m-type

Linopirdine (DuP 996) is a TRPV1 agonist. Linopirdine is an orally active and selective M-type K+ current (IM; Kv7; KCNQ Channels) inhibitor (IC50: 2.4 μM). Linopirdine is a cognitive enhancer. It acts by stimulating release of acetylcholine and other neurotransmitters.Linopirdine is a putative cognition-enhancing drug that increases acetylcholine release in rat brain tissue.

m-Nisoldipine (3-methyl 5-(2-methylpropyl) 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate) is a dihydropyridine calcium channel blocker, a derivative of nisoldipine, that blocks L-type calcium channels in the heart and smooth muscle cells for the treatment of hypertension and angina pectoris.

M1145 acetate, a chimeric peptide, is a selective galanin receptor type 2 (GAL2) agonist, with a Ki of 6.55 nM. M1145 acetate shows more than 90-fold higher affinity for GAL2 over GAL1 (Ki=587 nM) and a 76-fold higher affinity over GalR3 (Ki=497 nM). M1145 acetate has an additive effect on the signal transduction of galanin[1].

V-ATPase-IN-1 (Compound 3b-03) is an inhibitor of Vacuolar-type H+-ATPases (V-ATPase), exhibiting an inhibition constant (IC50) of 194.80 μM and effectively targeting the V-ATPase subunit A with a dissociation constant (Kd) of 0.803 μM. This compound demonstrates insecticidal activity against M. separata (LC50 = 2.64 mM), aiding in the development of chemical insecticides.

Pyraoxystrobin, a QoI-type fungicide, exhibits an EC50 of 0.0094 μg/mL against Magnaporthe oryzae (M. oryzae) isolates. It is utilized in the study of rice blast fungus in paddy fields.

EGFR-IN-96 (compound 7a) is a thiophene[2,3-d]pyrimidine EGFR inhibitor that can induce apoptosis. It causes HepG2 cells to arrest in the S and G2/M phases and inhibits the growth of cancer cells with wild-type EGFR and EGFRT790M.

Antibacterial agent 228 (Compound 8) inhibits mycobacterial ribosomes with an IC50 of 2.31 μM against Mycobacterium smegmatis. It demonstrates antibacterial activity with MIC values of 2 and 0.25 μg/mL against both wild-type and Δ1258c mutant strains of M. tuberculosis H37Rv, 8 μg/mL against wild-type and Δ2780c mutant strains of M. abscessus ATCC 19977, and 8 μg/mL against M. smegmatis.

PROTACERα Degrader-9 (Compound 18c) is a dual-targeting PROTAC degrader designed to diminish estrogen receptor α (ERα) and aromatase (ARO). It demonstrates a Ki of 0.25 μM for ERα binding and an IC50 of 4.6 μM for ARO inhibition. This compound curbs proliferation in wild-type MCF-7 cells (IC50=0.54 μM) and ERα mutant variants MCF-7EGFR (IC50=0.075 μM), MCF-7D538G (IC50=0.31 μM), and MCF-7Y537S (IC50=2.3 μM), while also downregulating ERS1 and MYC expression. PROTACERα Degrader-9 arrests the cell cycle at the G2/M phase and induces apoptosis in MCF-7 cells, exhibiting antitumor efficacy in mouse models.

CDK8-IN-20 (Compound 67j) is a highly selective and potent type I CDK8 inhibitor with oral bioavailability, exhibiting an IC50 value of 70.5 nM. The IC50 values for its action on homologous kinases CDK19, CDK7, and CDK9 are 147.8, 726.9, and 217.4 nM, respectively. CDK8-IN-20 effectively inhibits the proliferation of HCT-116, HT-29, and SW-480 cells with IC50 values of 5.9, 17.93, and 9.52 μM, respectively, while demonstrating low cytotoxicity toward normal gastric mucosal epithelial cells (GES-1) with an IC50 greater than 100 μM. It disrupts the Wnt/β-catenin pathway, downregulating β-catenin, Cyclin D1, and c-Myc expression. Additionally, CDK8-IN-20 induces reactive oxygen species (ROS) production and leads to G2/M phase and S phase cell cycle arrest. This compound is applicable in cancer research, such as colorectal cancer.

