An electroanalytical investigation on the redox properties of lacidipine supporting its anti-oxidant effect

Lacidipine: review of analytical methods developed for pharmaceutical dosage forms and biological fluids

Lacidipine (LAC) is a calcium antagonist used in the treatment of hypertension. It is a lipophilic drug containing dihydropyridine ring that is responsible for the activity. This review article gives an overview of various analytical techniques proposed for the determination of LAC in pharmaceutical dosage forms, in pure form, in biological fluids and to determine characteristics of LAC in modified release dosage forms. Ultra violet/visible spectrophotometric, spectroflourimetric, high performance liquid chromatography, high performance thin layer chromatography, electro-analytical, bioanalytical and miscellaneous methods such as microbiological assay, X-ray diffraction, differential scanning calorimetry, were discussed. Various parameters such as system suitability, selectivity, linearity, precision, accuracy, limit of detection, limit of quantification and robustness have been discussed for the employed methods.

Nanocrystalline ZnO: A Competent and Reusable Catalyst for the Preparation of Pharmacology Relevant Heterocycles in the Aqueous Medium

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Nanoparticle catalyzed synthesis is a green and convenient method to achieve most of the chemical transformations in water or other green solvents. Nanoparticle ensures an easy isolation process of catalyst as well as products from the reaction mixture avoiding the hectic work up procedure. Zinc oxide is a biocompatible, environmentally benign and economically viable nanocatalyst with effectivity comparable to the other metal nanocatalyst employed in several reaction strategies. This review mainly focuses on the recent applications of zinc oxide in the synthesis of biologically important heterocyclic molecules under sustainable reaction conditions.

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Application of zinc oxide in organic synthesis: Considering the achievable advantages of this nanocatalyst, presently several research groups are paying attention in anchoring zincoxide or its modified structure in several types of organic conversions e.g. multicomponent reactions, ligand-free coupling reactions, cycloaddition reaction, etc. The advantages and limitations of this nanocatalyst are also demonstrated. The present study aims to highlight the recent multifaceted applications of ZnO towards the synthesis of diverse heterocyclic motifs. Being a promising biocompatible nanoparticle, this catalyst has an important contribution in the fields of synthetic chemistry and medicinal chemistry.

Green electrochemical strategy for one-step synthesis of new catechol derivatives

In this paper, we present promising results in the green electrochemical oxidation of catechol in the presence of three different thiol nucleophiles at the surface of a glassy carbon electrode in an aqueous solution using cyclic voltammetry (CV). The outcome indicated the synthesis of some new heterocyclic compounds functionalized with phenolic, triazole, triazine and pyrimidine groups. The effects of repetitive cycling, nucleophile concentrations and sweep rates were explored to get more information about the systems. The voltammetric data showed that the electro-generated o-benzoquinone is a quite reactive intermediate, which in aqueous solutions can quickly participate in a Michael-addition reaction with any one of the nucleophiles to form the corresponding products. The structures of all newly electro-synthesized compounds were confirmed by elemental analyses and FT-IR, ¹H NMR, ¹³C-NMR and MS spectra. The one-pot synthesis strategy led to new organics with high purities and good yields under green conditions without harmful reagents.

In this paper, we present promising results in the green electrochemical oxidation of catechol in the presence of three different thiol nucleophiles at the surface of a glassy carbon electrode in an aqueous solution using cyclic voltammetry (CV).

Reducing power: the measure of antioxidant activities of reductant compounds?

Electrochemical assay has been employed recently to study the activity of antioxidants; however, there is controversy as to whether reducing power fully characterizes the antioxidant activity. This study provides some essential further evidence on this point based on the reported data and mechanisms underlying the antioxidant functions as well as the anodic oxidation of phenolic antioxidants, indicating that further consideration and investigation should be made before reducing power is used as the absolute measure of antioxidant activity.

Phenolic antioxidants: electrochemical behavior and the mechanistic elements underlying their anodic oxidation reaction

Electrochemical analysis has been widely used to assess activities of reductant antioxidants, but the mechanistic factors that determine reducing ability and their corresponding correlations remain to be explored further. In the present paper, the reactivity of a selection of phenolic compounds in anodic oxidation was investigated by cyclic voltammetry (CV). The effects of electron-donation ability, deprotonation equilibrium, stability of radicals and chemical hardness on reducing capacity were studied by computational chemistry methods and multiple linear regression analysis. The results suggested that all these factors made significant contributions to reducing potency although electron-donation ability of the parent molecule plays the most important role in the electrode reaction. With the majority of the compounds examined, the occurrence of multiple electrochemical reactions leading to irreversible anodic oxidation was implied by: (i) the characteristics of the radical cation intermediate; (ii) the propensity of the deprotonation reaction; and (iii) the reactivity of the parent molecule. Upon correlation analysis of oxidation potential and computed physicochemical descriptors, some new light was shed on the mechanism by which phenolic compounds act as antioxidant reductants in free radical reactions. A satisfactory multi-descriptor theoretical QSAR model was derived, which might be of predictive significance in the screening or design of new antioxidants.

Lacidipine

Lacidipine (Caldine, Lacimen, Lacipil, Midotens, Motens) is a once-daily, orally-administered, lipophilic dihydropyridine calcium antagonist with an intrinsically slow onset of activity, resulting in a lack of reflex tachycardia. It has a long duration of action and a high degree of vascular selectivity. In addition to calcium channel-modulated vasodilation, lacidipine displays antioxidant activity greater than that of other dihydropyridine calcium antagonists. In randomised, well-controlled trials, lacidipine 2-6 mg orally once daily had antihypertensive efficacy similar to that of other long-acting dihydropyridine calcium antagonists, thiazide diuretics, atenolol (a beta-blocker) and enalapril (an ACE inhibitor). Lacidipine was effective in elderly patients (including those with isolated systolic hypertension), African Nigerian patients and patients with concurrent type 2 diabetes mellitus. During long-term treatment for 4 or 5 years in patients with isolated systolic hypertension or essential hypertension, the incidence of cardiovascular events and mortality with lacidipine was similar to that with chlorthalidone or atenolol. The European Lacidipine Study on Atherosclerosis (ELSA), in which 2334 patients with hypertension were randomised to 4 years of therapy with lacidipine 4-6 mg/day or the beta-blocker atenolol 50-100 mg/day, demonstrated significantly lower atherosclerotic progression and plaque formation with lacidipine compared with atenolol in patients completing the full 4 years of the study. Between-group differences in favour of lacidipine for the primary efficacy variable (mean change in carotid artery intima-media thickness) did not reach statistical significance in the intent-to-treat population. The tolerability profile of lacidipine (headache, flushing, pedal oedema, dizziness and palpitations) is similar to that of other dihydropyridine calcium antagonists, but with a lower incidence of peripheral oedema. Data from the ELSA study suggest that the incidence of serious adverse events during long-term lacidipine therapy is similar to that with atenolol.

CONCLUSION

Lacidipine is an effective, well tolerated, once-daily, oral antihypertensive agent that can be used in a wide variety of patients. As with other members of its class, lacidipine has shown potentially beneficial antiatherosclerotic effects, although definitive data with respect to possible superiority over other drug classes are still required. Therefore, lacidipine is an attractive therapy for the long-term management of essential hypertension.