Ethyl 3,4-dihydroxybenzoate

Ethyl 3,4-dihydroxybenzoate (Protocatechuic acid ethyl ester) is an orally effective, blood-brain barrier-permeable, competitive prolyl hydroxylase (PHD) inhibitor that inhibits the hydroxylation modification of hypoxia-inducible factor (HIF) by PHD. Ethyl 3,4-dihydroxybenzoate stabilizes HIF-1α by inhibiting PHD, activates downstream pathways to induce autophagy and apoptosis of tumor cells, and regulates inflammatory responses, inhibits the NF-κB pathway, improves vascular permeability, and promotes osteoblast differentiation. Ethyl 3,4-dihydroxybenzoate has anti-tumor, anti-hypoxic injury, and bone metabolism regulation effects. It can also be used in the research of cardiovascular protection (such as reducing myocardial ischemic damage), bone tissue engineering (promoting osteogenesis/inhibiting osteoclast differentiation), and prevention and treatment of high-altitude cerebral edema^[1][2][3][4]. In Vitro:1. Apoptosis experiment of esophageal cancer cells:
Ethyl 3,4-dihydroxybenzoate (50 μg/mL; 24-72 h) induces S phase cell cycle arrest, loss of mitochondrial membrane permeability and caspase-dependent apoptosis in KYSE 170 and EC109 esophageal squamous cell carcinoma cells, and upregulates the expression of NDRG1, BNIP3, Beclin and other proteins^[1].
2. Myocardial protection experiment:
Ethyl 3,4-dihydroxybenzoate (1 mM; 15 min, pretreatment) can activate NOS in isolated cardiomyocytes through KATP channels, increase mitochondrial ROS levels, and exert myocardial protection^[2].
3. Osteocyte differentiation assay:
Ethyl 3,4-dihydroxybenzoate (5 mg/mL; 3-14 d) significantly increases alkaline phosphatase (ALP) activity, type I collagen deposition and mineralizes nodule formation in MC3T3-E1 osteoblast precursor cells, and inhibits TRAP-positive multinucleate cell differentiation and TRAP enzyme activity in RAW264.7 osteoclasts in a dose-dependent manner (2-4 mg/mL; 6 d)^[3].
In Vivo:1. In vivo bone tissue engineering experiment:
Ethyl 3,4-dihydroxybenzoate (5 mg/bead, 50 mg/bead; subcutaneous injection after Alginate gel embedding; single dose; 5-8 weeks) promotes the osteogenic differentiation of human mesenchymal stem cells, increases the expression of type I collagen and osteocalcin, and induces the formation of new bone tissue in the nude mouse subcutaneous transplantation model^[3].
2. High-altitude cerebral edema prevention and treatment experiment:
Ethyl 3,4-dihydroxybenzoate (50-100 mg/kg; intraperitoneal injection; once daily; 3 days) significantly reduces brain water content and vascular permeability in the rat acute hypobaric hypoxia model, down-regulates pro-inflammatory factors such as TNF-α and IL-6, and up-regulates antioxidant proteins such as HIF-1α and HO-1^[4].
3. Myocardial ischemia protection experiment:
Ethyl 3,4-dihydroxybenzoate (75 mg/kg; intraperitoneal injection; once daily; 3 days) reduces infarct area and inhibited NF-κB-mediated inflammatory response in the rat myocardial ischemia-reperfusion model by activating the NOS-NO pathway and mitochondrial K_ATP channel^[4].