The ameliorative effect of Piper trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional system of medicine, Piper species, or its components are widely used to treat many diseases including memory improvement. One of the wild species Piper trioicum Roxb. (Piperaceae) is found in South Asian countries. The whole plant is used as folk medicine to improve memory.

AIM OF THE STUDY

To our knowledge, no previous research has investigated the neuroprotective activities of P. trioicum. So, we studied the ameliorative effect of P. trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats.

MATERIALS AND METHODS

Wistar rats were exposed to scopolamine (3 mg/kg, i. p.) for 14 consecutive days, and the effect of P. trioicum (HAPT; oral, 300, 400 mg/kg) on scopolamine-invoked neurotoxicity in brain were studied. During the experimental period, behaviour analyses of rats were observed 30 min post-drug administration. The role of antioxidants of HAPT in scavenging cellular oxygen/peroxyl radicals were studied. Acetylcholinesterase and butyrylcholinesterase inhibitions, and mode of inhibition kinetics of HAPT were studied. Pathogenic cellular oxidative (MDA, GSH, SOD, and CAT), DNA damage (8-oxodG), neurochemical (acetyl- and, butyryl-cholinesterase), β-secretase (BACE-1 and 2), MAPτ, and neuroinflammation (IL-6, TNF-α) biomarkers in extension to the histopathological observation of brain cortex were studied. GC-MS/MS analysis was carried out to investigate the presence of bioactive constituents in HAPT.

RESULTS

HAPT, a rich source of phenol and flavonoid type antioxidants were responsible in quenching oxygen/peroxyl radicals and protected the cellular membrane, and lipoproteins against ROS in DPPH, ORAC, and CAPe tests. HAPT inhibited acetylcholinesterase and butyrylcholinesterase activities, and showed competitive-inhibition (reversible) towards cholinesterase activities. HAPT-400 significantly improved the learning and memory-impairment by restoring oxidative MDA, GSH, SOD, CAT, and DNA damage (8-oxodG) markers of serum, and cortex. It also improved acetyl- and, butyryl-cholinesterase, β-secretase, and MAPτ level in brain by restoring proinflammatory cytokines IL-6, and TNF-α indicators in neurotoxic rats. GC-MS/MS reported therapeutic significance active compounds were molecular-docked towards target proteins, found that proscillaridin showed the highest affinity towards AChE, BuChE, BACE1, and BACE2 with binding energy of ΔGb -9.1, ΔGb -10.2, ΔGb -11.4 and ΔGb -11.5 Kcal/mol, respectively. Cymarin and morphine-3-glucuronide showed the second highest binding affinity towards AChE (ΔGb -8.8) and BuChE (ΔGb -10.0), respectively. In BACE-1, betulin showed the second highest binding affinity ΔGb -10.7 Kcal/mol and in BACE-2, morphine-3-glucuronide showed the second highest binding affinity ΔGb -9.8 Kcal/mol.

CONCLUSIONS

Synergistic impact of proscillaridin, Cymarin, morphine-3-glucuronide, betulin like compounds in HAPT improved memory impairment, healing of tissue architecture of cortex with the restoration of neurochemical, neuroinflammation, and oxidative indicators in neurotoxic rats.

Arsenic album 30C exhibits crystalline nano structure of arsenic trioxide and modulates innate immune markers in murine macrophage cell lines

Macrophages are associated with innate immune response and M1-polarized macrophages exhibit pro-inflammatory functions. Nanoparticles of natural or synthetic compounds are potential triggers of innate immunity. As2O3 is the major component of the homeopathic drug, Arsenic album 30C.This has been claimed to have immune-boosting activities, however, has not been validated experimentally. Here we elucidated the underlying mechanism of Ars. alb 30C-mediated immune priming in murine macrophage cell line. Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) used for the structural analysis of the drug reveals the presence of crystalline As2O3 nanoparticles of cubic structure. Similarly, signatures of M1-macrophage polarization were observed by surface enhanced Raman scattering (SERS) in RAW 264.7 cells with concomitant over expression of M1 cell surface marker, CD80 and transcription factor, NF-κB, respectively. We also observed a significant increase in pro-inflammatory cytokines like iNOS, TNF-α, IL-6, and COX-2 expression with unaltered ROS and apoptosis in drug-treated cells. Enhanced expression of Toll-like receptors 3 and 7 were observed both in transcriptional and translational levels after the drug treatment. In sum, our findings for the first time indicated the presence of crystalline As2O3 cubic nanostructure in Ars. alb 30C which facilitates modulation of innate immunity by activating macrophage polarization.