KN-93 hydrochloride is a cell-permeable, reversible, and competitive inhibitor of calmodulin-dependent kinase type II (CaMKII) with a Ki of 370 nM. KN-93 hydrochloride induces G1 cell cycle arrest in 95% of treated cells after two days, with the arrest being reversible; one day after KN-93 withdrawal, a peak of cells progresses into S and G2-M phases, providing a robust tool for cell cycle regulation studies and mechanistic investigation of CaMKII-dependent signaling.

Palmitic acid-1,2,3,4-13C4 is intended for use as an internal standard for the quantification of palmitic acid by GC- or LC-MS. Palmitic acid (T2908) is a common 16-carbon saturated fat that represents 10-20% of human dietary fat intake and comprises approximately 25 and 65% of human total plasma lipids and saturated fatty acids, respectively.1,2Acylation of palmitic acid to proteins facilitates anchoring of membrane-bound proteins to the lipid bilayer and trafficking of intracellular proteins, promotes protein-vesicle interactions, and regulates various G protein-coupled receptor functions.1Red blood cell palmitic acid levels are increased in patients with metabolic syndrome compared to patients without metabolic syndrome and are also increased in the plasma of patients with type 2 diabetes compared to individuals without diabetes.3,4

Urocortin III is a neuropeptide hormone and member of the corticotropin-releasing factor (CRF) family which includes mammalian CRF , urocortin , urocortin II , frog sauvagine, and piscine urotensin I.1 Human urocortin III shares 90, 40, 37, and 21% identity to mouse urocortin III , mouse urocortin II , human urocortin , and mouse urocortin, respectively. Urocortin III selectively binds to type 2 CRF receptors (Kis = 21.7, 13.5, and >100 nM for rat CRF2α, rat CRF2β, and human CRF1, respectively). It stimulates cAMP production in CHO cells expressing rat CRF2α and mouse CRF2β (EC50s = 0.16 and 0.12 nM, respectively) as well as cultured anterior pituitary cells expressing endogenous CRF2β. Urocortin III is co-released with insulin to potentiate glucose-stimulated somatostatin release in vitro in human pancreatic β-cells.2 In vivo, urocortin III reduces food intake in a dose- and time-dependent manner in mice with a minimum effective dose (MED) of 0.3 nmol/animal.3 It increases swimming time in a forced swim test in mice, indicating antidepressant-like activity.4References1. Lewis, K., Li, C., Perrin, M.H., et al. Identification of urocortin III, an additional member of the corticotropin-releasing factor (CRF) family with high affinity for the CRF2 receptor. Proc. Natl. Acad. Sci. U.S.A. 98(13), 7570-7575 (2001).2. van der Meulen, T., Donaldson, C.J., Cáceres, E., et al. Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion. Nat. Med. 21(7), 769-776 (2015).3. Pelleymounter, M.A., Joppa, M., Ling, N., et al. Behavioral and neuroendocrine effects of the selective CRF2 receptor agonists urocortin II and urocortin III. Peptides 25(4), 659-666 (2004).4. Tanaka, M., Kádár, K., Tóth, G., et al. Antidepressant-like effects of urocortin 3 fragments. Brain Res. Bull. 84(6), 414-418 (2011). Urocortin III is a neuropeptide hormone and member of the corticotropin-releasing factor (CRF) family which includes mammalian CRF , urocortin , urocortin II , frog sauvagine, and piscine urotensin I.1 Human urocortin III shares 90, 40, 37, and 21% identity to mouse urocortin III , mouse urocortin II , human urocortin , and mouse urocortin, respectively. Urocortin III selectively binds to type 2 CRF receptors (Kis = 21.7, 13.5, and >100 nM for rat CRF2α, rat CRF2β, and human CRF1, respectively). It stimulates cAMP production in CHO cells expressing rat CRF2α and mouse CRF2β (EC50s = 0.16 and 0.12 nM, respectively) as well as cultured anterior pituitary cells expressing endogenous CRF2β. Urocortin III is co-released with insulin to potentiate glucose-stimulated somatostatin release in vitro in human pancreatic β-cells.2 In vivo, urocortin III reduces food intake in a dose- and time-dependent manner in mice with a minimum effective dose (MED) of 0.3 nmol/animal.3 It increases swimming time in a forced swim test in mice, indicating antidepressant-like activity.4 References1. Lewis, K., Li, C., Perrin, M.H., et al. Identification of urocortin III, an additional member of the corticotropin-releasing factor (CRF) family with high affinity for the CRF2 receptor. Proc. Natl. Acad. Sci. U.S.A. 98(13), 7570-7575 (2001).2. van der Meulen, T., Donaldson, C.J., Cáceres, E., et al. Urocortin3 mediates somatostatin-dependent negative feedback control of insulin secretion. Nat. Med. 21(7), 769-776 (2015).3. Pelleymounter, M.A., Joppa, M., Ling, N., et al. Behavioral and neuroendocrine effects of the selective CRF2 receptor agonists urocortin II and urocortin III. Peptides 25(4), 659-666 (2004).4. Tanaka, M., Kádár, K., Tóth, G., et al. Antidepressant-like effects of urocortin 3 fragments. Brain Res. Bull. 84(6), 414-418 (2011).

