Effects of a Mangifera indica L. stem bark extract and mangiferin on radiation-induced DNA damage in human lymphocytes and lymphoblastoid cells

OBJECTIVES

Mangifera indica L. (mango) stem bark aqueous extract (MSBE) that has antioxidant, anti-inflammatory and immunomodulatory properties, can be obtained in Cuba. It is rich in polyphenols, where mangiferin is the main component. In this study, we have tested DNA damage and protection effects of MSBE and mangiferin on primary human lymphocytes and lymphoblastoid cells.

MATERIAL AND METHODS

Cell suspensions were incubated with the products (50-1000 μg/ml) for experiments on damage induction, and evaluation of any potential protective effects (5-100 μg/ml) for 60 min at 37 °C. Irradiation was performed using a γ-ray source, absorbed dose 5 Gy. At the end of exposure, DNA damage, protection and repair processes were evaluated using the comet assay.

RESULTS

MSBE (100-1000 μg/ml) induced DNA damage in a concentration dependent manner in both cell types tested, primary cells being more sensitive. Mangiferin (200 μg/ml) only induced light DNA damage at higher concentrations. DNA repair capacity was not affected after MSBE or mangiferin exposure. On the other hand, MSBE (25 and 50 μg/ml) and mangiferin (5-25 ug/ml) protected against gamma radiation-induced DNA damage.

CONCLUSIONS

These results show MSBE has protector or harmful effects on DNA in vitro depending on the experimental conditions, which suggest that the extract could be acting as an antioxidant or pro-oxidant product. Mangiferin was involved in protective effects of the extract.

Evaluation of genotoxicity and DNA protective effects of mangiferin, a glucosylxanthone isolated from Mangifera indica L. stem bark extract

Mangiferin is a glucosylxantone isolated from Mangifera indica L. stem bark. Several studies have shown its pharmacological properties which make it a promising candidate for putative therapeutic use. This study was focused to investigate the in vitro genotoxic effects of mangiferin in the Ames test, SOS Chromotest and Comet assay. The genotoxic effects in bone marrow erythrocytes from NMRI mice orally treated with mangiferin (2000 mg/kg) were also evaluated. Additionally, its potential antimutagenic activity against several mutagens in the Ames test and its effects on CYP1A1 activity were assessed. Mangiferin (50-5000 μg/plate) did not increased the frequency of reverse mutations in the Ames test, nor induced primary DNA damage (5-1000 μg/mL) to Escherichia coli PQ37 cells under the SOS Chromotest. It was observed neither single strand breaks nor alkali-labile sites in blood peripheral lymphocytes or hepatocytes after 1h exposition to 10-500 μg/mL of mangiferin under the Comet assay. Furthermore, micronucleus studies showed mangiferin neither induced cytotoxic activity nor increased the frequency of micronucleated/binucleated cells in mice bone marrow. In short, mangiferin did not induce cytotoxic or genotoxic effects but it protect against DNA damage which would be associated with its antioxidant properties and its capacity to inhibit CYP enzymes.

Interactions of polyphenols with the P450 system: possible implications on human therapeutics

Polyphenols are a family of natural compounds with many biological properties. This review focuses on their potential interaction on the cytochrome P450 system. Effects of phenolic acids, anthocyanins, stilbenes, catechins and other flavonoids on the drug metabolising function are revised. Their daily intake and presence in herbal medicines justify the study of potential drug-interaction to prevent undesirable clinical consequences.

Effects of Mangifera indica L. aqueous extract (Vimang) on primary culture of rat hepatocytes

