Background: Indole derivatives and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazines are important heterocyclic compounds in medicinal chemistry. They have displayed broad spectrum of biological activities such as anticancer, antimicrobial, antioxidant and anti-inflammatory activities.

Objective: The objectives of this research were to synthesize 4-amino-5-mercapto-3-[(5-substituted- 2-methyl-1H-indol-3-yl)methyl]-1,2,4-triazoles and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazines incorporating an indole skeleton and to evaluate their antibacterial activity.

Methods: 4-Amino-5-mercapto-3-[(5-substituted-2-methyl-1H-indol-3-yl)methyl]-1,2,4-triazoles were synthesized from the fusion reaction of 5-substituted-2-methylindole-3-acetic acids with thiocarbohydrazide. The reaction of 4-amino-5-mercapto-3-[(5-substituted-2-methyl-1H-indol-3-yl)methyl]- 1,2,4-triazoles with a series of phenacyl bromides produced the corresponding 1,2,4-triazolo[3,4- b][1,3,4]thiadiazines. The structures of 1,2,4-triazoles and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazines were elucidated by IR, NMR and mass spectral data and were evaluated for their antibacterial activity using 96-well microbroth dilution assay.

Results: In the current study, two new 4-amino-5-mercapto-3-[(5-substituted-2-methyl-1H-indol-3- yl)methyl]-1,2,4-triazoles (2b-c) and twenty four new 1,2,4-triazolo[3,4-b][1,3,4]thiadiazines incorporating an indole skeleton (3a-h, 4a-h and 5a-h) have been synthesized.

Conclusion: Compound 4d bearing chlorinated indole moiety and 4-methylphenyl group at C-6 position of triazolothiadiazine ring showed promising inhibition activity against Bacillus subtilis subsp. spizizenni, Bacillus cereus and Staphylococcus aureus with MIC value 3.91 µg/ml. Compound 4d also exhibited promising activity against MRSA ATCC 29213 at MIC 7.81 µg/ml.

背景：吲哚衍生物和1,2,4-三唑并[3,4-b] [1,3,4]噻二嗪是药物化学中重要的杂环化合物。它们显示出广泛的生物学活性，例如抗癌，抗微生物，抗氧化剂和抗炎活性。

目的：本研究的目的是合成4-氨基-5-巯基-3-[（5-取代的2-甲基-1H-吲哚-3-基）甲基] -1,2,4-三唑和1 ，2,4-三唑并[3,4-b] [1,3,4]噻二嗪并入吲哚骨架并评估其抗菌活性。

方法：由5-取代基的融合反应合成了4-氨基-5-巯基-3-[（5-取代-2-甲基-1H-吲哚-3-基）甲基] -1,2,4-三唑。 -2-甲基吲哚-3-乙酸与硫代碳酰肼。4-氨基-5-巯基-3-[（5-取代-2-甲基-1H-吲哚-3-基）甲基] -1,2,4-三唑与一系列苯甲酰溴的反应产生了相应的1,2,4-三唑并[3,4-b] [1,3,4]噻二嗪。红外，核磁共振和质谱数据阐明了1,2,4-三唑和1,2,4-三唑并[3,4-b] [1,3,4]噻二嗪的结构并评估了其抗菌活性使用96孔微肉汤稀释法。

结果：在当前的研究中，有两个新的4-氨基-5-巯基-3-[（5-取代-2-甲基-1H-吲哚-3-基）甲基] -1,2,4-三唑（2b- c）和二十四个新的并入有吲哚骨架的1,2,4-三唑并[3,4-b] [1,3,4]噻二嗪（3a-h，4a-h和5a-h）已经合成。

结论：在三唑并噻二嗪环的C-6位置带有氯化吲哚部分和4-甲基苯基的化合物4d具有良好的抑制枯草芽孢杆菌亚种的活性。spizizenni，蜡状芽孢杆菌和金黄色葡萄球菌的MIC值为3.91 µg / ml。化合物4d的MIC为7.81 µg / ml，对MRSA ATCC 29213也显示出有希望的活性。