Crystal structure of the N-terminal domain of MtClpC1 in complex with the anti-mycobacterial natural peptide Lassomycin

Antibiotics form our frontline therapy against disease-causing bacteria. Unfortunately, antibiotic resistance is becoming more common, threatening a future where these medications can no longer cure infections. Furthermore, the emergence of multidrug-resistant (MDR), totally drug-resistant (TDR), and extensively drug-resistant (XDR) tuberculosis has increased the urgency of discovering new therapeutic leads with unique modes of action. Some natural peptides derived from actinomycetes, such as Cyclomarin A, Lassomycin, Rufomycin I, and Ecumicin, have potent and specific bactericidal activity against Mycobacterium tuberculosis, with the specificity owing to the fact that these peptides target the ClpC1 ATPase, an essential enzyme in mycobacteria, and inhibit/activate the proteolytic activity of the ClpC1/P1/P2 complex that participates in protein homeostasis. Here, we report the high-resolution crystal structure of the N-terminal domain of ClpC1 (ClpC1 NTD) in complex with Lassomycin, showing the specific binding mode of Lassomycin. In addition, the work also compares the Lassomycin complex structure with the previously known structures of ClpC1 NTD in complex with other natural peptides such as Cyclomarin A, Rufomycin I, and Ecumicin.

Thermodynamics of benzoquinone-induced conformational changes in nucleic acids and human serum albumin

Biological macromolecules such as proteins, nucleic acids, carbohydrates and lipids, play a crucial role in biochemical and molecular processes. Thus, the study of the structure-function relationship of biomolecules in presence of ligands is an important aspect of structural biology. The current communication describes the chemico-biological interaction between benzene metabolite para-benzoquinone (BQ) with B-form of nucleic acids (B-DNA) and human serum albumin (HSA). The binding ability of HSA towards bromocresol green (BCG) was significantly suppressed when exposed to increasing concentrations of BQ in the presence of various physiological buffers. Further, the native fluorescence of HSA was drastically reduced and the secondary structures of HSA were significantly compromised with increasing concentrations of BQ. In vitro and in silico studies also revealed that BQ binds to domains I and II of HSA and thus altering the conformation of HSA which may potentially affect plasma osmotic pressure, as well as the binding and transport of numerous endogenous and exogenous molecules. Similarly, BQ interacts directly to the GC region of B-DNA particularly in the minor groove which was also assessed by computational docking studies. Isothermal titration calorimetry data suggest higher binding affinity of BQ towards DNA than HSA. Various spectroscopic observations also suggest that BQ binds to DNA preferably in the minor grooves. Thus, the results revealed that BQ may play a key role in inducing mutagenicity, either by formation of adducts on GC regions or by accelerating oxidative damage to biomacromolecules through chemico-biological interactions.

Epigenetic signature in neural plasticity: the journey so far and journey ahead

Neural plasticity is a remarkable characteristic of the brain which allows neurons to rewire their structure in response to internal and external stimuli. Many external stimuli collectively referred to as 'epigenetic factors' strongly influence structural and functional reorganization of the brain, thereby acting as a potential driver of neural plasticity. DNA methylation and demethylation, histone acetylation, and deacetylation are some of the frontline epigenetic mechanisms behind neural plasticity. Epigenetic signature molecules (mostly proteins) play a pivotal role in epigenetic reprogramming. Though neuro-epigenetics is an incredibly important field of emerging research, the critical role of signature proteins associated with epigenetic alteration and their involvement in neural plasticity needs further attention. This study gives an integrated and systematic overview of the current state of knowledge with a clear idea of types of neural plasticity and the context-dependent role of epigenetic signature molecules and their modulation by some natural bioactive compounds.

