Displaying publications 21 - 40 of 103 in total

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  1. Fulltext C-phycocyanin confers protection against oxalate-mediated oxidative stress and mitochondrial dysfunctions in MDCK cells
    Farooq SM, Boppana NB, Devarajan A, Asokan D, Sekaran SD, Shankar EM, et al.
    PLoS One, 2014;9(4):e93056.
    PMID: 24691130 DOI: 10.1371/journal.pone.0093056
    Oxalate toxicity is mediated through generation of reactive oxygen species (ROS) via a process that is partly dependent on mitochondrial dysfunction. Here, we investigated whether C-phycocyanin (CP) could protect against oxidative stress-mediated intracellular damage triggered by oxalate in MDCK cells. DCFDA, a fluorescence-based probe and hexanoyl-lysine adduct (HEL), an oxidative stress marker were used to investigate the effect of CP on oxalate-induced ROS production and membrane lipid peroxidation (LPO). The role of CP against oxalate-induced oxidative stress was studied by the evaluation of mitochondrial membrane potential by JC1 fluorescein staining, quantification of ATP synthesis and stress-induced MAP kinases (JNK/SAPK and ERK1/2). Our results revealed that oxalate-induced cells show markedly increased ROS levels and HEL protein expression that were significantly decreased following pre-treatment with CP. Further, JC1 staining showed that CP pre-treatment conferred significant protection from mitochondrial membrane permeability and increased ATP production in CP-treated cells than oxalate-alone-treated cells. In addition, CP treated cells significantly decreased the expression of phosphorylated JNK/SAPK and ERK1/2 as compared to oxalate-alone-treated cells. We concluded that CP could be used as a potential free radical-scavenging therapeutic strategy against oxidative stress-associated diseases including urolithiasis.
    Matched MeSH terms: Enzyme Activation/drug effects
  2. Fulltext Cancer-associated fibroblasts promote proliferation of endometrial cancer cells
    Subramaniam KS, Tham ST, Mohamed Z, Woo YL, Mat Adenan NA, Chung I
    PLoS One, 2013;8(7):e68923.
    PMID: 23922669 DOI: 10.1371/journal.pone.0068923
    Endometrial cancer is the most commonly diagnosed gynecologic malignancy worldwide; yet the tumor microenvironment, especially the fibroblast cells surrounding the cancer cells, is poorly understood. We established four primary cultures of fibroblasts from human endometrial cancer tissues (cancer-associated fibroblasts, CAFs) using antibody-conjugated magnetic bead isolation. These relatively homogenous fibroblast cultures expressed fibroblast markers (CD90, vimentin and alpha-smooth muscle actin) and hormonal (estrogen and progesterone) receptors. Conditioned media collected from CAFs induced a dose-dependent proliferation of both primary cultures and cell lines of endometrial cancer in vitro (175%) when compared to non-treated cells, in contrast to those from normal endometrial fibroblast cell line (51%) (P<0.0001). These effects were not observed in fibroblast culture derived from benign endometrial hyperplasia tissues, indicating the specificity of CAFs in affecting endometrial cancer cell proliferation. To determine the mechanism underlying the differential fibroblast effects, we compared the activation of PI3K/Akt and MAPK/Erk pathways in endometrial cancer cells following treatment with normal fibroblasts- and CAFs-conditioned media. Western blot analysis showed that the expression of both phosphorylated forms of Akt and Erk were significantly down-regulated in normal fibroblasts-treated cells, but were up-regulated/maintained in CAFs-treated cells. Treatment with specific inhibitors LY294002 and U0126 reversed the CAFs-mediated cell proliferation (P<0.0001), suggesting for a role of these pathways in modulating endometrial cancer cell proliferation. Rapamycin, which targets a downstream molecule in PI3K pathway (mTOR), also suppressed CAFs-induced cell proliferation by inducing apoptosis. Cytokine profiling analysis revealed that CAFs secrete higher levels of macrophage chemoattractant protein (MCP)-1, interleukin (IL)-6, IL-8, RANTES and vascular endothelial growth factor (VEGF) than normal fibroblasts. Our data suggests that in contrast to normal fibroblasts, CAFs may exhibit a pro-tumorigenic effect in the progression of endometrial cancer, and PI3K/Akt and MAPK/Erk signaling may represent critical regulators in how endometrial cancer cells respond to their microenvironment.
