Medicinal Chemistry - Volume 8, Issue 4, 2012

In this paper the authors investigated a synergistic antimycotic effect between four antifungal drugs Amphotericin B, Fluconazole, Tioconazole, and Flucytosine individually combined with Anidulafungin compound. This latter is considered a drug of choice in the treatment of fungal infections; it has good activity both in vitro and in vivo against yeasts and moulds, as Candida and Aspergillus. The goal of this study was to evaluate the in vitro interaction of Anidulafungin in the synergic combinations with previous reported drugs against 12 Candida strains according to CLSI M27-A3 protocol. A synergistic interaction was observed against the most antifungal strains; in particular an increasing of the antimycotic efficacy was obtained from the association between Anidulafungin and Amphotericin B or Fluconazole (Mixture 4:6). In contrast the association Tioconazole/Anidulafungin was less effective on fungal species growth. The antimycotics MIC reduction values were more evident against some strains as C. glabrata, C. krusei, C. tropicalis and C. parapsilosis.

Dopamine (DA) agonists, bearing catechol or phenol rings, are endowed with low oral bioavailability and short effect duration. In this report, the synthesis of novel differently substituted 4-(3-pyridyl)-1,2,3,4-tetrahydroisoquinolines and (1,2,3,4-tetrahydroisoquinolin-4-yl)phenylmethanols as potential non phenolic and non catecholic DA receptor ligands is reported. The new compounds, evaluated by binding tests on cerebral striatal membranes, bound to DA receptors with moderate affinity. Anyhow, they may represent a starting point to develop new DA ligands endowed with better pharmacokinetic and metabolic properties.

Acylhydrazide Schiff bases 1-27 were evaluated for their in vitro DPPH radical and superoxide anion scavenging activity. They showed a varying degree of DPPH radical scavenging activity with IC50 values between 31.25 - 473.59 µM. Compounds 8, 2, and 10 have IC50 values 31.25 ± 1.32, 34.40 ± 0.66, and 37.24 ± 0.4 µM, respectively. Standard npropylgallate showed an IC50 value 30.12 ± 0.27 µM. Acylhydrazides 1-27 exhibited in vitro superoxide anion scavenging activities with IC50 values in the range of 175.6 - 450.89 µM. Results demonstrated that acylhyrazides 8, 2, and 10 have DPPH scavenging activity, comparable to standard n-propyl gallate while acylhyrazides 1-27 were found to be less superoxide anion scavenging active than the standard n-propyl gallate (IC50 = 106.34 ± 1.6 µM).

Multidrug resistance in cancer is a major cause of failure in cancer chemotherapy. In search of new compounds with strong reversal activity and simple molecular structure, we have synthesized a series of compounds in which different substituents were linked to the 2-position of the 6,7-dimethoxy-1-(3,4-dimethoxybenzyl)- tetrahydroisoquinoline system. Compounds were analyzed for their cytotoxicity by MTT in K562 cell line in vitro, all of the derivatives exhibited little cytotoxic activity. In the meantime, these compounds were evaluated by MTT in K562/A02 cell line in vitro, 6e, 6h and 7c exhibited similar or more potent activities than verapamil with the IC50 values at 0.66, 0.65 and 0.96μM, and with the ratio factor of 24.13, 24.50 and 16.59, respectively.

A QSAR study was performed on ninety eight substituted biphenyl analogues of 2-nitroimidazo-[2, 1-b] [1, 3]- oxazines as antitubercular agents to explore the importance of topological, thermodynamic, spatial and physicochemical properties of the molecules towards the antitubercular activity. Genetic function approximation (GFA) was used as the chemometric tool for the study. The study shows that ortho and meta linked attachments of the biphenyl analogs to 2- nitroimidazo-[2, 1-b] [1, 3]-oxazines are detrimental for the antitubercular activity. Hydrophobicity, branching and presence of electronegative atoms enhance the activity. Based on the rm 2 (overall) criterion, which considers both internal validation and external validation, a GFA model with spatial, thermodynamic and topological descriptors appears to be the best model (rm 2 (overall) =0.556).

