Abstract
A series of newly disubstituted (compounds 4a,b) and trisubstituted 1,3,4-thiadiazines 5a–l with various substituents was prepared utilizing different thiosemicarbazides and 3-α-bromoacetylcoumarins as starting compounds. The structures of the synthesized 1,3,4-thiadiazines are elucidated and confirmed utilizing the corresponding analytical and spectroscopic data. All of the new thiadiazine derivatives were tested for their antioxidant activity, employing different antioxidant assays (DPPH scavenging activity, iron chelating activity, power reducing activity). Compounds 5b, 5f, 5j and 4b were proven to be the best DPPH radical scavengers, while compounds 5h and 5j have shown the best iron chelating activity. Thiadiazine derivatives were also tested on their antifungal activity against four mycotoxicogenic fungi, Aspergillus flavus, A. ochraceus, Fusarium graminearum and F. verticillioides. The best antifungal against A. flavus was proven to be compound 5e, while compounds 4a and 5c were the best antifungals on A. ochraceus, and compound 5g showed the best antifungal activity on F. verticillioides.
Highlights
Coumarin (2-oxo-2H-chromene) and its derivatives represent one of the most important classes of compounds possessing numerous biological activities [1,2,3]
Coumarin derivatives are widely used as additives in food and cosmetics [12], pharmaceuticals and optical brighteners [13] and laser dyes [14]
Many thiadiazines have been discovered with possible applications in medical practice as sedatives, antianxiety agents, antiasthmatic agents, anticonvulsants, myorelaxants, coronary vasodilators, and spasmolytics
Summary
Coumarin (2-oxo-2H-chromene) and its derivatives represent one of the most important classes of compounds possessing numerous biological activities [1,2,3]. Some of these compounds have proven to be active as antibacterial [4,5,6], antifungal [7], anti-inflammatory [8], anticoagulant [9], anti-HIV [10]. Coumarins have proven to be an excellent antioxidants as well as antifungal agents [15]. Interest in thiadiazines has increased due to the high biological activity and broadspectrum action of their derivatives [16]. Synthesis of the 1,3,4-thiadiazine system employing a reaction of α-bromoacetophenone with thiosemicarbazide was first reported by Bose [17]
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