Hydroxyl substituted benzoic acid/cinnamic acid derivatives: Tyrosinase inhibitory kinetics, anti-melanogenic activity and molecular docking studies.

The inhibition of tyrosinase is an established strategy for treating hyperpigmentation. Our previous findings demonstrated that cinnamic acid and benzoic acid scaffolds can be effective tyrosinase inhibitors with low toxicity. The hydroxyl substituted benzoic and cinnamic acid moieties of these precursors were incorporated into new chemotypes that displayed in vitro inhibitory effect against mushroom tyrosinase. The most active compound, (2-(3-methoxyphenoxy)-2-oxoethyl (E)-3-(4-hydroxyphenyl) acrylate) 6c, inhibited tyrosinase with an IC50 of 5.7 µM, while (2-(3-methoxyphenoxy)-2-oxoethyl 2, 4-dihydroxybenzoate) 4d had an IC50 of 23.8 µM. In comparison, the positive control, kojic acid showed tyrosinase inhibition with an IC50 = 16.7 µM. Analysis of enzyme kinetics revealed that 6c and 4d displayed noncompetitive reversible inhibition of the second tyrosinase enzymatic reaction with Ki values of 11 µM and 130 µM respectively. In silico docking studies with mushroom tyrosinase (PDB ID 2Y9X) predicted possible binding modes in the catalytic site for these active compounds. The phenolic para-hydroxy group of the most active compound 6c is predicted to interact with the catalytic site Cu++ ion. The methoxy part of this compound is predicted to form a hydrogen bond with Arg 268. Compound 6c had no observable toxic effects on cell morphology or cell viability at the highest tested concentration of 91.4 µM. When dosed at 91.4 µM onto B16F10 melanoma cells in vitro6c showed anti-melanogenic effects equivalent to kojic acid at 880 µM. 6c displayed no PAINS (pan-assay interference compounds) alerts. Our results show that compound 6c is a more potent tyrosinase inhibitor than kojic acid and is a candidate for further development. Our exposition of the details of the interactions between 6c and the catalytic pocket of tyrosinase provides a basis for rational design of additional potent inhibitors of tyrosinase, built on the cinnamic acid scaffold.

Benzoic acid in nursery diets increases the performance from weaning to finishing by reducing diarrhoea and improving the intestinal morphology of piglets inoculated with Escherichia coli K88.

A total of 224 weaned pigs (DanBred sows x PIC 337 sires) with an average body weight (BW) of 6.37 ± 0.34 kg (21 days of age) were used to evaluate how different levels of benzoic acid fed to weaning pigs orally inoculated with Escherichia coli (K88+ ) affected the nursing and grow-finishing performance, the physicochemical properties of the intestine, the volatile fatty acid concentration in the caecum and the incidence of diarrhoea. Pigs were randomly allocated in an experimental design of randomized blocks in a 4 × 2 factorial design, and they were administered four levels of benzoic acid (0.00%, 0.25%, 0.50% and 0.75%) and inoculated (or not) in two consecutive days with 1 ml solution containing 106 CFU/ml of E. coli (K88+ ). Seven replicates (pens) per treatment were used, and four animals were kept per pen. Supplementation with 0.75% benzoic acid promoted better performance (p < 0.05) in the nursery phase as well as in the subsequent phases until slaughter, and it decreased the incidence of diarrhoea in piglets (p < 0.05). In the piglets fed the benzoic acid diet, the villus height in the jejunum and ileum was greater until 42 days of life (p < 0.05), the crypt depth was decreased in the caecum (p < 0.05), and the butyric acid concentration was increased in the caecal content tendencially (p = 0.0708). In conclusion, supplementation with 0.75% benzoic acid has a positive effect on piglets by reducing diarrhoea, improving intestinal health and promoting the performance from weaning to finishing. Thus, benzoic acid can be considered a potential alternative that can replace growth-promoting antibiotics.

Discovery of potent aryl-substituted 3-[(3-methylpyridine-2-carbonyl) amino]-2,4-dimethyl-benzoic acid EP4 antagonists with improved pharmacokinetic profile.

Two new series of EP4 antagonists containing a 3-methylaryl-2-carbonyl core have been identified. One series has a 3-substituted-phenyl core, while the other one incorporates a 3-substituted pyridine. Both series led to compounds with potent activity in functional and human whole blood (hWB) assays. In the pyridine series, compound 7a was found to be a highly potent and selective EP4 antagonist, with suitable rat and dog pharmacokinetic profiles.

