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Curcumin, the yellow pigment from the rhizoma of Curcuma longa, is a widely studied phytochemical with a variety of biological activities. The ongoing research and clinical trials have proved that this natural phenolic compound has great and diverse pharmacological potencies. Beside its effective antioxidant, antiinflammatory, and antimicrobial/antiviral properties, curcumin is also considered as a cancer chemopreventive agent. While the antioxidant activity of curcumin is well documented, its interaction with DNA and RNA is not fully investigated. This study was designed to examine the interactions of curcumin with calf thymus DNA and yeast RNA in aqueous solution at physiological conditions, using constant DNA and RNA concentration (6.25 mM) and various curcumin/polynucleotide (phosphate) ratios of 1/120, 1/80, 1/40, 1/20, and 1/10. Fourier transform infrared (FTIR) and UV-visible spectroscopic methods were used to determine the ligand binding modes, the binding constants, and the stability of curcumin-DNA and curcumin-RNA complexes in aqueous solution. Spectroscopic evidence showed that curcumin binds to the major and minor grooves of DNA duplex and to RNA bases as well as to the back bone phosphate group with overall binding constants of K(curcumin-DNA) = 4.255 x 10(4) M(-1) and K(curcumin-RNA) = 1.262 x 10(4) M(-1). Major DNA and RNA aggregation occurred at high pigment concentration. No conformational changes were observed upon curcumin interaction with these biopolymers; that is, DNA remains in the B, and RNA retains its A-family structure.

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In this study, we isolated and pharmacologically characterized the first a-like toxin from the venom of the scarcely studied Iranian scorpion Odonthobuthus doriae. The toxin was termed OD1 and its primary sequence was determined: GVRDA-YIADDKNCVYTCASNGYCNTECTKNGAESGYCQWIGR-YGNACWCIKLPDEVPIRIPGKCR. Using the two-electrode voltage clamp technique, the pharmacological effects of OD1 were studied on three cloned voltage-gated Na + channels expressed in Xenopus laevis oocytes (Na v 1.2/b 1 , Na v 1.5/b 1 , para/tipE). The inactivation process of the insect channel, para/tipE, was severely hampered by 200 nM of OD1 (EC 50 = 80 ± 14 nM) while Na v 1.2/ b 1 still was not affected at concentrations up to 5 lM. Na v 1.5/b 1 was influenced at micromolar concentrations.

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