Design, Synthesis and antiHIV activity of Novel Isatine-Sulphonamides

A series of novel isatine-sulphonamide derivatives have been synthesized by combining isatin derivatives with sulphonamides. The structure of the synthesized compounds were elucidated by spectral analysis (IR, NMR and Mass). Investigation of anti-HIV activity was done against HIV-1(IIIB) in MT-4 cells and HIV integrase inhibitory activity. 4-(1-acetyl-5-methyl-2-oxoindolin-3-ylideneamino)-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide (SPIII-5ME-AC) inhibits the HIV Integrase enzymatic activity as both over all and strand transfer reaction and 4-(1-benzoyl-5-chloro-2-oxoindolin-3-ylideneamino)-N-(4,6-dimethylpyrimidin-2-yl)benzene sulfonamide (SPIII-5Cl-BZ) exhibits 36 percent maximum protection against HIV-1 at sub toxic concentration.

Isatin (2,3-dioxoindole), a versatile lead molecule for potential bioactive agents and its derivatives were reported to possess wide spectrum of activity.Methisazone (N-methylisatin-ß-thiosemicarbazone) was one of the first clinically used synthetic antiviral agents 1 .N-Methyl isatin-β-4':4'diethylthiosemicarbazone was found to inhibit Maloney leukemia virus replication 2 .N,N-disubstituted thiosemicarbazone derivatives of isatin were tested for inhibition of HIV-1 replication 3 .Schiff and Mannich bases of isatin derivatives were synthesized and evaluated for antiviral activity.Some of their derivatives showed significant inhibitory activity against the replication of HIV-1 [4][5][6][7][8][9][10] .In earlier studies, some novel isatin derivatives were synthesized and evaluated for antiviral, anticancer and antibacterial activities 11,12 .These compounds showed significant inhibitory effects against HIV-1 replication.In this study we describe the antiviral activity of some novel of isatine-sulphonamide derivatives (Scheme 1) against HIV-1 in MT-4 cells.These studies prompted us to investigate their inhibitory effect against HIV integrase.
Melting points were determined using Thomas melting point apparatus and are uncorrected.The purity was checked by TLC using silica gel G as stationary phase.The structure of the synthesized compounds was elucidated using a Perkin Elmer FT-IR in KBr disc and PMR was taken on a Bruker AMX-(400 MHz) FT-NMR.Mass spectra were obtained on a Varian Atlas CH-7 Mass spectrometer at 70 eV.
To determine the susceptibility of the HIV-1 integrase enzyme towards different compounds we optimized enzyme-linked immunosorbent assays.These assays use an oligonucleotide substrate of which one oligo (5'-ACTGCTAGAGATTTT CCACACTGACTAAAAGGGTC-3') is labeled with biotin on the 3' end and the other oligo is labeled with digoxigenin at the 5' end.For the overall integration assay the second 5'-digoxigenin labeled oligo is (5'-GACCCTTTTAGTC AGTGTGGAAAATCTCTAGCAGT-3').For the antiHIV effect and all the compounds displayed cytotoxic properties in the lymphocyte cell line (MT-4 cells).The 50% effective concentration (EC 50 ) values of the synthesized compounds against the replication of HIV-1(IIIB) in acutely infected MT-4 cells were higher than the cytotoxic concentration (CC 50 ).Lead molecules isatins (isatin, 5-chloroisatin, 5-bromoisatin, and 5-methylisatin) and sulphadimidine not active against HIV-1(IIIB) in MT-4 cells, but the combined product isatinesulphadimidine (SPIII, Þ g. 1 and Table 1) were active against HIV-1 and 2 in MT-4 cells 13    Morbidity and mortality rate after both human and experimental spinal cord injury (SCI) are high.

TABLE 1 : ANTIHIV ACTIVITY AND CYTOTOXICITY OF ISATIN IN MT-4 CELLS
Concentrations of each compound required to inhibit the CPE of retroviruses in MT-4 cells by 50%.b Concentrations required to cause cytotoxicity to 50% of the MT-4 cells.@ SPIII lead value was taken from references 11 and 12 a

TABLE 2 : INHIBITION OF HIV-1 INTEGRASE ACTIVITY
a 50% inhibitory concentration or concentration of the compound required to inhibit the overall integration reaction by 50%, b 50% inhibitory concentration or concentration of the compound required to inhibit the strand transfer reaction by 50%.All the data represent mean value±SD for at least two separate experiments