Vimang is an aqueous extract from stem bark of Mangifera indica L. (Mango) with pharmacological properties. It is a mixture of polyphenols (as main components), terpenoids, steroids, fatty acids and microelements. In the present work we studied the cytotoxic effects of Vimang on rat hepatocytes, possible interactions of the extract with drug-metabolizing enzymes and its effects on GSH levels and lipid peroxidation. No cytotoxic effects were observed after 24 h exposure to Vimang of up to 1000 microg/mL, while a moderate cytotoxicity was observed after 48 and 72 h of exposure at higher concentrations (500 and 1000 microg/mL). The effect of the extract (50-400 microg/mL) on several P450 isozymes was evaluated. Exposure of hepatocytes to Vimang at concentrations of up to 100 microg/mL produced a significant reduction (60%) in 7-methoxyresorufin-O-demethylase (MROD; CYP1A2) activity, an increase (50%) in 7-penthoxyresorufin-O-depentylase (PROD; CYP2B1) activity, while no significant effect was observed with other isozymes. To our knowledge, this is the first report regarding the modulation of the activity of the P450 system by an extract of Mangifera indica L. The antioxidant properties of Vimang were also evaluated in t-butyl-hydroperoxide-treated hepatocytes. A 36-h pre-treatment of cells with Vimang (25-200 microg/mL) strongly inhibited the decrease of GSH levels and lipid peroxidation induced by t-butyl-hydroperoxide dose- and time-dependently.

Lack of in vivo embryotoxic and genotoxic activities of orally administered stem bark aqueous extract of Mangifera indica L. (Vimang)

Mango (Mangifera indica L.) stem bark aqueous extract (MSBE) is a new natural product with antioxidant, anti-inflammatory and immunomodulatory effects known by the brand name of its formulations as Vimang. Previously, the oral toxicity studies of the extract showed a low toxicity potential up to 2000 mg/kg. This work reports the results about teratogenic and genotoxicologic studies of MSBE. For embryotoxicity study, MSBE (20, 200, or 2000 mg/kg/day) was given to Sprague-Dawley rats by gavage on days 6-15 of gestation. For genotoxicity, MSBE was administered three times during 48 h to NMRI mice. Cyclophosphamide (50 mg/kg) was used as a positive control. No maternal or developmental toxicities were observed when the rats were killed on day 20th. The maternal body-weight gain was not affected. No dose-related effects were observed in implantations, fetal viability or external fetal development. Skeletal and visceral development was similar among fetuses from all groups. No genotoxicity was observed in bone marrow erythrocytes and liver cells after administration. MSBE appears to be neither embryotoxic nor genotoxic as measured by bone marrow cytogenetics in rodents.

Evaluation of the genotoxic potential of Mangifera indica L. extract (Vimang), a new natural product with antioxidant activity

Mangifera indica L. extract (Vimang) consists of a defined mixture of components (polyphenols, terpenoids, steroids, fatty acids and microelements). It contains a variety of polyphenols, phenolic esters, flavan-3-ols and a xanthone (mangiferin), as main component. This extract has antioxidant action, antitumor and immunemodulatory effects proved in experimental models in both in vitro and in vivo assays. The present study was performed to investigate the genotoxicity potential activity of Vimang assessed through different tests: Ames, Comet and micronucleus assays. Positive and negative controls were included in each experimental series. Histidine requiring mutants of Salmonella typhimurium TA1535, TA1537, TA1538, TA98, TA100 and TA102 strains for point-mutation tests and in vitro micronucleus assay in primary human lymphocytes with and without metabolic activation were performed. In addition, genotoxic effects were evaluated on blood peripheral lymphocytes of NMRI mice of both sexes, which were treated during 2 days with intraperitoneal doses of M. indica L. extract (50-150 mg/kg). The observed results permitted to affirm that Vimang (200-5,000 microg/plate) did not increase the frequency of reverse mutations in the Ames test in presence or not of metabolic activation. Results of Comet assay showed that the extract did not induce single strand breaks or alkali-labile sites on blood peripheral lymphocytes of treated animals compared with controls. On the other hand, the results of the micronucleus studies (in vitro and in vivo) showed Vimang induces cytotoxic activity, determined as cell viability or PCE/NCE ratio, but neither increased the frequency of micronucleated binucleate cells in culture of human lymphocytes nor in mice bone marrow cells under our experimental conditions. The positive control chemicals included in each experiment induced the expected changes. The present results indicate that M. indica L. extract showed evidences of light cytotoxic activity but did not induce a mutagenic or genotoxic effects in the battery of assays used.

