Isoleucine with secondary sulfonamide functionality as anticancer, antibacterial and antifungal agents.

Isoleucine substituted analogues with secondary sulfonamide group (I1-I6) have been synthesized. Structures of synthesized analogues have been confirmed by Fourier Transform-Infrared Red, Nuclear Magnetic Resonance (1H and 13C) and ESI-MS spectroscopic tools. Cytotoxic screenings of synthesized analogues have been done on MCF-7 (breast), Prostate Cancer-3 (PC-3) and A549 (lung) cancer cell lines. N-(1-isobutyl-2-oxo-2-anilinoethyl) p-toluene sulfonamide (I5) screened to be better cytotoxic agent on MCF-7 and A549 cell lines whereas N-(1-isobutyl-2-oxo-2-p-chloroanilino ethyl) benzene sulfonamide (I3) against PC-3 cell line. Cell cycle analysis of N-(1-isobutyl-2-oxo-2-anilinoethyl) p-toluene sulfonamide (I5) analogue has been carried out on A549 cell line in comparison to control and Vinblastine (standard drug). Complete arrest in G0 and G1 phase along with mild disturbance in S-phase of cell cycle has been observed. The screened analogues (I1-I6) also showed good antifungal and antibacterial potential against gram positive as well as gram negative strains. Computer simulation indicated good bioactivity prediction by the 'Lipinski rule' and synthesized analogues did not violate this rule. Docking study of isoleucine sulfonamide analogues (I1-I6) were carried out to determine the possible interaction sites of the analogues with p53 tumor suppressor-DNA complex and demonstrate that the analogues confirmed binding and inhibition with the most mutated residues of p53. Density functional theory has been used to correlate the electronic and chemical properties of analogues and they were found to be stable and chemically reactive. Thus the results suggest that isoleucine substituted sulfonamide analogues can serve as a structural model for the design of anticancer agents, antibacterial agents as well as antifungal agents with better inhibitory potential.Communicated by Ramaswamy H. Sarma.

Juvenile hormone mimics with phenyl ether and amide functionality to be insect growth regulators (IGRs): synthesis, characterization, computational and biological study.

A series of substituted phenyl ethers derivatives as juvenile hormone (JH) mimics (V1-V8) have been synthesized. Substituted phenoxyacetic acid and amino acid ethyl ester hydrochloride were prepared using NaOH, SOCl2. DCC method has been used for amide linkage. The structure of prepared compounds has been confirmed by Fourier Transform Infra-Red (FT-IR), Electrospray ionization-Mass spectrometry (ESI-MS), Proton and Carbon-13 nuclear magnetic resonance (1H-NMR, 13C-NMR) spectroscopic techniques. Biological efficacy of synthesized analogs has been carried out under laboratory conditions. Galleria mellonella (honey bee pest) has been chosen as testing insect. Juvenile hormone (JH) activity of synthesized compounds has been tested at different concentrations and compared with the standard juvenile hormone analogs (JHAs) pyriproxyfen (M1) and fenoxycarb (M2) against the fifth larval instar of G. mellonella. Compound ethyl 2-[2-(4-methylphenoxy)aminoacetyl]-3-phenyl-propanoate (V6) exhibited better activity among all the synthesized compounds (V1-V8) with LC50 and LC90 values of 0.11 mg/mL and 0.56 mg/mL respectively. Compounds showed insect growth regulating (IGR) activity at lower concentrations. In silico screening of all synthesized compounds with the W-cavity of juvenile hormone-binding protein (JHBP) of insect G. mellonella has been carried out. Chemical reactivity of synthesized series has been studied using DFT/B3LYP/6-311 + G(d,2p) method. Non-toxic behavior of molecules has also been observed from ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) study using discovery studio client 3.0.Communicated by Ramaswamy H. Sarma.

Sulfonamide phenylalanine (SPA) series of analogues as an antibacterial, antifungal, anticancer agents along with p53 tumor suppressor-DNA complex inhibitor - part 1.