    Matched MeSH terms: Enzyme Activation/drug effects
  3. Fulltext Cardioprotection by isosteviol derivate JC105: A unique drug property to activate ERK1/2 only when cells are exposed to hypoxia-reoxygenation
    Mohammed Abdul KS, Rayadurgam J, Faiz N, Jovanović A, Tan W
    J Cell Mol Med, 2020 09;24(18):10924-10934.
    PMID: 32794652 DOI: 10.1111/jcmm.15721
    In the present study, we have investigated potential cardioprotective properties of Isosteviol analogue we recently synthesized and named JC105. Treatment of heart embryonic H9c2 cells with JC105 (10 μM) significantly increased survival of cells exposed to hypoxia-reoxygenation. JC105 (10 μM) activated ERK1/2, DRP1 and increased levels of cardioprotective SUR2A in hypoxia-reoxygenation, but did not have any effects on ERK1/2, DRP1 and/or SUR2A in normoxia. U0126 (10 μM) inhibited JC105-mediated phosphorylation of ERK1/2 and DRP1 without affecting AKT or AMPK, which were also not regulated by JC105. Seahorse bioenergetic analysis demonstrated that JC105 (10 μM) did not affect mitochondria at rest, but it counteracted all mitochondrial effects of hypoxia-reoxygenation. Cytoprotection afforded by JC105 was inhibited by U0126 (10 μM). Taken all together, these demonstrate that (a) JC105 protects H9c2 cells against hypoxia-reoxygenation and that (b) this effect is mediated via ERK1/2. The unique property of JC105 is that selectively activates ERK1/2 in cells exposed to stress, but not in cells under non-stress conditions.
    Matched MeSH terms: Enzyme Activation/drug effects
  4. Caspase-dependent and -independent mechanisms in apoptosis induced by hydroquinone and catechol metabolites of remoxipride in HL-60 cells
    Inayat-Hussain SH, McGuinness SM, Johansson R, Lundstrom J, Ross D
    Chem Biol Interact, 2000 Aug 15;128(1):51-63.
    PMID: 10996300
    The hydroquinone and catechol like metabolites, NCQ344 and NCQ436 respectively, of the antipsychotic remoxipride have recently been demonstrated to induce apoptosis in myeloperoxidase (MPO)-rich human bone marrow progenitor and HL-60 cells [S.M. McGuinness, R. Johansson, J. Lundstrom, D. Ross, Induction of apoptosis by remoxipride metabolites in HL-60 and CD34+/CD19- human bone marrow progenitor cells: potential relevance to remoxipride-induced aplastic anemia, Chem. Biol. Interact. 121 (1999) 253-265]. In the present study, we determined the molecular mechanisms of apoptosis induced by these remoxipride metabolites in HL-60 cells. Our results show that apoptosis was accompanied by phosphatidylserine (PS) exposure, activation of caspases-9, -3, -7 and DNA cleavage. In HL-60 cells treated with the hydroquinone NCQ344 and catechol NCQ436, the general caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp. fluoromethyl ketone (Z-VAD.FMK) blocked DNA cleavage and activation of caspases-9, -3/-7. In addition, PS exposure was significantly but not completely inhibited by Z-VAD.FMK. These results demonstrate that although Z-VAD.FMK inhibitable caspases are necessary for maximal apoptosis induced by NCQ344 and NCQ436, additional caspase-independent processes may orchestrate changes leading to PS exposure during apoptosis induced by the remoxipride polyphenolic metabolites.
    Matched MeSH terms: Enzyme Activation
  5. Caspases-3 and -7 are activated in goniothalamin-induced apoptosis in human Jurkat T-cells
    Inayat-Hussain SH, Osman AB, Din LB, Ali AM, Snowden RT, MacFarlane M, et al.
    FEBS Lett., 1999 Aug 13;456(3):379-83.
    PMID: 10462048
    Goniothalamin, a plant styrylpyrone derivative isolated from Goniothalamus andersonii, induced apoptosis in Jurkat T-cells as assessed by the externalisation of phosphatidylserine. Immunoblotting showed processing of caspases-3 and -7 with the appearance of their catalytically active large subunits of 17 and 19 kDa, respectively. Activation of these caspases was further evidenced by detection of poly(ADP-ribose) polymerase cleavage (PARP). Pre-treatment with the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethyl ketone (Z-VAD.FMK) blocked apoptosis and the resultant cleavage of these caspases and PARP. Our results demonstrate that activation of at least two effector caspases is a key feature of goniothalamin-induced apoptosis in Jurkat T-cells.
    Matched MeSH terms: Enzyme Activation/drug effects
  6. Catalase and superoxide dismutase activities and the total protein content of protocorm-like bodies of Dendrobium sonia-28 subjected to vitrification
    Poobathy R, Sinniah UR, Xavier R, Subramaniam S
    Appl Biochem Biotechnol, 2013 Jul;170(5):1066-79.