A computational insight on the inhibitory potential of 8-Hydroxydihydrosanguinarine (8-HDS), a pyridone containing analogue of sanguinarine, against SARS CoV2

The unprecedented global pandemic of COVID‐19 has created a daunting scenario urging an immediate generation of therapeutic strategy. Interventions to curb the spread of viral infection primarily include setting targets against the virus. Here in this study we target S protein to obstruct the viral attachment and entry and also the M pro to prevent the viral replication. For this purpose, the interaction of S protein and M pro with phytocompounds, sanguinarine and eugenol, and their derivatives were studied using computational tools. Docking studies gave evidence that 8‐Hydroxydihydrosanguinarine, a derivative of sanguinarine, showed maximum binding affinity with both the targets. The binding energies of the ligand with S protein and M pro scored to be ΔGb ‐9.4 Kcal/mol and ΔGb ‐10.3 Kcal/mol respectively. MD simulation studies depict that the phytocompound could effectively cause structural perturbations in the targets which would affect their functions.8‐Hydroxydihydrosanguinarine distorts the α‐helix in the secondary structure of M pro and RBD site of S protein. Protein‐protein interaction study in presence of 8‐hydroxydihydrosanguinarine (8‐HDS) also corroborate the above findings which indicate that this polyphenol interfere in the coupling of S Protein and ACE2. The alterations in protonation of M pro suggest that the protein structure undergoes significant structural changes at neutral pH. ADME (Physicochemical, Lipophilicity, Water Solubility, Pharmacokinetics, Drug‐likeness) property of 8‐ hydroxydihydrosanguinarine indicates this could be a potential drug. This makes the phyto‐alkaloid a possible therapeutic molecule for antiCOVID‐19 drug design.

Epigenomic interplay in tumor heterogeneity: Potential of epidrugs as adjunct therapy

"Heterogeneity" in tumor mass has immense importance in cancer progression and therapy. The impact of tumor heterogeneity is an emerging field and not yet fully explored. Tumor heterogeneity is mainly considered as intra-tumor heterogeneity and inter-tumor heterogeneity based on their origin. Intra-tumor heterogeneity refers to the discrepancy within the same cancer mass while inter-tumor heterogeneity refers to the discrepancy between different patients having the same tumor type. Both of these heterogeneity types lead to variation in the histopathological as well as clinical properties of the cancer mass which drives disease resistance towards therapeutic approaches. Cancer stem cells (CSCs) act as pinnacle progenitors for heterogeneity development along with various other genetic and epigenetic parameters that are regulating this process. In recent times epigenetic factors are one of the most studied parameters that drive oxidative stress pathways essential during cancer progression. These epigenetic changes are modulated by various epidrugs and have an impact on tumor heterogeneity. The present review summarizes various aspects of epigenetic regulation in the tumor microenvironment, oxidative stress, and progression towards tumor heterogeneity that creates complications during cancer treatment. This review also explores the possible role of epidrugs in regulating tumor heterogeneity and personalized therapy against drug resistance.

Therapeutic potential and ethnopharmacology of dominant mangroves of Bhitarkanika National Park, Odisha, India

Bhitarkanika National Park, is the second largest contiguous mangrove forest of India. Despite being one of the most diverse mangrove habitations of India, its phytoresources has not been adequately explored for their therapeutic potentials. However, the ethnopharmacological practices are comparatively lower than the other mangrove regions of India and Southeast Asia. Ageold ethnobotanical informations have always led biologists, chemists and pharmacists in quenching the demands of therapeutically important phytocompounds and their possible use for the betterment of mankind. The present review is aimed to congregate information on the therapeutic potential and ethnopharmacology of nine dominant mangrove species of the National Park. It will manifest the demand of social awareness among the mangrove dwellers to promote uses of folklore medicine as a complementary step to strengthen community health.

The modulatory role of prime identified compounds in Geophila repens in mitigating scopolamine-induced neurotoxicity in experimental rats of Alzheimer's disease via attenuation of cholinesterase, β-secretase, MAPt levels and inhibition of oxidative stress imparts inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Geophila repens (L.) I.M. Johnst (Rubiaceae) is a small perennial creeper native to India, China, and other countries in Southeast Asia. The hot decoction of leaves is used orally for memory enhancing by the local folk of Andhra Pradesh, India. The ethnomedicinal claim of G. repens as memory enhancer was initially studied by the authors. Results demonstrated the important antioxidant and anticholinesterase activities of isolated molecule Pentylcurcumene and bioactive hydroalcohol extract of leaves of G. repens (GRHA).

AIM OF THE STUDY

Based on the previous findings, additional research is needed to examine the efficacy of GRHA for memory enhancing properties. We therefore investigated the modulatory role of prime identified compounds in GRHA in mitigating scopolamine-induced neurotoxicity in experimental rats of Alzheimer's disease (AD) via attenuation of cholinesterase, β-secretase, MAPt levels and inhibition of oxidative stress imparts inflammation.

