Maryam Nakhjavani

Odontobuthos doriae, a native scorpion in southern tropical parts of Iran, can cause serious health threats and wide ranges of pharmacological disturbances. α-toxins in its venom cause prolongation of Na+ channels activity. In this study, reversing effects of lidocaine, as a Na+-channel blocker, was studied on mice following exposure to venom. Lidocaine (up to 500 mg/kg) and O. doriae crude venom (up to 12 µg/mice) was used in a 14-day acute toxicity test, to yield LD50s of 110mg/kg and 10µg/mice, respectively. Afterward, different sub-acute amounts of lidocaine (25%, 50% and 80% of LD50) were used in the presence of venom (80%, 100% and 120% of LD50). Our results show 80% LD50 of lidocaine, and not higher concentrations, could cause 50% reduction in lethality rate induced by O. doriae venom at LD50 concentration, showing the Na+-channel function in this event. Reducing the amount of lidocaine to safer doses show no significant effect in this aspect. Finally, lidocaine (80% LD50) can partially decrease the O. doriae venom mortality. However, due to some other systemic dangerous lidocaine adverse effects, it is doubtful that it can be a relevant life-saving agent in this case. Further to lidocaine failure in reversing the complete venom toxicity, it would be explained that high Na+ current induced by venom might prevent lidocaine effect at above doses, while higher concentrations also can cause lidocaine toxicity, which restricts our further investigation. Preferably, it would be suggested to use other medical approaches and medication to save the envenomed victim’s life.

Parabens are a group of preservatives that have vast indications in pharmaceuticals, cosmetics and food industries. Recently, there have been reports about the estrogenic effects of these compounds which raised concerns about the possibility of involvement of parabens in estrogen-responsive cancers. In the current study, the effect of methylparaben (MP) and propylparaben (PP) was assessed on the growth pattern of human breast adenocarcinoma cell line, MCF-7. 17-ß-estradiol (EST) and tamoxifen (TAM) were used as estrogenic and anti-estrogenic compounds. EC50 of EST and IC50 of TAM were calculated to be 1.206 and 7.017 µg/ml, respectively, based on trypan blue dye exclusion assay in a 5-day exposure. Proliferation kinetics of MCF-7 cells in a 10 day exposure to these compounds showed that EST (1.206 µg/ml) could induce cell proliferation, while exposure of MP or PP (at the same dose) did not change the growth curve of MCF-7. TAM, on the other hand could decrease the proliferation rate of MCF-7. This inhibition was more exacerbated when MP and PP were added to the culture media, suggesting a competitive binding of these compounds to receptors. In conclusion, the data propose the probable estrogenic effect of MP and PP with less potency compared to EST and less competitive binding to ERs compared to TAM.