    PMID: 23640259 DOI: 10.1007/s12010-013-0241-z
    Dendrobium sonia-28 is an important ornamental orchid in the Malaysian flower industry. However, the genus faces both low germination rates and the risk of producing heterozygous progenies. Cryopreservation is currently the favoured long-term storage method for orchids with propagation problems. Vitrification, a frequently used cryopreservation technique, involves the application of pretreatments and cryoprotectants to protect and recover explants during and after storage in liquid nitrogen. However, cryopreservation may cause osmotic injuries and toxicity to cryopreserved explants from the use of highly concentrated additives, and cellular injuries from thawing, devitrification and ice formation. Reactive oxygen species (ROS), occurring during dehydration and cryopreservation, may also cause membrane damage. Plants possess efficient antioxidant systems such as the superoxide dismutase (SOD) and catalase (CAT) enzymes to scavenge ROS during low temperature stress. In this study, protocorm-like bodies (PLBs) of Dendrobium sonia-28 were assayed for the total protein content, and both SOD and CAT activities, at each stage of a vitrification exercise to observe for deleterious stages in the protocol. The results indicated that cryopreserved PLBs of Dendrobium sonia-28 underwent excessive post-thawing oxidative stress due to decreased levels of the CAT enzyme at the post-thawing recovery stage, which contributed to the poor survival rates of the cryopreserved PLBs.
    Matched MeSH terms: Enzyme Activation
  7. Catalysis by Glomerella cingulata cutinase requires conformational cycling between the active and inactive states of its catalytic triad
    Nyon MP, Rice DW, Berrisford JM, Hounslow AM, Moir AJ, Huang H, et al.
    J Mol Biol, 2009 Jan 9;385(1):226-35.
    PMID: 18983850 DOI: 10.1016/j.jmb.2008.10.050
    Cutinase belongs to a group of enzymes that catalyze the hydrolysis of esters and triglycerides. Structural studies on the enzyme from Fusarium solani have revealed the presence of a classic catalytic triad that has been implicated in the enzyme's mechanism. We have solved the crystal structure of Glomerella cingulata cutinase in the absence and in the presence of the inhibitors E600 (diethyl p-nitrophenyl phosphate) and PETFP (3-phenethylthio-1,1,1-trifluoropropan-2-one) to resolutions between 2.6 and 1.9 A. Analysis of these structures reveals that the catalytic triad (Ser136, Asp191, and His204) adopts an unusual configuration with the putative essential histidine His204 swung out of the active site into a position where it is unable to participate in catalysis, with the imidazole ring 11 A away from its expected position. Solution-state NMR experiments are consistent with the disrupted configuration of the triad observed crystallographically. H204N, a site-directed mutant, was shown to be catalytically inactive, confirming the importance of this residue in the enzyme mechanism. These findings suggest that, during its catalytic cycle, cutinase undergoes a significant conformational rearrangement converting the loop bearing the histidine from an inactive conformation, in which the histidine of the triad is solvent exposed, to an active conformation, in which the triad assumes a classic configuration.
    Matched MeSH terms: Enzyme Activation/drug effects
  8. Cellular and hormonal control in glycogen metabolism--recent advances
    Thambyrajah V, Karunairatnam MC
    Med J Malaya, 1972 Sep;27(1):33-9.
    PMID: 4345646
    Matched MeSH terms: Enzyme Activation
  9. Effects of glycyrrhizic acid on 11 β-hydroxysteroid dehydrogenase (11 βHSD1 and 2) activities and HOMA-IR in rats at different treatment periods
    Chia YY, Yin YY, Ton SH, Kadir KB
    Exp. Clin. Endocrinol. Diabetes, 2010 Oct;118(9):617-24.
