Purple mangosteen (Garcinia mangostana) has several biological applications such as anticancer, antitubercular and antioxidant agents. In this work, we isolated and studied the optical properties of the natural pigments from the purple mangosteen peels. To isolate the natural pigments, the mangosteen peels were macerated using distilled water, ethanol, or acetone for 24 h. The extracts were filtrated and characterized using spectrophotometers of Fourier transform infrared (FTIR), ultraviolet-visible (UV-Vis), and spectrofluorometer. The extracts gave the FTIR vibration peaks of O-H, C-H sp3, C=O, C=C, and C-O functional groups, while absorption peaks at 210–374 nm were observed in the UV-Vis spectra of the extracts due to the presence of mangostins, anthocyanins, and phenolic acids. The three-dimensional fluorescence spectra showed that the excitation and emission peaks of the mangosteen peels extracted with ethanol were found at 444 and 498 nm, respectively, while that extracted with distilled water gave no significant fluorescence peaks. On the other hand, the mangosteen peels extracted with acetone gave the strongest emission intensity at 472 and 502 nm due to the most intense color intensity. This study provided useful information about the optical properties of natural pigments extracted from purple mangosteen peels through a simple isolation technique.
The pyrazine-2-carboxylic acid derivatives 1a-c with aromatic, cyclic, and aliphatic side chain were successfully synthesized. The structures of derivatives were confirmed by spectroscopic methods (FTIR, NMR, HRMS). The molecular docking was performed to determine the possible binding interaction between 1a-c with Mycobacterium tuberculosis InhA protein. The derivative 1c showed the lowest rerank score (-86.4047 kcal mol−1) and it might correspond to the lowest experimental MIC value.
This study examined the synthesis of isoniazid-isatin hydrazone derivatives 5-7, followed by an investigation on the in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv, and molecular docking. A yield of 81 - 92 % of these compounds was achieved, with structural characterization by spectroscopic methods (FTIR, NMR, HRMS). The in vitro antitubercular activity was evaluated against M. tuberculosis H37Rv, and the highest effect was observed in compound 7, with a minimum inhibitory concentration (MIC) of 0.017 mM, lower than rifampicin (MIC 0.048 mM), which served as the positive control. In addition, the molecular docking of 5-7 was performed to visualize the interaction of isoniazid-isatin hydrazone derivatives with the active site of InhA receptor, which was in agreement with the experimental data. The hydrogen bonding with Ser94 and pi-pi interaction with Phe41 and/or Phe97 on the InhA active site was pivotal for the antitubercular activity. HIGHLIGHTS Tuberculosis caused by Mycobacterium tuberculosis is one of the top ten leading causes of death globally The first and second lines of antituberculosis drugs are the prevalent treatment for this disease, but they show several drawbacks and are exacerbated by the occurrence of drug resistance The isoniazid-isatin hydrazone derivatives were designed through molecular hybridization and synthesized effectively and exhibited moderate to high activity against tuberculosis H37Rv Molecular docking study demonstrated that the hydrogen bonding with Ser94 and the pi-pi interaction with Phe41 and/or Phe97 are important for antitubercular activity GRAPHICAL ABSTRACT
In the present work, a comprehensive statistical analysis was performed to evaluate the potential application of peel of local fruits from Malang, i.e. mangosteen, honey pineapple and red dragon fruits for natural yellow coloring agents. The yellow pigments from those fruit peels were extracted through a simple maceration method using distilled water, acetone and ethanol as the solvents. The CIE color space of the extracts was measured to obtain L*, a* and b* values. The obtained data were further analyzed using Principal Component Analysis (PCA), Multivariate Analysis of Variance (MANOVA) and Duncan Test to determine the most potent natural yellow coloring agent. All the extracts were appeared as mild to strong yellow liquid except for acetone extract for the peel of red dragon fruit extracts. From the CIE color space and PCA analysis, either ethanolic or acetone extracts of mangosteen appears as a strong yellow liquid and they are statistically not different. Interestingly, the MANOVA and Duncan test results are able to distinguish that the ethanolic extract of mangosteens’ peel as the best candidate for natural yellow coloring agents because of its lowest L* and also highest b* variable values.
One of the most lethal and frequent infectious diseases worldwide is tuberculosis. Multi and extensively tuberculosis drug-resistant constitutes a serious problem and emphasizes the need for novel anti-tubercular agents. Accordingly, various pyrazine-2-carboxamides were synthesized and evaluated as potential anti-tuberculosis agents. The synthesis involved reaction of pyrazinoic acids with thionyl chloride to yield acyl chlorides which on treatment with various anilines gave various pyrazine-2-carboxamides. Based on structure-activity relationships extracted from previously published, this paper reported the synthesis and molecular docking study of 6-chloropyrazine-2-carboxamides. Synthesis involved reaction of 6-chloropyrazinoic acid with 2,4,6-trichlorobenzoyl chloride instead of thionyl chloride which listed under the Chemical Weapons Convention as it may use for the production of chemical weapons. Structure identification of 6-chloropyrazine-2-carboxamides was carried out by 1H NMR, 13C NMR, FTIR, and high-resolution mass spectroscopy. It is predicted that 6-chloro-N-octylpyrazine-2-carboxamide has better bioactivity against Mycobacterium tuberculosis, based on molecular docking study.
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