The effect of arsenic exposure on the biochemical and mineral contents of Labeo rohita bones: An FT-IR study

Arsenic compounds are ubiquitous and widespread in the environment as a result of natural or anthropogenic occurrence. Fish are the major source of protein for human consumption. They are also a source of contamination, because of the amounts of heavy elements they can contain, some of which are highly toxic. Fish bones are high in calcium, which is an essential mineral for normal body function. It consists of water, organic material, and mineral matter. Chelating agents have been used clinically as antidotes for acute and chronic metal intoxications. In the present study, an attempt is made to investigate the bio-accumulation of arsenic and its effect on the biochemical and mineral contents of Labeo rohita bones using, Fourier transform infrared (FT-IR) spectroscopy. The results of the present study indicate that arsenic exposure induces significant reduction on the biochemical and mineral contents of the L. rohita bones. Further, the DMSA treatment significantly improves these levels. This shows that DMSA is an effective chelator for arsenic toxicity. Quantitative curve-fitting analyses of amide I band have proved useful in studying the nature and the extent of protein conformational changes. A decrease in α-helical and random coil structures and an increase in β-sheet structures have been observed due to arsenic exposure. In conclusion, the present study shows that the FT-IR spectroscopy coupled with second derivative and curve-fitting analysis gives useful information about the biochemical and mineral contents of the L. rohita bones.     

FTIR study of zinc-induced biochemical changes in the liver of Indian carp <Emphasis Type="Italic">Labeo rohita</Emphasis>

Zinc is an essential metal for different physiological functions and becomes toxic when elevated concentrations are introduced into the environment. In the present study, an attempt is made to analyze zinc-induced biochemical changes in the liver tissues of freshwater fingerlings of Labeo rohita using Fourier Transformation Infrared Spectroscopy. Several important features have been observed in the FTIR spectra of zinc-intoxicated liver tissues, namely, altered membrane lipid, altered protein profile, and increased glycogen content, indicating an alteration in the lipid and protein profiles leading to modification in membrane composition. Further, it is observed that acute exposure to zinc causes some alteration in protein profile with a decrease in α-helix and an increase in random coil structure. Treatment with the chelating agent D-penicillamine reduces the biochemical contents in the liver tissues. This shows that D-penicillamine is a good antidote for zinc toxicity. Published in Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 746–752, September–October, 2008.     

Role of electron correlation in the polydeprotonation of benzene to form trianions

Computations for anion, dianions, and trianions of benzene are carried out to study the role of electron correlation in the polydeprotonation of benzene leading to benzene trianions both in the singlet and triplet states. The computations, while assessing the use of polarization and diffuse functions, are performed with Møller–Plesset second‐order (MP2) perturbation theory and coupled‐cluster theory up to the level of CCSD(T)/6‐311++G(d,p)//MP2/6‐311++G(d,p), and with density functional theory (DFT) employing a hybrid, B3LYP, and a meta‐hybrid, M05‐2X, exchange‐correlation functionals with Gaussian basis set 6‐311++G(d,p) and correlation consistent basis set aug‐cc‐pVDZ. The deprotonation energies, including zero‐point energy correction, of benzene anion and dianions are found to be highly sensitive to the quantum mechanical method and the basis set used. The formation of dianions and trianions, where the anionic centers lie adjacent to each other, is observed with unusual behavior in the deprotonation energy and the geometrical parameters obtained from the different level of the theories. The two exchange‐correlation functionals compared show contrasting and unusual results for the trianionic species particularly for the triplet states, even if the diffuse functions are included in the basis set. Besides this, the ortho‐dianion and 1,3,5‐trianion are predicted to be ground‐state triplet at CCSD(T)/6‐311++G(d,p)//MP2/6‐311++G(d,p) and DFT/M05‐2X/6‐311++G(d,p) levels, whereas DFT/B3LYP/6‐311++G(d,p) predicts meta‐dianion and 1,2,3‐trianion to be ground‐state triplet where all the anionic centers lie adjacent to each other. Copyright © 2014 John Wiley & Sons, Ltd.     

Developing a structure-function relationship for anionic porphyrazines exhibiting selective anti-tumor activity

The porphyrazines (pzs) are a class of porphyrin derivatives being studied for their use as optical imaging agents and photodynamic therapy (PDT) anti-tumor agents. A previous study revealed that the anionic pz, 18--of the form H2[pz(An;B4-n)], where A is [S(CH2)3CO2-], B is a fused beta',beta'-diisopropyloxy benzo group, with n=2 (trans)--selectively killed tumor cells, while analogous neutral and positively charged pzs lacked this property. In this report, we compare the properties of a suite of three H2[pz(An;B4-n)] pzs containing the same A and B groups as 18, but differing in their values of n: pzs 4 (n=4) and 11 (n=3), and 18 (n=2, trans) exhibit a progressive variation in charge due to the carboxylates, balance between hydrophobic/hydrophilic character, as well as a progressive variation in the singlet oxygen quantum yield (PhiDelta): PhiDelta (18)>PhiDelta (11)>PhiDelta (4). The biological activity of the pzs was tested in human lung carcinoma (A549) and SV40 transformed embryonic (WI-38 VA13) cell lines. Pzs 4 and 11 exhibited significant toxicity in both tumor and normal cells, while 18 showed selective anti-tumor cell activity in a dose-dependent manner. As the number of net negative charges decreased, the compounds became less toxic to normal cells, and the killing effect observed with these compounds was light independent. These observations indicate that the toxicity may have little to do with singlet oxygen quantum yields, but rather is more dependent on the net number of negative charges a pz contains. The study reported herein presents an example of how the porphyrazines can be easily modified to vary their biological behavior and specifically suggest that anionic porphyrazines pzs with lower n (fewer carboxylates, larger hydrophobic core) are more specific tumor killers, while those with larger n (increased net negative charge) are more potent tumor killers.