    PMID: 19998240 DOI: 10.1055/s-0029-1237703
    Glycyrrhizic acid (GA) has been reported to inhibit postprandial blood glucose rise and 11 β-hydroxysteroid dehydrogenase 1 (11 βHSD1) activity. As not much work has been done on GA effects on 11 βHSD1 and 2 and HOMA-IR at different treatment periods, this work was conducted. 60 male Sprague Dawley rats fed AD LIBITUM were assigned into six groups of control and treated that were given GA at different duration namely 12, 24 and 48 h. Treated and control groups were intraperitoneally administered with GA (50 mgkg (-1)) and saline respectively. Blood and subcutaneous (ATS) and visceral adipose tissue (ATV), abdominal (MA) and quadriceps femoris muscle (MT), liver (L) and kidney (K) were examined. HOMA-IR in GA-treated rats decreased in all groups (P<0.05). In the 12-h and 24-h treated rats, 11 βHSD1 activities decreased in all tissues (P<0.05) except MA and MT (P>0.05) in the former and ATV (P>0.05) in the latter. However, 11 βHSD1 activities decreased significantly in all tissues ( P<0.05) in the 48-h treated rats. Significant decrease in 11 βHSD2 (P>0.05) activities were observed in the L of all treatment groups and K in the 24-h and 48-h treated rats (P<0.05). Histological analysis on ATS showed increase in the number of small-size adipocytes while ATV adipocytes showed shrinkage after GA administration. Increased glycogen deposition in the L was observed in the GA-administered rats in all the treatment periods. In conclusion, GA treatment showed a decrease in the HOMA-IR and both 11 βHSD1 and 2 activities in all tissues, with more profound decrease in the 48-h treated rats.
    Matched MeSH terms: Enzyme Activation/drug effects
  10. Effects of iridoids on lipoxygenase and hyaluronidase activities and their activation by beta-glucosidase in the presence of amino acids
    Ling SK, Tanaka T, Kouno I
    Biol Pharm Bull, 2003 Mar;26(3):352-6.
    PMID: 12612446
    Enzyme inhibitory activities of 14 iridoids previously obtained from two Malaysian medicinal plants, Saprosma scortechinii and Rothmannia macrophylla, were evaluated in vitro using soybean lipoxygenase and bovine testis hyaluronidase. Most of the iridoids, including asperulosidic acid, paederosidic acid, and an epimeric mixture of gardenogenins A and B, did not show any effect on the enzyme activities, except for the bis-iridoids, which inhibited the lipoxygenase activity with their IC(50) values of approximately 1.3 times that of a known inhibitor, fisetin. Structural modification of asperulosidic acid and paederosidic acid through enzymatic hydrolysis by beta-glucosidase resulted in their inhibition towards the enzyme activities, and these activities were enhanced by the presence of some amino acids (lysine, leucine or glutamic acid) or ammonium acetate. Mixtures of gardenogenins A and B; isomers of non-glucosidic iridoids, incubated with amino acid or ammonium acetate did not show any inhibitory effect on the enzyme activities during the 6 h incubation period, except for lysine where spontaneous reaction between the iridoids and amino acid resulted in the inhibition of lipoxygenase activity. The results from these biomimetic reactions suggested that the iridoid aglycons and the intermediates formed by these reactive species could inhibit the enzyme activities, and thus substantiate previous reports that the formation of iridoidal aglycons is a prerequisite for the iridoid glycosides to demonstrate some of the biological activities. In addition, the results also indicated that it is worthwhile to further explore these intermediates as potential anti-inflammatory agents.
    Matched MeSH terms: Enzyme Activation/drug effects
  11. Effects of novel diarylpentanoid analogues of curcumin on secretory phospholipase A2 , cyclooxygenases, lipo-oxygenase, and microsomal prostaglandin E synthase-1
    Ahmad W, Kumolosasi E, Jantan I, Bukhari SN, Jasamai M
    Chem Biol Drug Des, 2014 Jun;83(6):670-81.
    PMID: 24406103 DOI: 10.1111/cbdd.12280
    Arachidonic acid and its metabolites have generated a heightened interest due to their significant role in inflammation. Inhibiting the enzymes involved in arachidonic acid metabolism has been considered as the synergistic anti-inflammatory effect. A series of novel curcumin diarylpentanoid analogues were synthesized and evaluated for their inhibitory effects on activity of secretory phospholipase A2 , cyclooxygenases, soybean lipo-oxygenase as well as microsomal prostaglandin E synthase-1. Among the curcumin analogues, compounds 3, 6, 9, 12, and 17 exhibited strong inhibition of secretory phospholipase A2 activity, with IC50 values ranging from 5.89 to 11.02 μm. Seven curcumin analogues 1, 3, 6, 7, 9, 11, and 12 showed inhibition of cyclooxygenases-2 with IC50 values in the range of 46.11 to 94.86 μm, which were lower than that of curcumin. Compounds 3, 6, 7, 12, and 17 showed strong inhibition of lipo-oxygenase enzyme activity. Preliminary screening of diarylpentanoid curcumin analogues for microsomal prostaglandin E synthase-1 activity revealed that four diarylpentanoid curcumin analogues 5, 6, 7, and 13 demonstrated higher inhibition of microsomal prostaglandin E synthase-1 activity with IC50 ranging from 2.41 to 4.48 μm, which was less than that of curcumin. The present results suggest that some of these diarylpentanoid analogues were able to inhibit the activity of these enzymes. This raises the possibility that diarylpentanoid analogues of curcumin might serve as useful starting point for the design of improved anti-inflammatory agents.