A series of N-[1-benzyl-2-oxo-2-substituted(ethyl)] benzene/p-toluene sulfonamide (K1-K12) are synthesized. Structure of the synthesized analogues has been confirmed by FT-IR, 1H & 13C NMR and ESI-MS spectroscopic techniques. All the synthesized analogues (K1-K12) have also been examined for their in-vitro antibacterial and antifungal activities. Compounds showed good antibacterial and antifungal activity against standard drug. Anticancer study has been carried out on three cancer cell lines PC-3, MCF-7 and A549 on two different concentrations (mg/mL and µg/mL). The K4 sulfonamide analogue showed better anticancer activity amongst all analogues against PC-3 and A549 cell lines. K4 inhibit G0/G1 phase in cell-cycle analysis experiment. All synthesized molecules (K1-K12) dock at junction p53-DNA and make hydrogen bonded with residues of p53 protein as per docking study. ADMET predictions of synthesized phenylalanine sulfonamide analogues (K1-K12) has been done using 'Lipinski rule' and it has been observed that all synthesized analogues did not violate the rule. Electronic, chemical properties and mulliken atomic charges of analogues were calculated using density functional theory (DFT). Communicated by Ramaswamy H. Sarma.

Structural and biological study of synthesized anthraquinone series of compounds with sulfonamide feature.

1, 4 and 5, 8-Positions as well as type of functionalities on these positions at anthraquinone-9, 10-dione are proposed to be significant for anticancer activity. Therefore, keeping this into consideration, a series of 1-substituted anthraquinone-based compounds are designed, synthesized, characterized and biologically evaluated for anticancer activity. The structure of synthesized compounds is confirmed by spectroscopic analysis, i.e. 1D (1H and 13C) nuclear magnetic resonance (NMR), electrospray ionization-mass spectrometry (ESI-MS) studies and Fourier transform infrared (FT-IR) tools. Synthesized 1-substituted anthraquinone compounds showed cytotoxic effect against human breast cancer cell line (MCF-7), human prostate cancer cell line (PC-3) and Hela derivative human cell line (Hep 2C) (Hela derivative) cell lines. All the compounds showed mild antibacterial property in comparison to standard antibiotic streptomycin against Gram + ve and -ve bacteria. They also exhibit mild antifungal activity. In vitro calf thymus (ct)-DNA binding studies of synthesized series using UV-visible absorption spectra measurement and fluorescence tools indicate partial intercalative mode of binding. Electronic properties of synthesized analogues and mitoxantrone are compared using highest occupied molecular orbital-lowest occupied molecular orbital (HOMO-LUMO) calculation. Low energy gap between HOMO and LUMO of 1-substituted anthraquinone compounds indicates the highly charged structure of the molecules in comparison to mitoxantrone, and the same is proposed to be responsible for comparable cytotoxic activities of the synthesized 1-substituted anthraquinone molecules. Docking interaction of synthesized 1-substituted anthraquinone compounds and i-motif sequence indicates intercalative mode of binding of compounds with telomeric junction. Communicated by Ramaswamy H. Sarma.

Synthesis, Spectral Characterization, Antibacterial and Anticancer Activity of some Titanium Complexes.

BACKGROUND: After the discovery of cisplatin, first non platinum anticancer drugs having excellent efficacy were budotitane and TiCl2(cp)2 but action mechanism is not clear. Therefore, we hereby reporting synthesis and biological activities novel titanium complexes to explore their mode of action. OBJECTIVES: Synthesis, spectral characterization, antibacterial and anticancer activity of some titanium complexes. Antibacterial studies on various bacterial strains and anticancer studies on HeLa, C6, CHO cancerous cell lines have been performed. Further, the cell death mechanistic study was done on CHO cell lines. METHOD: Titanium complexes with and without labile groups have been synthesized by reacting of TiCl4 with nitrogen containing ligands viz. 1,2-diaminocyclohexane, 1,10-Phenanthroline, adamantylamine, 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine in predetermined molar ratios. Antibacterial and anticancer studies were performed by agar well diffusion method and MTT assay respectively. Cell cycle analysis is done by using flow cytometry. RESULTS: Complex 2 i.e TiCl2(Phen)2 showed better activity than other complexes as an antibacterial as well as anticancer agent. Phase contrast imaging indicates that observed morphological changes of cells was dose dependent. Cell death mechanistic study have shown the increase in sub G0 phase population as well as formation of blebbing and fragmentation of chromatin material which is an indicative measure of apoptosis. CONCLUSION: Complex 2 proved to be more effective bactericide and cytotoxic agent. Cell cycle analysis showed cell arrest in G0 phase. Apoptosis percentage was found to increase in a dose dependent manner. So, prepared titanium complexes can be put to use as an important chemotherapeutic agents.

