RESUMO
Since the introduction of gliclazide in the pharmaceutical industry, a large number of research groups have been engaged in various investigations aiming to enhance its biomedical application. But, very limited efforts have been made to study polymorphism of gliclazide. Therefore, this study focuses on solvent-induced polymorphism of gliclazide and its characterization by thermal methods. Three polymorphs namely, Form-I, II and III and an amorphous powder were produced from different solvents and solvent mixtures. Crystals were analyzed using infrared spectroscopy, differential scanning calorimetry, X-ray powder diffraction and single crystal x-ray diffraction. Polymorph Form-I is found to exist in centro-symmetric triclinic P-1 space group and has endothermic peak at 162.93°. Form-II has endothermic peak from 171.2° to 172.35° and exists in centro-symmetric monoclinic P21/a space group while Form-III has endothermic peak from 168.93° to 169.86° and exists in centro-symmetric monoclinic P21/n space group. The equilibrium solubility values of Form-I, II, III and the amorphous form were 0.4825±0.025, 0.2341±0.042, 0.2581±0.038 and 0.5213±0.072 mg/ml, respectively. The Form-I has relatively higher solubility and similar to that of amorphous gliclazide. Form-II and Form-III are relatively most stable and least soluble. However, there was no remarkable difference in their aqueous solubility under the conditions in which study was conducted.
RESUMO
In this study, we have demonstrated the conformational changes to DNA induced by abnormal interactions of copper using circular dichroism, in combination with UV-absorbance and fluorescence spectroscopy. Results confirm that binding of copper to bases of DNA in chromatin is concentration dependent. Binding efficiency of Cu2+ ions to DNA is increased in proportion to the degree of unwinding of the double helix induced by denaturation. Altered B-DNA conformation will alter the integrity of DNA which may affect the normal process of DNA replication and transcription. Copper induced DNA damage in the brain may cause neurotoxicity and the neuronal cell death and is implicated in Alzheimer's disease and other neurological disorders.
RESUMO
Ocimum is a genus of aromatic herbs, undershurbs or shrubs distributed in the tropical and warm temperate regions of the world. Larvicidal activity of essential oils and different extracts of O. sanctum, O. basilicum and O. gratissimum were compared on laboratory reared and field collected larvae of Culex quinquefasciatus. Thin layer chromatographic analysis revealed that all the three species have similar components and results showed the presence of steroids and triterpenoids. The larvicidal activity was determined in terms of LD50 value on late third or early fourth instar larvae for a period of 24 h. A comparison of LD50 value has shown that O. basilicum is more active than the other two species. The LD50 value of O. basilicum and O. sanctum oil were 39.31 and 40.02 on laboratory reared larvae and 129.53 and 139.49 on field collected larvae. Laboratory reared larvae were more sensitive than field collected larvae.
