Anti-malarial and Multi-bioactive Co (II), Cu (II) and Ni (II) Salen Complexes: Synthesis, Characterization and Computational Studies.

Herein, we report anti-malarial, anti-bacterial and anti-inflammatory activities of theN2O2 donor tetradentate salen ligand and its CoL, NiL, and CuL metal complexes. All the compoundswere synthesized and characterized by various spectroscopic analytical methods.Thein-vitro antimalarial investigations revealed that the complex CuL exhibited equipotency with quinine drug having IC50 value 0.25 µg/mL.The compound L shows significant inhibition of bacterial spp.viz.E. Coli, P. Aeruginosa, and S. Aureus (MIC=12.5-50µg/mL), while the compound CoL (MIC=12.5µg/mL) exhibited potency against gram-positive bacteria. In the in-vitro anti-inflammatory study, the compound CuL has moderate activity than other tested compounds. The compound CuL showedthe highest anti-malarial docking score with enzyme pLDH at -8.12 Kcal/mol. The DFT study also gives authentication of higher antimalarial activity of CuL due to high dipole moment. None of the potent compound was found cytotoxic towards verocell lines.

A dual-function fluorescence 'turn-on' probe that allows Zn (II) bioimaging and quantification of water in the organic solvent.

Herein, a Eugenol-derived fluorescence 'turn-on' probe FLHE was synthesized by condensing 2-((3-(trifluoromethyl)phenyl)amino)benzohydrazide with 5-allyl-2-hydroxy-3-methoxybenzaldehyde. FLHE demonstrated very low fluorescence in the studied organic solvents of varying polarities. However, upon titration with Zn2+ in HEPES buffer (pH = 7.4, 50% ACN, v/v), FLHE showed 40-fold higher fluorescence signals indicating the formation of the FLHE-Zn2+ complex. The fluorescence turn-on phenomenon upon FLHE-Zn2+ complex formation results from a chelation-enhanced fluorescence (CHEF) effect. The FLHE-Zn2+ complexation demonstrated a stokes shift of 156 nm (λex = 350 nm, λem = 506 nm) and an about 33-fold increase in the quantum yield (FLHE, Φ = 0.007; FLHE-Zn2+ complex, Φ = 0.23). The binding constant (Ka) determined by the Benesi-Hildebrand plot for interaction between FLHE and Zn2+ was 5.33 × 103 M-1. FLHE demonstrated a LOD of 31.8 nM for detecting Zn2+ in the environmental samples without interference from other cations and anions. FLHE-based paper strip (FLHE-PS) assay was developed to quantify the Zn2+ ions in water and the water content of organic solvent. FLHE-PS allows the detection of Zn2+ in aqueous solutions with a LOD of 63.2 nM and quantifying water in acetonitrile with a LOD of 0.14%. These results indicate that the FLHE has high applicability for detecting Zn2+ in living cells and environmental samples and detecting the presence of water in the organic solvents.

Insect growth regulatory activity of carvacrol-based 1,3,4-thiadiazoles and 1,3,4-oxadiazoles.

In designing of novel insect growth regulators (IGRs), biologically occurring carvacrol has been structurally modified to thiadiazole and oxadiazole moieties. Two series of carvacrol analogs containing 1,3,4-thiadiazole (VIIIa-e) and 1,3,4-oxadiazole (IXa-e) derivatives are designed and synthesized. Their structures are confirmed by FT-IR, [Formula: see text] NMR, [Formula: see text]C NMR and LC-MS. IGR activity is tested against Spodoptera litura. Several analogs displayed IGR activity against this insect pest. Compounds VIIIe and IXe displayed relatively good IGR activity with [Formula: see text]values 117.43 and 108.83 ppm against Spodoptera litura, respectively. Synthesis, characterization and evaluation of carvacrol-based 1,3,4-thiadiazole and 1,3,4-oxadiazole derivatives as potent insect growth regulators (IGRs).

Perspectives on medicinal properties of natural phenolic monoterpenoids and their hybrids.

Carvacrol, thymol and eugenol belong to a class of naturally presenting phenols with a ten-carbon unit, which are present in essential oils of many plants. These versatile molecules are incorporated as useful ingredients in many food products and find applications in agricultural, pharmaceutical, fragrance, cosmetic, flavor and other industries. They are wide ranging of biological and pharmaceutical activities: anti-inflammatory, antimicrobial, analgesic, anticancer and antioxidant. This review summarizes pharmacological and medicinal activities of these phytochemicals and their synthetic hybrids.

Fluorescence Chemosensor for HSO4 (-) Ion Based on Pyrrole-Substituted Salicylimine Zn (2+) Complex: Nanomolar Detection.

