SYNTHESIS OF POTENTIAL ANTIEXUDATIVE PREPARATIONS FOR 2-((4-AMINO-5-(FURAN-2-IL)-1,2,4-TRIAZOLE-(4H)-3-YL)-SULFANYL)-N-ACETAMIDE SERIES

Мета. Провести цілеспрямований синтез нових потенційних біологічно-активних речовин похідних 2((4-аміно-5-(фуран-2-іл)-1,2,4-тріазол(4Н)-3-іл)-сульфаніл)-N-ацетамідів та оцінити їх антиексудативну активність на моделі формалінового набряку у щурів. Матеріали та методи. У роботі використовували стандартні методи органічного синтезу, фізикохімічні методи доведення будови синтезованих сполук, елементний аналіз, H ЯМР-спектроскопію, хромато-мас-спектрометрію, антиексудативну активність вивчено на моделі формалінового набряку у щурів за допомогою цифрового плетизмометра. Результати. Шляхом алкілування 2-((4-аміно-5-(фуран-2-іл))-4Н-1,2,4-тріазол-3-тіона Nарилзаміщеними α-хлорацетамідами в етанолі у лужному середовищі одержані відповідні 2-((4-аміно-5(фуран-2-іл)-1,2,4-тріазол(4Н)-3-іл)-сульфаніл)-N-ацетаміди. Після кристалізації отримували білі або світло-жовті кристалічні речовини з чіткими температурами плавлення. На моделі формалінового набряку у щурів вивчили антиексудативну активність нових, синтезованих нами 2-((4-аміно-5-(фуран-2іл)-1,2,4-тріазол(4Н)-3-іл)-сульфаніл)-N-ацетамідів. За результатами проведених досліджень встановлено залежність «хімічна структура – антиексудативна активність» вперше синтезованих сполук. Результати експериментальних досліджень показали, що п'ятнадцять із двадцять однієї сполуки виявили антиексудативну активність, вісім із них перевищували цю активність, або були на рівні референспрепарату – диклофенаку натрію. Висновки. Здійснено синтез двадцяти однієї сполуки похідних 2-((4-аміно-5-(фуран-2-іл)-1,2,4тріазол(4Н)-3-іл)-сульфаніл)-N-ацетамідів та проведено оцінку антиексудативної активності, встановлено залежність «хімічна структура – антиексудативна активність». Виявлено сполуки-лідери за актиексудативною активністю Ключові слова: синтез, 4-аміно-3-тіо-5-(фуран-2-іл)-1,2,4-тріазол, ацетаміди, алкілування, антиексудативна активність, формаліновий набряк


Introduction
The value of nonsteroidal anti-inflammatory drugs (NSAIDs) in modern therapies of various diseases cannot be overestimated. Non-treatment of inflammatory processes often leads to prolonged incapacity to work and even to the disability of the population [1,2]. At the same time, a significant spectrum of existing side effects of NSAIDs can impair the quality of life of patients [3]. Therefore, today there is an active search for new "small" molecules with a clear anti-inflammatory action, suitable for creating on their basis more effective NSAIDs with a higher safety profile and selectivity of action [4,5].

Formulation of the problem in a general way, the relevance of the theme and its connection with important scientific and practical issues
Thanks to the fundamental research in the field of organic synthesis and pharmaceutical chemistry, there is a modern concept for the creation of new pharmaceutical products. One of the basic principles of which is the synthesis of structures containing pharmacophorial fragments, which allows to predict the pharmacological properties of substances at the stage of planning their synthesis. Therefore, the design of the presented study consisted in the implementation of the concept of structural modification of the "triazol" matrix in order to achieve the required pharmacological profile, namely anti-inflammatory action [6,7].

Analysis of recent studies and publications in which a solution of the problem and which draws on the author
Derivatives of 1,2,4-triazole-3-thione have a significant pharmacological potential, which is primarily due to the low toxicity of this class of compounds, as well as the ability to influence various biological targets [8,9]. A significant number of studies [10,11] is devoted to the search for derivatives of 1,2,4-triazole-3-thione substances with analgesic and anti-inflammatory activity, in some cases selectivity of inhibitory activity on cyclooxygenase-2 and also on lipoxygenase-5 [12,13].