Comparative effects of various commercially available mouthrinse formulations on oral malodor.

OBJECTIVES: The primary aim of this study was to compare a new mouthwash (SB12®) containing 0.025% chlorhexidine and 0.3% zinc for oral malodor reduction against four commercially available mouthwashes and negative control. A secondary aim was to compare the two methods for measuring volatile sulphur compounds (VSC) by halimetry and OralChroma. METHODS: Organoleptic scale, halimeter and the OralChroma were used to assess oral malodour and VSC. The effects of five test formulations and water (negative control) were assessed after 30, 60, 90 and 180 min, with 1 week between the treatments to avoid any cross-over effect. RESULTS: Reduction in H(2) S by halimetry and malodour levels by organoleptic assessment ranged from, slight (LacerFresh®) (P > 0.05), moderate (BreathRx®, SmartMouth® (P < 0.01) to marked effects (SB12®, Listerine®) (P < 0.001) at all time points compared with water. The largest differences were observed at 30 min and decreased with time. SB12® showed separation from Listerine® at 180 min, using ANOVA plus Bonferroni's Multiple Comparison post-test (P < 0.05). Relationships between organoleptic, halimeter and OralChroma were between R² = 0.795 and 0.926. CONCLUSION: SB12 shows a consistent and reproducible inhibitory effect on oral malodor parameters, which in turn correlate well with each other.

A novel Ca2+/calmodulin antagonist HBC inhibits angiogenesis and down-regulates hypoxia-inducible factor.

Recent reports have shown that Ca(2+)/calmodulin (Ca(2+)/CaM) signaling plays a crucial role in angiogenesis. We previously developed a new Ca(2+)/CaM antagonist, HBC (4-{3,5-bis-[2-(4-hydroxy-3-methoxyphenyl)ethyl]-4,5-dihydropyrazol-1-yl}benzoic acid), from a curcumin-based synthetic chemical library. Here, we investigated its anti-angiogenic activity and mode of action. HBC potently inhibited the proliferation of human umbilical vascular endothelial cells with no cytotoxicity. Furthermore, HBC blocked in vitro characteristics of angiogenesis such as tube formation and chemoinvasion, as well as neovascularization of the chorioallantoic membrane of growing chick embryos in vivo. Notably, HBC markedly inhibited expression of hypoxia-inducible factor-1alpha (HIF-1alpha) at the translational level during hypoxia, thereby reducing HIF-1 transcriptional activity and expression of its major target gene, vascular endothelial growth factor. In addition, combination treatment with HBC and various HIF-1 inhibitors, including suberoylanilide hydroxamic acid, rapamycin, and terpestacin, had greater anti-angiogenic activity than treatment with each single agent. Collectively, our findings indicate that HBC is a new anti-angiogenic agent targeting HIF that can be used to explore the biological role of Ca(2+)/CaM in angiogenesis.

2-hydroxy 4-methoxy benzoic acid isolated from roots of Hemidesmus indicus ameliorates liver, kidney and pancreas injury due to streptozotocin-induced diabetes in rats.

Protective effect was evaluated in streptozoticin (STZ)-induced diabetes rats. 2-Hydroxy 4-methoxy benzoic acid (HMBA) was isolated from the roots of Hemidesmus indicus and administered (500 microg/kg body weight) orally for 7 weeks to STZ-induced diabetic and non-diabetic rats to study its effect on protein metabolism, serum electrolytes and on liver and kidney lipid peroxides. Oral administration of HMBA restored the altered biochemical parameters such as urea, uric acid, creatinine, plasma proteins and serum electrolytes to near-normal levels. HMBA treatment significantly decreased lipid peroxidation and malondialdehyde levels in diabetic liver and kidney. Effect of HMBA was equivalent to that of the standard drug, tolbutamide (100 mg/kg body wt). The histological changes were also in correlation with the biochemical findings. The present study showed that HMBA isolated from H. indicus roots had ameliorative effect on liver, kidney and pancreatic injury in STZ-induced diabetic rats.

Deficiency of the carnitine transporter (OCTN2) with partial N-acetylglutamate synthase (NAGS) deficiency.