METHODS

Scopolamine (3 mg/kg) induced experimental rats of AD were treated with GRHA (300, 400 mg/kg) for 14 days. During the experimental period, elevated T-maze and locomotion-activity were performed to assess learning and memory efficacy of GRHA. At the end of the experiment, biochemical, neurochemical, neuroinflammation and histopathological observation of brain cortex were examined. GC-MS/MS analysis reported 31 compounds, among them 8 bioactive compounds possess antioxidant, neuroinflammation, neuroprotective activities, and were considered for docking analysis towards cholinesterase, β-secretase activities in AD.

RESULTS

GRHA 400 significantly improved learning and memory impairment with the improvement of oxidative stress (MDA, SOD, GSH, CAT), DNA damage (8-OHdG), neurochemical (AChE, BuChE, BACE1, BACE2, MAPt), neuroinflammation (IL-6, TNF-α) markers in neurotoxic rats. Docking studies of 8 compounds demonstrated negative binding energies for cholinesterase and β-secretase indicating high affinity for target enzymes in AD. Test results were corroborated by the improvement of cellular tissue architecture of brain cortex in AD rats.

CONCLUSION

Synergistic action of genistin, quercetin-3-D-galactoside, 9,12,15-octadecatrienoic-acid methyl-ester, phytol, retinal, stigmasterol, n-hexadecanoic acid, β-sitosterol in GRHA restores memory-deficits via attenuation of cholinesterase, β-secretase, MAPt level and inhibition of oxidative-stress imparts inflammation in AD.

Oxidative stress correlates well with markers of metabolic syndrome in clinically hypothyroid cases: a hospital based study in a remote tribal district

Relevance. Dislipidemia is one of the major manifestation of thyroid disease process due to alteration of metabolic parameters which are also seen in metabolic syndrome. Though oxidative stress has been implicated in both processes, controversial results have been obtained. Objective. To determine the status of lipid peroxidation product (Lpx) in the study group and identify the association of different components of metabolic syndrome. Material and Methods: 102 patients comprising of 60 healthy euthyroid controls and 42 hypothyroid patients served as the study group. Blood samples were collected for fasting blood sugar, renal parameters, lipid profile, tri-iodothyronin (T3), thyroxine (T4) and thyroid stimulating hormone (TSH). Level of lipid peroxidation in the samples was determined by monitoring the level of thiobarbituric acid like substances (TBARS) like substances. Results. The demographic parameters were significantly altered in hypothyroid patients. Systolic and diastolic blood pressure amongst both the groups was observed to have higher mean value in hypothyroid patients. The fasting blood sugar (FBS), total cholesterol, triacylglycerol, low density lipoprotein (LDL) and high density lipoprotein (HDL) in the hypothyroid was significantly higher than euthyroid control groups. The most frequent alteration in the hypothyroid patients was rise in SBP (95 %), Hypertriglyceridemia (50 %) and raised waist circumference (48 %) and DBP (42 %). A fourfold rise in Lpx was observed in hypothyroid subjects (p0.001). Robust positive association was observed between TSH and Lpx. Multiple linear regressions revealed strongest and statistically significant association between serum serum thyroid stimulating hormone and waist circumference. Conclusion. The hypothyroid patients have significant higher degree of oxidative stress and the components of metabolic syndrome. They are the candidates for preventive health intervention.

Factors regulating dynamics of angiotensin-converting enzyme-2 (ACE2), the gateway of SARS-CoV-2: Epigenetic modifications and therapeutic interventions by epidrugs

Angiotensin-converting enzyme-2 (ACE2) is one of the major components of the renin-angiotensin system (RAS) and participates in the physiological functions of the cardiovascular system and lungs. Recent studies identified ACE2 as the receptor for the S-protein of the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and thus acts as the gateway for viral entry into the human body. Virus infection causes an imbalance in the RAS axis and induces acute lungs injury and fibrosis. Various factors regulate ACE2 expression patterns as well as control its epigenetic status at both transcription and translational levels. This review is mainly focused on the impact of environmental toxicants, drugs, endocrine disruptors, and hypoxia as controlling parameters for ACE2 expression and its possible modulation by epigenetic changes which are marked by DNA methylation, histone modifications, and micro-RNAs (miRNAs) profile. Furthermore, we have emphasized on interventions of various phytochemicals and bioactive compounds as epidrugs that regulate ACE2-S-protein interaction and thereby curb viral infection. Since ACE2 is an important component of the RAAS axis and a crucial entry point of SARS-CoV-2, the dynamics of ACE2 expression in response to various extrinsic and intrinsic factors are of contemporary relevance. We have collated updated information on ACE2 expression modulated by epidrugs, and urge to take over further studies on these important physiological regulators to unravel many more systemic linkages related to both metabolic and infectious diseases, in general and SARS-CoV-2 in particular for further development of targeted interventions.

