Asankur Sekhar Das

Folic Acid or Combination of Folic Acid and Vitamin B12 Prevents Short-Term Arsenic Trioxide-Induced Systemic and Mitochondrial Dysfunction and DNA Damage

The effect of folic acid and folic acid + vitamin B12 supplementation upon short‐term arsenic‐induced systemic and pancreatic islet cell mitochondria oxidative stress was investigated in male rats. Arsenic trioxide was administered orally at a dose of 3 mg kg body weight−1 day−1 for 30 days, and folic acid and vitamin B12 were administered at a dose of 36 and 0.63 μg kg body weight−1 day−1, respectively, for 30 days. Compared to control, arsenic‐treated group showed a significant increase in the levels of systemic oxidative markers, malondialdehyde (MDA), nitric oxide (NO), and hydroxyl radical (OH−) formation, which were found decreased significantly after supplementation either with folic acid or a combination of folic acid + vitamin B12. Similar supplementations were found effective against arsenic‐induced oxidative marker changes (MDA, NO, and OH−) in pancreatic islet cell mitochondria. Also, low activities of antioxidant defense enzymes such as superoxide dismutase and catalase, and level of antioxidant glutathione, all could regain significantly on supplementations both against systemic and islet cell mitochondria oxidative stress. Results of agarose‐gel electrophoresis of DNA from lymphocytes and islet cells of arsenic‐exposed rats showed DNA smearing, which could be reduced with simultaneous administration either with folic acid or a combination of folic acid + vitamin B12. Significantly, similar supplementations were found effective in increasing the urinary clearance of arsenic. Together, these results indicate that folic acid and vitamin B12 may be effective to reduce the arsenic‐induced damage at molecular target level.

Protective action of aqueous black tea (Camellia sinensis) extract (BTE) against ovariectomy-induced oxidative stress of mononuclear cells and its associated progression of bone loss.

The protective action of aqueous black tea extract (BTE) against ovariectomy‐induced oxidative stress of mononuclear cells and its associated progression of bone loss was demonstrated in this study. Eighteen female adult 6‐month‐old Wistar albino rats were divided into three groups: sham‐control (A), bilaterally ovariectomized (B) and bilaterally ovariectomized + BTE supplemented (C). Studies included the measurement of oxidative (nitric oxide, lipid peroxidation) and antioxidative (superoxide dismutase, catalase) markers, inflammatory cytokines (IL‐6, TNF‐α), osteoclast differentiation factor (RANKL) and bone resorption markers (tartrate‐resistant acid phosphatase and hydroxyproline). Also quantitative histomorphometry and histological studies were undertaken. The bone breaking force was measured. The results indicate that BTE was effective in preserving and restoring skeletal health by reducing the number of active osteoclasts. Such changes with BTE supplementation were steadily linked with the reduced oxidative stress of mononuclear cells, serum levels of bone resorbing cytokines, osteoclast differentiation factor and resorption markers. The results of the bone breaking force, histological and histomorphometric analyses further supported the hypothesis. This study suggests that BTE has both protective and restorative actions against ovariectomy‐induced mononuclear cell oxidative stress and associated bone loss. Copyright

Black tea prevents high fat diet-induced non-alcoholic steatohepatitis.

The chemoprotective actions of aqueous black tea extract (BTE) against high‐fat diet (HFD) (60%)‐induced non‐alcoholic steatohepatitis (NASH) were examined in Wistar rats of both sexes. The results indicated that the HFD rats had higher concentrations of serum glucose, cholesterol, triglycerides, low‐density lipoprotein, very low‐density lipoprotein, high‐density lipoprotein and bilirubin than the corresponding control rats. The enzymes serum aspartate aminotransferase and alanine aminotransferase, which are indicators of liver function, also exhibited higher levels of activity in HFD rats. BTE extract supplementation was found to correct such steatohepatitis‐linked biochemical changes. HFD‐induced steatohepatitis was associated with substantial pro‐oxidant conditions in rat liver, as evidenced by the higher content of malondialdehyde, nitric oxide production and glutathione depletion, with a concomitant decrease in liver antioxidant status caused by reducing superoxide dismutase and catalase activity. In addition, rats with steatohepatitis showed a significantly higher expression of inducible nitric oxide synthase, caspase‐3 activity and DNA fragmentation. BTE reversed the changes in the pro‐oxidant and antioxidant status of the liver, and protected against apoptotic, cytogenetic and hepatocellular damage. In summary, these data suggest that nutritional support with antioxidants may be useful in preventing oxidative damage and the progression of NASH. Copyright