Nitisinone-13C6 is intended for use as an internal standard for the quantification of nitisinone by GC- or LC-MS. Nitisinone (T1684) is an inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), which converts 4-hydroxyphenylpyruvate (HPPA) to homogentisate in the tyrosine catabolic pathway.1Nitisinone increases urinary levels of HPPA and 4-hydroxyphenyllactate (HPLA) in rats when administered at a dose of 10 mg/kg. Nitisinone (T1684) (3 mg/kg) prevents the neonatal lethality of fumarylacetoacetate hydrolase (FAH) deficiency in mice when administered to pregnant dams.2It exhibits hepatoprotective effects inFAH-/-mice, such as prevention of increases in plasma levels of aspartate serine aminotransferase (AST) and conjugated bilirubin, when administration is continued following birth at a dose of 1 mg/kg. Nitisinone (T1684) (100 μg) decreases urinary excretion of homogentisate and increases urinary excretion of HPPA, HPLA, and 4-hydroxyphenylacetate in a mouse model of alkaptonuria induced by ethylnitrosourea.3Formulations containing nitisinone have been used in the treatment of hereditary tyrosinemia type 1 (HT-1).

3β-OH-7-Oxocholenic acid is a bile acid.1 It is also a metabolite of 7β-hydroxy cholesterol in rats. Conjugated forms of 3β-OH-7-oxocholenic acid have been found in the urine of patients with Neimann-Pick disease type C.2,3 |1. Norii, T., Yamaga, N., and Yamasaki, K. Metabolism of 7β-hydroxycholesterol-4-14C in rat. Steroids 15(3), 303-326 (1970).|2. Alvelius, G., Hjalmarson, O., Griffiths, W.J., et al. Identification of unusual 7-oxygenated bile acid sulfates in a patient with Niemann-Pick disease, type C. J. Lipid Res. 42(10), 1571-1577 (2001).|3. Maekawa, M., Omura, K., Sekiguchi, S., et al. Identification of two sulfated cholesterol metabolites found in the urine of a patient with Niemann-Pick disease type C as novel candidate diagnostic markers. Mass Spectrom. (Tokyo) 5(2), S0053 (2016).