Interface-based design of the favipiravir-binding site in SARS-CoV-2 RNA-dependent RNA polymerase reveals mutations conferring resistance to chain termination

Favipiravir is a broad‐spectrum inhibitor of viral RNA‐dependent RNA polymerase (RdRp) currently being used to manage COVID‐19. Accumulation of mutations in severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) RdRp may facilitate antigenic drift, generating favipiravir resistance. Focussing on the chain‐termination mechanism utilized by favipiravir, we used high‐throughput interface‐based protein design to generate > 100 000 designs of the favipiravir‐binding site of RdRp and identify mutational hotspots. We identified several single‐point mutants and designs having a sequence identity of 97%–98% with wild‐type RdRp, suggesting that SARS‐CoV‐2 can develop favipiravir resistance with few mutations. Out of 134 mutations documented in the CoV‐GLUE database, 63 specific mutations were already predicted as resistant in our calculations, thus attaining ˜ 47% correlation with the sequencing data. These findings improve our understanding of the potential signatures of adaptation in SARS‐CoV‐2 against favipiravir.

A primer on cytokines

Cytokines are pleiotropic polypeptides that control the development of and responses mediated by immune cells. Cytokine classification predominantly relies on [1] the target receptor(s), [2] the primary structural features of the extracellular domains of their receptors, and [3] their receptor composition. Functionally, cytokines are either pro-inflammatory or anti-inflammatory, hematopoietic colony-stimulating factors, developmental and would healing maintaining immune homeostasis. When the balance in C can form complex networks amongst themselves that may affect the homeostasis and diseases. Cytokines can affect resistance and susceptibility for many diseases and their availability in the host cytokine production and interaction is disturbed, immunopathogenesis sets in. Therefore, cytokine-targeting bispecific, and chimeric antibodies form a significant mode of immnuo-therapeutics Although the field has grown deep and wide, many areas of cytokine biology remain unknown. Here, we have reviewed these cytokines along with the organization, signaling, and functions through respective cytokine-receptor-families. Being part of the special issue on the Role of Cytokines in Leishmaniasis, this review is intended to be used as an organized primer on cytokines and not a resource for detailed discussion- for which a two-volume Handbook of cytokines is available- on each of the cytokines. Priming the readers on cytokines, we next brief the role of cytokines in Leishmaniasis. In the brief, we do not provide an account of each of the involved cytokines known to date, instead, we offer a temporal relationship between the cytokines and the progress of the infection towards the alternate outcomes- healing or non-healing- of the infection.

Catechin and curcumin interact with S protein of SARS-CoV2 and ACE2 of human cell membrane: insights from computational studies

The recent outbreak of the coronavirus (SARS-CoV2) is an unprecedented threat to human health and society across the globe. In this context, development of suitable interventions is the need of the hour. The viral spike protein (S Protein) and the cognate host cell receptor ACE2 can be considered as effective and appropriate targets for interventions. It is evident from the present computational study, that catechin and curcumin, not only exhibit strong binding affinity to viral S Protein and host receptor ACE2 but also to their complex (receptor-binding domain (RBD) of the spike protein of SARS-CoV2 and ACE2; RBD/ACE2-complex). The binding affinity values of catechin and curcumin for the S protein, ACE2 and RBD/ACE2-complex are − 10.5 and − 7.9 kcal/mol; − 8.9 and − 7.8 kcal/mol; and − 9.1 and − 7.6 kcal/mol, respectively. Curcumin directly binds to the receptor binding domain (RBD) of viral S Protein. Molecular simulation study over a period of 100 ns further substantiates that such interaction within RBD site of S Protein occurs during 40–100 ns out of 100 ns simulation trajectory. Contrary to this, catechin binds with amino acid residues present near the RBD site of S Protein and causes fluctuation in the amino acid residues of the RBD and its near proximity. Both catechin and curcumin bind the interface of ‘RBD/ACE2-complex’ and intervene in causing fluctuation of the alpha helices and beta-strands of the protein complex. Protein–protein interaction studies in presence of curcumin or catechin also corroborate the above findings suggesting the efficacy of these two polyphenols in hindering the formation of S Protein-ACE2 complex. In conclusion, this computational study for the first time predicts the possibility of above two polyphenols for therapeutic strategy against SARS-CoV2.