In silico and bio assay of juvenile hormone analogs as an insect growth regulator against Galleria mellonella (wax moth) - Part I.

Juvenile hormone (JH) analogs are nowadays in use to control harmful pests. In order to develop new bioactive molecules as potential pesticides, we have incorporated different active structural features like sulfonamide, aromatic rings, amide group, and amino acid moiety to the base structure. We have screened a series of designed novel JH analogs against JH receptor protein (jhbpGm-2RCK) of Galleria mellonella in comparison to commercial insect growth regulators (IGRs) - Pyriproxyfen (T1) and Fenoxycarb (T2). All analogs exhibit the binding energy profile comparable to commercial IGRs. Based upon these results, a series of sulfonamide-based JHAs (T3-T8) as IGRs have been synthesized and characterized. Further, the efficacy of synthesized analogs (T3-T8) and commercial IGRs (Pyriproxyfen and Fenoxycarb) has been assessed against fourth instars larvae of G. mellonella under the laboratory conditions. LC50 values of all the analogs (T1-T8) against the fourth instars larvae were 9.99, 10.12, 24.76, 30.73, 38.45, 34.15, 34.14, 19.48 ppm and the LC90 153.27, 131.69, 112.15, 191.46, 427.02, 167.13, 217.10, 172.00 ppm, respectively. Among these analogs, N-(1-isopropyl-2-oxo-3-aza-3-N-ethyl-pentanyl)-p-toluene sulfonamide (T8) and N-(1-isopropyl-2-oxo-3-aza-3-N-ethyl-pentanyl) benzene sulfonamide (T7) exhibited the good pest larval mortality at different exposure periods (in hours) and different concentrations (in ppm) in comparison to in use IGRs- T1 and T2. Bio assay results are supported by docking at higher concentration. The present investigation clearly exhibits that analog T8 could serve as a potential IGR in comparison to in use IGRs (T1 and T2). The results are promising and provide new array of synthetic chemicals that may be utilized as IGRs.

Synthesis, Characterization, Biological Evaluation and Docking Study of Heterocyclic-Based Synthetic Sulfonamides as Potential Pesticide Against G. mellonella.

Juvenile hormone is an important hormone which controls the developmental process in the lepidopteran insects, hence, referred as insect growth regulator. Juvenile hormone binding proteins are the carrier of juvenile hormone from the site of secretion to the site of action and play vital role in juvenile hormone action. We have designed four different juvenile hormone analogs incorporating sulfonamide and heterocyclic moieties using computer-aided tools. All analogs (T3-T6) gave comparative energy profile in comparison to in use insect growth regulators like fenoxycarb (T2) and pyriproxyfen (T1). Further, theses analogs have been screened on biological model Galleria mellonella (wax moth) for their mortality rate. All analogs were evaluated using three different concentrations (1000, 1500, and 2000 ppm) and five different exposure periods (2, 4, 6, 8, and 10 h). In vivo study showed that analog N-(1-isopropyl-2-oxo-2-morpholino-ethyl) toluene sulfonamide (T6) and N-(1-isopropyl-2-oxo-2-piperidino-ethyl) toluene sulfonamide (T4) exhibit the good larval mortality at lower concentration (1000 ppm) after 8 h exposure in comparison to pyriproxyfen (T1) and fenoxycarb (T2). The findings demonstrate the effectiveness and validity of the virtual screening approach (docking) and provide a starting point for the development of novel juvenile hormone analogs to counter G. mellonella.

Comparative In Vitro Binding Studies of TiCl2(dpme)2, Ti(ada)2(bzac)2, and TiCl2(bzac)(bpme) Titanium Complexes with Calf-Thymus DNA.

