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Displaying publications 521 - 524 of 524 in total

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Evaluation of in vitro antidiabetic and antioxidant characterizations of Elettaria cardamomum (L.) Maton (Zingiberaceae), Piper cubeba L. f. (Piperaceae), and Plumeria rubra L. (Apocynaceae)

Ahmed AS, Ahmed Q, Saxena AK, Jamal P

Pak J Pharm Sci, 2017 Jan;30(1):113-126.
PMID: 28603121

Inhibition of intestinal α-amylase and α-glucosidase is an important strategy to regulate diabetes mellitus (DM). Antioxidants from plants are widely regarded in the prevention of diabetes. Fruits of Elettaria cardamomum (L.) Maton (Zingiberaceae) and Piper cubeba L. f. (Piperaceae) and flowers of Plumeria rubra L. (Apocynaceae) are traditionally used to cure DM in different countries. However, the role of these plants has been grossly under reported and is yet to receive proper scientific evaluation with respect to understand their traditional role in the management of diabetes especially as digestive enzymes inhibitors. Hence, methanol and aqueous extracts of the aforementioned plants were evaluated for their in vitro α-glucosidase and α-amylase inhibition at 1 mg/mL and quantification of their antioxidant properties (DPPH, FRAP tests, total phenolic and total flavonoids contents). In vitro optimization studies for the extracts were also performed to enhance in vitro biological activities. The % inhibition of α-glucosidase by the aqueous extracts of the fruits of E. cardamomum, P. cubeba and flowers of P. rubra were 10.41 (0.03), 95.19 (0.01), and -2.92 (0.03), while the methanol extracts exhibited % inhibition 13.73 (0.02), 92.77 (0.01), and -0.98 (0.01), respectively. The % inhibition of α-amylase by the aqueous extracts were 82.99 (0.01), 64.35 (0.01), and 20.28 (0.02), while the methanol extracts displayed % inhibition 39.93 (0.01), 31.06 (0.02), and 39.40 (0.01), respectively. Aqueous extracts displayed good in vitro antidiabetic and antioxidant activities. Moreover, in vitro optimization experiments helped to increase the α-glucosidase inhibitory activity of E. cardamomum. Our findings further justify the traditional claims of these plants as folk medicines to manage diabetes, however, through digestive enzymes inhibition effect.

Matched MeSH terms: Oxidation-Reduction
Exposure to Electrophiles Impairs Reactive Persulfide-Dependent Redox Signaling in Neuronal Cells

Ihara H, Kasamatsu S, Kitamura A, Nishimura A, Tsutsuki H, Ida T, et al.

Chem Res Toxicol, 2017 09 18;30(9):1673-1684.
PMID: 28837763 DOI: 10.1021/acs.chemrestox.7b00120

Electrophiles such as methylmercury (MeHg) affect cellular functions by covalent modification with endogenous thiols. Reactive persulfide species were recently reported to mediate antioxidant responses and redox signaling because of their strong nucleophilicity. In this study, we used MeHg as an environmental electrophile and found that exposure of cells to the exogenous electrophile elevated intracellular concentrations of the endogenous electrophilic molecule 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP), accompanied by depletion of reactive persulfide species and 8-SH-cGMP which is a metabolite of 8-nitro-cGMP. Exposure to MeHg also induced S-guanylation and activation of H-Ras followed by injury to cerebellar granule neurons. The electrophile-induced activation of redox signaling and the consequent cell damage were attenuated by pretreatment with a reactive persulfide species donor. In conclusion, exogenous electrophiles such as MeHg with strong electrophilicity impair the redox signaling regulatory mechanism, particularly of intracellular reactive persulfide species and therefore lead to cellular pathogenesis. Our results suggest that reactive persulfide species may be potential therapeutic targets for attenuating cell injury by electrophiles.

Matched MeSH terms: Oxidation-Reduction
Proteomic Signatures of Sperm Mitochondria in Varicocele: Clinical Use as Biomarkers of Varicocele Associated Infertility

Samanta L, Agarwal A, Swain N, Sharma R, Gopalan B, Esteves SC, et al.