A novel hypoxia-selective epigenetic agent RRx-001 triggers apoptosis and overcomes drug resistance in multiple myeloma cells

The hypoxic bone marrow (BM) microenvironment confers growth/survival and drug resistance in multiple myeloma (MM) cells. Novel therapies targeting the MM cell in its hypoxic BM milieu may overcome drug resistance. Recent studies led to the development of a novel molecule RRx-001 with hypoxia-selective epigenetic and nitric oxide-donating properties. Here, we demonstrate that RRx-001 decreases the viability of MM cell lines and primary patient cells, as well as overcomes drug resistance. RRx-001 inhibits MM cell growth in the presence of BM stromal cells. RRx-001-induced apoptosis is associated with: (i) activation of caspases; (ii) release of ROS and nitrogen species; (iii) induction of DNA damage via ATM/γ-H2AX; and (iv) decrease in DNA methyltransferase (DNMT) and global methylation. RNA interference study shows a predominant role of DNMT1 in MM cell survival versus DNMT3a or DNMT3b. The deubiquitylating enzyme USP7 stimulates DNMT1 activity, and conversely, USP7-siRNA reduced DNMT1 activity and decreased MM cell viability. RRx-001 plus USP7 inhibitor P5091 triggered synergistic anti-MM activity. MM xenograft studies show that RRx-001 is well tolerated, inhibits tumor growth and enhances survival. Combining RRx-001 with pomalidomide, bortezomib or SAHA induces synergistic anti-MM activity. Our results provide the rationale for translation of RRx-001, either alone or in combination, to clinical evaluation in MM.

Antiapoptotic efficacy of folic acid and vitamin B12 against arsenic-induced toxicity

Earlier, we proposed that the ability of folic acid and vitamin B12 to preserve systemic and mitochondrial function after short‐term exposure to arsenic may prevent further progression to more permanent injury and pathological changes leading to cell death. To elucidate its mechanism, the present study examined the antiapoptotic efficacy of folic acid and vitamin B12 against short‐term arsenic exposure‐induced hepatic mitochondria oxidative stress and dysfunction. Sixteen to eighteen weeks old male albino rats weighing 140–150 × g were divided into five groups: Control (A), Arsenic‐treated (B), Arsenic + folic acid (C), Arsenic +vitamin B12 (D), and Arsenic + folic acid + vitamin B12 (E). Data generated indicated that folic acid and vitamin B12 separately or in combination can give significant protection against alterations in oxidative stress and apoptotic marker parameters and downstream changes in mitochondria, namely pro‐oxidative (NO, TBARS, OH−) and antioxidative defense (SOD, CAT, GSH) markers, iNOS protein expression, mitochondrial swelling, cytochrome c oxidase and Ca2+‐ATPase activity, Ca2+ content, caspase‐3 activity. Additionally, results of hepatic cell DNA fragmentation, arsenic load of blood, hepatic tissue and urine, and histological observations, all strongly support that both these supplements have efficacy in preventing apoptotic changes and cellular damage. As the mechanisms of actions of both of these supplements are methylation related, a combined application was more effective. Results further reveal new molecular targets through which folic acid and vitamin B12 separately or in combination work to alleviate one critical component of arsenic‐induced liver injury: mitochondria dysfunction.

Arsenic-induced hepatic mitochondrial toxicity in rats and its amelioration by dietary phosphate.

The present study was aimed to test the hypothesis that inorganic phosphate may reduce arsenic toxicity by decreasing its intestinal transference. Co-administration of inorganic phosphate (6.56 M) and arsenic (6.07 mM) in the intestinal loops of rats, in situ, caused significant reduction of arsenic transference. Short-term arsenic exposure (3mg/kg body weight/day for 30 days) caused liver damage evidenced by activities of liver enzymes and necroinflammatory changes. These effects of arsenic were coupled with enhanced mitochondrial swelling, inhibition of cytochrome c oxidase, Ca(2+)-ATPase, a decrease in mitochondrial calcium content, changes in indices of hepatic mitochondrial oxidative stress and iNOS expression. Arsenic also increased hepatic caspase 3 activity and DNA fragmentation. All these apoptosis-related molecular changes caused by arsenic could be alleviated by supplementation with inorganic phosphate, which likely suggests a protective role of phosphate against arsenic-induced hepatotoxic changes.