March of Mycobacterium: miRNAs intercept host cell CD40 signalling

The disease tuberculosis is fatal if untreated. It is caused by the acid‐fast bacilli Mycobacterium tuberculosis. Mycobacterium resides and replicates within the alveolar macrophages, causing inflammation and granuloma, wherein macrophage‐T cell interactions enhance the inflammation‐causing pulmonary caseous lesions. The first interactions between Mycobacterium and the receptors on macrophages decide the fate of Mycobacterium because of phagolysosomal impairments and the expression of several miRNAs, which may regulate CD40 expression on macrophages. While the altered phagolysosomal functions impede antigen presentation to the T cell‐expressed antigen receptor, the interactions between the macrophage‐expressed CD40 and the T cell‐expressed CD40‐ligand (CD40L or CD154) provide signals to T cells and Mycobacterium‐infected macrophages. These two functions significantly influence the resolution or persistence of Mycobacterium infection. CD40 controls T‐cell polarisation and host‐protective immunity by eliciting interleukin‐12p40, nitric oxide, reactive oxygen species and IFN‐γ production. Indeed, CD40‐deficient mice succumb to low‐dose aerosol infection with Mycobacterium because of deficient interleukin (IL)‐12 production leading to impaired IFN‐γ‐secreting T‐cell response. In contrast, despite generating fewer granulomas, the CD40L‐deficient mice developed anti‐mycobacterial T‐cell responses to the levels observed in the wild‐type mice. These host‐protective responses are significantly subdued by the Mycobacterium‐infected macrophage produced TGF‐β and IL‐10, which promote pro‐mycobacterial T‐cell responses. The CD40‐CD40L‐induced counteractive immune responses against Mycobacterium thus present a conundrum that we explain here with a reconciliatory hypothesis. Experimental validation of the hypothesis will provide a rationale for designing anti‐tubercular immunotherapy.

Neonatal Exposure to 6-n-Propyl-Thiouracil, an Anti-Thyroid Drug, Alters Expression of Hepatic DNA Methyltransferases, Methyl CpG-Binding Proteins, Gadd45a, p53, and PCNA in Adult Male Rats

BACKGROUND

Neonatal 6-n-propyl-2-thiouracil (PTU) exposure to male rats is reported to impair liver function in adulthood. However, the mechanism by which the drug impairs liver function is not well known.

OBJECTIVES

The objectives of the study were to investigate the effects of neonatal exposure of PTU on the expression of DNA methyltransferases (DNMTs), methyl-DNA binding proteins (MBDs), Gadd45a, p53, and proliferating cell nuclear antigen (PCNA) in adult rat liver.

METHODS

The effects of neonatal transient (from birth to 30 days of age) and persistent (from birth to 90 days of age) treatment of PTU on DNA damage and on the expression of p53, PCNA, DNMTs, and MBDs were investigated at transcriptional and translational levels in male adult liver.

RESULTS

Persistent exposure to PTU from birth caused significant downregulation of expression of DNMT1 and DNMT3a and upregulation of DNMT3b, MBD4, and Gadd45a without any damage to DNA. Although MeCp2 transcripts were significantly low in the liver of adult rats after persistent exposure to PTU compared to controls, its translated products were significantly higher than in controls. The expression of p53 and PCNA in PTU-treated rats was significantly higher and lower, respectively, than that in control rats.

CONCLUSION

The results suggest that neonatal exposure of male rats to PTU resulted in alteration in the expression of proteins that are associated with DNA methylation and genome stabilization in adult rat liver.

Neonatal Persistent Exposure to 6-Propyl-2-thiouracil, a Thyroid-Disrupting Chemical, Differentially Modulates Expression of Hepatic Catalase and C/EBP-β in Adult Rats

Persistent exposure of rats to 6-propyl-2-thiouracil (PTU) from birth resulted in decreases in plasma thyroid hormone (TH) levels and hepatic expression of catalase and CCAAT enhancer binding protein β (C/EBP-β). Catalase promoter region (-185 to +52) that contains binding sites for C/EBP-β showed an augmentation in the methylation level along with a change in methylation pattern of CpG islands in response to PTU treatment. PTU withdrawal on 30 days of birth restored TH levels and C/EBP-β to control rats in adulthood. Although catalase expression was restored to some extent in adult rats in response to PTU withdrawal, a permanent change in its promoter CpG methylation pattern was recorded. The results suggest that downregulation of adult hepatic catalase gene in response to persistent neonatal PTU exposure may not solely be attributed to thyroid-disrupting properties of PTU. It is possible that besides thyroid-disrupting behavior, PTU may impair expression of hepatic catalase by altering methylation pattern of its promoter.