Folic acid receptors (FR) are usually over expressed in many cancer cells and are considered as potential targeted therapy agent. Generation of five polyamido amine (PAMAM) dendrimer folic acid conjugate was synthesised and radiolabelled with 188Re, furthermore the in vitro/in vivo stability was evaluated accordingly. The labelling yield of the conjugate G5-FA-DTPA-188Re was 67.1 % and its radiochemical purity exceeded 95 %. The conjugate also showed high in vitro stability and potential value for further structure modifications and evaluations.

The development of new antimicrobial agents for the treatment of infectious diseases remains challenging due to the increasing impact of antibiotic resistance. Since salicylanilides and esters of pyrazine-2-carboxylic acid have been described as potential antimicrobials, we have designed and synthesized a series of 2-(phenylcarbamoyl)phenyl pyrazine-2-carboxylates. These were evaluated in vitro for the activity against fungi and Gram-positive and Gram-negative bacteria. All derivatives showed significant antibacterial activity against Gram-positive strains (MIC ≥ 0.98 µmol/L) including methicillin-resistant Staphylococcus aureus. The most active molecule was 5-chloro-2-(3-chlorophenylcarbamoyl)phenyl pyrazine-2-carboxylate. With one exception these esters were at least partly active against fungi tested strains, in particular against mould strains (MIC ≥ 1.95 µmol/L). The most active antifungal agent overall proved to be 2-(4-bromophenylcarbamoyl)-4-chlorophenyl pyrazine-2-carboxylate.

Fifteen derivatives of 8-oxocoptisine were prepared based on that 8-oxocoptisine showed potent reversing effect against human cancer cells charactering multidrug resistance (MDR). The derivatives were evaluated for their growth inhibition and effects on reversing P-gp-mediated MDR against MCF-7/AMD cells. 12, 13-dinitro-8-oxocoptisine (6c), the most potential candidate with weak growth inhibition, significantly increased the sensitivity of adriamycin (ADM) against MCF-7/ADM cells by 213-fold at 10μM that was comparable to the reference compound verapamil. The preliminary structure-activity relationships (SARs) of these derivatives were discussed on the basis of the in vitro MDR reversal activities.

The role of vasopressin (AVP) in the pathophysiology of cardiovascular disease is controversial, but this peptide hormone is elevated in heart failure and some forms of hypertension. Also, AVP has vasoconstrictor, mitogenic, hyperplasic and renal fluid retaining properties which, by analogy with angiotensin II, may have deleterious effects when present in chronic excess. Furthermore, cholesterol blood levels are also associated with hypertension, although the underlying mechanism is not known. Here we analyze the relationship between blood total cholesterol levels and serum vasopressin- degrading cystyl-aminopeptidase activity (AVP-DA) in healthy humans, and the differences between men and women. Linear correlation coefficients were calculated to test relationships between AVP-DA and blood total cholesterol levels. Sex differences were observed for AVP-DA, being this activity higher in men than in women. According to the linear model of the regression analysis, AVP-DA showed a significant negative correlation with blood total cholesterol levels in men, whereas no correlation was observed in women. Several studies in humans demonstrate the existence of greater plasma AVP concentrations in normal men compared to normal women, which could explain the genderdifferences observed in the present work in relation with AVP-DA. However, AVP-DA is related to blood cholesterol levels only in men, although in our hands, women showed higher blood cholesterol levels than men. This could indicate that the risk of high cholesterol-related hypertension is more probable in men than in women. Although AVP-DA misregulation could be involved in the pathogenesis of hypertension, its relation with cholesterol levels appears only in men, but not in women.

Poor bioavailability of topically instilled drug is the major concern in the field of ocular drug delivery. Efflux transporters, static and dynamic ocular barriers often possess rate limiting factors for ocular drug therapy. Different formulation strategies like suspension, ointment, gels, nanoparticles, implants, dendrimers and liposomes have been employed in order to improve drug permeation and retention by evading rate limiting factors at the site of absorption. Chemical modification such as prodrug targeting various nutrient transporters (amino acids, peptide and vitamin) has evolved a great deal of interest to improve ocular drug delivery. In this review, we have discussed various prodrug strategies which have been widely applied for enhancing therapeutic efficacy of ophthalmic drugs. The purpose of this review is to provide an update on the utilization of prodrug concept in ocular drug delivery. In addition, this review will highlight ongoing academic and industrial research and development in terms of ocular prodrug design and delivery.