In Vitro, Oral Acute, and Repeated 28-Day Oral Dose Toxicity of a Mixed-Valence Polyoxovanadate Cluster.

Polyoxovanadates (POV) are a subgroup of polyoxometalates (POM), which are nanosized clusters with reported biological activities. This manuscript describes the first toxicity evaluation of a mixed-valence polyoxovanadate, pentadecavanadate, (Me4N)6[V15O36Cl], abbreviated as V15. Cytotoxicity experiments using peripheral blood mononuclear cells (PBMC), larvae of Artemia salina Leach, and in vivo oral acute and repeated 28-day doses in mice was carried out. The LC50 values in PBMC cells and A. salina were 17.5 ± 5.8 µmol L-1, and 17.9 µg L-1, respectively, which indicates high cytotoxic activity. The toxicity in mice was not observed upon acute exposure in a single dose, however, the V15 repeated 28-day oral administration demonstrated high toxicity using 25 mg/kg, 50 mg/kg and, 300 mg/kg doses. The biochemical and hematological analyses during the 28-day administration of V15 showed significant alteration of the metabolic parameters related to the kidney and liver, suggesting moderate toxicity. The V15 toxicity was attributed to the oxidative stress and lipid peroxidation, once thiobarbituric acid (TBAR) levels significantly increased in both males and females treated with high doses of the POV and also in males treated with a lower dose of the POV. This is the first study reporting a treatment-related mortality in animals acutely administrated with a mixed-valence POV, contrasting with the well-known, less toxic decavanadate. These results document the toxicity of this mixed-valence POV, which may not be suitable for biomedical applications.

Evaluation of cytotoxicity and wound healing activity of Avicennia schaueriana in cream.

Avicennia schaueriana is found in Brazilian mangrove coast. The cytotoxicity in vitro of the Aqueous Extract of Leaves of Avicennia schaueriana (AELAs) and the healing activity of the plant in cream on mice skin wounds were evaluated in this study. The cytotoxic evaluation was performed on Vero cells. The healing activity was evaluated on mice treated during 5, 10 and 15 days with cream at 5%, solution of sodium chloride at 0.9% and dexpanthenol in cream at 5%. The extract did not show cytotoxicity, but showed mitogenic activity (100µg/ml). In morphometric analysis, the percentage of wound contraction after 10 days was higher in dexpanthenol group (93.41%). In 15 days, the lowest percentage of contraction was observed in the dexpanthenol group (94.41%) and the highest in the AELAs cream group (98.50%). In histomorphometry the dexpanthenol showed the lowest length of re-epithelialization in 10 days. In 15 days, the AELAs cream group showed 100% of re-epithelialization. The number of fibroblasts found in AELAs cream group was higher than the saline solution in 10 days. In 15 days, AELAs cream group maintained a higher amount of fibroblasts when compared to the others. A. schaueriana did not show cytotoxicity. Furthermore, topical application of AELAs cream decreased the wound area, stimulated the re-epithelialization and increased the number of fibroblasts. The species A. schaueriana could become a topical treatment in tissue repair process.

Evaluation of embryotoxic and embryostatic effects of the aqueous extract of Rhizophora mangle and tannic acid on eggs and larvae of Aedes aegypti.

Rhizophora mangle is an abundant plant in mangroves and tannic acid is a polyphenol produced by the secondary metabolism of plants. The aim of the study was to evaluate the embryotoxic and embriostatic effects of the aqueous extract of R. mangle and synthetic tannic acid on eggs and larvae of Aedes aegypti. A. aegypti eggs were exposed in duplicate at concentrations of 250, 500, 750 and 1000 µg/mL of extract and tannic acid for a period of 14 days. Mineral water was used as a negative control. The eggs were observed and counted in a stereomicroscope (1.2x). In all extract concentrations there was stimulation in hatching in relation to the control, but only in concentration of 750 mg/mL it was statistically significant. In tannic acid (250µg/ml) there was significant stimulus in hatching, but in 500, 750 and 1000 µg/mL there was significant inhibition. All concentrations of aqueous extract and tannic acid on larvae showed embryotoxic and embryostatic effects when compared to the control. The aqueous extract of R. mangle showed effect on hatching of A. aegypti eggs and synthetic tannic acid showed embryotoxic and embryostatic effects. On larvae, both the aqueous extract as tannic acid showed embryotoxic and embryostatic effects.