C6 urea ceramide is an inhibitor of neutral ceramidase.1 It increases total ceramide levels in wild-type mouse embryonic fibroblasts (MEFs) and in HT-29 colon cancer cells but not in MEFs lacking neutral ceramidase. It inhibits proliferation of, and induces apoptosis and autophagy in HT-29, but not non-cancerous RIE-1, cells when used at concentrations of 5 and 10 μM. C6 urea ceramide decreases total β-catenin, increases phosphorylated β-catenin, and induces colocalization of β-catenin with the 20S proteasome in HT-29 and HCT116, but not RIE-1, cells. It reduces tumor growth and increases C16, C18, C20, and C24 ceramide levels in tumor tissue in an HT-29 mouse xenograft model when administered at doses of 1.25, 2.5, and 5 mg/kg for five days. |1. García-Barros, M., Coant, N., Kawamori, T., et al. Role of neutral ceramidase in colon cancer. FASEB J. 30(12), 4159-4171 (2016).

Urocortin II is a neuropeptide hormone and member of the corticotropin-releasing factor (CRF) family which includes mammalian CRF , urocortin , urocortin III , frog sauvagine, and piscine urotensin I.1 Mouse urocortin II shares 34 and 42% sequence homology with rat CRF and urocortin . It is expressed in mouse paraventricular, supraoptic, and arcuate nuclei of the hypothalamus, the locus coeruleus, and in motor nuclei of the brainstem and spinal ventral horn. Urocortin II selectively binds to CRF1 over CRF2 receptors (Kis = 0.66 and >100 nM, respectively) and induces cAMP production in CHO cells expressing CRF2 (EC50 = 0.14 nM). In vivo, urocortin II suppresses nighttime food intake by 35% in rats when administered intracerebroventricularly at a dose of 1 μg. Urocortin II (0.1 and 0.5 μg, i.c.v) stimulates fecal pellet output, increases distal colonic transit, and inhibits gastric emptying in mice.2References1. Reyes, T.M., Lewis, K., Perrin, M.H., et al. Urocortin II: A member of the corticotropin-releasing factor (CRF) neuropeptide family that is selectively bound by type 2 CRF receptors. Proc. Natl. Acad. Sci. U.S.A. 98(5), 2843-2848 (2001).2. Martinez, V., Wang, L., Million, M., et al. Urocortins and the regulation of gastrointestinal motor function and visceral pain. Peptides 25(10), 1733-1744 (2004). Urocortin II is a neuropeptide hormone and member of the corticotropin-releasing factor (CRF) family which includes mammalian CRF , urocortin , urocortin III , frog sauvagine, and piscine urotensin I.1 Mouse urocortin II shares 34 and 42% sequence homology with rat CRF and urocortin . It is expressed in mouse paraventricular, supraoptic, and arcuate nuclei of the hypothalamus, the locus coeruleus, and in motor nuclei of the brainstem and spinal ventral horn. Urocortin II selectively binds to CRF1 over CRF2 receptors (Kis = 0.66 and >100 nM, respectively) and induces cAMP production in CHO cells expressing CRF2 (EC50 = 0.14 nM). In vivo, urocortin II suppresses nighttime food intake by 35% in rats when administered intracerebroventricularly at a dose of 1 μg. Urocortin II (0.1 and 0.5 μg, i.c.v) stimulates fecal pellet output, increases distal colonic transit, and inhibits gastric emptying in mice.2 References1. Reyes, T.M., Lewis, K., Perrin, M.H., et al. Urocortin II: A member of the corticotropin-releasing factor (CRF) neuropeptide family that is selectively bound by type 2 CRF receptors. Proc. Natl. Acad. Sci. U.S.A. 98(5), 2843-2848 (2001).2. Martinez, V., Wang, L., Million, M., et al. Urocortins and the regulation of gastrointestinal motor function and visceral pain. Peptides 25(10), 1733-1744 (2004).

(E)-Guggulsterone is an isomer of guggulsterone. As an FXR antagonist, it reduces blood lipids, induces heme oxygenase-1 expression, blocks DENV NS2B/3B activity, and inhibits DENV replication.

