Biochemical Characterization of Ferulic Acid and Caffeic Acid Which Effectively Inhibit Melanin Synthesis via Different Mechanisms in B16 Melanoma Cells.

In this study, we examined the inhibitory effects of ferulic acid and caffeic acid on melanin production using a murine B16 melanoma cell line. The mechanisms by which the two acids inhibit melanin production were investigated by evaluating their effects on the activity of tyrosinase, which is involved is the first step of melanin biosynthesis. Ferulic acid showed no toxicity against the melanoma cells at any dose, whereas caffeic acid exerted cellular toxicity at concentrations higher than 0.35 mM. Both ferulic and caffeic acids effectively inhibited melanin production in the B16 melanoma cells. Ferulic acid reduced tyrosinase activity by directly binding to the enzyme, whereas no binding was observed between caffeic acid and tyrosinase. Both ferulic acid and caffeic acid inhibited casein kinase 2 (CK2)-induced phosphorylation of tyrosinase in a dose-dependent manner in vitro. Ferulic acid was found to be a more effective inhibitor of melanin production than caffeic acid; this difference in the inhibitory efficacy between the two substances could be attributable to the difference in their tyrosine-binding activity. Our analysis revealed that both substances also inhibited the CK2-mediated phosphorylation of tyrosinase.

Synthesis of 6-(2-Methoxynaphthyl)-2,3-dihydro-1,2,4-triazine-3-thione as a New Reagent for Spectrophotometric Determination of Copper.

A simple, sensitive, accurate, and green spectrophotometric method for the determination of Cu(II) using newly synthesized reagent, 6-(2-methoxynaphthyl)-2,3-dihydro-1,2,4-triazine-3-thione (MNDTT), has been developed. MNDTT was synthesized based on the acylation of methoxy naphthalene and reaction of the product with amyl nitrite, which upon reaction with thiosemicarbazide yielded 6-(2-meyhoxynaphthyl)-2,3-dihydro-1,2,4-triazine-3-thione. MNDTT produces a dark red complex with copper in methanol according to the 1 : 2 stoichiometry. Beer's law was obeyed over the concentration range of 2.5-20 µg/mL with r (2) = 0.992. The limit of detection and limit of quantification were 0.33 and 1.10 µg/mL, respectively. Within-day and between-day precision values were less than 3.68%. Finally, the method has been applied to a dental alloy (110-plus) successfully and the results were compared with atomic absorption method. The results showed that there was no significant difference between the two methods (P > 0.05).

Spectrophotometric Determination of Cu(2+) and Monitoring of Hg(2+) and Ni(2+) in some Iranian Vegetables Using 6-(2-Naphthyl)-2, 3-Dihydro-as-triazine-3-thione.

Recently, 6-(2-naphthyl)-2, 3-dihydro-as-triazine-3-thione (NDTT) was synthesized in laboratory and used successfully for the spectrophotometric determination of nanogram levels of Cu(2+) in aqueous solution. This reagent forms a specific red complex with Cu(2+) ions after the extraction by chloroform at alkaline pH. The absorption of the complex in the UV region (313 nm) is about 8 times as strong as in the visible one (510 nm). Mercury and nickel ions form yellow complexes with NDTT under the same conditions which interfere in the UV region and without effect on Cu (II) absorbance in the visible region. The studied vegetables include Mentha pipereta L., Anethum graveolens L., Beta vulgaris L., Coriandrum sativum, Petroselinum hortense H., Ocimum basilicum L., Spinacia oleracea L., Lactuca sativa L., and Brassica oleracea L.

Synthesis and In-vitro Antibacterial Activities of Acetylanthracene and Acetylphenanthrene Derivatives of Some Fluoroquinolones.

Novel analogues of N-piperazinyl fluoroquinolones were prepared and evaluated against a panel of Gram-positive and Gram-negative bacteria, to study the effect of introducing bulky anthracene and phenanthrene moieties on the antibacterial effects of norfloxacin, ciprofloxacin and gatifloxacin. Although most of the novel synthesized compounds had lower antibacterial effects, some derivatives showed better activity in comparison with mother drugs based on molar concentration; for example, the 3-acetyl phenanthrene analogue of norfloxacin was more effective than E. coli and K. pneumonia.

Biochemical characterization of epigallocatechin-3-gallate as an effective stimulator for the phosphorylation of its binding proteins by glycogen synthase kinase-3ß in vitro.

The stimulatory and inhibitory effects of epigallocatechin-3-gallate (EGCG) and its related two compounds (luteolin and quercetin) on the phosphorylation of four proteins [bovine myelin basic protein (bMBP), human recombinant tau protein (hrTP), human recombinant vimentin (hrVM) and rat collapsin response mediator protein-2 (rCRMP-2)] by glycogen synthase kinase-3ß (GSK-3ß) were comparatively determined in vitro. We found that (i) EGCG, not quercetin and luteolin, highly stimulated the GSK-3ß-mediated phosphorylation of hrTP and significantly stimulated the phosphorylation of bMBP and hrVM by the kinase; (ii) these three polyphenols inhibited dose-dependently the phosphorylation of rCRMP-2 by GSK-3ß; (iii) only EGCG significantly enhanced autophosphorylation of GSK-3ß; and (iv) EGCG had a binding-affinity with two basic proteins (bMBP and hrTP) and a low affinity with rCRMP-2 rather than hrVM in vitro. In addition, the binding of EGCG to these two basic proteins induced to highly stimulate their phosphorylation, including novel potent sites for GSK-3ß, and to significantly reduce the K(m) value and increase the V(max) value of these two substrate proteins for the kinase in vitro. These results provided here suggest that EGCG acts as an effective stimulator for the GSK-3ß-mediated phosphorylation of its binding proteins containing EGCG-inducible phosphorylation sites for the kinase in vitro.