Clove (Syzygium aromaticum Linn) extract rich in eugenol and eugenol derivatives shows bone-preserving efficacy

This study examined the efficacy of hydroalcoholic extract of dried clove buds, which is rich in phenolic compounds namely eugenol and eugenol derivatives (precursors of flavones, isoflavones and flavonoids), on different primary and secondary osteoporotic marker changes in an ovariectomised (OVX) rat model of osteoporosis. Female Wistar rats were randomly divided into three groups: sham-operated control (A), OVX (B) and OVX plus 50% hydroalcoholic extract of dried clove buds for 4 weeks (C). Results indicated that, compared to control, serum alkaline phosphatase (AP; 48.25%, p < 0.01), serum tartrate-resistant acid phosphatase (TRAP; 63.48%, p < 0.01), urinary calcium (14.70%, p < 0.01), urinary phosphate (50.30%, p < 0.01) and urinary creatinine (122.44%, p < 0.01) were significantly altered in OVX rats. All these altered responses were significantly restored (AP: 27.53%, p < 0.01; TRAP: 33.51%, p < 0.01; calcium: 53.15%, p < 0.01; phosphate: 27.49%, p < 0.01; creatinine: 46.40%, p < 0.01) by supplementation with hydroalcoholic extract of dried clove buds. Results of bone density, bone mineral content, bone tensile strength and histological analysis also showed similar trend of results, which supported initial observations of this study. It is proposed that hydroalcoholic extract of dried clove buds has bone-preserving efficacy against hypogonadal osteoporosis.

Black Tea May Be a Prospective Adjunct for Calcium Supplementation to Prevent Early Menopausal Bone Loss in a Rat Model of Osteoporosis

The present study was undertaken to find out the ability of black tea extract (BTE) as a suitable alternative of adjunct for calcium supplementation in treating an ovariectomized rat model of early osteoporosis. Female Wistar rats weighing 140–150 g were divided into four groups consisting of six animals in each group: (A) sham-operated control; (B) bilaterally ovariectomized; (C) bilaterally ovariectomized + BTE; (D) bilaterally ovariectomized + 17β-estradiol. Results suggest that BTE could promote intestinal absorption of calcium significantly (P < 0.01 for duodenum and ileum; and P < 0.05 for jejunum). This was found associated with enhanced activities of two relevant intestinal mucosal enzymes alkaline phosphatase (P < 0.01 for duodenum, jejunum, and ileum) and Ca2+ activated ATPase (P < 0.01 for duodenum, jejunum, and ileum). Such BTE-mediated promotion of calcium absorption was coupled with increase in serum estrogen titer (P < 0.01) and recovery of all urinary, bone, and serum osteoporotic marker parameters, including bone histological features. Serum parathyroid hormone level, however, was not altered in these animals (P > 0.05). A comparative study with 17β-estradiol, a well-known adjunct for calcium supplementation, indicated that efficacy of BTE in maintaining skeletal health is close to that of 17β-estradiol. This study suggests that simultaneous use of BTE is promising as a prospective candidate for adjunctive therapies for calcium supplementation in the early stage of menopausal bone changes.

Black Tea (Camellia sinensis) and Bone Loss Protection

The possible beneficial health effects of black tea consumption have been suggested by epidemiological studies and supported by laboratory findings. Animal studies in hypogonadal rats have indicated that black tea has phytoestrogenic potential and putative bone protection as well as restorative actions. These are evidenced by an increase in serum estrogen level, uterotrophic action, prevention of bone loss, increase in bone density (bone breaking strength) and preservation of microarchitecture of bone through modulation of several endogenous factors of bone metabolism. These actions of black tea have been attributed to its flavonoid and flavonol content, particularly theaflavins and thearubigins.

Protective Role of Black Tea Extract against Nonalcoholic Steatohepatitis-Induced Skeletal Dysfunction.

Aim. This paper aimed to examine the chemoprotective actions of aqueous black tea extract (BTE) against nonalcoholic steatohepatitis- (NASH-) induced skeletal changes in rats. Material. Wistar rats (body wt. 155–175 g) of both sexes, aged 4–5 months, were randomly assigned to 3 groups; Group A (control), Group B (60% high-fat diet; HFD), and Group C (HFD + 2.5% BTE). Methods. Several urinary (calcium, phosphate, creatinine, and calcium-to-creatinine ratio) serum (alkaline phosphatase and serum tartrate-resistant acid phosphatase), and molecular markers of bone turnover (receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), and estrogen) were tested. Also, several bone parameters (bone density, bone tensile strength, bone mineral content, and bone histology) and calcium homeostasis were checked. Results. Results indicated that HFD-induced alterations in urinary, serum, and bone parameters as well as calcium homeostasis, all could be significantly ameliorated by BTE supplementation. Conclusion. Results suggest a potential role of BTE as a protective agent against NASH-induced changes in bone metabolism in rats.