NG 25 is a type II kinase inhibitor that inhibits MAP4K2 and TAK1 (IC50s = 21.7 and 149 nM, respectively).1It also inhibits the Src family kinases Src and LYN (IC50s = 113 and 12.9 nM, respectively) and Abl family kinases (IC50s = 75.2 nM), as well as CSK, FER, and p38α (IC50s = 56.4, 82.3, and 102 nM, respectively). NG 25 (100 nM) prevents TNF-α-induced IKKα/β phosphorylation and IκB-α degradation in L929 cells. It inhibits secretion of IFN-α and IFN-β induced by CpG type B and CL097, respectively, in Gen2.2 cells in a concentration-dependent manner.2NG 25 decreases cell viability of HCT116KRASWT, and to a greater degree of HCT116KRASG13D, colorectal cancer cells in a concentration-dependent manner.3It also reduces tumor growth and increases the number of TUNEL-positive tumor cells in a CT26KRASG12Dmouse orthotopic model of colorectal cancer. 1.Tan, L., Nomanbhoy, T., Gurbani, D., et al.Discovery of type II inhibitors of TGFβ-activated kinase 1 (TAK1) and mitogen-activated protein kinase kinase kinase kinase 2 (MAP4K2)J. Med. Chem.58(1)183-196(2015) 2.Pauls, E., Shpiro, N., Peggie, M., et al.Essential role for IKKβ in production of type 1 interferons by plasmacytoid dendritic cellsJ. Biol. Chem. 287(23)19216-19228(2012) 3.Ma, Q., Gu, L., Liao, S., et al.NG25, a novel inhibitor of TAK1, suppresses KRAS-mutant colorectal cancer growth in vitro and in vivoApoptosis24(1-2)83-94(2019)

Norhyodeoxycholic acid (NHDCA) is a synthetic bile acid and a derivative of hyodeoxycholic acid .1,2 NHDCA is an intermediate in the synthesis of 3β-sulfooxy-7β-hydroxy-24-nor-5-cholen-23-oic acid, which has been used as an internal standard for the quantification of δ5-bile acid conjugates that have been identified in patients with Niemann-Pick disease type C1.3 |1. Schteingart, C.D., and Hofmann, A.F. Synthesis of 24-nor-5β-cholan-23-oic acid derivatives: A convenient and efficient one-carbon degradation of the side chain of natural bile acids. J. Lipid Res. 29(10), 1387-1395 (1988).|2. Une, M., and Hoshita, T. Natural occurrence and chemical synthesis of bile alcohols, higher bile acids, and short side chain bile acids. Hiroshima J. Med. Sci. 43(2), 37-67 (1994).|3. Kakiyama, G., Muto, A., Shimada, M., et al. Chemical synthesis of 3β-sulfooxy-7β-hydroxy-24-nor-5-cholenoic acid: An internal standard for mass spectrometric analysis of the abnormal δ5-bile acids occurring in Niemann-Pick disease. Steroids 74(9), 766-772 (2009).

Lysosphingomyelin is an endogenous bioactive sphingolipid and a constituent of lipoproteins.1,2It is produced by the removal of the acyl group from sphingomyelin by a deacylase and acts as a precursor in the biosynthesis of sphingosine-1-phosphate . D-erythroLysosphingomyelin is an agonist of the S1P receptors S1P1, S1P2, and S1P3(EC50s = 167.7, 368.1, and 482.6 nM, respectively, for the human receptors).3It is also an agonist of the orphan receptor ovarian cancer G protein-coupled receptor 1 (ORG1) that induces calcium accumulation in cells overexpressing OGR1 (EC50= ~35 nM).4Levels of D-erythrolysosphingomyelin are increased in skin isolated from patients with atopic dermatitis, as well as postmortem brain from patients with Niemann-Pick disease type A, but not type B.2,5L-threolysosphingomyelin is also an S1P1-3agonist (EC50s = 19.3, 131.8, and 313.3 nM, respectively).3This product is a mixture of D-erythroand L-threolysosphingomyelin. [Matreya, LLC. Catalog No. 1321] 1.Ito, M., Kurita, T., and Kita, K.A novel enzyme that cleaves the N-acyl linkage of ceramides in various glycosphingolipids as well as sphingomyelin to produce their lyso formsJ. Biol. Chem.270(41)24370-24374(1995) 2.Nixon, G.F., Mathieson, F.A., and Hunter, I.The multi-functional role of sphingosylphosphorylcholineProg. Lipid Res.47(1)62-75(2008) 3.Im, D.-S., Clemens, J., Macdonald, T.L., et al.Characterization of the human and mouse sphingosine 1-phosphate receptor, S1P5 (Edg-8): Structure-activity relationship of sphingosine1-phosphate receptorsBiochemistry40(46)14053-14060(2001) 4.Meyer zu Heringdorf, D., Himmel, H.M., and Jakobs, K.H.Sphingosylphosphorylcholine-biological functions and mechanisms of actionBiochim. Biophys. Acta1582(1-3)178-189(2002) 5.Rodriguez-Lafrasse, C., and Vanier, M.T.Sphingosylphosphorylcholine in Niemann-Pick disease brain: Accumulation in type A but not in type BNeurochem. Res.24(2)199-205(1999)