Evaluation of the reproductive and developmental toxicity of the D-003, a mixture of long-chain fatty acids, in rats and rabbits

D-003 is a mixture of long-chain fatty acids isolated and purified from sugar cane wax with cholesterol-lowering properties. D-003 given orally (500 and 1000 mg/kg/day) to female rats for 15 days prior to mating, through mating and gestation to day 21 of lactation and male rats for 4 weeks prior and during mating did not induce toxic effects on reproduction. There were no significant reductions in the number of animals that conceived, in the numbers of pups born to those that did conceive, in the numbers of pups that survived until weaning, and in their body weights at weaning. Drug-treated and control groups' offspring were comparable in growth, physical and behavioral development, spontaneous activity and reproductive performance. Pregnant New Zealand rabbits were given D-003 as oral doses of 500 and 1000 mg/kg/day on days 6 through 18 of gestation without any evidence of embryotoxicity or teratogenicity. The no-observed-effect dose in these two experimental studies was 1000 mg/kg/day. After assessment of the potential of high doses of D-003 to act on developing embryo and reproduction process, no evidence supports the conclusion that D-003 is a reproductive and developmental toxicant/teratogen.

Inhibition of rat lipoprotein lipid peroxidation by the oral administration of D003, a mixture of very long-chain saturated fatty acids

Previous results have demonstrated that policosanol, a mixture of aliphatic primary alcohols isolated and purified from sugar cane wax, whose main component is octacosanol, inhibited lipid peroxidation in experimental models and human beings. D003 is a defined mixture of very long-chain saturated fatty acids, also isolated and purified from sugar cane wax, whose main component is octacosanoic acid followed by traicontanoic, dotriacontanoic, and tetracontanoic acids. Since very long-chain fatty acids are structurally related to their corresponding alcohols, we investigated the effect of oral treatment with D003 (0.5, 5, 50, and 100 mg/kg) over 4 weeks in reducing the susceptibility of rat lipoprotein to oxidative modification. The combined rat lipoprotein fraction VLDL + LDL was subjected to several oxidation systems, including those containing metal ions (CuSO4), those having the capacity to generate free radicals 2,2-azobis-2-amidinopropane hydrochloride (AAPH), and a more physiological system (resident macrophages). D003 (5, 50, and 100 mg/kg) significantly inhibited copper-mediated conjugated-diene generation in a concentration-dependent manner. D003 increased lag phase by 53.1, 115.3, and 119.3%, respectively, and decreased the rate of conjugate-diene generation by 16.6, 21.5, and 19.6%, respectively. D003 also inhibited azo-compound initiated and macrophage-mediated lipid peroxidation as judged by the significant decrease in thiobarbituric acid reactive substance (TBARS) generation. In all the systems the maximum effect was attained at 50 mg/kg. There was also a parallel attenuation in the reduction of lysine amino groups and a significant reduction of carbonyl content after oxidation of lipoprotein samples. Taken together, the present results indicate that oral administration of D003 protects lipoprotein fractions against lipid peroxidation in the lipid as well in the protein moiety.

One-year dog toxicity study of D-002, a mixture of aliphatic alcohols

D-002 is a mixture of high-molecular-weight aliphatic alcohols, obtained from bees wax (Apis mellifera), with mild anti-inflammatory properties and effective anti-ulcer activities demonstrated in experimental models. This study investigated the oral toxicity of D-002 administered for 1 year to beagle dogs. Twenty-four beagle dogs (12 males and 12 females) were distributed randomly in three experimental groups (four animals per group): a control and two treated groups received D-002 at 50 and 250 mg kg(-1) (7 days/week) by gastric gavage. Overall, D-002 was well tolerated throughout the study. No signs or symptoms of toxicity were observed, and no mortality occurred during the study. All groups showed similar weight gain and food consumption. No hematological, blood biochemical or histopathological disturbances attributable to treatment were observed. This study shows no drug-related toxicity induced by long-term administration of up to 250 mg kg(-1) D-002 to beagle dogs.

Policosanol modulates HMG-CoA reductase activity in cultured fibroblasts

BACKGROUND

Cholesterol biosynthesis is strictly controlled by 3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase.

METHODS

Transfer of cultured fibroblasts to a lipid-depleted medium (LDM) up-regulates the enzyme levels. This, in turn, is followed by an accelerated biosynthesis of cholesterol.

