Free radical scavenging actions of hippocampal metallothionein isoforms and of antimetallothioneins: an electron spin resonance spectroscopic study.

The high concentration of zinc in the hippocampal mossy fiber axon boutons is localized in the vesicles and is mobilized by exocytosis of the zinc-laden vesicles. Furthermore, the mammalian hippocampi contain metallothionein (MT) isoforms which regulate the steady state concentration of zinc, an important antioxidant. Indeed, zinc deprivation leads to an increased lipid peroxidation, reduces the activity of Cu++-Zn++ superoxide dismutase, and protect against oxidative stress such as exposure to ultraviolet A irradiation. By employing electron spin resonance (ESR) spectroscopy, we have demonstrated that rat hippocampal MT isoforms 1 and 2 were able to scavenge 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), hydroxyl radicals (*OH) generated in a Fenton reaction, and superoxide anions (O2*-) generated by the hypoxanthine and xanthine oxidase system. In addition, MT-1 isoform protected the isolated hepatocytes from lipid peroxidation as determined by thiobarbituric acid bound malondialdehyde. MT antibodies scavenged DPPH radicals, hydroxyl radicals and reactive oxygen species but not superoxide anions. The results of these studies suggest that although both isoforms of MT are able to scavenge free radicals, the MT-1 appears to be a superior scavenger of superoxide anions and 1,1-diphenyl-2-picrylhydrazyl radicals. Moreover, antibodies formed against MT isoform retain some, but not all, free radical scavenging actions exhibited by MT-1 and MT-2.     

Biased signaling: potential agonist and antagonist of PAR2

Protease activated receptor 2 (PAR2) has emerged as one of the promising therapeutic targets to inhibit rapidly metastasizing breast cancer cells. However, its elusive molecular mechanism of activation and signaling has made it a difficult target for drug development. In this study, in silico methods were used to unfold PAR2 molecular mechanism of signaling based on the concept of GPCR receptor plasticity. Although, there are no conclusive evidences of the presence of specific endogenous ligands for PAR2, the efficacy of synthetic agonist and antagonist in PAR2 signaling has opened up the possibilities of ligand-mediated signaling. Furthermore, it has been proved that ligands specific for one GPCR can induce signaling in GPCRs belonging to other subfamilies. Therefore, the aim of this study was to identify potential agonists and antagonists from the GPCR ligand library (GLL), which may induce biased signaling in PAR2 using the concept of existence of multiple ligand-stabilized receptor conformations. The results of our in silico study suggest that PAR2 may show biased signaling mainly with agonists of serotonin type 1, β-adrenergic type 1,3 and antagonists of substance K (NK1), serotonin type 2, dopamine type 4, and thromboxane receptors. Further, this study also throws light on the putative ligand-specific conformations of PAR2. Thus, the results of this study provide structural insights to putative conformations of PAR2 and also gives initial clues to medicinal chemists for rational drug design targeting this challenging receptor.     

ABO segregation distortion in Visakhapatnam, India.

Distortions in mother-infant, mother-child and father-child segregation for the ABO system as well as in the sex of offspring are described in a sample from a maternity service and from families of Visakhapatnam, India. Some distortions follow the expected fetomaternal incompatibility depression, others the expected feto-maternal induction of tolerance, and some remain unexplained. A differential action of selective factors on male and female fetuses, infants and children was also found, but no hypothesis could be postulated to explain it. The mother-infant matrix was found to be different from the mother-child matrix probably due to the inclusion of the reproductive time only in the mother-infant matrix. Unexpectedly, father-child segregation distortions were also found.     

Starvation induced cholesterogenesis in hepatic and extra hepatic tissues of climbing Perch,Anabas testudineus (Bloch)

Cholesterol is a structural lipid, which may be differentially utilized or synthesized in response to stress or during insulin deficient states such as starvation. In the present investigation we estimated the levels of cholesterol in Anabas testudineus, which was subjected to brief (15 days) and prolonged fasting (60 days). Tissues such as liver, kidney, brain, accessory respiratory organ, pectoral and lateral line muscle were selected for the study. Cholesterol content was estimated by the Crawford method (1958). Both the starvation regimes showed a significant increase in cholesterol levels in almost all the tissues, but for liver, which strangely showed an insignificant decline during the short-term starvation. This overall upsurge in cholesterol levels observed in all extra hepatic tissues may be attributed to the synthesis of stress hormones such as glucocorticoids, which may promote gluconeogenesis and adrenocorticoids, which may help the animal to combat the stressful condition of starvation. Anabas adapted well to starvation stress and survived all throughout the experimental period.     

