Browsing by Author "Gatchie, Linda"

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    Biotransformation of chrysin to baicalein: Selective C6- hydroxylation of 5,7-dihydroxyflavone using whole yeast cells stably expressing human CYP1A1 enzyme
    (ACS Publications, 2017-08-07) Williams, Ibidapo Steven; Chib, Shifali; Nuthakki, V.; Gatchie, Linda; Joshi, Prashant; Narkhede, N.; Vishwakarma, R. A.; Bharate, Sandip B.; Saran, S.; Chaudhuri, Bhabatosh
    Naturally occurring polyphenolic compounds are of medicinal importance because of their unique antioxidant, anticancer and chemopreventive properties. Baicalein, a naturally occurring polyhydroxy flavonoid possessing a diverse range of pharmacological activities, has been used in traditional medicines for treatment of various ailments. Apart from its isolation from natural sources, its synthesis has been reported via multi-step chemical approaches. Here we report a preparative-scale biotransformation, using whole yeast cells stably expressing human cytochrome P450 1A1 (CYP1A1) enzyme, that allows regioselective C6-hydroxylation of 5,7-dihydroxyflavone (chrysin) to form 5,6,7- trihydroxyflavone (baicalein). Molecular modelling reveals why chrysin undergoes such specific hydroxylation mediated by CYP1A1. More than 92% reaction completion was obtained using a shake flask based process that mimics fed-batch fermentation. Such highly efficient selective hydroxylation, using recombinant yeast cells, has not been reported earlier. Similar CYP-expressing yeast cell-based systems are likely to have wider applications in the syntheses of medicinally important polyphenolic compounds
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    Discovery and characterization of novel CYP1B1 inhibitors based on heterocyclic chalcones: Overcoming cisplatin resistance in CYP1B1-overexpressing lines
    (Elsevier, 2017-02-09) Horley, Neill; Beresford, Kenneth J. M.; Chawla, Tarun; McCann, Glen J. P.; Ruparelia, K. C.; Gatchie, Linda; Sonawane, Vinay; Williams, Vinay R.; Tan, Hoon Leong; Joshi, Prashant; Bharate, Sonali S.; Kumar, Vikas; Bharate, Sandip B.; Chaudhuri, Bhabatosh
    The structure of alpha-napthoflavone (ANF), a potent inhibitor of CYP1A1 and CYP1B1, mimics the structure of chalcones. Two potent CYP1B1 inhibitors 7k (DMU2105) and 6j (DMU2139) have been identified from two series of synthetic pyridylchalcones. They inhibit human CYP1B1 enzyme bound to yeast-derived microsomes (Sacchrosomes™) with IC50 values of 10 and 9 nM, respectively, and show a very high level of selectivity towards CYP1B1 with respect to the IC50 values obtained with CYP1A1, CYP1A2, CYP3A4, CYP2D6, CYP2C9 and CYP2C19 Sacchrosomes™. Both compounds also potently inhibit CYP1B1 expressed within ‘live’ recombinant yeast and human HEK293 kidney cells with IC50 values of 63, 65, and 4, 4 nM, respectively. Furthermore, the synthesized pyridylchalcones possess better solubility and lipophilicity values than ANF. Both compounds overcome cisplatineresistance in HEK293 and A2780 cells which results from CYP1B1 overexpression. These potent cell-permeable and water-soluble CYP1B1 inhibitors are likely to have useful roles in the treatment of cancer, glaucoma, ischemia and obesity.
