Chiral
enantiomeric amino acid Schiff base copper(II) complexes 1 and 2 (a and b) were
synthesized and characterized by various spectroscopic techniques
(Fourier transform infrared, UV–vis, electron paramagnetic
resonance, electrospray ionization-mass spectrometry, and circular
dichroism) and single X-ray crystal diffraction analyses. To understand
the selectivity and enantiomeric behavior of the complexes, binding
interaction with ct-DNA and tRNA biomolecules was investigated by
widely employed optical and hydrodynamic techniques. The binding experiments
demonstrated that complexes 1 and 2 (a and b) interact strongly via the intercalative
mode with preferential binding toward the tRNA biomolecule compared
to ct-DNA. Furthermore, the order of binding propensity was 2a > 2b > 1a > 1b,
implicating greater binding affinity of l-enantiomeric complexes,
and complex 2a showed the highest binding propensity
possessing a rigid aromatic group in the amino acid framework. Scanning
electron microscopy analyses of complexes 1a and 2a revealed the formation of different morphologies with ct-DNA/tRNA
molecules depending on the nature and extent of condensation induced
by the complexes. The cleavage activities of complexes 1a and 2a showed a preferential oxidative cleavage mechanism
toward the pBR322 plasmid DNA mediated by reactive oxygen species
radical scavengers involving singlet oxygen (1O2) and superoxide anions (O2
•–). The tRNA cleavage mechanism of complexes 1a and 2a revealed time- and concentration-dependent activities of
these Schiff base Cu(II) complexes. In vitro cytotoxic activities
of complexes 1 and 2 (a and b) revealed that among all, complex 2a showed
the highest cytotoxicity, being selectively targeted toward the human
breast cancer cell line (MCF-7) with a GI50 value of <1
μM. The results suggest that the l-enantiomeric complexes
are more avid binders toward the tRNA molecule and showed better cytotoxicity.
An 8-week feeding trial was conducted in a flow-through system (1-1.5 L min -1 ) at 27°C to determine dietary protein requirement for Channa punctatus fingerlings (4.58 ± 0.29 g) by feeding six isocaloric diets (18.39 kJ g -1 , gross energy). Diets containing graded levels of protein (300, 350, 400, 450, 500 and 550 g kg -1 ) were fed to triplicate groups of fish to apparent satiation at 09:00 and 16:00 h. Maximum absolute weight gain (AWG; 8.11 g fish -1 ), specific growth rate (SGR; 1.82%) and best feed conversion ratio (FCR; 1.48) were recorded in fish fed diet containing 450 g kg -1 protein, whereas protein efficiency ratio (PER; 1.52), protein retention efficiency (PRE; 25%), energy retention efficiency (ERE; 78%) and RNA/DNA ratio (3.01) were maximum for the group fed dietary protein at 400 g kg -1 . Second-degree polynomial regression analysis of AWG, SGR and FCR data against varying levels of dietary protein yielded optimum dietary protein requirement of fingerling between 462.24 and 476.72 g kg -1 , whereas the regression analysis of PER, PRE, ERE and RNA/DNA ratio data showed a lower protein requirement of 438.28-444.43 g kg -1 of the diet. Considering the PER, PRE, ERE and RNA/DNA ratio as more reliable indicators, this protein requirement is recommended for developing quality protein commercial feeds for C. punctatus fingerlings.
A 12-week experiment was conducted to quantify dietary lysine requirement of fingerling Catla catla (3.65 ± 0.05 cm; 0.58 ± 0.02 g) by feeding casein-gelatine-based diets (33.0 % crude protein; 14.3 kJ/g digestible energy) with six levels of L-lysine (1.25, 1.50, 1.75, 2.00, 2.25 and 2.50 % dry diet). The experiment was conducted in eighteen 70-L indoor polyvinyl circular troughs provided with a water flow-through system (1-1.5 L/min). Live weight gain (LWG), feed conversion ratio (FCR), protein deposition (PD), lysine retention efficiency (LRE%) and RNA/DNA ratio were used as the response criteria. Second-degree polynomial regression analysis at 95 % maximum and minimum response of LWG and FCR data exhibited the lysine requirement between 1.8 and 1.9 % dry diet, corresponding to 5.5-5.7 % dietary protein. Regression analysis of PD, LRE and RNA/DNA ratio yielded the requirement between 1.7 and 1.8 % dry diet, corresponding to 5.2-5.5 % dietary protein. Since live weight gain and protein deposition are the key parameters for estimating nutrient requirement, these tools were used to recommend the lysine requirement of fingerling C. catla which ranges between 1.7 and 1.8 % dry diet. Data generated during this study will be useful to formulate lysine-balanced feed for intensive culture of this fish.
Bio-/environment-friendly cationic gemini surfactant, ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy)dichloride, referred to as 16-E2-16, was synthesized and characterized. Corrosion inhibition effects of 16-E2-16 on mild steel (MS) surface in 1 M HCl solution at 30, 40, 50 and 60°C were evaluated using gravimetric analysis, potentiodynamic polarisation and electrochemical impedance spectroscopy measurements. The nature of the protective inhibitor film formed on the MS surface was analysed by SEM, EDAX and FT-IR, while TGA was used to assure the thermal behaviour and stability of the film at high temperature. The formation of [inhibitor-Fe 2? ] on the surface of MS was confirmed by UV-visible spectroscopy. The inhibition efficiency of the studied inhibitor increased with increasing concentration and solution temperature. The compound behaved as a mixed type inhibitor and acted by blocking the electrode surface by means of adsorption obeying the Langmuir adsorption isotherm. Surface active properties and corrosion inhibition effects of 16-E2-16 in the presence of inorganic (NaI) and organic (NaSal) salts were also investigated and are discussed. Density functional theory calculations have been carried out to correlate the efficiency of the compound with its intrinsic molecular parameters.
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