CAY10787 is an oxysterol and a negative allosteric modulator of GABAAreceptors.1,2It reduces GABA-induced currents in HEK cells expressing α1β1γ2or α4β3γ2subunit-containing GABAAreceptors (IC50s = 1.5 and 1 μM, respectively).2CAY10787 (500 nM) reduces GABA-induced depolarization of peptidergic and non-peptidergic nociceptors, C-LTMRs, and cold thermosensors in isolated mouse dorsal root ganglion (DRG) neurons.In vivo, CAY10787 (2, 10, and 50 mg/kg) increases latency to nocifensive behaviors in the hot plate test in mice. 1.Hahn, M., Tang, M., and Subbiah, M.T.Cholest-3,5-dien-7-one formation in peroxidized human plasma as an indicator of lipoprotein cholesterol peroxidation potentialBiochim. Biophys. Acta1255(3)341-343(1995) 2.Niu, C., Leavitt, L.S., Lin, Z., et al.Neuroactive type-A γ-aminobutyric acid receptor allosteric modulator steroids from the hypobranchial gland of marine mollusk, Conus geographusJ. Med. Chem.64(10)7033-7043(2021)

Ru360, an oxygen-bridged dinuclear ruthenium amine complex, is a selective mitochondrial calcium uptake inhibitor. Ru360 potently inhibits Ca2+ uptake into mitochondria with an IC50 of 0.184 nM. Ru360 binds to mitochondria with high affinity (Kd of 0.34 nM). Ru360 has antiarrhythmic and cardioprotective effects[1][2]. Ru360 permeates slowly into the cell, and specifically inhibits mitochondrial calcium uptake in intact cardiomyocytes and in isolated heart. 1 μm Ru360 is taken up by myocardial cells and accumulated in the cytosol in a biphasic manner[1]. During pelleting hypoxia, Ru360 (10 µM) significantly improves cell viability in wild type cardiomyocytes[3]. Ru360 (15-50 nmol/kg) treatment abolishes the incidence of arrhythmias and haemodynamic dysfunction elicited by reperfusion in a whole rat model. Ru360 administration partially inhibits calcium uptake, preventing mitochondria from depolarization by the opening of the mitochondrial permeability transition pore (mPTP)[1]. [1]. G de J García-Rivas, et al. Ru360, a Specific Mitochondrial Calcium Uptake Inhibitor, Improves Cardiac Post-Ischaemic Functional Recovery in Rats in Vivo. Br J Pharmacol. 2006 Dec;149(7):829-37. [2]. M A Matlib, et al. Oxygen-bridged Dinuclear Ruthenium Amine Complex Specifically Inhibits Ca2+ Uptake Into Mitochondria in Vitro and in Situ in Single Cardiac Myocytes. J Biol Chem. 1998 Apr 24;273(17):10223-31. [3]. Lukas J Motloch, et al. UCP2 Modulates Cardioprotective Effects of Ru360 in Isolated Cardiomyocytes During Ischemia. Pharmaceuticals (Basel). 2015 Aug 4;8(3):474-82.