Synergistic enhancement of apoptosis by coralyne and paclitaxel in combination on MDA-MB-231 a triple-negative breast cancer cell line

Triple-negative breast cancer (TNBC) is the most outrageous subtype of breast cancer. Emphasizing the urge of new approach in cancer therapy, combinational drug therapy may be proven as an effective strategy. In our previous study, we reported that coralyne (COR) with paclitaxel (PTX) efficiently decreases the proliferation of MDA-MB-231 compared with MCF-7 cell line. Thus, we studied the effect of COR and PTX in combination on apoptosis of MDA-MB-231 cell line. In silico results demonstrated that COR intercalates DNA at a minor groove. In vitro approaches revealed that in combination (COR and PTX) increases the efficacy of apoptosis in MDA-MB-231 cell line by a significant increase in G1/S phase arrest, DNA fragmentation, and change in mitochondria membrane potential. The expression of ATM and ATR a serine/threonine-protein kinase, ataxia telangiectasia and Rad3-related protein were depleted with an increase in time from 24 to 48 hours in concurrent with increased levels of γH2AX indicating that DNA damage routes cells to enter apoptosis. This was confirmed by high levels of caspase-3 and cytochrome c. Also, the decrease in the expression levels of matrix metalloproteinase-9 confirmed the antimetastatic efficacy of COR + PTX. The present study indicates that the synergistic effect of COR and PTX can enhance apoptosis in MDA-MB-231 cell line and may be proven as a potential anticancer therapy against TNBC.     

Minerals,PUFAs and antioxidant properties of some tropical seaweeds from Saurashtra coast of India

Twenty-two tropical seaweeds from the Rhodophyta, Phaeophyta and Chlorophyta were examined for their possible use as nutritional supplements. All seaweeds contained balanced Na/K and C/N ratio and high amounts of macroelements (Na, K, Ca, and Mg) as compared to the terrestrial vegetables. Among the microelements, Fe was the highest followed by Zn, Mn, Cu and other trace elements. Fatty acid distribution showed high level of n-6 and n-3 polyunsaturated fatty acids (PUFAs), and their ratios were within the WHO prescribed limits. The higher ratios of PUFA/SFA (>0.4) are in agreement with the recommendations of nutritional guidelines. Most of the species, especially the Chlorophyta and Phaeophyta, had permissible intake values of unsaturation, atherogenic and thrombogenic indexes comparable to milk-based products. Principal component analysis demonstrated a correlation between total phenolic content, total antioxidant activity, DPPH, and O₂^•− radical scavenging activity, suggesting polyphenols as the chief contributor to the antioxidant activity in seaweeds. These results indicate that these seaweeds could be a potential source of natural antioxidants, minerals and high-quality PUFAs and may be efficiently used as ingredients in functional foods.     

Ab Initio Coordination Chemistry for Nickel Chelation Motifs

Chelation therapy is one of the most appreciated methods in the treatment of metal induced disease predisposition. Coordination chemistry provides a way to understand metal association in biological structures. In this work we have implemented coordination chemistry to study nickel coordination due to its high impact in industrial usage and thereby health consequences. This paper reports the analysis of nickel coordination from a large dataset of nickel bound structures and sequences. Coordination patterns predicted from the structures are reported in terms of donors, chelate length, coordination number, chelate geometry, structural fold and architecture. The analysis revealed histidine as the most favored residue in nickel coordination. The most common chelates identified were histidine based namely HHH, HDH, HEH and HH spaced at specific intervals. Though a maximum coordination number of 8 was observed, the presence of a single protein donor was noted to be mandatory in nickel coordination. The coordination pattern did not reveal any specific fold, nevertheless we report preferable residue spacing for specific structural architecture. In contrast, the analysis of nickel binding proteins from bacterial and archeal species revealed no common coordination patterns. Nickel binding sequence motifs were noted to be organism specific and protein class specific. As a result we identified about 13 signatures derived from 13 classes of nickel binding proteins. The specifications on nickel coordination presented in this paper will prove beneficial for developing better chelation strategies.     

Functional interpretation and structural insights of Arabidopsis lyrata cytochrome P450 CYP71A13 involved in auxin synthesis

Cytochrome P450 CYP71A13 of Arabidopsis lyrata is a heme protein involved in biosynthesis of indole-3-acetonitrile which leads to the formation of indolyl-3-acetic acid. It catalyzes a unique reaction: formation of a carbon-nitrogen triple bond and dehydration of indolyl-3-acetaldoxime. Homology model of this 57 kDa polypeptide revealed that the heme existed between H-helix and J- helix in the hydrophobic pocket, although both helixes are involved in catalytic activity, where Gly305 and Thr308, 311 of H- helix were involved in its stabilization. The substrate indole-3-acetaldoxime was tightly fitted into the substrate pocket with the aromatic ring being surrounded by amino acid residues creating a hydrophobic environment. The smaller size of the substrate binding pocket in cytochrome P450 CYP71A13 was due to the bulkiness of the two amino acid residues Phe182 and Trp315 pointing into the substrate binding cavity. The apparent role of the heme in cytochrome P450 CYP71A13 was to tether the substrate in the catalysis by indole-3-acetaldoxime dehydratase. Since the crystal structure of cytochrome P450 CYP71A13 has not yet been solved, the modeled structure revealed mechanism of substrate recognition and catalysis.