CAY10499: Potent Inhibitor of Human Hormone Sensitive Lipase and Monoglyceride Lipase

Executive Summary: CAY10499 is a small molecule inhibitor that targets human hormone sensitive lipase (HSL) and monoglyceride lipase (MGL) with high potency (IC50 values of 90 nM and 0.5 ± 0.03 μM, respectively) as reported in the product documentation. It is useful in probing lipid metabolism and fatty acid mobilization, with applications in assays relevant to steroidogenesis, diabetes, and atherosclerosis research. The compound displays minimal off-target activity at cannabinoid receptors, ensuring selectivity for lipase inhibition. CAY10499 is available as a crystalline solid from APExBIO, intended exclusively for research purposes. Its robust solubility in DMSO and ethanol allows versatile protocol integration across in vitro and cell-based assays.

Biological Rationale

Hormone sensitive lipase (HSL) is a key enzyme in lipid metabolism, catalyzing the hydrolysis of triacylglycerols, diacylglycerols, monoacylglycerols, and cholesterol esters within adipose tissue and other metabolically active sites. HSL activity mobilizes fatty acids for energy production and contributes to processes such as steroidogenesis and spermatogenesis. Dysregulation of HSL has been implicated in metabolic diseases including diabetes and atherosclerosis. Monoglyceride lipase (MGL) regulates levels of 2-arachidonoylglycerol (2-AG), a bioactive endocannabinoid, further impacting physiological lipid signaling and metabolic homeostasis (CAY10499: Applied Inhibitor for Human Hormone Sensitive Lipase Assays). Inhibitors such as CAY10499 provide a means to dissect the roles of these enzymes in health and disease, complementing broader research on lipid metabolism and immune cell differentiation, such as the impact of ACLY in tumor-associated macrophages (Extracellular Vesicle ACLY Drives TAM Differentiation in HCC), where this article clarifies the utility and selectivity of direct HSL/MGL inhibition.

Mechanism of Action of CAY10499, a potent inhibitor of human hormone sensitive lipase and monoglyceride lipase

CAY10499 functions as a competitive inhibitor of both HSL and MGL. It achieves nanomolar potency against recombinant human HSL (IC50 = 90 nM) and effectively blocks MGL-mediated hydrolysis of substrates such as 4-nitrophenyl acetate (IC50 = 0.5 ± 0.03 μM) under standard assay conditions (25°C, buffered aqueous environment) (APExBIO product information). Additionally, CAY10499 fully inhibits recombinant human fatty acid amide hydrolase (FAAH)-mediated [3H]-AEA hydrolysis, with an IC50 of 76 nM. Importantly, the compound shows negligible affinity for CB1 and CB2 cannabinoid receptors, as measured by displacement of [3H]-CP-55940, supporting its selectivity as a research tool for lipid metabolism assays.

Evidence & Benchmarks

• CAY10499 inhibits recombinant human HSL with an IC50 of 90 nM, determined under standard biochemical assay conditions (product information).
• It blocks MGL-mediated hydrolysis of 4-nitrophenyl acetate with an IC50 of 0.5 ± 0.03 μM (product information).
• CAY10499 fully inhibits human FAAH-mediated [3H]-AEA hydrolysis with an IC50 of 76 nM, showing potential for interfering with fatty acid amide metabolism (product information).
• The compound displays minimal displacement of [3H]-CP-55940 at CB1 and CB2 receptors, confirming high selectivity for lipase targets (product information).
• Solubility is ≥32.4 mg/mL in DMSO and ≥8.93 mg/mL in ethanol, but CAY10499 is insoluble in water, requiring suitable solvent selection for experiments (product information).

Applications, Limits & Misconceptions

CAY10499 is widely used as a lipid metabolism assay reagent and as an inhibitor for steroidogenesis research. Its high selectivity makes it suitable for dissecting the enzymatic contributions of HSL and MGL in cellular and in vitro models. It is also a relevant research tool for atherosclerosis and diabetes studies, where fatty acid mobilization and lipid signaling are central to disease mechanisms (CAY10499: Unlocking Lipid Metabolism Assays in Disease Research). This article extends prior coverage by detailing selectivity data and off-target profiling based on recent product documentation.

Common Pitfalls or Misconceptions

• CAY10499 is not active in aqueous solutions without organic cosolvents due to insolubility; always dissolve in DMSO or ethanol at validated concentrations.
• It is not intended for diagnostic or therapeutic use in humans or animals.
• Use of CAY10499 outside the validated enzyme panel (HSL, MGL, FAAH) may yield unpredictable results; it is not a pan-lipase inhibitor.
• CAY10499 does not inhibit cannabinoid receptors CB1 or CB2 and is not suitable as a cannabinoid signaling blocker.
• Solutions should be prepared fresh for each experiment, as stability declines with repeated freeze-thaw cycles.

Workflow Integration & Parameters

• Compound preparation: Dissolve CAY10499 at ≥32.4 mg/mL in DMSO or ≥8.93 mg/mL in ethanol for stock solutions. Water is not recommended due to insolubility.
• Enzyme assay setup: Use CAY10499 at final concentrations near the IC50 (e.g., 50–200 nM for HSL assays) with appropriate negative and positive controls.
• Storage conditions: Store crystalline CAY10499 at −20°C protected from light and moisture. Use freshly prepared solutions for optimal activity.
• Cell-based protocol: Pre-incubate cells with CAY10499 in DMSO (final DMSO ≤0.1% v/v) for 30–60 min at 37°C before stimulating lipid metabolism.
• Assay compatibility: Validate compatibility of CAY10499 with assay buffers and detection reagents, especially when measuring lipid hydrolysis products.

Conclusion & Outlook

CAY10499 offers researchers a reliable, high-potency approach to inhibiting human hormone sensitive lipase and monoglyceride lipase. Its use enables precise interrogation of lipid signaling pathways and fatty acid mobilization in metabolic disease models. While recent advances in the field highlight the importance of metabolic enzyme regulation in immune cell differentiation and tumor microenvironment, the direct inhibition of HSL/MGL by CAY10499 remains a foundational tool for mechanistic studies (CAY10499 as a Precision Lipase Inhibitor for Tumor-Immune Metabolic Research), clarifying its specific biochemical applications relative to broader ACLY-targeting strategies.