    Matched MeSH terms: Enzyme Activation/drug effects
  12. Effects of tocotrienols on cell viability and apoptosis in normal murine liver cells (BNL CL.2) and liver cancer cells (BNL 1ME A.7R.1), in vitro
    Har CH, Keong CK
    Asia Pac J Clin Nutr, 2005;14(4):374-80.
    PMID: 16326644
    The effects of tocotrienols on murine liver cell viability and their apoptotic events were studied over a dose range of 0-32 microg mL(-1). Normal murine liver cells (BNL CL.2) and murine liver cancer cells (BNL 1ME A.7R.1) were treated with tocotrienols (T(3)), alpha tocopherol (alpha-T) and the chemo drug, Doxorubicin (Doxo, as a positive control). Cell viability assay showed that T(3) significantly (P < or = 0.05) lowered the percentage of BNL 1ME A.7R.1 cell viability in a dose-responsive manner (8-16 microg mL(-1)), whereas T did not show any significant (P>0.05) inhibition in cell viability with increasing treatment doses of 0-16 microg mL(-1). The IC(50) for tocotrienols were 9.8, 8.9, 8.1, 9.7, 8.1 and 9.3 microg mL(-1) at 12, 24, 36, 48, 60 and 72 hours respectively. Early apoptosis was detected 6 hours following T(3) treatment of BNL 1ME A.7R.1 liver cancer cells, using Annexin V-FITC fluorescence microscopy assay for apoptosis, but none were observed for the non-treated liver cancer cells at the average IC(50) of 8.98 microg mL(-1) tocotrienols for liver cancer cells. Several apoptotic bodies were detected in BNL 1ME A.7R.1 liver cancer cells at 6 hours post-treatment with tocotrienols (8.98 microg mL(-1)) using Acridine Orange/Propidium Iodide fluorescence assay. However, only a couple of apoptotic bodies were seen in the non-treated liver cancer cells and the BNL CL.2 normal liver cells. Some mitotic bodies were also observed in the T(3)-treated BNL 1ME A.7R.1 liver cancer cells but were not seen in the untreated BNL 1ME A.7R.1 cells and the BNL CL.2 liver cells. Following T(3)-treatment (8.98 microg mL(-1)) of the BNL 1ME A.7R.1 liver cancer cells, 24.62%, 25.53% and 44.90% of the cells showed elevated active caspase 3 activity at 9, 12 and 24 hours treatment period, respectively. DNA laddering studies indicated DNA fragmentation occurred in the T(3)-treated liver cancer cells, BNL 1ME A.7R.1 but not in non-treated liver cancer cells and the T(3)-treated and non-treated normal liver cells. These results suggest that tocotrienols were able to reduce the cell viability in the murine liver cancer cells at a dose of 8-32 microg mL(-1) and that this decrease in percentage cell viability may be due to apoptosis.
    Matched MeSH terms: Enzyme Activation
  13. Evaluation of BP-M-CPF4 polyhydroxyalkanoate (PHA) synthase on the production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from plant oil using Cupriavidus necator transformants
    Tan HT, Chek MF, Lakshmanan M, Foong CP, Hakoshima T, Sudesh K
    Int J Biol Macromol, 2020 Sep 15;159:250-257.
    PMID: 32417540 DOI: 10.1016/j.ijbiomac.2020.05.064
    Among the various types of polyhydroxyalkanoate (PHA), poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] has a high potential to serve as commercial bioplastic due to its striking resemblance to petroleum-based plastics. In this study, five different genotypes of Cupriavidusnecator transformants harbouring the phaCBP-M-CPF4 gene (including PHB¯4/pBBR1-CBP-M-CPF4) were developed to evaluate the efficiency of 3HHx monomer incorporation. The fraction of 3-hydroxyhexanoate (3HHx) monomer that was incorporated into the PHA synthesized by these C. necator transformants using palm oil as the sole carbon source, was examined. Overall, co-expression of enoyl-CoA hydratase gene (phaJ1) from Pseudomonas aeruginosa, along with PHA synthase (PhaC), increased the 3HHx composition in the PHA copolymer. The differences in the enzyme activities of β-ketothiolase (PhaACn) and NADPH-dependent acetoacetyl-CoA reductase (PhaBCn) of the C. necator mutant hosts used in this study, were observed to alter the 3HHx composition and molecular weight of the PHA copolymer produced. The 3HHx fractions in the P(3HB-co-3HHx) produced by these C. necator transformants ranged between 1 and 18 mol%, while the weight-average molecular weight ranged from 0.7 × 106 to 1.8 × 106 Da. PhaCBP-M-CPF4 displayed a typical initial lag-phase and a relatively low synthase activity in the in vitro enzyme assay, which is thought to be the reason for the higher molecular weights of PHA obtained in this study.
