptosis and disturbances of the cell cycle progression. With the last method we determined a significant increase in the amount of apoptotic cells, mainly in the 72-96 h period. Our results established that Al caused deleterious DNA and cellular effects in the tested organism, and they suggested the pertinence of evaluating toxicity induced by the metal in organisms living in contaminated water bodies.

Antigenotoxic Studies of Different Substances to Reduce the DNA Damage Induced by Aflatoxin B1 and Ochratoxin A

Mycotoxins are produced mainly by the mycelial structure of filamentous fungi, or more specifically, molds. These secondary metabolites are synthesized during the end of the exponential growth phase and appear to have no biochemical significance in fungal growth and development. The contamination of foods and feeds with mycotoxins is a significant problem for the adverse effects on humans, animals, and crops that result in illnesses and economic losses. The toxic effect of the ingestion of mycotoxins in humans and animals depends on a number of factors including intake levels, duration of exposure, toxin species, mechanisms of action, metabolism, and defense mechanisms. In general, the consumption of contaminated food and feed with mycotoxin induces to neurotoxic, immunosuppressive, teratogenic, mutagenic, and carcinogenic effect in humans and/or animals. The most significant mycotoxins in terms of public health and agronomic perspective include the aflatoxins, ochratoxin A (OTA), trichothecenes, fumonisins, patulin, and the ergot alkaloids. Due to the detrimental effects of these mycotoxins, several strategies have been developed in order to reduce the risk of exposure. These include the degradation, destruction, inactivation or removal of mycotoxins through chemical, physical and biological methods. However, the results obtained with these methods have not been optimal, because they may change the organoleptic characteristics and nutritional values of food. Another alternative strategy to prevent or reduce the toxic effects of mycotoxins is by applying antimutagenic agents. These substances act according to several extra- or intracellular mechanisms, their main goal being to avoid the interaction of mycotoxins with DNA; as a consequence of their action, these agents would inhibit mutagenesis and carcinogenesis. This article reviews the main strategies used to control AFB1 and ochratoxin A and contains an analysis of some antigenotoxic substances that reduce the DNA damage caused by these mycotoxins.

Antigenotoxic Effect of Chamomilla recutita (L.) Rauschert Essential Oil in Mouse Spermatogonial Cells, and Determination of Its Antioxidant Capacity in Vitro

Chamomilla recutita (L.) Rauschert (Asteraceae), popularly known as chamomile, is a plant used in traditional medicine for various therapeutic purposes. Chamomile essential oil (CEO) is particularly known to inhibit the genotoxic damage produced by mutagens in mice somatic cells. The aim of this research was to determine the inhibitory potential of CEO on the genotoxic damage produced by daunorubicin (DAU) in mice germ cells. We evaluated the effect of 5, 50, and 500 mg/kg of essential oil on the rate of sister chromatid exchange (SCE) induced in spermatogonia by 10 mg/kg of the mutagen. We found no genotoxicity of CEO, but detected an inhibition of SCE after the damage induced by DAU; from the lowest to the highest dose of CEO we found an inhibition of 47.5%, 61.9%, and 93.5%, respectively. As a possible mechanism of action, the antioxidant capacity of CEO was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method and ferric thiocyanate assays. In the first test we observed a moderate scavenging potential of the oil; nevertheless, the second assay showed an antioxidant capacity similar to that observed with vitamin E. In conclusion, we found that CEO is an efficient chemoprotective agent against the damage induced by DAU in the precursor cells of the germinal line of mice, and that its antioxidant capacity may induce this effect.

Antioxidant and Anticlastogenic Capacity of Prickly Pear Juice

Plants belonging to the genus Opuntia spp. are the most abundant of the Cactaceae family, grown throughout America and the Mediterranean central area. Its fruit, known as cactus pear or prickly pear, is an oval berry grouped in different colors. Some studies have shown its antioxidant activities which may help in preventing chronic pathologies such as diabetes. The purpose of the study was to evaluate the antioxidant capacity of three varieties of prickly pear juice (red-purple, white-green and yellow-orange) in five different concentrations (100, 250, 500, 750, and 1000 mg/mL) by DPPH (1,1-diphenyl-2-picrylhydrazyl radical) colorimetric method, selecting the best variety to determine its anticlastogenic potential against methyl methanesulfonate (MMS). The results indicate that the highest antioxidant was found in the juice of the prickly pear red-purple variety (PPRP), in all concentrations. Its anticlastogenic potential was therefore evaluated with a micronucleus assay. The experiment was run over two weeks. A negative control was included along with a positive control with MMS (40 mg/kg), a group of mice treated with PPRP (25 mL/kg), and three groups with PPRP (in doses of 25, 16.5 and 8.3 mL/kg) plus the mutagen. The PPRP was administered daily by oral gavage and the MMS was injected intraperitoneally five days prior to the end of the experiment. Blood samples were obtained at 0, 24, 48, 72 and 96 h in order to determine the frequency of micronucleated polychromatic erythrocytes (MNPE). The results indicated that PPRP is not a genotoxic agent, on the contrary, it may reduce the number of MNPE. In this regard, the PPRP showed an anticlastogenic effect directly proportional to its concentrations. Thus, the highest protection was obtained with a concentration of 25 mL/kg after 48 h of treatment.

Grapefruit juice suppresses azoxymethane-induced colon aberrant crypt formation and induces antioxidant capacity in mice.

In the present report we determined the protective capacity of grapefruit juice (GJ) against molecular and cellular damage in azoxymethane (AOM) treated mice. Animals were daily administered GJ orally (0.8, 4.1, and 8.2 μl/g) for seven weeks, as well as intraperitoneally (ip) injected with AOM twice (weeks 2 and 3 of the assay). Control groups administered with water, with the high dose of GJ, and with AOM injected in weeks 2 and 3 were also included. The results showed a significant, dose-dependent protection of GJ on the number of colon aberrant crypts (AC) induced by AOM. The highest inhibitory effect was reached with the highest tested dose of GJ, decreasing ACF by 51% and 43% at weeks 4 and 7 of the assay. Regarding protein and lipid oxidation we also found a dose-dependent decrease caused with GJ in comparison with the increased levels produced by AOM. Therefore, our results established chemopreventive potential for GJ, and suggested effects related to its antioxidant capacity. Finally, we found that the tested agents induced neither micronuclei increase nor alteration in bone marrow cytotoxicity.

Inhibitory effect of grapefruit juice on the genotoxicity induced by hydrogen peroxide in human lymphocytes.

By means of the comet assay we demonstrated a strong effect by hydrogen peroxide (HP) and no damage by grapefruit juice (GJ) in human lymphocytes. Cells exposed to HP and treated with three concentrations of GJ (10-90 min) showed an increase of DNA damage by HP over the control level, and a decrease of such damage by GJ. With the comet assay plus formamidopyrimidine-DNA-glycosylase we found the strongest increase of DNA damage by HP over the control level, and the strongest reduction of such damage by GJ. By applying the comet/FISH method we determined 98% of the p53 gene signals in the comet head of control cells along the experiment (10-90 min), in contrast with about 90% signals in the comet tail of cells exposed to HP. Cells treated with both agents showed a significant, concentration/time dependent return of p53 signals to the head, suggesting enhancement of the gene repair. Finally, with the annexin V assay we found an increase in apoptosis and necrosis by HP, and no effect by GJ; when GJ was added to HP treated cells no modification was observed in regard to apoptosis, although a decrease of necrosis was observed.