A novel pyrrole-substituted salicylimine zinc (II) ion complex has been synthesized and evaluated its anion binding affinity. The probe 4 has high selectivity for HSO4 (-) over other anions in CH3OH:H2O (70:30, v/v) solvent system. The emission intensity of 4 was quenched upon addition of HSO4 (-). The probe 4 is highly selective for HSO4 (-) with a detection limit of 40 nm. Photoinduced electron transfer (PET) is responsible for observed change. The binding affinity of 4 for HSO4 (-) was further authenticated through ratiometric change in absorbance profile.

Pyrrole-coupled salicylimine-based fluorescence "turn on" probe for highly selective recognition of Zn²âº ions in mixed aqueous media: Application in living cell imaging.

Cation sensing behaviour of a pyrrole-based derivative (2-hydroxyl 3 methyl 6 isopropyl benzaldehyde}-3,4-dimethyl-1H-pyrrole-2-carbohydrazide (receptor 3) has been explored and is found to be selective towards Zn(2+) over a variety of tested cations. The receptor 3 has shown high selectivity and sensitivity towards Zn(2+) over the other alkali, alkaline earth and transition metal ions. In the presence of Zn(2+), absorption band of receptor 3 has shown the red shift. The sensing behaviour has been suggested to continue via enhancement process which has further been supported by UV-vis absorption and theoretical density functional theory (DFT) calculations indicating the formation of a 1:1 complex between the pyrrole based receptor 3 and Zn(2+). The present work is presenting a highly selective dual channel colorimetric sensor for zinc with great sensitivity. The developed sensor was successfully applied to image intracellular Zn(2+) in living cells.

A novel phthalazine based highly selective chromogenic and fluorogenic chemosensor for Co(2+) in semi-aqueous medium: application in cancer cell imaging.

A new phthalazine based chemosensor was developed for the highly selective and sensitive detection of Co(2+) in the mixed solvent system, CH3CN-H2O (1 : 1, v/v). In the presence of Co(2+), the colour of the solution changed from yellow to green; the absorption maxima of was red-shifted from 383 nm to 435 nm, and the fluorescence of at 550 nm was significantly enhanced. The sensor showed a detection limit down to 25 nM by forming a complex species with Co(2+) in 1 : 1 stoichiometry. Furthermore, by means of confocal laser scanning microscopy experiments, it has demonstrated that it can be used as a fluorescent probe for monitoring Co(2+) in living cells.

A fluorescent and colorimetric sensor for nanomolar detection of Co2+ in water.

A new disulfide-based, imine-linked fluorescent receptor 1 was processed into organic nanoparticles (ONPs) with an average particle size of 79 nm. The photophysical properties of the ONPs were evaluated by UV/Vis absorption spectroscopy. Receptor 1 selectively recognized Co(2+) ions in water with a detection limit down to 88 nm.

Highly selective turn-on fluorescent sensor for nanomolar detection of biologically important Zn2+ based on isonicotinohydrazide derivative: application in cellular imaging.

A new Zn(2+) selective chemosensor (3) was synthesized by condensation of commercially available substituted salicylaldehyde and isonicotinohydrazide, and characterized by single crystal X-ray crystallography. Receptor 3 with Zn(2+) exhibited a highly selective and pronounced enhancement in the fluorescence emission among different cations by forming a 2:1 complex. The receptor can detect Zn(2+) up to nanomolar level (6.75 nM) with good tolerance of other metal ions and can be used for in vitro cellular imaging.

Highly sensitive ratiometric chemosensor for selective 'naked-eye' nanomolar detection of Co(2+) in semi-aqueous media.

An easy-to-prepare chemosensor, (E)-1-(phthalazine-4-yl)-2-(1-(pyridine-2-yl)ethylidene) hydrazine (3), structurally characterized by single X-ray crystallography, is developed for the selective and sensitive detection of Co(2+) in aqueous media. Chemosensor 3 shows both absorption and fluorescence responses to Co(2+) by forming a 1:1 complex (among the surveyed metal ions) with a detection limit down to 50 nM. It can also be used as a 'naked-eye' sensor due to the outstanding visible and emission color changes from yellow to red and blue to orange, respectively.

Bis(2-hydroxy-3-isopropyl-6-methyl-benzaldehyde)ethylenediamine: a novel cation sensor.

