An Efficient Method for Synthesis of Some Novel Spirooxindole-4H-Pyran Derivatives

One Pot Synthesis and Biological Activity Studies of New Spirooxindoles

This article reports one-pot synthesis of ten novel spirooxindoles using 5-methyl-2-thiohydantoin, isatin derivatives, and malononitrile in good to high yields (65-90 %). The structures of the synthesized compounds were deduced by 1H-NMR, 13C NMR, FT-IR, and Mass spectral data. The antibacterial activity of the compounds was evaluated against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) based on the Kirby-Bauer method. According to the obtained data, the synthesized compounds show more activity against Gram-positive bacteria than Gram-negative bacteria. Also, the antioxidant activity of these compounds was measured using the DPPH radical scavenging test method, which showed good to excellent activity (59.65-94.03 %). Among them, the chlorinated derivatives (4 f-j) exhibited more antioxidant activity (84.85-94.03 %) than the other compounds (4 a-e) (56.65-74.4 %) and even ascorbic acid as a standard antioxidant compound (82.3 %).

A novel heterogeneous acid-base nano-catalyst designed based on graphene oxide for synthesis of spiro-indoline-pyranochromene derivatives

Nano graphene oxide/3-aminopyridine has been introduced as a new, efficient and robust heterogeneous organic catalyst for synthesis of spiro-indoline-pyranochromene derivatives. Nano graphene oxide/3-aminopyridine was provided in an easy and green way from GO. Firstly, graphene oxide (GO) was synthesized and then 3-aminopyridine was immobilized with covalent bonds on its surface as a nitrogenous organic compound, in this step we didn't use any organic or toxic substance. This bonding was easily performed due to the presence and reactivity of the epoxy groups in the GO structure. Because of its vast-surface nano-layers, GO could be effective in appropriate dispersion of 3-aminopyridine on its surface and increasing the catalyst performance. The new catalyst was analysed using different microscopic and spectroscopic techniques such as Fourier-transform infrared (FT-IR), field emission scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Our results showed that the distance between GO plates was increased in the presence of the modifying agent. This is due to the placement of the organic compound between the GO sheets. Finally, the ability of our new nano-catalyst in the synthesis of some spiro-indoline-pyranochromene and dihydropyranochromene derivatives was evaluated and acceptable results were obtained. Eight analogous of spiro-indoline-pyranochromene (4a-4 h) were synthesized in high yields and characterized. Using 3-aminopyridine as an organic and efficient catalyst, its stabilization by a simple method on GO, recycling of the catalyst up to 7 times and obtaining a highly pure product were the points that made the present work more attractive.

Synthesis, Antileishmanial Activity and in silico Studies of Aminoguanidine Hydrazones (AGH) and Thiosemicarbazones (TSC) Against Leishmania chagasi Amastigotes

BACKGROUND

Leishmaniasis is a worldwide health problem, highly endemic in developing countries. Among the four main clinical forms of the disease, visceral leishmaniasis is the most severe, fatal in 95% of cases. The undesired side-effects from first-line chemotherapy and the reported drug resistance search for effective drugs that can replace or supplement those currently used an urgent need. Aminoguanidine hydrazones (AGH's) have been explored for exhibiting a diverse spectrum of biological activities, in particular the antileishmanial activity of MGBG. The bioisosteres thiosemicarbazones (TSC's) offer a similar biological activity diversity, including antiprotozoal effects against Leishmania species and Trypanosoma cruzi.

OBJECTIVE

Considering the impact of leishmaniasis worldwide, this work aimed to design, synthesize, and perform a screening upon L. chagasi amastigotes and for the cytotoxicity of the small "in-house" library of both AGH and TSC derivatives and their structurally-related compounds.

METHOD

A set of AGH's (3-7), TSC's (9, 10), and semicarbazones (11) were initially synthesized. Subsequently, different semi-constrained analogs were designed and also prepared, including thiazolidines (12), dihydrothiazines (13), imidazolines (15), pyrimidines (16, 18) azines (19, 20), and benzotriazepinones (23-25). All intermediates and target compounds were obtained with satisfactory yields and exhibited spectral data consistent with their structures. All final compounds were evaluated against L. chagasi amastigotes and J774.A1 cell line. Molecular docking was performed towards trypanothione reductase using GOLD® software.

RESULT

The AGH's 3i, 4a, and 5d, and the TSC's 9i, 9k, and 9o were selected as valuable hits. These compounds presented antileishmanial activity compared with pentamidine, showing IC50 values ranged from 0.6 to 7.27 μM, maximal effects up to 55.3%, and satisfactory SI values (ranged from 11 to 87). On the other hand, most of the resulting semi-constrained analogs were found cytotoxic or presented reduced antileishmanial activity. In general, TSC class is more promising than its isosteric AGH analogs, and the beneficial aromatic substituent effects are not similar in both series. In silico studies have suggested that these hits are capable of inhibiting the trypanothione reductase from the amastigote forms.

CONCLUSION

The promising antileishmanial activity of three AGH's and three TSC's was characterized. These compounds presented antileishmanial activity compared with PTD, showing IC50 values ranged from 0.6 to 7.27 μM, and satisfactory SI values. Further pharmacological assays involving other Leishmania strains are under progress, which will help to choose the best hits for in vivo experiments.