RESEARCH MONOGRAPH · KDC-MN-327

HU-308

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

76/100

Cleanest CB2-selective agonist in the research toolkit, irreplaceable for separating CB1 and CB2 pharmacology

HU-308 is Mechoulam-lab's gift to anyone trying to do clean CB2 biology. The compound was published in 1999 specifically as a CB2-selective tool to escape the CB1-confound that plagues every other cannabinoid agonist. Selectivity over CB1 is roughly 400-fold, which is unusual for the class, and the in vivo behavior matches: no central THC-like effects at doses that produce real peripheral CB2 effects.

This selectivity matters more than people often appreciate. Most of the early cannabinoid pharmacology was confounded by CB1 activity because the standard tools (anandamide, 2-AG, WIN55,212-2, CP-55940, JWH-133 to a lesser extent) all hit both receptors with similar affinity. Separating CB2-mediated effects from CB1-mediated effects in vivo required either knockouts or a genuinely selective ligand, and HU-308 is one of a small handful that work for that.

The biology HU-308 has helped establish: peripheral CB2 immunomodulation in inflammation models, anti-osteoporotic effects via CB2 on bone-forming cells (Bab and colleagues, beautiful papers), antifibrotic effects in liver and cardiac models, antinociceptive effects in chronic pain without central side effects. The hepatoprotection literature in NAFLD/NASH models is genuinely interesting and underappreciated.

Mechanism is straightforward: high-affinity, high-efficacy CB2 agonist, well-characterized Ki, predictable downstream signaling through Gi/o coupling. No major polypharmacology surprises in the published literature.

Sourcing: HU-308 is a research-only compound, available from specialized cannabinoid suppliers, synthetic, HPLC and NMR characterization is the standard QC. Purity matters because the bioactive enantiomer dominates the activity. Cost per mg is higher than the bulk phytocannabinoids but reasonable for a research compound. Storage is straightforward, more stable than the endocannabinoids because there's no oxidation-prone arachidonoyl chain.

What we like: actual selectivity, clean pharmacology, well-validated by multiple independent groups, useful in both rodent in vivo and cell-culture work. For CB2 mechanism work it's basically a default tool.

What we dont like is mostly the lack of human data. No clinical development, no human PK, so any in vivo work you do has to bridge from rodent to whatever you care about with the usual species-extrapolation caveats.

Reference tool for CB2-selective research. Worth knowing well.

Evidence: 65
Mechanism: 88
Reliability: 80
Safety: 82
Sourcing: 75
Value: 70
Signal: 70
Staying power: 75

Plain-language summary Intrigue 52 / 100

HU-308 is a synthetic cannabinoid built by the Mechoulam laboratory in Jerusalem to bind the CB2 receptor about 440 times more tightly than CB1. CB2 receptors live mostly on immune cells outside the brain, so a CB2-selective compound activates immune signaling without producing the psychoactive high that comes from CB1 engagement. It is used almost exclusively as a research probe to dissect what CB2 does in inflammation, bone metabolism, and tissue protection, and to validate CB2 as a drug target without confounding CB1 effects. Not a clinical compound; lives entirely in the lab. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

Synthetic CB2-selective cannabinoid

A synthetic CB2-selective cannabinoid agonist; a research tool for CB2 pharmacology without psychoactive CB1 activity.

Abstract

HU-308 ([4-[4-(1,1-dimethylheptyl)-2,6-dimethoxyphenyl]-6,6-dimethyl-bicyclo[3.1.1]hept-2-en-2-yl]methanol; CAS 256934-39-1; molecular formula C27H42O4; molecular weight 430.62) is a synthetic CB2-selective cannabinoid agonist developed by Mechoulam and colleagues at Hebrew University. The compound is a pinene-scaffold cannabinoid with high CB2 affinity (Ki approximately 23 nM) and minimal CB1 binding (greater than 440-fold selectivity), eliminating the psychoactivity associated with CB1-mediated cannabinoid effects. CB2 is expressed predominantly in peripheral immune cells (macrophages, B cells, T cells, microglia in CNS); selective activation produces anti-inflammatory and analgesic effects without psychotropic side effects. Preclinical studies demonstrate efficacy in inflammatory bowel disease, neuropathic pain, hepatic ischemia, and atherosclerosis models. Plasma half-life is approximately 2 to 3 hours. Used as the canonical CB2-selective research probe in academic immunology and pain research.

Mechanism of action

CB2-selective cannabinoid agonist (~440-fold over CB1); peripheral immune cell activation without psychotropic effects.

Reported research dose ranges

Rodent research 1 to 30 mg/kg.

References

Hanus L, et al. HU-308: a specific agonist for CB2, a peripheral cannabinoid receptor. Proc Natl Acad Sci 1999.
Pacher P, Mechoulam R. Is lipid signaling through cannabinoid 2 receptors part of a protective system? Prog Lipid Res 2011.
Whiteside GT, et al. The role of the cannabinoid CB2 receptor in pain transmission and therapeutic potential of small molecule CB2 receptor agonists. Curr Med Chem 2007.

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The full reference document is available as a research-use-only PDF download. Note: PDFs for newly added compounds may take a few hours to propagate after this article was published.

KDC-MN-327

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

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HU-308

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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