RESULTS

Exposure of Vero fibroblasts to LDM and policosanol (0.5-50 microg/mL), a new cholesterol-lowering drug purified from sugarcane (Saccharum officinarum L.) wax, decreased in a dose-dependent manner cholesterol biosynthesis from [14C]-acetate and 3H-water, but not from [14C]-mevalonate.

CONCLUSIONS

This suggests an effect on HMG-CoA reductase, the rate-controlling enzyme in cholesterol biosynthesis. When enzyme activity was measured in the presence of various concentrations of policosanol (0.5-50 microg/mL), reductase was not suppressed. Therefore, there was no evidence for a competitive or noncompetitive inhibition of enzyme activity. However, after treatment of intact cells with policosanol (50 microg/mL) in the presence of LDM, a suppressive effect on enzyme activity was observed, suggesting a modulatory effect of policosanol on reductase activity. The previous inhibition of enzyme up-regulation by policosanol suggests to date a depression of de novo synthesis of HMG-CoA reductase and/or stimulation of its degradation. However, the exact mechanism by which policosanol inhibits the activity of HMG-CoA reductase still remains unclear. Further studies are needed to clarify the precise mechanism of its inhibitory action on cholesterol biosynthesis.

Reference data for the principal physiological indicators in three species of laboratory animals

This paper contains the reference data for the main physiological indicators of three species of laboratory animals: mice, rabbits and dogs. Data listed include the mean and the standard deviation of haematology, serum biochemistry and organ weight to body weight ratio. In addition, pathological studies including microscopical examination of organs and tissues were also done. Comparisons between sexes were analysed.

Effects of policosanol treatment on the susceptibility of low density lipoprotein (LDL) isolated from healthy volunteers to oxidative modification in vitro

AIMS

The aim of this study was to investigate the effect of policosanol on the susceptibility of LDL-C to in vitro lipid peroxidation in human healthy volunteers.

METHODS

The effect of policosanol (5 and 10 mg day(-1) on LDL-C oxidation was studied in a double-blind, randomized, placebo-controlled trial conducted in 69 subjects. LDL-C samples isolated at baseline and after 8 weeks were subjected to in vitro tests of LDL-C oxidation. We tested the susceptibility of LDL-C to lipid peroxidation in a cell-free system by the addition of copper ions as well as in a more physiological system, macrophage-mediated oxidation.

RESULTS

At baseline all groups were well matched regarding all variables. After 8 weeks of therapy policosanol administered at 5 and 10 mg, significantly and in a dose-dependent manner increased the lag phase of conjugated diene generation (mean +/- s.d.) from 83.79+/-29.16 min to 94.90+/-25.50 min (5 mg day(-1)) and from 82.74+/-17.16 min to 129.89+/-35.71 min (10 mg day(-1)), while in the placebo group LDL-C oxidation did not change significantly. Policosanol (10 mg day(-1)), but not placebo, significantly decreased the rate of conjugated diene generation. Comparison with placebo after therapy also showed significant differences. Macrophage mediated-oxidation was also inhibited by policosanol as evident by measuring thiobarbituric acid reactive substances (TBARS). Policosanol (10 mg day(-1)) significantly lowered malondialdehyde (MDA) generation from 8.50+/-0.91 to 5.76+/- 1.01 nmol mg(-1) protein. Comparison with placebo after 5 and 10 mg day(-1) showed significant differences. Policosanol significantly lowered total cholesterol by 10.5% (5 mg day(-1)) and 12.4% (10 mg day(-1)) and LDL-C by 16.7% and 20.2%, respectively. Also, policosanol (10 mg day(-1)) increased HDL-C by 15.2%. Five subjects withdrew from the study, none because of adverse experiences. No clinical or blood biochemical drug-related disturbances were found.

CONCLUSIONS

The present study demonstrated that policosanol administered within its therapeutic dosage for lowering cholesterol (5 and 10 mg day(-1)), decreased the susceptibility of LDL-C to lipid peroxidation in vitro.