A patient with recurrent episodes of hyperammonaemia (highest ammonia level recorded 229 micromol/L, normal 9-33) leading to altered levels of consciousness was diagnosed with partial N-acetylglutamate synthase (NAGS) deficiency (9% residual activity) at age 5 years and was treated with ammonia-conjugating agents (Ucephan 250 mg/kg per day and later sodium phenylbutyrate 200-250 mg/kg per day) for 15 years. A chronically low serum carnitine level (pretreatment plasma free carnitine 4 nmol/L, normal 37 +/- 8 nmol/L; total carnitine 8 nmol/L, normal 46 +/- 10) was assumed to be secondary and was treated with supplemental carnitine (30-50 mg/kg per day). Hypoglycaemia (blood sugar 35 mg/dl, normal 70-100), cardiomegaly, and fatty liver were also noted at diagnosis. The patient died unexpectedly at age 20 years. In retrospect, it was learned that the patient had stopped his carnitine without medical consultation several weeks prior to his death. Additional molecular investigations identified two mutations (R254X and IVS3 + 1G > A) in the patient's OCTN2 (SLC22A5) gene, consistent with a diagnosis of primary carnitine deficiency due to carnitine transporter defect. R245X is a founder mutation in Southern Chinese populations. It is unknown whether the original NAGS deficiency was primary or secondary, but molecular analysis of the NAGS gene failed to identify mutations. Urea cycle enzyme expression may be affected by fatty acid suppression of an AP-1 binding site in the promoter enhancer region of the urea cycle gene. Regardless, it is clear that the NAGS abnormality has led to delay of recognition of the OCTN2 defect, and modified the clinical course in this patient.

Benzoate treatment and the glycine index in nonketotic hyperglycinaemia.

High-dose benzoate treatment aimed at reducing plasma glycine levels to normal reduces seizures and increases wakefulness in patients with nonketotic hyperglycinaemia (NKH). Since benzoate metabolism is dependent on the available glycine pool, and since the glycine pool is variably affected by the deficiency in the glycine cleavage enzyme system, we examined the importance of interpatient variability in benzoate requirement. To correct for the dietary glycine contribution, the glycine index was introduced as the molar requirement of benzoate dose necessary to normalize plasma glycine levels and subtracting from that the dietary glycine intake, both corrected for weight. The glycine index varied between 3.62 and 4.87 mmol/kg per day in five patients with a poor neurodevelopmental outcome and between 0.92 and 1.90 mmol/kg per day in four patients with a better neurodevelopmental outcome, and was 2.54 mmol/kg per day in a single patient with an intermediate outcome. The glycine index was stable over time within each patient. Exceeding the balance by either increasing food glycine intake or decreasing the benzoate dose resulted in increased glycine levels. Exceeding the glycine tolerance by increasing benzoate resulted in elevated and toxic levels of benzoate. The glycine index is a stable, individually specific parameter in patients with NKH. It has clinical consequences for the dose of benzoate required and the role of dietary management. Through its correlation with neurodevelopmental outcome, the glycine index points to potential genetic factors that could contribute to the psychomotor retardation in NKH.

Cutaneous field stimulation of sensory nerve fibers reduces itch without affecting contact dermatitis.

BACKGROUND: A new technique, cutaneous field stimulation (CFS), which activates electrically unmyelinated C-fibers, is used to treat localized itch. Its action is similar to that of capsaicin, the pungent agent in hot peppers, which enhances delayed allergic reactions. The aim of the study was to investigate how experimental contact dermatitis responds to CFS. METHODS: Twelve patients with contact dermatitis in response to nickel were treated by CFS for 1 h each for four consecutive days. A flexible plate containing electrodes was applied to a test area on the upper arm and was stimulated by a constant current (0.8 mA). On the fifth day, patients were provoked by epicutaneous application of nickel sulfate (allergic contact dermatitis) and benzalkonium chloride (irritant contact dermatitis), and by intradermal tuberculin (delayed immunologic reaction). Twelve other patients with IgE-mediated allergy were treated by CFS on the lower arm for 1 h and were then pricked with histamine and allergen extracts (wheal volume was measured) and were tested using benzoic acid (nonimmunologic contact urticaria; closed test). Ten of these patients were also treated by CFS for four days, and experiments were performed on the fifth day. RESULTS: Test reactions to nickel, benzalkonium, and tuberculin were found to be unaffected by CFS treatment. Although allergic prick test reactions were enhanced (by 28%) after a single CFS treatment, the associated itch was significantly reduced both after single and repeated CFS treatments (by 65% and 38%, respectively). CONCLUSIONS: Repeated use of CFS to reduce itch has no adverse effects on contact dermatitis.