Statement of the basic material of the study (methods and objects) with the justification of the results
To establish the prospects of synthesis and optimization of further pharmacological screening, we made a preliminary forecast of the biological activity of the compounds planned for synthesis using the computer program PASS [20]. 4-amino-3-thio-5-(pyridine-2(3)yl)-4H-1,2,4-triazole acetamides were selected for synthesis for which an analgesic and anti-inflammatory effect was predicted (Ra ≥ 0.50).
All solvents and reagents were obtained from commercial sources. The melting points (˚С) were determined using the Kofler device. The 1 H NMR spectrum was recorded on a Bruker Varian Mercury (400 MHz) device in DMSO-d6, an internal TMS standard. The chromatographic mass spectrometry analysis was performed on a PE SCIEX API 150EX chromatograph. Elemental analysis was performed on a micro-analyzer Euro Vector EA-3000 (Eurovector SPA, Redavalle, Ita-ly). The content of the elements was within ± 0.4 % of the theoretical values.
Antiexudative activity was studied on models of formalin swelling of the paws in rats. The studies were conducted on 138 white male rats weighing 180-200 g. Edema was modeled using subplanetary administration in the posterior right paw of 0.1 ml of 2 % formalin solution. The volume of the paw was measured using a digital plethysmometer prior to the administration of the drugs and on the background of maximal edema 4 hours after the formalin injection simulation [22,23]. The studied compounds 2-((4-amino-5-(furan-2-yl) -4H-1,2,4triazol-3-yl) sulfanyl) -N-acetamide were administered to test animals at a dose of 10 mg / kg, reference diclofenac sodium at a dose of 8 mg / kg (D-Na) [24].
An increase in edema was expressed in milliliters. Percent inhibition of inflammation was calculated by the formula: where V kvolume of foot in control minus the output volume of this foot before swelling, ml; 24 V оvolume of the foot that is swollen in the experiment minus the output volume of this foot, ml.
Statistical processing of the obtained results was carried out using the methods of variation statistics using the t-criterion of the Student using computer programs

Results and their discussion
Synthesis of the starting 4-amino-3-thio-5-(furan-2yl)-4H-1,2,4-triazole-3-thiol (1) was carried out using the one-pot method described earlier [21]. Reactions were started with furan-2-carboxylic acid hydrazide with carbon disulfide in ethyl alcohol in the presence of potassium hydroxide to form potassium dithiocarbazinate intermediate, followed by cyclical condensation with excess hydrazine, yielding tiotriazole (1) as a white solid with a good yield. Hydrazide of furan-2-carboxylic acid, in turn, was synthesized from the corresponding ether of furan-2-carboxylic acid by reaction with hydrazine hydrate.
Acetamides (3.1-3.21) were obtained with satisfactory yields (Tab. 1). Purification of the synthesized compounds was carried out by crystallization from ethanol, resulting in white crystalline substances with clear melting temperatures. According to chromatomass spectrometry, products synthesized are individual substances.  Table 1 Physicochemical characteristics of synthesized 2-((4-amino-5-(furan-2-yl)-1,2,4-triazolo (4H) -3-yl) -sulfanyl)-N-acetamides (3. The structure of synthesized acetamides 3.1-3.21 was confirmed by data from elemental analysis, 1 H NMR spectroscopy and chromatographic mass spectrometry (Tab. 1, 2). 1 H NMR spectra of compounds 3.1-3.21 are characterized by the presence of: signals of the phosphorus residue protons in the position of 5 triazolal cycles, which resonate in the form of two doublets in the sites 8.00-7.90 and 7.25-7.15 (H-5, H-3 , respectively), as well as the triplet H-4 at 6.72-6.70 ppm; the singlet signal of the proton group SCH2 at 4.28-4.12 ppm; a singlet of NH-acetamide residue in a weak field (11.00-9.21 ppm). Signals of protons of aryl radicals in terms of intensity, multiplicity, and location on the spectrum correspond to the placement of substituents.
Differently, the anti-exudative activity of fluorinated derivatives was found: compounds with trifluoromethyl-(3.7) and 3-fluorophenyl (3.10) radicals had a slight suppression of edema -9.1 % and 16.3 %, respectively. At the same time, the presence of 4-fluorophenyl radical (3.11) led to suppression of edema by 50 %, which even exceeds the value of the reference drug.
It was not possible to find clear regularities in the case of chlorinated derivatives: only the compound with 4-chlorophenyl (3.9) radical reduced the swelling by 55.5 %, while the 3-Cl-substituted derivative (3.8) did not completely reduce it (0 %). Dichloro-substituted compounds (3.16) and (3.17) have mean values of antiexudative activity (38.8 and 11.0 %, respectively).