Extraction of bioactive compounds and free radical scavenging activity of purple basil (Ocimum basilicum L.) leaf extracts as affected by temperature and time

In the current study, response surface methodology (RSM) was used to assess the effects of extraction time and temperature on the content of bioactive compounds and antioxidant activity of purple basil leaf (Ocimum basilicum L.) extracts. The stability of anthocyanins in relation to temperature, light and copigmentation was also studied. The highest anthocyanin content was 67.40 mg/100 g extracted at 30 °C and 60 min. The degradation of anthocyanins with varying temperatures and in the presence of light followed a first-order kinetics and the activation energy was 44.95 kJ/mol. All the extracts exposed to light showed similar half-lives. The extracts protected from light, in the presence of copigments, showed an increase in half-life from 152.67 h for the control to 856.49 and 923.17 h for extract in the presence of gallic acid and phytic acid, respectively. These results clearly indicate that purple basil is a potential source of stable bioactive compounds

Potentiometric and spectrophotometric studies of MnII and NiII cimetidine complexes

Cimetidine is an important hydrogen histamine receptor which has the ability to chelate metal ions in blood plasma and in different tissues. This study aimed to determine the stability constants for the cimetidine ligand with MnII and NiII metallic ions, synthesizing complexes and characterizing them by infrared spectroscopy, IR, and hydrogen nuclear magnetic resonance, ¹H NMR. Cimetidine protonation constant regarding to the imidazole group was logK 7.05 and the stability constants for MnII and NiII complexes, ML2 species were logK 3.75 and 2.97, respectively, in 0.100 mol L-1 KCI. The interpretation of IR and H¹ NMR spectra for complexes MnII-cim2 and NiII-cim2 indicated that their formation occurs through the sulfur atoms in the thiol group, nitrogen atoms of imidazole ring, and nitrogen atoms of secondary amine. The nitrile group seems to be involved in the complexation of the NiII-cim2 complex