The binding of TiCl2(dpme)2 (1), (dpme = 6,6'-dimethyl-2,2'-bipyridine), Ti(ada)2(bzac)2 (2), (ada = adamantylamine; bzac = benzoylacetone), and TiCl2(bzac)(bpme) (3), (bpme = 4,4'-dimethyl-2,2'-bipyrdine) with calf thymus (ct) DNA has been studied by UV-visible spectroscopy, thermal denaturation, and circular dichroism spectroscopy. In UV-visible study complexes 1, 2, and 3 showed red, blue, and red shifts, respectively, upon the addition of ct-DNA along with a significant hyperchromism. The intrinsic binding constants (K b ) calculated from UV-visible absorption studies were 2.3 × 10(3) M(-1), 3.3 × 10(3) M(-1) and, 7.1 × 10(3) M(-1) for complexes 1, 2, and 3, respectively. The change in melting temperature (ΔT m ) was calculated to be 2-3°C for each complex. Circular dichroism (CD) study showed blue shift for complex 2 and red shift for complexes 1 and 3 along with rise in molecular ellipticity upon the addition of complexes. Results suggest a binding mode of complex 2 different than 1 and 3.

Synthesis, spectral characterization, and antiproliferative studies of mixed ligand titanium complexes of adamantylamine.

Titanium complexes have been synthesized by the reaction between titanium tetrachloride (TiCl4), respective bidentate ligand [4,4' -dimethoxy-2,2' -bipyridine (bpome), 6,6'-dimethyl-2,2'-bipyridine (dpme), 1,2-diaminocyclohexane (dach), 1,10-phenanthroline (phen), and benzoylacetone (bzac)], and adamantylamine (ada) in 1 : 2 : 2 molar ratios, respectively. The structure of synthesized complexes was confirmed using elemental analysis, FTIR, UV-visible, (1)H NMR, and mass spectrometry techniques. The nanocrystalline nature of complexes was confirmed by powder XRD study. The complexes were evaluated for cytotoxic potential in HeLa (cervical), C6 (glioma), and CHO (Chinese hamster ovarian) cell lines. The complex E was found to be more effective cytotoxic agent against HeLa cell line with an IC50 value of 4.06 µM. Furthermore, the effect of synthesized complexes was studied on different stages of the cell cycle in CHO cells. All complexes exhibited the dose dependent increase in cytotoxicity. The results have shown an increase in sub-G0 population with increase in concentration which is an indicative measure of apoptosis.

NMR-based structure of anticancer drug mitoxantrone stacked with terminal base pair of DNA hexamer sequence d-(ATCGAT)2.

Mitoxantrone is a promising antitumor drug having considerably reduced cardiotoxicity as compared to anthracyclines. Its binding to deoxyhexanucleotides sequence d-(ATCGAT)2 has been studied by proton and phosphorous-31 nuclear magnetic resonance spectroscopy. The stoichiometry reveals that 1:1 and 2:1 mitoxantrone-d(ATCGAT)2 complexes are formed in solution. Significant upfield shifts in 6H/7H, 2H/3H, 11NH, and 12NH protons (∼.5 ppm) of mitoxantrone and T6NH imino protons (∼.3 ppm) are observed. The phosphorous resonances do not shift significantly indicating that the base pairs do not open at any nucleotide step along the sequence of hexamer. Several inter-molecular Nuclear Overhauser Enhancement connectivities between mitoxantrone and hexanucleotide protons indicate that mitoxantrone chromophore stacks with terminal A1-T6 base pair and side chains involving 12CH2, 12NH, and 14OH protons are in close proximity of A1, T2, A5, and T6 bases. Absorption and emission spectra show red shift in wavelength maxima, which is characteristic of stacking interaction. At higher mitoxantrone to nucleic acid ratios, electrostatic interactions are dominant. The 2:1 drug/DNA stoichiometric structure obtained by restrained Molecular Dynamics simulations shows considerable distortions in backbone torsional angles and helicoidal parameters although structural fluctuations in 25 ps analysis of trajectory are found to be negligible. Mitoxantrone binds as a monomer at either or both ends of hexamer externally with side chains interacting specifically with DNA. The findings are relevant to the understanding of pharmacological action of drug.

Multispectroscopic methods reveal different modes of interaction of anti cancer drug mitoxantrone with Poly(dG-dC).Poly(dG-dC) and Poly(dA-dT).Poly(dA-dT).

