Substituted 4-Formyl-2H-chromen-2-ones: Their Reaction with N-(2,3,4,6-Tetra-Oacetyl- β-D-galactopyranosyl)thiosemicarbazide, Antibacterial and Antifungal Activity of Their Thiosemicarbazone Products

Abstract

: Several 6- and 7-alkoxy-2-oxo-2H-chromene-4-carbaldehydes were prepared from corresponding alkyl ethers of 6- and 7-hydroxy-4-methyl-2-oxo-2H-chromen-2-ones by oxidation using selenium dioxide. 6- and 7-Alkoxy-4-methyl-2Hchromenes were obtained with yields of 57−85%. Corresponding 4-carbaldehyde derivatives were prepared with yields of 41−67%. Thiosemicarbazones of these aldehydes with D-galactose moiety were synthesized by reaction of these aldehydes with N-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)thiosemicarbazide with yields of 62−74%. These thiosemicarbazones were screened for their antibacterial and antifungal activities in vitro against bacteria, such as Staphylococcus aureus, Escherichia coli, and fungi, such as Aspergillus niger, Candida albicans. Several compounds exhibited strong inhibitory activity with MIC values of 0.78−1.56 μM, including 8a (against S. aureus, E. coli, and C. albicans), 8d (against E. coli and A. niger), 9a (against S. aureus), and 9c (against S. aureus and C. albicans).

New Thiosemicarbazide Derivatives with Multidirectional Biological Action

“…Thiosemicarbazides are compounds with a broad spectrum of biological activity. Their antimicrobial properties deserve special attention [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Derivatives with antiviral, antimalarial, and anticancer activity are also known [26][27][28][29][30].…”

Design, Synthesis, Antibacterial Evaluations and In Silico Studies of Novel Thiosemicarbazides and 1,3,4-Thiadiazoles

“…In recent years, scientists have been interested in the use of small organic molecules, including heterocyclic compounds, as promising therapeutic substances [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Literature data from our review indicate that 1,3,4-thiadiazole derivatives and intermediates in their synthesis, 1,4-disubstituted thiosemicarbazides, are commonly reported as promising antimicrobial agents [ 1 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Compounds containing these structures often show higher activity than standard antibacterial drugs, such as penicillin [ 10 ].…”

“…Compounds containing these structures often show higher activity than standard antibacterial drugs, such as penicillin [ 10 ]. Thiosemicarbazide derivatives are commonly reported as anti-tuberculosis [ 20 ], antiviral [ 21 ], antimalarial and antibacterial [ 14 , 15 , 22 ] therapeutics. These compounds are synthesized not only as potential drugs, but also as precursors for the synthesis of heterocyclic compounds such as oxadiazoles, thiadiazoles and triazoles [ 22 , 23 ].…”