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    (E)-3-(3,4,5-Trimethoxyphenyl)-1-(pyridin-4-yl)prop-2-en-1-one, a heterocyclic chalconeis a potent and selectiveCYP1A1 inhibitor and cancerchemopreventative agent
    (Elsevier, 2017-11-06) Horley, Neill; Beresford, Kenneth J. M.; Kaduskar, S.; Joshi, Prashant; McCann, Glen J. P.; Ruparelia, K. C.; Williams, Ibidapo Steven; Gatchie, Linda; Sonawane, Vinay; Bharate, Sandip B.; Chaudhuri, Bhabatosh
    The overexpression of CYP1 family of enzymes is reported to be associated with development of human carcinomas. It has been well reported that CYP1A1 specific inhibitors prevents carcinogenesis. Herein, thirteen pyridine-4-yl series of chalcones were synthesized and screened for inhibition of CYP1 isoforms 1A1, 1B1 and 1A2 in SacchrosomesTM and live human HEK293 cells. The structure-activity relationship analysis indicated that chalcones bearing tri-alkoxy groups (8a and 8k) on nonheterocyclic ring displayed selective inhibition of CYP1A1 enzyme, with IC50 values of 58 and 65 nM, respectively. The 3,4,5-trimethoxy substituted derivative 8a have shown >10 fold selectivity towards CYP1A1 with respect to other enzymes of the CYP1 subfamily and >100-fold selectivity with respect to CYP2 and CYP3 family of enzymes. The potent and selective CYP1A1 inhibitor 8a displayed antagonism of B[a]P mediated activation of aromatic hydrocarbon receptor (AhR) in yeast cells, and also protected human cells from CYP1A1-mediated B[a]P toxicity in human cells. This potent and selective inhibitor of CYP1A1 enzyme have a potential for development as cancer chemopreventive agent.
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    Glycyrrhiza glabra extract and quercetin reverses cisplatin resistance in triple-negative MDA-MB-468 breast cancer cells via inhibition of cytochrome P450 1B1 enzyme
    (ELSEVIER, 2017-11-07) Sharma, Rajni; Gatchie, Linda; Williams, Ibidapo Steven; Shreyans, K. J.; Vishwakarma, R. A.; Chaudhuri, Bhabatosh; Bharate, Sandip B.
    The development of multi-drug resistance to existing anticancer drugs is one of the major challenges in cancer treatment. The over-expression of cytochrome P450 1B1 enzyme has been reported to cause resistance to cisplatin. With an objective to discover cisplatin-resistance reversal agents, herein, we report the evaluation of Glycyrrhiza glabra (licorice) extracts and its twelve chemical constituents for inhibition of CYP1B1 (and CYP1A1) enzyme in Sacchrosomes and live human cells. The hydroalcoholic extract showed potent inhibition of CYP1B1 in both Sacchrosomes as well as in live cells with IC50 values of 21 and 16 mg/ mL, respectively. Amongst the total of 12 constituents tested, quercetin and glabrol showed inhibition of CYP1B1 in live cell assay with IC50 values of 2.2 and 15 mM, respectively. Both these natural products were found to be selective inhibitors of CYP1B1, and does not inhibit CYP2 and CYP3 family of enzymes (IC50 > 20 mM). The hydroalcoholic extract of G. glabra and quercetin (4) showed complete reversal of cisplatin resistance in CYP1B1 overexpressing triple negative MDA-MB-468 breast cancer cells. The selective inhibition of CYP1B1 by quercetin and glabrol over CYP2 and CYP3 family of enzymes was studied by molecular modeling studies.
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    Identification of karanjin isolated from the Indian beech tree as a potent CYP1 enzyme inhibitor with cellular efficacy via screening of a natural product repository
    (Medicinal Chemistry Communications, 2018-02-01) Joshi, Prashant; Sonawane, Vinay; Williams, Ibidapo Steven; McCann, Glen J. P.; Gatchie, Linda; Sharma, Rajni; Satti, Naresh; Chaudhuri, Bhabatosh; Bharate, Sandip B.