The interaction of mitoxantrone with alternating Poly(dG-dC).Poly(dG-dC) and Poly(dA-dT).Poly(dA-dT) duplex has been studied by absorption, fluorescence and Circular Dichroism (CD) spectroscopy at Drug to Phosphate base pair ratios D/P=20.0-0.04. Binding to GC polymer occurs in two distinct modes: partial stacking characterized by red shifts of 18-23nm at D/P=0.2-0.8 and external binding at D/P=1.0-20.0 whereas that to AT polymer occurs externally in the entire range of D/P. The binding constant and number of binding sites is 3.7×10(5)M(-1), 0.3 and 1.3× 10(4)M(-1), 1.5 in GC and AT polymers, respectively at low D/P ratios. CD binding isotherms show breakpoints at D/P=0.1, 0.5 and 0.25, 0.5 in GC and AT polymers, respectively. The intrinsic CD bands indicate that the distortions in GC polymer are significantly higher than that in AT polymer. Docking studies show partial insertion of mitoxantrone rings between to GC base pairs in alternating GC polymer. Side chains of mitoxantrone interact specifically with base pairs and DNA backbone. The studies are relevant to the understanding of suppression or inhibition of DNA cleavage on formation of ternary complex with topoisomerase-II enzyme and hence the anti cancer action.

Interaction of anticancer drug mitoxantrone with DNA hexamer sequence d-(CTCGAG)2 by absorption, fluorescence and circular dichroism spectroscopy.

The interaction of mitoxantrone with d-(CTCGAG)2 has been studied by absorption, fluorescence and circular dichroism (CD) spectroscopy. The hypochromism and quenching of fluorescence showed that about four mitoxantrone molecules may be binding externally to DNA hexamer sequence at high drug to nucleic (D/N) acid duplex ratios (28.0-1.1). At lower D/N ratios (1.0-0.2), a red shift in absorption maxima at 610 and 660 nm by 15 and 20 nm, respectively and a red shift in emission maxima by 11 nm accompanied by increase in absorbance and emission has been observed. The equilibrium constant for binding at low (1.0-0.2) and high (28.0-1.1) D/N ratios is 1.8×10(5) M(-1) and 1.38×10(6) M(-1), respectively. The CD spectra show change in intensity of bands accompanied by appearance of induced bands at 325 nm and 650-700 nm. The 251 nm band shows blue shift at D/N ratio of 0.25 and 0.5. The binding isotherms show stoichiometry of 0.25 and 0.5 mitoxantrone molecules binding per duplex. The results suggest stacking of aromatic chromophore of mitoxantrone with terminal base pair of DNA strand forming a sandwiched structure of mitoxantrone between four and two duplex molecules. These investigations are relevant to the formation of ternary complex with topoisomerase enzyme and hence an understanding of anti tumor action of mitoxantrone.

Molecular modeling study of interaction of anthracenedione class of drug mitoxantrone and its analogs with DNA tetrameric sequences.

Numbers of drugs are being synthesized every year to meet the target of safe and disease-free society. Presently molecular modeling technique is used to unfold the mechanism of action of drugs alone or in conjunction with experimental methodologies. There are a number of drugs which are successfully developed using this methodology. Mitoxantrone (MTX) - 1, 4-dihydroxy-5, 8-bis {[2-(2-hydroxyethyl) amino] amino}-9, 10-anthracenedione is marketed under the name Novantrone, an anticancer drug used in chemotherapy. Its important analog ametantrone and various other analogs differ from one another in the position of side chain or functionalities on the chromophore eventually exhibit varied biological activities. DNA binding is an important phenomenon for anticancer activity of these drugs. In order to understand the interactions of the drug molecules with its receptor site, at atomic level, we have carried out computer simulations of drug and DNA alone and also in complex mode in water as a medium. All the simulations are being carried out using molecular operating environment (MOE) and X3DNA software tools on SUN SOLARIS platform. Interaction energy of all the drug molecules with DNA is determined and compared. Also the structural changes in DNA and drug before and after complex formation are studied extensively.

Structure of daunomycin complexed to d-TGATCA by two-dimensional nuclear magnetic resonance spectroscopy.

