Discovery of a New Analgesic Peptide, Leptucin, from the Iranian Scorpion, Hemiscorpius lepturus.

Hemiscorpius lepturus scorpion stings do not induce considerable pain based on epidemiological surveys conducted in the southwest part of Iran. Accordingly, this study was aimed to identify the analgesic molecule in H. lepturus venom by analyzing a cDNA library of the scorpion venom gland looking for sequences having homology with known animal venom analgesic peptides. The analgesic molecule is a cysteine rich peptide of 55 amino acids. the synthetic peptide was deprotected and refolded. RP-HPLC, Ellman's, and DLS assays confirmed the refolding accuracy. Circular dichroism (CD) showed helix and beta sheet contents. This peptide, called leptucin, demonstrated 95% analgesic activity at the dose of 0.48 mg/kg in hot plate assay. Leptucin at the doses of 0.32, 0.48, and 0.64 mg/kg showed 100% activity in thermal tail flick test. No hemolysis or cytotoxicity was observed at 8 and 16 µg. Histopathology evaluations indicated no hepatotoxicity, nephrotoxicity, and cardiotoxicity. We thus report that leptucin is the analgesic agent of H. lepturus venom. Regarding the high in vivo efficacy of leptucin and the fact it shows no observable toxicity, it could be suggested as a drug lead in a preclinical study of acute pain as well as the study of its mechanism of action.

Comparison of the effects of Origanum vulgare with LHRH-A2 and 17ß-estradiol on the ultrastructure of gonadotroph cells and ovarian oogenesis in immature Trichogaster trichopterus.

Origanum vulgare is a plant of the mint family that contains phytoestrogens. This study compared the effects of O. vulgare, LHRH-A2, and 17ß-estradiol on the ultrastructure of gonadotroph cells and ovarian oogenesis in immature Trichogaster trichopterus. Fish (5.1±0.032cm and 2.1±0.043g, n=150) were randomly divided into four treatment groups (three hormonal treatments and control) and treated intramuscularly at four levels with 17ß-estradiol or O. vulgare at 10, 20, 30 and 50mg/kg body weight and with LHRH-A2 at 0.001, 0.002, 0.003, and 0.005mg/kg body weight. There were three control treatments: saline, ethanol and placebo. Fish were kept in 15 tanks, with 10 fish per tank, injected a total of seven doses over 13 days. Gonadosomatic index (GSI) and oocyte diameter were lower (P≤0.05) in the control than in the three hormonal treatments. The highest GSI and oocyte diameter responses were observed in fish treated with 17ß-estradiol (2.76±0.23%, 149.8±15.43mm) followed by O. vulgare (1.86±0.18%, 104.3±11.5mm) and LHRH-A2 (1.52±0.12%, 91.75±9.02mm) (P≤0.05). Moreover, there was a significant effect of dose level within all the hormonal treatments (P≤0.05). The effect of treatment on the length and weight was likely GSI. Ovarian tissue results showed faster oogenesis of oocytes in fish treated with O. vulgare, after 17ß-estradiol. Ultrastructure of gonadotroph cells demonstrated less stimulation by O. vulgare than by 17ß-estradiol and LHRH-A2. This study suggests that compared with the two hormonal treatments, O. vulgare dose-dependently affects ovarian oogenesis and gonadotroph cells.