Synthesis and biological evaluation of 2-phenylthiazole-4-carboxamide derivatives as anticancer agents.

A series of substituted 2-phenylthiazole-4-carboxamide derivatives were synthesized as potential cytotoxic agents and evaluated against three human cancer cell lines including T47D (Breast cancer), Caco-2 (Colorectal cancer) and HT-29 (Colon cancer). The SAR of the arylacetamido pendent connected to the para-position of 2-phenylthiazole were explored. It was found that substitution at the 4-position by a methoxy group led to improvement of activity against Caco-2 cells while 2-methoxy substituent could maintain the high activity against HT-29 and T47D cell lines. Also, 3-fluoro analog showed good cytotoxic activity profile against all cell lines with IC(50) values less than 10 µg/mL.

Preparation and in-vitro Antibacterial Evaluation of Electroless Silver Coated Polymers.

Long-term use of indwelling medical catheters has often been hindered by catheter-associated nosocomial infections. In this study the effectiveness of silver coating of polystyrene and polyethylene polymers was investigated. Polymer pieces of 2 cm(2) each were coated with a thin layer of silver using electroless plating technique. Silver-coated polymers were challenged with cultures of four different microorganisms known for their involvement in nosocomial infections in both solid and broth media. The tested bacteria included Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa. Silver release from the coated polymers was 2-5 µg/cm(2) which was confirmed by chemical and biological methods. The silver coating thickness ranged between 20-450 nm. P. aeruginosa and S. aureus were the most adherent bacteria to polystyrene sheets while E. coli showed minimum adherence effect. The survival rate of different bacteria after 80 min in a time course experiment tended to dominate E. coli as the most sensitive bacteria to the effect of silver with zero survival rate while around 4% of P. aeruginosa were detected after same period. Silver coating of indwelling polymers by electroless technique seems promising in combating nosocomial infections due to long-term catheterization.

A time course analysis of systemic administration of aqueous licorice extract on spatial memory retention in rats.

In the present study, the time course of the effects of Glycyrrhiza glabra L. (Leguminosae) aqueous extract (GE), administered systemically to rats, on the spatial memory retention in the Morris water maze was investigated. The dose of glycyrrhizin (GL), i. e., 0.5, 2.5 and 5 mg/mL in daily water intake of GE was administered to three groups of rats. The first, second and third groups received GE for 1, 2 and 4 weeks, respectively (each group included 3 subgroups). Three additional control groups of animals received only tap water during the same periods of time. After terminating the treatments, all animals were trained for four days; each day included one block and each block contained four trials. Test trials were conducted 48 h after the completion of the training period. Nicotine (1 microg/side) was infused into the CA1 region of the hippocampus as a positive drug control. GE treatment decreased both escape latency and traveled distance, but not swimming speed, compared with control, suggesting significant spatial memory retention enhancement by GE. Statistical analysis did not show any significant difference between GE-treated animals and the nicotine group in escape latency and traveled distance. At the end of the testing trials plasma samples were collected and the concentrations of glycyrrhetinic acid (GA) as a major metabolite of GL were measured in the different groups of treated rats. The maximum concentration was observed after four weeks of GE administration at 5 mg/mL of GL. These results showed that the enhancement effect of GE on spatial memory retention does not correlate with GA blood levels.

Anti-inflammatory effects of butadiene Diels-Alder adducts to some 1-dehydroglucocorticoids in rats.

Three compounds (C1, C2 and C3) were synthesized by reacting dexamethasone as a strong anti-inflammatory drug or prednisolone as a moderate one with 1,3-butadiene under Diels-Alder reaction conditions to produce pentacyclic compounds. The structures of C1 [(11 beta,16 alpha,17 alpha)-9 alpha-fluoro-11,17,21-trihydroxy-16-methyl pregna [1 alpha,2 beta]-cyclohex 3',4-diene, 3,20-dione], C2 [(11 beta,16 alpha,17 alpha)-9 alpha-fluoro-11,17,21-trihydroxy-16-methyl pregna [1 alpha,2 alpha]-cyclohex 3',4-diene, 3,20-dione], and C3 [(11 beta,17 alpha)-11,17,21-trihydroxy-pregna [1 alpha,2 alpha]-cyclohex 3',4-diene, 3,20-dione] were concluded based on GC-mass and 1H NMR spectroscopic data. The compounds were used to evaluate the effect of introducing extra ring in the structure of the above drugs on their anti-inflammatory behavior. The potencies of the three compounds were compared with that of the mother drugs by the rat hind paw edema test. The results indicate a decrease in C1 potency, expressed as percentage of inflammation inhibition (16.5% versus 24.3% for Dex) or loss of C2 potency (2.0% versus 24.3% for Dex) in dexamethasone adducts. On the other hand, although the prednisolone adduct C3 lost potency too (3.95% versus 26.3% for Pred), but instead it lowered significantly the prednisolone potency on subsequent administration before prednisolone (C3+Pred) (1.30% versus 17.10% for Pred). When prednisolone was administered in equal doses after C3 (10mg/kg), it restored about 60% of its activity. This observation indicates that C3 still retain affinity toward GR without eliciting subsequent events. In other words it has anti prednisolone effect, i.e. anti-glucocorticoid property.