    Matched MeSH terms: Enzyme Activation
  14. Fulltext F16, a fraction from Eurycoma longifolia jack extract, induces apoptosis via a caspase-9-independent manner in MCF-7 cells
    Tee TT, Cheah YH, Hawariah LP
    Anticancer Res, 2007 Sep-Oct;27(5A):3425-30.
    PMID: 17970090
    F16 is a plant-derived pharmacologically active fraction extracted from Eurycoma longifolia Jack. Previously, we have reported that F16 inhibited the proliferation of MCF-7 human breast cancer cells by inducing apoptotic cell death while having some degree of cytoselectivity on a normal human breast cell line, MCF-10A. In this study, we attempted to further elucidate the mode of action of F16. We found that the intrinsic apoptotic pathway was invoked, with the reduction of Bcl-2 protein. Then, executioner caspase-7 was cleaved and activated in response to F16 treatment. Furthermore, apoptosis in the MCF- 7 cells was accompanied by the specific proteolytic cleavage of poly(ADP-ribose) polymerase-1 (PARP-1). Surprisingly, caspase-9 and p53 were unchanged with F16 treatment. We believe that the F16-induced apoptosis in MCF-7 cells occurs independently of caspase-9 and p53. Taken together, these results suggest that F16 from E. longifolia exerts anti-proliferative action and growth inhibition on MCF-7 cells through apoptosis induction and that it may have anticancer properties.
    Matched MeSH terms: Enzyme Activation/drug effects
  15. Fulltext Flavokawain C Inhibits Cell Cycle and Promotes Apoptosis, Associated with Endoplasmic Reticulum Stress and Regulation of MAPKs and Akt Signaling Pathways in HCT 116 Human Colon Carcinoma Cells
    Phang CW, Karsani SA, Sethi G, Abd Malek SN
    PLoS One, 2016;11(2):e0148775.
    PMID: 26859847 DOI: 10.1371/journal.pone.0148775
    Flavokawain C (FKC) is a naturally occurring chalcone which can be found in Kava (Piper methysticum Forst) root. The present study evaluated the effect of FKC on the growth of various human cancer cell lines and the underlying associated mechanisms. FKC showed higher cytotoxic activity against HCT 116 cells in a time- and dose-dependent manner in comparison to other cell lines (MCF-7, HT-29, A549 and CaSki), with minimal toxicity on normal human colon cells. The apoptosis-inducing capability of FKC on HCT 116 cells was evidenced by cell shrinkage, chromatin condensation, DNA fragmentation and increased phosphatidylserine externalization. FKC was found to disrupt mitochondrial membrane potential, resulting in the release of Smac/DIABLO, AIF and cytochrome c into the cytoplasm. Our results also revealed that FKC induced intrinsic and extrinsic apoptosis via upregulation of the levels of pro-apoptotic proteins (Bak) and death receptors (DR5), while downregulation of the levels of anti-apoptotic proteins (XIAP, cIAP-1, c-FlipL, Bcl-xL and survivin), resulting in the activation of caspase-3, -8 and -9 and cleavage of poly(ADP-ribose) polymerase (PARP). FKC was also found to cause endoplasmic reticulum (ER) stress, as suggested by the elevation of GADD153 protein after FKC treatment. After the cells were exposed to FKC (60μM) over 18hrs, there was a substantial increase in the phosphorylation of ERK 1/2. The expression of phosphorylated Akt was also reduced. FKC also caused cell cycle arrest in the S phase in HCT 116 cells in a time- and dose-dependent manner and with accumulation of cells in the sub-G1 phase. This was accompanied by the downregulation of cyclin-dependent kinases (CDK2 and CDK4), consistent with the upregulation of CDK inhibitors (p21Cip1 and p27Kip1), and hypophosphorylation of Rb.
    Matched MeSH terms: Enzyme Activation/drug effects
  16. Fulltext Functional expression of a novel α-amylase from Antarctic psychrotolerant fungus for baking industry and its magnetic immobilization
    He L, Mao Y, Zhang L, Wang H, Alias SA, Gao B, et al.