The anthracycline antibiotic daunomycin, having four fused rings and an amino sugar, is being used in the treatment of acute leukemia. Binding to DNA is generally believed to be essential for its activity. We have studied the interaction of daunomycin with DNA hexamer sequence d-(TGATCA)2 by titrating up to two drug molecules per duplex using nuclear magnetic resonance spectroscopy. The solution structure of 2:1 drug to DNA complex based on two dimensional nuclear Overhauser enhancement (NOE) spectroscopy and molecular dynamics calculations has been studied. The change in conformation of drug molecule on binding to DNA, deoxyribose conformation and glycosidic bond rotation has been obtained. The absence of sequential NOE connectivities at d-T1pG2 and d-C5pA6 sites shows that the drug chromophore intercalates between these two base pairs. This is substantiated by intermolecular NOEs observed between nucleotide base protons and aromatic ring protons of drug molecule. A set of 17 intermolecular NOE interactions allowed the structure to be derived by restrained molecular dynamics simulations, which have been compared with that obtained by X-ray analysis. Several specific interactions between the drug and DNA protons are found to stabilize the formation of drug-DNA complex.

Structure of DNA sequence d-TGATCA by two-dimensional nuclear magnetic resonance spectroscopy and restrained molecular dynamics.

The 5' d-TpG 3' element is a part of DNA sequences involved in regulation of gene expression and is also a site for intercalation of several anticancer drugs. Solution conformation of DNA duplex d-TGATCA containing this element has been investigated by two-dimensional NMR spectroscopy. Using a total of 12 torsional angles and 121 distance constraints, structural refinement has been carried out by restrained molecular dynamics (rMDs) in vacuum up to 100 ps. The structure is characterized by a large positive roll at TpG/CpA base pair step and large negative propeller twist for AT and TA base pairs. The backbone torsional angle, gamma(O5'-C5'-C4'-C3'), of T1 residue adopts a trans-conformation which is corroborated by short intra nucleotide T1H6-T1H5' (3.7A) distance in nuclear overhauser effect spectroscopy (NOESY) spectra while the backbone torsional angle, beta(P-O5'-C5'-C4'), exists in trans as well as gauche state for T1 and C5 residues. There is evidence of significant flexibility of the sugar-phosphate backbone with rapid inter-conversion between two different conformers at TpG/CpA base pair step. The base sequence dependent variations and local structural heterogeneity have important implications in specific recognition of DNA by ligands.

Structure of DNA hexamer sequence d-CGATCG by two-dimensional nuclear magnetic resonance spectroscopy and restrained molecular dynamics.

Solution conformation of self-complementary DNA duplex d-CGATCG, containing 5' d-CpG 3' site for intercalation of anticancer drug, daunomycin and adriamycin, has been investigated by nuclear magnetic resonance (NMR) spectroscopy. Complete resonance assignments of all the protons (except some H5'/H5" protons) have been obtained following standard procedures based on double quantum filtered correlation spectroscopy (dQF COSY) and two-dimensional nuclear Overhauser effect (NOE) spectra. Analysis of sums of coupling constants in one-dimensional NMR spectra, cross peak patterns in dQF COSY spectra and inter proton distances shows that the DNA sequence assumes a conformation close to the B-DNA family. The deoxyribose sugar conformation is in dynamic equilibrium with predominantly S-type conformer and a minor N-type conformer with N<-->S equilibrium varying with temperature. At 325 K, the mole fraction of the N-conformer increases for some of the residues by approximately 9%. Using a total of 10 spin-spin coupling constants and 112 NOE intensities, structural refinement has been carried out using Restrained Molecular Dynamics (rMD) with different starting structures, potential functions and rMD protocols. It is observed that pseudorotation phase angle of deoxyribose sugar for A3 and T4 residues is approximately 180 degrees and approximately 120 degrees, respectively while all other residues are close to C2'endo-conformation. A large propeller twist (approximately -18 degrees) and smallest twist angle (approximately 31 degrees) at A3pT4 step, in the middle of the sequence, a wider (12 A) and shallower (3.0 A) major groove with glycosidic bond rotation as high anti at both the ends of hexanucleotide are observed. The structure shows base-sequence dependent variations and hence strong local structural heterogeneity, which may have implications in ligand binding.