J Urol, 2018 08;200(2):414-422.
PMID: 29530785 DOI: 10.1016/j.juro.2018.03.009

PURPOSE: Varicocele may disrupt testicular microcirculation and induce hypoxia-ischemia related degenerative changes in testicular cells and spermatozoa. Superoxide production at low oxygen concentration exacerbates oxidative stress in men with varicocele. Therefore, the current study was designed to study the role of mitochondrial redox regulation and its possible involvement in sperm dysfunction in varicocele associated infertility.
MATERIALS AND METHODS: We identified differentially expressed mitochondrial proteins in 50 infertile men with varicocele and in 10 fertile controls by secondary liquid chromatography-tandem mass spectroscopy data driven in silico analysis. Identified proteins were validated by Western blot and immunofluorescence. Seminal oxidation-reduction potential was measured.
RESULTS: We identified 22 differentially expressed proteins related to mitochondrial structure (LETM1, EFHC, MIC60, PGAM5, ISOC2 and import TOM22) and function (NDFSU1, UQCRC2 and COX5B, and the core enzymes of carbohydrate and lipid metabolism). Cluster analysis and 3-dimensional principal component analysis revealed a significant difference between the groups. All proteins studied were under expressed in infertile men with varicocele. Liquid chromatography-tandem mass spectroscopy data were corroborated by Western blot and immunofluorescence. Impaired mitochondrial function was associated with decreased expression of the proteins (ATPase1A4, HSPA2, SPA17 and APOA1) responsible for proper sperm function, concomitant with elevated seminal oxidation-reduction potential in the semen of infertile patients with varicocele.
CONCLUSIONS: Impaired mitochondrial structure and function in varicocele may lead to oxidative stress, reduced ATP synthesis and sperm dysfunction. Mitochondrial differentially expressed proteins should be explored for the development of biomarkers as a predictor of infertility in patients with varicocele. Antioxidant therapy targeting sperm mitochondria may help improve the fertility status of these patients.

Matched MeSH terms: Oxidation-Reduction
Mechanism of the induction of endoplasmic reticulum stress by the anti-cancer agent, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT): Activation of PERK/eIF2α, IRE1α, ATF6 and calmodulin kinase

Merlot AM, Shafie NH, Yu Y, Richardson V, Jansson PJ, Sahni S, et al.

Biochem Pharmacol, 2016 06 01;109:27-47.
PMID: 27059255 DOI: 10.1016/j.bcp.2016.04.001

The endoplasmic reticulum (ER) plays a major role in the synthesis, maturation and folding of proteins and is a critical calcium (Ca(2+)) reservoir. Cellular stresses lead to an overwhelming accumulation of misfolded proteins in the ER, leading to ER stress and the activation of the unfolded protein response (UPR). In the stressful tumor microenvironment, the UPR maintains ER homeostasis and enables tumor survival. Thus, a novel strategy for cancer therapeutics is to overcome chronically activated ER stress by triggering pro-apoptotic pathways of the UPR. Considering this, the mechanisms by which the novel anti-cancer agent, Dp44mT, can target the ER stress response pathways were investigated in multiple cell-types. Our results demonstrate that the cytotoxic chelator, Dp44mT, which forms redox-active metal complexes, significantly: (1) increased ER stress-associated pro-apoptotic signaling molecules (i.e., p-eIF2α, ATF4, CHOP); (2) increased IRE1α phosphorylation (p-IRE1α) and XBP1 mRNA splicing; (3) reduced expression of ER stress-associated cell survival signaling molecules (e.g., XBP1s and p58(IPK)); (4) increased cleavage of the transcription factor, ATF6, which enhances expression of its downstream targets (i.e., CHOP and BiP); and (5) increased phosphorylation of CaMKII that induces apoptosis. In contrast to Dp44mT, the iron chelator, DFO, which forms redox-inactive iron complexes, did not affect BiP, p-IRE1α, XBP1 or p58(IPK) levels. This study highlights the ability of a novel cancer therapeutic (i.e., Dp44mT) to target the pro-apoptotic functions of the UPR via cellular metal sequestration and redox stress. Assessment of ER stress-mediated apoptosis is fundamental to the understanding of the pharmacology of chelation for cancer treatment.

Matched MeSH terms: Oxidation-Reduction