    BMC Biotechnol, 2017 02 28;17(1):22.
    PMID: 28245836 DOI: 10.1186/s12896-017-0343-8
    BACKGROUND: α-Amylase plays a pivotal role in a broad range of industrial processes. To meet increasing demands of biocatalytic tasks, considerable efforts have been made to isolate enzymes produced by extremophiles. However, the relevant data of α-amylases from cold-adapted fungi are still insufficient. In addition, bread quality presents a particular interest due to its high consummation. Thus developing amylases to improve textural properties could combine health benefits with good sensory properties. Furthermore, iron oxide nanoparticles provide an economical and convenient method for separation of biomacromolecules. In order to maximize the catalytic efficiency of α-amylase and support further applications, a comprehensive characterization of magnetic immobilization of α-amylase is crucial and needed.

    RESULTS: A novel α-amylase (AmyA1) containing an open reading frame of 1482 bp was cloned from Antarctic psychrotolerant fungus G. pannorum and then expressed in the newly constructed Aspergillus oryzae system. The purified recombinant AmyA1 was approximate 52 kDa. AmyA1 was optimally active at pH 5.0 and 40 °C, and retained over 20% of maximal activity at 0-20 °C. The K m and V max values toward soluble starch were 2.51 mg/mL and 8.24 × 10-2 mg/(mL min) respectively, with specific activity of 12.8 × 103 U/mg. AmyA1 presented broad substrate specificity, and the main hydrolysis products were glucose, maltose, and maltotetraose. The influence of AmyA1 on the quality of bread was further investigated. The application study shows a 26% increase in specific volume, 14.5% increase in cohesiveness and 14.1% decrease in gumminess in comparison with the control. AmyA1 was immobilized on magnetic nanoparticles and characterized. The immobilized enzyme showed improved thermostability and enhanced pH tolerance under neutral conditions. Also, magnetically immobilized AmyA1 can be easily recovered and reused for maximum utilization.

    CONCLUSIONS: A novel α-amylase (AmyA1) from Antarctic psychrotolerant fungus was cloned, heterologous expression in Aspergillus oryzae, and characterized. The detailed report of the enzymatic properties of AmyA1 gives new insights into fungal cold-adapted amylase. Application study showed potential value of AmyA1 in the food and starch fields. In addition, AmyA1 was immobilized on magnetic nanoparticles and characterized. The improved stability and longer service life of AmyA1 could potentially benefit industrial applications.

    Matched MeSH terms: Enzyme Activation
  17. Garlic flavonoids alleviate H2 O2 induced oxidative damage in L02 cells and induced apoptosis in HepG2 cells by Bcl-2/Caspase pathway
    Gao X, Yanan J, Santhanam RK, Wang Y, Lu Y, Zhang M, et al.
    J Food Sci, 2021 Feb;86(2):366-375.
    PMID: 33448034 DOI: 10.1111/1750-3841.15599
    Liver damage is a common liver disorder, which could induce liver cancer. Oral antioxidant is one of the effective treatments to prevent and alleviate liver damage. In this study, three flavonoids namely myricetin, isoquercitrin, and isorhamnetin were isolated and identified from Laba garlic. The isolated compounds were investigated on the protective effects against H2 O2 -induced oxidative damages in hepatic L02 cells and apoptosis inducing mechanism in hepatic cancer cells HepG2 by using MTT assay, flow cytometry and western blotting analysis. Myricetin, isoquercitrin, and isorhamnetin showed proliferation inhibition on HepG2 cells with IC50 value of 44.32 ± 0.213 µM, 49.68 ± 0.192 µM, and 54.32 ± 0.176 µM, respectively. While they showed low toxicity on normal cell lines L02. They could significantly alleviate the oxidative damage towards L02 cells (P < 0.05), via inhibiting the morphological changes in mitochondria and upholding the integrity of mitochondrial structure and function. The fluorescence intensity of L02 cells pre-treated with myricetin, isoquercitrin, and isorhamnetin (100 µM) was 89.23 ± 1.26%, 89.35 ± 1.43% and 88.97 ± 0.79%, respectively. Moreover, the flavonoids could induce apoptosis in HepG2 cells via Bcl-2/Caspase pathways, where it could up-regulate the expression of Bax and down-regulate the expression of Bcl-2, Bcl-xL, pro-Caspase-3, and pro-Caspase-9 proteins in a dose dependent manner. Overall, the results suggested that the flavonoids from Laba garlic might be a promising candidate for the treatment of various liver disorders. PRACTICAL APPLICATION: Flavonoids from Laba garlic showed selective toxicity towards HepG2 cells in comparison to L02 cells via regulating Bcl-2/caspase pathway. Additionally, the isolated flavonoids expressively barred the oxidative damage induced by H2 O2 in L02 cells. These results suggested that the flavonoids from laba garlic could be a promising agent towards the development of functional foods.
