A Highly Sensitive and Selective Quinazoline-Based Colorimetric Probe for Naked-Eye Detection of Fe3+ Ions.

A novel quinazoline-based colorimetric sensor (probe 1) that detected Fe3+ via naked-eye in a buffered MeOH: H2O (8:2) solvent system within a neutral pH range was synthesized and its structure was confirmed by 1H-NMR, 13C-NMR, FT-IR, and Mass spectroscopy. Its photophysical properties were also studied. The sensitivity and selectivity factor in the presence of 16 metal ions was examined by utilizing absorption titrations. Based on the selectivity test, probe 1 exhibited excellent selectivity and sensitivity toward Fe3+ ions among various other ions. The competitive effect indicated relatively low interference of other cations on the interaction of probe 1/Fe3+. To specify the sensing behavior of probe 1 to Fe 3+, the mole ratio method was carried out. After addition of around 500 µL of Fe3+, the absorption of probe1 reached saturation, and the reaction was completed. The effect of pH on the absorption and stability of probe 1 towards Fe3+ was examined. The pH range from 5.0 to 9.0 was appropriate for detection of Fe3+. To find the binding stoichiometric of the complex, Job's plot studies were carried out by varying the molar ratio of Fe3+. A 1:2 binding ratio was proposed. Under the optimal conditions, a good linear relationship (R2 = 0.9886) was at the concentration of Fe3+ over the range of 50-110 µM, with a detection limit of 47.44 nM. Our quinazoline-based probe has shown good results for the quantitative determination of Fe3+ in samples of urine with high recovery.

Antioxidant and free radical scavenging activity of H. officinalis L. var. angustifolius, V. odorata, B. hyrcana and C. speciosum.

Extracts of 4 medicinal and aromatic plants were investigated for their antioxidant potency employing six various established in vitro system: H. officinalis L. var. angustifolius aerial parts, C. speciosum flowers, V. odorata and B. hyrcana leaves.With regard to IC50 values (microg/ml), the order in DPPH radical-scavenging were CS (585.6) > HO (311) > VO (245.1) > and BH (113.1). Effectiveness in reducing powers were high and in a descending order of HO > CS > BH > VO (at the concentrations of 25-800 microg/ml). IC50 for Fe2+ chelating ability were 188, 750 and 980 microg/ml for VO, CS and HO, respectively. BH extract has shown only 38% inhibition at 800 microg/ml. The extracts showed weak nitric oxide-scavenging activity. All extracts exhibited very low and moderate concentration-dependent antioxidant activity in FTC methods. IC50 for scavenging of H2O2 were 169 for BH, 175 for CS, 640 for VO and 663 microg/ml for HO. The content of total phenolic compounds and flavonoids were measured in plant extracts. The data obtained in the in vitro models clearly establish the antioxidant potency of all extracts.

The kinetics of interactions between fecapentaene-12 and DNA.

Fecapentaene-12 (Fp-12) is a potent colon cancer mutagen, which interacts with DNA. In this study, the kinetics of its interactions with DNA is investigated. Various pHs are used. Three first-order rates are observed at each pH. This suggests that interaction between Fp-12 and DNA occurs through three different mechanisms.