    CYP1A1 is thought to mediate carcinogenesis in oral, lung and epithelial cancers. In order to identify a CYP1A1 inhibitor from an edible plant, 394 natural products in the IIIM's natural product repository were screened, at 10 μM concentration, using CYP1A1-Sacchrosomes™ (i.e. microsomal enzyme isolated from recombinant baker's yeast). Twenty-seven natural products were identified that inhibited 40–97% of CYP1A1's 7-ethoxyresorufin-O-deethylase activity. The IC50 values of the ‘hits’, belonging to different chemical scaffolds, were determined. Their selectivity was studied against a panel of 8 CYP-Sacchrosomes™. In order to assess cellular efficacy, the ‘hits’ were screened for their capability to inhibit CYP enzymes expressed within live recombinant human embryonic kidney (HEK293) cells from plasmids encoding specific CYP genes (1A2, 1B1, 2C9, 2C19, 2D6, 3A4). Isopimpinellin (IN-475; IC50, 20 nM) and karanjin (IN-195; IC50, 30 nM) showed the most potent inhibition of CYP1A1 in human cells. Isopimpinellin is found in celery, parsnip, fruits and in the rind and pulp of limes whereas different parts of the Indian beech tree, which contain karanjin, have been used in traditional medicine. Both isopimpinellin and karanjin negate the cellular toxicity of CYP1A1-mediated benzo[a]pyrene. Molecular docking and molecular dynamic simulations with CYP isoforms rationalize the observed trends in the potency and selectivity of isopimpinellin and karanjin.
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    Quinazoline derivatives as selective CYP1B1 inhibitors
    (Elsevier, 2017-02-16) Siddique, Mohd Usman Mohd; McCann, Glen J. P.; Sonawane, Vinay; Horley, Neill; Gatchie, Linda; Joshi, Prashant; Bharate, Sandip B.; Jayaprakash,Venkatesan; Sinha, Barij N.; Chaudhuri, B.
    CYP1B1 is implicated to have a role in the development of breast, ovarian, renal, skin and lung carcinomas. It has been suggested that identification of potent and specific CYP1B1 inhibitors can lead to a novel treatment of cancer. Flavonoids have a compact rigid skeleton which fit precisely within the binding cavity of CYP1B1. Systematic isosteric replacement of flavonoid 'O' atom with 'N' atom led to the prediction that a 'quinazoline' scaffold could be the basis for designing potential CYP1B1 inhibitors. A total of 20 quinazoline analogs were synthesized and screened for CYP1B1 and CYP1A1 inhibition in Sacchrosomes™. IC50 determinations of six compounds with capability of inhibiting CYP1B1 identified quinazolines 5c and 5h as the best candidates for CYP1B1 inhibition, with IC50 values in the nM range. Further selectivity studies with homologous CYPs, belonging to the CYP1, CYP2 and CYP3 family of enzymes, showed that the compounds are likely to be free from critical drug-drug interaction liability. Molecular modelling studies were performed to rationalize the observed enzymatic inhibitions. Further biological studies in live yeast and human cells, harboring CYP1A1 and CYP1B1 enzymes, have illustrated the most potent compounds' cellular permeability and capability of potently inhibiting CYP1B1 enzyme expressed within live cells.
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    Synthesis and biological evaluation of pyrrole-based chalcones as CYP1 enzyme inhibitors, for possible prevention of cancer and overcoming cisplatin resistance
    (Elsevier, 2017-07-04) Williams, Ibidapo Steven; Joshi, Prashant; Gatchie, Linda; Sharma, M.; Satti, N. K.; Vishwakarma, R. A.; Chaudhuri, Bhabatosh; Bharate, Sandip B.
    Inhibitors of CYP1 enzymes may play vital roles in the prevention of cancer and overcoming chemo-resistance to anticancer drugs. In this letter, we report synthesis of twenty-three pyrrole based heterocyclic chalcones which were screened for inhibition of CYP1 isoforms. Compound 3n potently inhibited CYP1B1 with an IC50 of 0.2 lM in SacchrosomesTM and CYP1B1-expressing live human cells. However, compound 3j which inhibited both CYP1A1 and CYP1B1 with an IC50 of 0.9 mM, using the same systems, also potently antagonized B[a]P-mediated induction of AhR signaling in yeast (IC50, 1.5 mM), fully protected human cells from B[a]P toxicity and completely reversed cisplatin resistance in human cells that overexpress CYP1B1 by restoring cisplatin’s cytotoxicity. Molecular modeling studies were performed to rationalize the observed potency and selectivity of enzyme inhibition by compounds 3j and 3n.