OH-Pen (Lipid Radical Inhibitor)

Product#: FDV-0043
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Lipid Radical Inhibitor


OH-Pen is a specific inhibitor for lipid radical that does not react with other reactive oxygen species. OH-Pen can suppress the LPO signaling via specific reaction with lipid radicals.
Catalog Number : FDV-0043
Size : 0.1 mg
Formulation : C13H26NO2
Chemical structure FDV-0043.png
Molecular weight : 228.19 g/mol
Solubility : Soluble in DMSO
"OH-Pen” is also powerful tools to research LPO. This is a unique lipid radical specific inhibitor which will not react with other reactive oxygen species. OH-Pen has similar structure to LipiRADICAL Green; NBD in LipiRADICAL Green was just converted to hydroxyl group.
Product Background
Lipid peroxidation (LPO) is one of the several degradation processes of lipids under oxidative stress (Figure 1).Primary products in LPO are lipid radicals and there are two major initiators to induce LPO process, pro-oxidants and lipid oxidative enzymes, including lipoxygenase (LOX) and cytochrome P450 (CYP).

LPO process (1): Pro-oxidants
For pro-oxidantinduced LPO, lipids containing unsaturated fatty acid, especially polyunsaturated fatty acids (PUFAs), are attacked by pro-oxidants, including reactive oxygen species (ROS) and form lipid-derived radicals. Lipid radical (L • ) can be easily oxidized to lipid peroxyl radical (LOO • ). Unstable LOO •  immediately extracts a hydrogen from another lipid molecule generating a lipid hydroperoxide (LOOH) and a new lipid radical (L • ).

LPO process (2): Lipid oxidative enzymes
Another pathway enzymeinduced LPO, lipids containing PUFAs are oxidized to lipid hydroperoxides (LOOH), which decomposes to lipid peroxyl radicals LOO •  or alkoxyl radicals LO •  by metal ions (Fe2+ etc.).

Once lipid radical is produced by the above two processes, lipid radicals expand the radical chain reaction (radical propagation step). In the termination reaction, antioxidants donate a hydrogen atom to the lipid peroxy radical (LOO • ) species resulting in the formation of many different aldehydes, including malondialdehyde (MDA), acrolein, propanal, hexanal, and 4-hydroxynonenal (4-HNE). These aldehydes are cytotoxic because reactive aldehydes attack biomolecules (proteins, DNA/RNA, etc.) to form secondary products. These reactive aldehydes are considered causative factors of organ injury, ferroptosis and ER-stress. To understand the molecular mechanism and physiological relevance of LPO, detection and quantification methods for lipid radicals are required. However, the conventional detection methods are highly limited. For example, electron spin resonance (ESR) is a major strategy to detect radical products but not applied to cell-based applications. 
Overview of lipid radicals in LPO pathway

  • OH-Pen can be used as LPO suppressor via neutralizing lipid radicals
  • OH-Pen is a very stable compound though it is a radical compound and can be stably injected into animals
  • OH-Pen neutralizes lipid radicals in situ

Reconstitution and Storage
Reconstitution: stock solution recommended concentration 1-10 mM in 100% DMSO
Storage : Store powder at -20°C.
After reconstitution in DMSO, aliquot and store at -20 °C, avoid repeated freeze-thaw cycles.
Application data
Inhibition of nitrosamine-induced carcinogenesis by OH-Pen

Rats received diethylnitrosamine (DEN, 100 mg/kg body weight), which is a well-known hepatic procarcinogen. Subsequently, rats received OH-Pen (2.5 μmol/kg body weight) by intraperitoneal injection after 1 hour DEN administration. For the acute model and chronic model, livers were dissected after 24 hours and 12 weeks DEN administration, respectively.

(Upper panel) Livers from chronic hepatocelluar carcinoma model and total foci number .

(Middle panel) Quantification of LPO-derived aldehydes in acute model livers.

(Lower panel) Quantification of tissue damage markers. In all panels, OH-Pen clearly suppressed DEN-induced hepatocellular carcinoma.

  1. Yamada et al., Nat. Chem. Biol., 12, 608-613 (2016) Fluorescence probes to detect lipid-derived radicals.
  2. Matsuoka et al., Anal. Chem., 92, 6993-7002, (2020) Method for structural determination of lipid-derived radicals


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