Luminescent enzyme substrate

P-glycoprotein-mediated efflux transport of coelenterazine was the cause of the poor bioluminescence observed in HCT-8 control cells transiently expressing Renilla luciferase (RLuc). On the other hand, strong bioluminescence is shown in HCT-8 cells that transiently produce RLuc, a condition in which shRNAi downregulates P-glycoprotein [3].

After giving animals an intravenous injection of coelenterazine (2 mg/kg), which was followed by five minutes of exposure to a charge-coupled device (CCD) camera, the in vivo growth potential of HCC1806-RR was observed. Rluc activity was observed as luminosity released by tumor cells and was captured as pseudocolor images overlaying monochrome animal photos. The majority of animals also displayed metastases to the inguinal ILN in addition to exhibiting extremely high Rluc activity at the main location [4].

Bioluminescence is a widespread natural phenomenon. Luminous organisms are found among bacteria, fungi, protozoa, coelenterates, worms, molluscs, insects, and fish. Studies on bioluminescent systems of various organisms have revealed an interesting feature - the mechanisms underlying visible light emission are considerably different in representatives of different taxa despite the same final result of this biochemical process. Among the several substrates of bioluminescent reactions identified in marine luminous organisms, the most commonly used are imidazopyrazinone derivatives such as coelenterazine and Cypridina luciferin. Although the substrate used is the same, bioluminescent proteins that catalyze light emitting reactions in taxonomically remote luminous organisms do not show similarity either in amino acid sequences or in spatial structures. In this review, we consider luciferases of various luminous organisms that use coelenterazine or Cypridina luciferin as a substrate, as well as modifications of these proteins that improve their physicochemical and bioluminescent properties and therefore their applicability in bioluminescence imaging in vivo.[1]

The oxidation of free coelenterazine by superoxide anion was analyzed and compared to the oxidation by the semisynthetic photoprotein obelin, prepared by incorporation of synthetic coelenterazine into apoobelin. The oxidation of bound coelenterazine was triggered upon binding of calcium to the reconstituted photoprotein. The oxidation of free synthetic coelenterazine, in the absence of the apoprotein, was triggered by superoxide anion. The production of reactive oxygen metabolites by fMet-Leu-Phe- and 4b-phorbol 12b-myristate 13a-acetate-stimulated neutrophils was studied by means of the luminescence of synthetic coelenterazine. The features of this chemiluminescent probe were compared with those of luminol and are summarized as follows: (a) coelenterazine-dependent chemiluminescence was inhibited by superoxide dismutase; (b) coelenterazine was as sensitive as luminol in detecting the oxidative burst of neutrophils; (c) azide failed to inhibit coelenterazine chemiluminescence; (d) in contrast with luminol, which requires the catalytic removal of hydrogen peroxide, coelenterazine chemiluminescence did not depend on the activity of cell-derived myeloperoxidase. These results indicate the usefulness of coelenterazine as a very sensitive and specific chemiluminescence probe of superoxide anion.[2]

[1]. Coelenterazine-dependent luciferases. Biochemistry (Mosc). 2015 Jun;80(6):714-32.

[2]. Coelenterazine is a superoxide anion-sensitive chemiluminescent probe: its usefulness in the assay of respiratory burst in neutrophils. Anal Biochem. 1992 Nov 1;206(2):273-7.

[3]. In vivo RNA interference-mediated ablation of MDR1 P-glycoprotein. Clin Cancer Res. 2005 Jun 15;11(12):4487-94.

[4]. Novel model for basaloid triple-negative breast cancer: behavior in vivo and response to therapy. Neoplasia. 2012 Oct;14(10):926-42.

Oplophorus luciferin is an imidazopyrazine that is imidazo[1,2-a]pyrazin-3(7H)-one in which positions 2, 6, and 8 are substituted by 4-hydroxybenzyl, 4-hydroxyphenyl, and benzyl groups, respectively. It has a role as a luciferin. It is a member of phenols and an imidazopyrazine. It derives from a hydride of an imidazo[1,2-a]pyrazine.
Coelenterazine has been reported in Pandalus danae, Pandalus borealis, and other organisms with data available.

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Multidrug resistance (MDR) remains a major obstacle to successful chemotherapeutic treatment of cancer and can be caused by overexpression of P-glycoprotein, the MDR1 gene product. To further validate a knockdown approach for circumventing MDR, we developed a P-glycoprotein inhibition strategy using short hairpin RNA interference (shRNAi) and now show efficacy and target specificity in vivo. Two of eight tested shRNAi constructs targeted against human MDR1 mRNA inhibited expression of P-glycoprotein by >90%, whereas control shRNAi had no effect. Ablation of P-glycoprotein in cells stably transduced with retroviral-mediated shRNAi was documented by Western blot and functionally confirmed by increased sensitivity of MDR1-transfected cells toward the cytotoxic drugs vincristine, paclitaxel, and doxorubicin as well as by transport of (99m)Tc-Sestamibi. shRNAi-mediated down-regulation of P-glycoprotein transport activity both in cultured cells and in tumor implants in living animals could be followed by direct noninvasive bioluminescence imaging using the Renilla luciferase fluorophore, coelenterazine, a known P-glycoprotein transport substrate. Furthermore, after somatic gene transfer by hydrodynamic infusion of a MDR1-Firefly luciferase (MDR1-FLuc) fusion construct into mouse liver, the effect of shRNAi delivered in vivo on P-glycoprotein-FLuc protein levels was documented with bioluminescence imaging using d-luciferin. ShRNAi against MDR1 reduced bioluminescence output of the P-glycoprotein-FLuc reporter 4-fold in vivo compared with mice treated with control or scrambled shRNAi. Targeted down-regulation of a somatically transferred P-glycoprotein-eGFP fusion reporter also was observed using fluorescence microscopy. Our results show that shRNAi effectively inhibited MDR1 expression and function in cultured cells, tumor implants and mammalian liver, documenting the feasibility of a knockdown approach to reversing MDR in vivo.[3]

C26H21N3O3

423.46

423.158

C, 73.74; H, 5.00; N, 9.92; O, 11.33

55779-48-1

Coelenteramide;50611-86-4

135445694

Light yellow to khaki solid powder

1.3±0.1 g/cm3

641.4±65.0 °C at 760 mmHg

341.7±34.3 °C

0.0±2.0 mmHg at 25°C

1.689

3.87

3

5

5

32

585

0

LNCOEGVEEQDKGX-UHFFFAOYSA-N

InChI=1S/C26H21N3O3/c30-20-10-6-18(7-11-20)15-23-26(32)29-16-24(19-8-12-21(31)13-9-19)27-22(25(29)28-23)14-17-4-2-1-3-5-17/h1-13,16,30-32H,14-15H2

8-benzyl-6-(4-hydroxyphenyl)-2-[(4-hydroxyphenyl)methyl]imidazo[1,2-a]pyrazin-3-ol

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: (1). This product requires protection from light (avoid light exposure) during transportation and storage.  (2). Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.  (3). This product is not stable in solution, please use freshly prepared working solution for optimal results.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 0.2 mg/mL (0.47 mM) (saturation unknown) in 10% EtOH + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 2.0 mg/mL clear EtOH stock solution to 400 μL of PEG300 and mix evenly; then add 50 μL of Tween-80 to the above solution and mix evenly; then add 450 μL of normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 0.2 mg/mL (0.47 mM) (saturation unknown) in 10% EtOH + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 2.0 mg/mL clear EtOH stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 0.2 mg/mL (0.47 mM) (saturation unknown) in 10% EtOH + 90% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)