Novel substituted phenol-based new symmetrical bis(2-hydroxy-3-isopropyl-6-methyl-benzaldehyde)ethylenediamine (1) has been designed and synthesized. The compound 1 fluorometrically recognized Cu(2+) ion in CH3OH/H2O (90:10, v/v) by exhibiting an increase in emission upon complexation. In addition, Cu(2+) gave rise to a change in colour of the solution of compound 1, which was clearly visible to the naked eye under UV irradiation. The association constant (K) of compound 1 with Cu(2+) ion was computed with the Benesi-Hildebrand plot and Scatchard plot at 43,000 M(-1) and 43,011 M(-1) respectively.

Hybrid molecules of carvacrol and benzoyl urea/thiourea with potential applications in agriculture and medicine.

Benzoyl phenyl urea, a class of insect growth regulator's acts by inhibiting chitin synthesis. Carvacrol, a naturally occurring monoterpenoid is an effective antifungal agent. We have structurally modified carvacrol (2-methyl-5-[1-methylethyl] phenol) by introducing benzoylphenyl urea linkage. Two series of benzoylcarvacryl thiourea (BCTU, 4a-f) and benzoylcarvacryl urea (BCU, 5a-f) derivatives were prepared and characterized by elemental analysis, IR, (1)H and (13)C NMR and Mass spectroscopy. Derivatives 4b, 4d, 4e, 4f and 5d, 5f showed comparable insecticidal activity with the standard BPU lufenuron against Dysdercus koenigii. BCTU derivatives 4c, 4e and BCU 5c showed good antifungal activity against phytopathogenic fungi viz. Magnaporthe grisae, Fusarium oxysporum, Dreschlera oryzae; food spoilage yeasts viz. Debaromyces hansenii, Pichia membranifaciens; and human pathogens viz. Candida albicans and Cryptococcus neoformans. Compounds 5d, 5e and 5f showed potent activity against human pathogens. Moderate and selective activity was observed for other compounds. All the synthesized compounds were non-haemolytic. These compounds have potential application in agriculture and medicine.

Design and development of novel insect growth regulators: synthesis, characterization and effect of benzoyl thymyl thioureas and ureas on total haemocyte count of Dysdercus koenigii.

Insect-growth regulators (IGRs) have been receiving foremost attention as potential means of selective insect control. Benzoyl phenyl urea (BPU) is a well-known IGR having chitin synthesis inhibitor activity. Mimics of BPU have been synthesized by suitable derivatization of a naturally occurring monoterpenoid, thymol (2-isopropyl-5-methyl phenol) to form a = series of substituted benzoyl thymyl thioureas (BTTUs) [IVa-f] and benzoyl thymyl ureas (BTUs) [Va-f]. The synthesized compounds have been characterized by (1)H and (13)C NMR, LC-MS and elemental analysis. These derivatives have been screened for their effect on total haemocyte count of Dysdercus koenigii. It has been observed that the introduction of substituted benzoyl thiourea and urea linkage into a thymol ring via an amino group results in higher activity than the parent compound thymol and a comparable pattern of results with the standard insect-growth regulators, Penfluron. Urea [Va-f] compounds exhibited greater effect on Total Haemocyte Count (THC) than thiourea [IVa-f]. Fluoro substitution enhanced the effect on THC more than chloro substituted compounds, while ortho-substitution resulted in a better effect than para-substitution. The results described in this paper are promising and provide new array of synthetic chemicals that may be utilized as insect growth regulators.

2-{[{2-Hy-droxy-3-[2-methyl-5-(propan-2-yl)phen-oxy]prop-yl}(pyridin-2-ylmeth-yl)amino]-meth-yl}phenol.

In the title racemic compound, C(26)H(32)N(2)O(3), an intra-molecular O-H⋯N hydrogen bond is formed between the phenolic OH group and the tertiary amine N atom. Another O-H⋯N hydrogen bond that is formed between the OH group and the pyridine N atom links the mol-ecules into a polymeric chain extending along the a axis. The structure is further stabilized by intramolecular and intermolecular C-H⋯O interactions.

(Z)-2-(2-Isopropyl-5-methyl-phen-oxy)-N'-(2-oxoindolin-3-yl-idene)acetohydrazide.

In the title Mannich base, C(20)H(21)N(3)O(3), an isatin derivative of thymol, the O-CH(2)-C(=O)-N(H)-N fragment connect-ing the aromatic and fused-ring systems is approximately planar, with the N-N single bond in a Z configuration. The amino H atom of this N-N fragment is intra-molecularly hydrogen bonded to the carbonyl O atom of the indolinone fused ring as well as to the phen-oxy O atom of the aromatic ring. The amino H atom of the indoline fused ring forms a hydrogen bond with the double-bond O atom of an adjacent mol-ecule, this hydrogen bond giving rise to a linear chain motif.