    Matched MeSH terms: Enzyme Activation/drug effects
  18. Fulltext Genome wide transcriptome profiling of a murine acute melioidosis model reveals new insights into how Burkholderia pseudomallei overcomes host innate immunity
    Chin CY, Monack DM, Nathan S
    BMC Genomics, 2010;11:672.
    PMID: 21110886 DOI: 10.1186/1471-2164-11-672
    At present, very little is known about how Burkholderia pseudomallei (B. pseudomallei) interacts with its host to elicit melioidosis symptoms. We established a murine acute-phase melioidosis model and used DNA microarray technology to investigate the global host/pathogen interaction. We compared the transcriptome of infected liver and spleen with uninfected tissues over an infection period of 42 hr to identify genes whose expression is altered in response to an acute infection.
    Matched MeSH terms: Enzyme Activation
  19. Fulltext Goniothalamin induces coronary artery smooth muscle cells apoptosis: the p53-dependent caspase-2 activation pathway
    Chan KM, Rajab NF, Siegel D, Din LB, Ross D, Inayat-Hussain SH
    Toxicol. Sci., 2010 Aug;116(2):533-48.
    PMID: 20498002 DOI: 10.1093/toxsci/kfq151
    Goniothalamin (GN), a styryl-lactone isolated from Goniothalamus andersonii, has been demonstrated to possess antirestenostic properties by inducing apoptosis on coronary artery smooth muscle cells (CASMCs). In this study, the molecular mechanisms of GN-induced CASMCs apoptosis were further elucidated. Apoptosis assessment based on the externalization of phosphatidylserine demonstrated that GN induces CASMCs apoptosis in a concentration-dependent manner. The GN-induced DNA damage occurred with concomitant elevation of p53 as early as 2 h, demonstrating an upstream signal for apoptosis. However, the p53 elevation in GN-treated CASMCs was independent of NAD(P)H: quinone oxidoreductase 1 and Mdm-2 expression. An increase in hydrogen peroxide and reduction in free thiols confirmed the role for oxidative stress in GN treatment. Pretreatment with the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD-FMK) that significantly abrogated GN-induced CASMCs apoptosis suggested the involvement of caspase(s). The role of apical caspase-2, -8, and -9 was then investigated, and sequential activation of caspase-2 and -9 but not caspase-8 leading to downstream caspase-3 cleavage was observed in GN-treated CASMCs. Reduction of ATP level and decrease in oxygen consumption further confirmed the role of mitochondria in GN-induced apoptosis in CASMCs. The mitochondrial release of cytochrome c was seen without mitochondrial membrane potential loss and was independent of cardiolipin. These data provide insight into the mechanisms of GN-induced apoptosis, which may have important implications in the development of drug-eluting stents.
    Matched MeSH terms: Enzyme Activation
  20. Goniothalamin selectively induces apoptosis on human hepatoblastoma cells through caspase-3 activation
    Al-Qubaisi M, Rosli R, Subramani T, Omar AR, Yeap SK, Ali AM, et al.
    Nat Prod Res, 2013;27(23):2216-8.
    PMID: 23767409 DOI: 10.1080/14786419.2013.800979
    Goniothalamin is a biologically active styrylpyrone derivative isolated from various Goniothalamus species. The ability of goniothalamin to induce apoptosis via caspase-3 activation against hepatoblastoma (HepG2) and normal liver cells (Chang cells) was studied using morphological and biochemical evaluations. HepG2 and Chang cells were treated with goniothalamin for 72 h and analysed by TUNEL and Annexin-V/PI staining. Furthermore, the post-mitochondrial caspase-3 was quantified using ELISA. In view of our results, goniothalamin induced apoptosis on treated cells via alteration of cellular membrane integrity and cleavage of DNA. On the other hand, post-mitochondrial caspase-3 activity was significantly elevated in HepG2 cells treated with goniothalamin after 72 h. These findings suggest that goniothalamin induced apoptosis on HepG2 liver cancer cells via induction of caspase-3 with less sensitivity on the cell line of Chang cells.
    Matched MeSH terms: Enzyme Activation
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