Oxidative Damaged Products, Level of Hydrogen Peroxide, and Antioxidant Protection in Diapausing Pupa of Tasar Silk Worm, Antheraea mylitta: A Comparative Study in Two Voltine Groups

The present study demonstrates tissue-specific (hemolymph and fat body) and inter-voltine [bivoltine (BV) and trivoltine (TV)] differences in oxidatively damaged products, H2O2 content, and the relative level of antioxidant protection in the diapausing pupae of Antheraea mylitta. Results suggest that fat body (FB) of both the voltine groups has oxidative predominance, as evident from the high value of lipid peroxidation and H2O2 content, despite better enzymatic defenses in comparison to hemolymph (HL). This may be attributed to the higher metabolic rate of the tissue concerned, concomitant with high lipid content and abundance of polyunsaturated fatty acids (PUFA). Nondetectable catalase activity in the pupal hemolymph of both strains apparently suggests an additional mechanism for H2O2 metabolism in the tissue. Inter-voltine comparison of the oxidative stress indices and antioxidant defense potential revealed that the TV group has a higher oxidative burden, lower activities for the antioxidant enzymes, and compensatory nonenzymatic protection from reduced glutathione and ascorbic acid.

Effect of heavy metals on growth response and antioxidant defense protection in Bacillus cereus

Bacterial cells in aerobic environment generate reactive oxygen species which may lead to oxidative stress, induced by a wide range of environmental factors including heavy metals. In the present context an attempt has been made to determine the toxic impact of cadmium and copper on growth performance, oxidative stress, and relative level of antioxidant protection in Bacillus cereus. Outcome of this study suggests that both the metal ions depleted the growth rate in this organism with respect to time and concentration of the metal ions. CdCl2 exposure induced extracellular glutathione (GSH) production, whereas, its level was declined in response to CuSO4. Superoxide dismutase (SOD) activity and hydrogen peroxide (H2 O2 ) content was elevated under CdCl2 stress but the activity of catalase (CAT) was inhibited. In contrast, incubation of bacteria with CuSO4 exhibited decreased SOD activity with concomitant rise in CAT activity and H2 O2 content. We also observed elevation of intracellular GSH level in this bacteria following supplementation of N-acetyl cysteine (NAC) in the medium. Overall findings of this study indicated differential toxicity of CdCl2 and CuSO4 in inducing oxidative stress, depleting growth rate and the possible involvement of GSH and CAT in adaptive antioxidant response.

Hypothyroidism modulates renal antioxidant gene expression during postnatal development and maturation in rat

In the present study effects of 6-n-propyl thiouracil (PTU)-induced hypothyroidism on renal antioxidant defence system during postnatal development (from birth to 7, 15 and 30days old) and on adult rats were reported. Hypothyroidism in rats was induced by feeding the lactating mothers (from the day of parturition till weaning, 25days old) or directly to the pups with 0.05% PTU in drinking water. The activities of Cu/Zn-superoxide dismutase (SOD1) and glutathione peroxidase (GPx) were increased in 30days old hypothyroid rats with respect to their respective controls, on the other hand, levels of translated products and activities of Mn-superoxide dismutase (SOD2) and catalase (CAT) were decreased in hypothyroid rats of all age groups as compared to their respective control rats. SOD1 activity remained unchanged in persistent (PTU-treatment from birth to 90days old) hypothyroid rats as compared to euthyroid. However, a decreased activity of SOD1 was recorded in transient (PTU-treatment from birth to 30days then withdrawal till 90days old) hypothyroid rats with respect to control rats. The mRNA level, protein expression and activity of SOD2 and CAT were significantly decreased in persistent hypothyroid rats as compared to euthyroid rats. The activity of GPx was significantly increased in both persistent and transient hypothyroid rats with respect to euthyroid rats. The present study indicates modulation of antioxidant defence status of rat kidney during postnatal development and maturation by hypothyroidism.