Reference database of the main physiological parameters in Sprague-Dawley rats from 6 to 32 months

A reference database comprising body weight gain, exploratory activity, hot plate response, serum biochemistry, haematology, organ weight (%) and a complete anatomopathological study containing non-neoplastic and neoplastic lesions over 1200 Sprague-Dawley rats from 6 to 32 months is described. Comparisons between age and sex were analysed.

Preclinical oral toxicology in rats of D-002, a natural drug with antiulcer effects

D-002 is a mixture of higher aliphatic primary alcohol isolated from bees wax (Apis mellifera) with effective antiulcer effects demonstrated in different experimental models. Oral toxicity of D-002 (5-5000 mg/kg) was evaluated in sub-acute (14 days), subchronic (90 days) and chronic (1 year) studies in Sprague-Dawley rats from both sexes. There was no treatment-related toxicity. Thus, effects on body weight, food consumption, clinical observations, blood parameters, organ weight ratios and histopathological findings were similar in control and treated groups. These short and long-term studies support a wide safety margin for this product.

Possible cytoprotective mechanism in rats of D-002, an anti-ulcerogenic product isolated from beeswax

D-002 is an anti-ulcerogenic product, isolated from beeswax, which consists of a well-defined mixture of higher primary aliphatic alcohols. It is highly effective against ethanol-induced ulcers. This study was designed to determine if D-002 shows cytoprotective properties on gastric mucosa in ethanol-induced ulcers. The involvement of endogenous prostaglandins in the protective effect of D-002 was also investigated. When a subulcerogenic dose of indomethacin (10 mg kg-1) was injected simultaneously with oral administration of ethanol, oral pre-treatment with D-002 (5-100 mg kg-1) partially inhibited the gastric protection. D-002 (5 and 25 mg kg-1) administered to normal rats significantly increased the soluble mucus content and also prevented its reduction in rats with ethanol-induced ulcers. In addition, D-002 administered at 5 and 25 mg kg-1 prevented the increase of vascular permeability induced by ethanol (60%) and reduced the concentration of thromboxane B2 (TXB2) in gastric mucosa of rats with ethanol-induced ulcers. These results support the hypothesis that the anti-ulcerogenic properties of D-002 could be related to a cytoprotective mechanism.

Toxicity of policosanol in beagle dogs: one-year study

Policosanol is a new chemical entity composed of 8 higher aliphatic alcohols obtained from sugar cane (Saccharum officinarum), L. wax, whose cholesterol-lowering effects have been demonstrated in experimental models, healthy volunteers and patients with type II hypercholesterolemia. This study investigated the oral toxicity of policosanol administered for 52 weeks to beagle dogs. Twenty-four beagle dogs (12 males and 12 females) were distributed randomly in 3 experimental groups (4 animals/group): a control and 2 treated groups receiving policosanol at 30 and 180 mg/kg daily (7 days/week) by gavage. No mortality was observed in any group. Overall, policosanol was well tolerated throughout the study and no toxic symptoms were observed. All groups showed similar weight gain and food consumption. Lipid profile determinations showed that policosanol decreased total cholesterol by 20% approximately from 8 to 52 weeks. Cholesterol-lowering effects did not wear off during the study, thus demonstrating the persistence of the effectiveness. Triglycerides and high density lipoprotein-cholesterol (HDL-C) were not changed significantly. No blood biochemistry or histopathological disturbances attributable to treatment were observed. This study has shown that no drug-related toxicity was induced by policosanol administered up to 180 mg/kg/day for 52 weeks to beagle dogs. Since this dose is approximately 620 times higher than the maximal recommended therapeutic dose (20 mg/day) it indicates a good safety margin of this product.

A 12-month study of policosanol oral toxicity in Sprague Dawley rats

Policosanol is a natural mixture of higher aliphatic primary alcohols. Oral toxicity of policosanol was evaluated in a 12-month study in which doses from 0.5 to 500 mg/kg were given orally to Sprague Dawley (SD) rats (20/sex/group) daily. There was no treatment-related toxicity. Thus, effects on body weight gain, food consumption, clinical observations, blood biochemistry, hematology, organ weight ratios and histopathological findings were similar in control and treated groups. This study supports the wide safety margin of policosanol when administered chronically.