Synthesis and biological activity of guanylhydrazones of 2- and 4-pyridine and 4-quinoline carboxaldehydes

Synthesis and Biological Activity of Hydrazones and Derivatives: A Review

Hydrazones and their derivatives are very important compounds in medicinal chemistry due to their reported biological activity for the treatment of several diseases, like Alzheimer's, cancer, inflammation, and leishmaniasis. However, most of the investigations on hydrazones available in literature today are directed to the synthesis of these molecules with little discussion available on their biological activities. With the purpose of bringing lights into this issue, we performed a revision of the literature and wrote this review based on some of the most current research reports of hydrazones and derivatives, making it clear that the synthesis of these molecules can lead to new drug prototypes. Our goal is to encourage more studies focused on the synthesis and evaluation of new hydrazones, as a contribution to the development of potential new drugs for the treatment of various diseases.

Development and Validation of HPLC-DAD and UHPLC-DAD Methods for the Simultaneous Determination of Guanylhydrazone Derivatives Employing a Factorial Design

Guanylhydrazones are molecules with great pharmacological potential in various therapeutic areas, including antitumoral activity. Factorial design is an excellent tool in the optimization of a chromatographic method, because it is possible quickly change factors such as temperature, mobile phase composition, mobile phase pH, column length, among others to establish the optimal conditions of analysis. The aim of the present work was to develop and validate a HPLC and UHPLC methods for the simultaneous determination of guanylhydrazones with anticancer activity employing experimental design. Precise, exact, linear and robust HPLC and UHPLC methods were developed and validated for the simultaneous quantification of the guanylhydrazones LQM10, LQM14, and LQM17. The UHPLC method was more economic, with a four times less solvent consumption, and 20 times less injection volume, what allowed better column performance. Comparing the empirical approach employed in the HPLC method development to the DoE approach employed in the UHPLC method development, we can conclude that the factorial design made the method development faster, more practical and rational. This resulted in methods that can be employed in the analysis, evaluation and quality control of these new synthetic guanylhydrazones.

A new guanylhydrazone derivative as a potential acetylcholinesterase inhibitor for Alzheimer's disease: synthesis, molecular docking, biological evaluation and kinetic studies by nuclear magnetic resonance

Molecular docking, in silico studies and NMR show that the new guanylhydrazone is a promising compound for the treatment of Alzheimer's disease.

Azine-Hydrazone Tautomerism of Guanylhydrazones: Evidence for the Preference Toward the Azine Tautomer

Guanylhydrazones have been known for a long time and have wide applications in organic synthesis, medicinal chemistry, and material science; however, little attention has been paid toward their electronic and structural properties. Quantum chemical analysis on several therapeutically important guanylhydrazones indicated that all of them prefer the azine tautomeric state (by about 3-12 kcal/mol). A set of simple and conjugated azines were designed using quantum chemical methods, whose tautomeric preference toward the azine tautomer is in the range of 3-8 kcal/mol. Twenty new azines were synthesized and isolated in their neutral state. Variable temperature NMR study suggests existence of the azine tautomer even at higher temperatures with no traces of the hydrazone tautomer. The crystal structures of two representative compounds confirmed that the title compounds prefer to exist in their azine tautomeric form.

Synthesis and antimycobacterial activity of new S-alkylisothiosemicarbazone derivatives

A new series of S-alkylisothiosemicarbazones of 3- and 4-pyridincarboxaldehyde and 4-fluoro- and 4-trifluoromethylbenzaldehyde was synthesized and evaluated for biological activity against various Mycobacterium strains. Inhibitory activity against Mycobacterium tuberculosis H37Rv ATCC 27294 and INH-R ATCC 35822 was compared with activity against clinical isolated Mycobacteria as well as against MOTT. Some of newly prepared compounds showed best inhibitory values against clinical isolated Mycobacteria, besides to low citotoxicity values.

Synthesis and antihypertensive activity of N-(alkyl/alkenyl/aryl)-N-heterocyclic ureas and thioureas

A variety of N-(alkyl/alkenyl/aryl-N-heterocyclic ureas and thioureas were synthesized as potential antihypertensives. The selected heterocyclic nuclei were the 6-substituted quinoline and the pyridine. Eleven synthesized compounds and seven related compounds in the series were evaluated orally at a dose of 100 mg/kg in conscious deoxycorticosterone acetate/saline-treated hypertensive rats by the tail-cuff method. Seventeen out of the eighteen tested compounds possessed significant antihypertensive activity (p < 0.05). 1-n-Propyl-3-[2'-(6-methoxy)quinolyl]urea (9), showing 29.1% reduction in systolic blood pressure, was the most active compound in the series. Two other compounds producing a fall in systolic blood pressure of the same magnitude were 1-allyl-3-[2'-(6-methyl)quinolyl]thiourea (4) and 1-n-propyl-3-[(2'-pyridyl)methyl]urea (17). Compound 17 with rapid onset caused significant relaxation (p < 0.01) of isolated rabbit femoral artery and guinea pig atrium but had no effect on heart rate. However, none of these exhibited higher potency than prazosin (5 mg/kg). The potency, onset, and duration of action improved when the heterocyclic nucleus was pyridine.