Expression of antioxidant genes in renal cortex of PTU-induced hypothyroid rats: effect of vitamin E and curcumin

The present study was undertaken to investigate the effect of vitamin E and curcumin on the expression of antioxidant genes in 6-propyl-2-thiouracil (PTU)-induced hypothyroid rat renal cortex. The levels of lipid peroxidation and protein carbonylation were increased in hypothyroid rat kidney. Co-administration of vitamin E and curcumin to hypothyroid rats resulted in amelioration of lipid peroxidation level, whereas curcumin alone alleviated the protein carbonylation level. The mRNA levels of SOD1 and SOD2 were decreased in hypothyroid rats. Decreased level of SOD1 transcripts was observed in hypothyroid rats supplemented with curcumin alone or co-administrated with vitamin E. Translated products of SOD1 and SOD2 in hypothyroid rats was elevated in response to supplementation of both the antioxidants. Decreased SOD1 and SOD2 activities in hypothyroid rats compared to control were either unaltered or further decreased in response to the antioxidants. Expressions of CAT at transcript and translate level along with its activity were down regulated in hypothyroid rats. Administration of vitamin E to hypothyroid rats resulted in elevated CAT mRNA level. In contrast, expression of CAT protein was elevated in response to both the antioxidants. However, CAT activity was unaltered in response to vitamin E and curcumin. GPx1 and GR mRNA level and the activity of glutathione peroxidase (GPx) were not affected in response to induced hypothyroidism. The activity of GPx was increased in response to vitamin E treatment, whereas decreased GR activity in hypothyroid rats was further declined by the administration of antioxidants. The over all results suggest that vitamin E and curcumin differentially modulate the altered antioxidant defence mechanism of rat kidney cortex under experimental hypothyroidism.

Lipid peroxidation and antioxidant defence status during larval development and metamorphosis of giant prawn, Macrobrachium rosenbergii

In the present communication we studied the involvement of reactive oxygen species and alteration in antioxidant defence status during larval development and metamorphosis of giant prawn, Macrobrachium rosenbergii. Overall results indicate that there was a decline in endogenous lipid peroxidation level during larval development. Activity of superoxide dismutase was the lowest in early larval stages (Zoea-I and II) and thereafter increased in V and VI stages, followed by a decrease in the subsequent larval stages. Catalase and glutathione peroxidase did not exhibit specific pattern of changes during development. Reduced glutathione content exhibited an incremental increase during larval progression until metamorphosis. Ascorbic acid content of the larval tissue remained unaltered during development but a sharp fall was marked in its content in the post-larvae. Hence it is concluded that early larvae face high oxidative stress as evident from the high content of thiobarbituric acid reactive substances. This may be due to direct exposure of larvae to ambient oxygen of the water as well as their low antioxidant potential. However, during development with the augmentation in antioxidant reserve of the larval tissues a diminution in the oxidative stress was recorded. Thus it is presumed that antioxidant defences play an important role in providing protection to the developing larvae from oxidative assault during larval progression and metamorphosis.

Dietary vitamin-E modulates antioxidant defence system in giant freshwater prawn, Macrobrachium rosenbergii

The objectives of the present study were to determine the effect of supplementary vitamin-E (200, 400 and 600 mg/kg feed) on lipid peroxidation (LPX) and antioxidant defence system in gills and hepatopancreas of the freshwater prawn, Macrobrachium rosenbergii. Results indicated that vitamin-E inhibited LPX in the hepatopancreas in a comparatively lower dose than gills. Superoxide dismutase (SOD) activity was decreased significantly in gills in response to all the three supplemented diet, but in hepatopancreas decrease was observed only in response to higher doses of vitamin-E (400 and 600 mg/kg feed). Catalase (CAT) activity was reduced significantly only in gills but not in hepatopancreas. While glutathione peroxidase (GPX) activity was significantly elevated in the hepatopancreas by vitamin-E, its activity remains unaltered in gills. On the contrary, glutathione reductase (GR) activity was decreased in gills but that of hepatopancreas was constant. Glutathione (GSH) content of both gills and hepatopancreas was substantially elevated in the vitamin-E supplemented prawns. Although the ascorbic acid (ASA) content of gills was unchanged by vitamin-E, its level elevated significantly in hepatopancreas. Thus the findings of the present investigation suggest that dietary vitamin-E is capable of reducing LPX level and can modulate antioxidant defence system in gills and hepatopancreas, nevertheless, the response is highly tissue specific. It is further observed that highest dose of vitamin-E (600 mg/kg feed) could not render much additional protection in both the tissues.