Toxicology, genotoxicity, and cytotoxicity of three extracts of Solanum chrysotrichum

ETHNOPHARMACOLOGICAL RELEVANCE

Infusions of Solanum chrysotrichum (Schldl.) or "sosa" are employed in Traditional Mexican Medicine for the local and systemic treatment of skin and mucosal infections. Different studies have verified its antifungal effectiveness and therapeutic safety in superficial mycosis caused by dermatophytes or yeasts, and have identified a group of spirostanic saponins, denominated SC-2-SC-6, as responsible for the antifungal activity. Of these, SC-2 is the most active molecule. Electron microscopy studies showed that SC-2 disintegrates cell wall and internal membranes of the fungi studied. In order to continue the systematic study of Solanum chrysotrichum, the goal of the present study was to evaluate the toxicity, genotoxicity, and cytotoxicity of the three different extracts of Solanum chrysotrichum.

MATERIALS AND METHODS

From the dried leaves of Solanum chrysotrichum, we obtained the aqueous, hydroalcoholic, and ethanolic extracts. Saponins (SC-2-SC-6) were quantified by High-performance liquid chromatography (HPLC). For the toxicology study, we formed four groups: three experimental groups, treated with each of the extracts at 1-g/kg doses per os (po) during 4 weeks, and a negative control group treated with the vehicle. For the genotoxicity study, we added another group, which was treated with cyclophosphamide for 1 week. The cytotoxicity study was carried out with international methods and employing the nasopharyngeal cancer (KB) and breast cancer (MDA) cell lines.

RESULTS

The three evaluated extracts did not modify either of the behavioral parameters, and on the hepatic-function biochemical tests (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]), did not showed significant increase on comparing to placebo. The genotoxicity parameters did not exhibit differences between the experimental groups and the placebo (control) group. Histologic analysis showed that the three extracts caused amyloidosis and moderate necrosis in liver, and focal tumefaction in kidney, as well as significant, but clinically irrelevant, elevations of creatinine with the aqueous and hydroalcoholic, but not with the ethanolic, extracts. In addition, the aqueous and ethanolic extracts exhibited interesting cytotoxic activity against the KB cell line.

CONCLUSIONS

At the doses administered, the ethanolic extract of Solanum chrysotrichum showed a slightly toxic effect on liver and kidney, without biochemical or genotoxic repercussions and with cytotoxic activity against the KB cell line.

Pharmacological and chemical study to identify wound-healing active compounds in Ageratina pichinchensis

The aerial parts of Ageratina pichinchensis are used in Mexican traditional medicine for the treatment of skin wounds. Recently, it was demonstrated that the aqueous extract of this plant reduced the time required to cicatrize a wound induced in the rat. The same extract showed a capability to induce overgrowth in normal fetal lung cells (MRC-5). The objective of the present study was isolating and identifying the active compounds in A. pichinchensis that are capable of inducing cellular overgrowth, as well as performing a preliminary evaluation of their anti-inflammatory and toxic effects. By means of bioguided chemical separation of an aqueous extract of A. pichinchensis, the most active compound capable of inducing cellular overgrowth was identified as 7-O-(β-D-glucopyranosyl)-galactin. In vivo inflammation induced with carrageenan in mice was significantly reduced by the aqueous extract of A. pichinchensis, reaching a decrease of up to 60.6 %. Acute (2 g/kg) and subchronic (1 g/kg for 28 days) oral administration of the aqueous extract of this plant did not affect hepatic function (through alanine aminotransferase and aspartate aminotransferase activity evaluation), while no alterations of the histologic samples of liver and kidney were evidenced.

Antidiabetic activities of Tecoma stans (L.) Juss. ex Kunth

ETHNOPHARMACOLOGICAL RELEVANCE

Tecoma stans aqueous extract (TAE) is widely used as a traditional antidiabetic remedy in Mexico; its rational use is controversial. We provide evidence of its main antidiabetic activities.

AIM OF THE STUDY

To evaluate in vivo and in vitro intestinal alpha-glucosidases inhibition as the possible mode of action of TAE on type 2 diabetes mellitus (DM2) animal models, and to test the effects of its sub-chronic administration on lipids and glucose blood levels.

MATERIALS AND METHODS

In healthy and streptozotocin (STZ)-induced diabetic male Sprague-Dawley rats, glucose or cornstarch was administered after an oral dose of TAE, acarbose, tolbutamide or vehicle, in order to build starch and glucose tolerance curves (STC and GTC). An intestinal brush border preparation was used to evaluate the TAE alpha-glucosidases inhibitory activity. Moreover, in STZ-induced diabetic rats TAE, tolbutamide or vehicle was administered for 21 days for evaluate their effects on fasting glucose cholesterol and triglycerides. Also, TAE total phenolic compounds were quantified.

RESULTS

In STC, TAE decreased hyperglycemic peak values in both healthy and STZ-treated rats, in a magnitude similar to that of acarbose. The in vitro preparation showed a dose-dependent inhibition of glucose release from starch. Sub-chronic administration of TAE significantly reduced cholesterol and triglycerides levels. Moreover, we confirmed that acute and sub-chronic administration of TAE (500mg/kg) in both rat models did not diminish fasting glucose and did not modify the GTC.

CONCLUSIONS

The study present evidence that the main antidiabetic effect of TAE is due to intestinal alpha-glucosidase inhibition by decreasing the postprandial hyper-glycaemia peak; in addition, TAE sub-chronic administration reduces triglycerides and cholesterol, without modifying fasting glucose.