Pancuronium is an aminosteroid antagonist of muscle-type nicotinic acetylcholine receptors (nAChRs) with an IC50value of 14.8 nM using patch clamp electrophysiology in BOSC23 cells expressing mouse nAChRs.1It acts as a non-depolarizing neuromuscular blocking agent.2Pancuronium enhances anesthesia induced by isoflurane , reducing immobilization with an ED50value of 1.62 μg/kg.3 1.Liu, M., and Dilger, J.P.Site selectivity of competitive antagonists for the mouse adult muscle nicotinic acetylcholine receptorMol. Pharmacol.75(1)166-173(2009) 2.Buckett, W.R., Marjoribanks, C.E., Marwick, F.A., et al.The pharmacology of pancuronium bromide (Org.NA97), a new potent steroidal neuromuscular blocking agentBr. J. Pharmacol. Chemother.32(3)671-682(1968) 3.Miyazaki, Y., Sunaga, H., Hobo, S., et al.Pancuronium enhances isoflurane anesthesia in rats via inhibition of cerebral nicotinic acetylcholine receptorsJ. Anesth.30(4)671-676(2016)

Quorum sensing is a regulatory process used by bacteria for controlling gene expression in response to increasing cell density.[1] This regulatory process manifests itself with a variety of phenotypes including biofilm formation and virulence factor production.[2] Coordinated gene expression is achieved by the production, release, and detection of small diffusible signal molecules called autoinducers. The N-acylated homoserine lactones (AHLs) comprise one such class of autoinducers, each of which generally consists of a fatty acid coupled with homoserine lactone (HSL). AHLs vary in acyl group length (C4-C18), in the substitution of C3 (hydrogen, hydroxyl, or oxo group) and in the presence or absence of one or more carbon-carbon double bonds in the fatty acid chain. These differences confer signal specificity through the affinity of transcriptional regulators of the LuxR family.[3] C16:1-Δ9-(L)-HSL is a long-chain AHL that functions as a quorum sensing signaling molecule in strains of S. meliloti.[4],[5],[6],[7] Regulating bacterial quorum sensing signaling can be used to inhibit pathogenesis and thus, represents a new approach to antimicrobial therapy in the treatment of infectious diseases.[8] Reference：[1]. González, J.E., and Keshavan, N.D. Messing with bacterial quorum sensing. Microbiol. Mol. Biol. Rev. 70(4), 859-875 (2006).[2]. Gould, T.A., Herman, J., Krank, J., et al. Specificity of acyl-homoserine lactone syntheses examined by mass spectrometry. J. Bacteriol. 188(2), 773-783 (2006).[3]. Penalver, C.G.N., Morin, D., Cantet, F., et al. Methylobacterium extorquens AM1 produces a novel type of acyl-homoserine lactone with a double unsaturated side chain under methylotrophic growth conditions. FEBS Lett. 580(2), 561-567 (2006).[4]. Teplitski, M., Eberhard, A., Gronquist, M.R., et al. Chemical identification of N-acyl homoserine lactone quorum-sensing signals produced by Sinorhizobium meliloti strains in defined medium. Archives of Microbiology 180, 494-497 (2003).[5]. Gao, M., Chen, H., Eberhard, A., et al. sinI- and expR-dependent quorum sensing in Sinorhizobium meliloti. Journal of Bacteriology 187(23), 7931-7944 (2005).[6]. Marketon, M.M., Glenn, S.A., Eberhard, A., et al. Quorum sensing controls exopolysaccharide production in Sinorhizobium meliloti. Journal of Bacteriology 185(1), 325-331 (2003).[7]. Marketon, M., Gronquist, M.R., Eberhard, A., et al. Characterization of the Sinorhizobium meliloti sinR/sinI locus and the production of novel N-Acyl homoserine lactones. Journal of Bacteriology 184(20), 5686-5695 (2002).[8]. Cegelski, L., Marshall, G.R., Eldridge, G.R., et al. The biology and future prospects of antivirulence therapies. Nat. Rev. Microbiol. 6(1), 17-27 (2008).