Toxicological and cytotoxic evaluation of standardized extracts of Galphimia glauca

Galphimia glauca Cav (Malpighiaceae) has been widely used in Mexican traditional medicine as a remedy for the treatment of mental disorders, principally as a sedative and tranquilizer. The sedative activity of extracts obtained from this plant has been demonstrated with different neuropharmacological models. Different triterpenes, known as galphimines, have been identified from the active extract. Galphimine-B (G-B) possesses anxiolytic activity and is able to selectively inhibit discharges of dopaminergic neurons in the ventral tegmental area in rats. Nevertheless, there have been no toxicological investigations carried out with products obtained from this plant. In this work three different extracts (aqueous, ethanolic, and methanolic) of Galphimia glauca, standardized in the content of three galphimines, were evaluated for their behavioral and pharmaco-toxicological effects. After administering the extracts to mice for 28 days (2.5g/kg, p.o.), no deaths were found and the histopathological analysis of different organs did not show alterations; only the behavioral parameters analyzed showed a diminution of spontaneous activity. The administration of these extracts for 56 days (same doses and route) in mice did not cause any changes in the biochemical parameters that evaluate liver function. On the other hand, no cytotoxic effects were found on KB, UISO, and OVCAR-5 transformed cell lines, but all extracts specifically inhibited colon cancer cell line growth with an ED(50) lower than 2microg/ml. The extracts were also evaluated in genotoxicity tests in vitro (250, 100 and 50microg/ml), which demonstrate that none of the three extracts from Galphimia glauca showed a genotoxic effect.

Hypoglycemic effect and chlorogenic acid content in two Cecropia species

The hypoglycemic effect of methanol leaf extracts from Cecropia obtusifolia and C. peltata was evaluated in healthy mice. A significant decrease (p < 0.05) in plasma glucose levels was recorded 2 and 4 h after a single oral administration of methanol extracts (1 g/kg). This effect was correlated with the chlorogenic acid contents in both species; C. peltata, containing 19.84 +/- 1.64 mg of chlorogenic acid/g of dried leaves produced the highest decrease (D(alpha 2,60) = 20.18, p < 0.05) of plasma glucose levels (52.8%). The extracts of C. obtusifolia from Tabasco and Veracruz, showed similar hypoglycemic effects (33.3% and 35.7%, respectively) and chlorogenic acid contents (Tukey(0.05) = 1.8859) (13.3 +/- 3.2 mg/g and 13.1 +/- 1.6 mg/g, respectively). The hypoglycemic effect produced by different doses (0.1, 0.25, 0.50, 0.75 and 1 g/kg body wt, p.o.) of C. peltata showed a lineal relationship with chlorogenic acid content, reaching an ED(50) = 0.540 g/kg body wt for extract, and an ED(50) = 10.8 mg/kg body wt for chlorogenic acid. These results suggest that C. peltata is a better hypoglycemic agent than C. obtusifolia, and it could be considered for developing a phytomedicinal product to carry out clinical trials.

Clinical trial of Cecropia obtusifolia and Marrubium vulgare leaf extracts on blood glucose and serum lipids in type 2 diabetics

Cecropia obtusifolia and Marrubium vulgare have been widely used in Mexican traditional medicine for the control of type 2 diabetes. In order to evaluate the clinical effect produced by the aqueous extract from these species on type 2 non-controlled diabetes mellitus, a total of 43 outpatients were included. Based on the European NIDDM (policy group) criteria, only patients with poor response to the conventional treatment were selected. All patients maintained their medical treatment and also received a prepared infusion of the dry leaves of the plant treatment for 21 days. In a double-blind manner, the patients were randomly grouped as follows: 22 patients were treated with C. obtusifolia and 21 with M. vulgare. The fasting blood glucose values were reduced by 15.25% on patients treated with C. obtusifolia, while cholesterol and triglycerides were decreased by 14.62% and 42.0%, respectively (ANOVA p< 0.02). In the case of patients treated with M. vulgare, the plasma glucose level was reduced by 0.64% and cholesterol and triglycerides by 4.16% and 5.78%, respectively. When the results were compared between groups, significant differences in glucose and cholesterol diminution were found. The obtained results showed that the infusion prepared with the leaves of C. obtusifolia (containing 2.99+/-0.14mg of chlorogenic acid/g of dried plant) produced beneficial effects on carbohydrate and lipid metabolisms when it was administered as an adjunct on patients with type 2 diabetes with poor response to conventional medical treatment.

Evaluation of the calcium-antagonist, antidiarrhoeic and central nervous system activities of Baccharis serraefolia

Baccharis serraefolia is a widely used plant to treat diarrhoea in Mexican traditional medicine. Although the methanolic extract of this plant has shown an important dose-dependent spasmolytic activity, its underlying mechanism has not been studied. In the present work, the methanolic extract of B. serraefolia significantly delayed the onset of tonic seizures induced by strychnine and pentylenetetrazol; besides, it diminished the death rate and number of animals that exhibited convulsions. It produced potentiation of the hypnotic effect of pentobarbital. Oral administration produced an inhibition of gastrointestinal transit in mice as effective as that produced by loperamide. As to the effect on smooth muscles, the active extract produced an inhibition of contraction induced electrically, which could not be reversed by naloxone. The calcium concentration-contraction curve showed a rightward displacement when the extract was added to isolated guinea pig ileum depolarized with high K+ and cumulative concentrations of Ca2+. The results suggest that the methanolic extract does not interact with classical opiate receptors and its effects, at least that produced on smooth muscle, may be due to a probable interference with calcium influx and/or calcium release from an intra-cellular store.