Ridaifen-B

Ridaifen-B is an antagonist of estrogen receptor α (ERα; IC₅₀ = 52.4 nM), an inverse agonist of cannabinoid (CB) receptor 2 (CB₂; K_i = 43.7 nM), and a derivative of tamoxifen (Item No. 13258).¹ It is selective for CB₂ over CB₁ receptors (K_i = 732 nM).² Ridaifen-B was designed to be cytotoxic to cancer cells independent of ER binding; it inhibits growth of ER-positive and ER-negative cells in a panel of 39 cancer cell lines (GI₅₀s = 0.20-2.14 µM).³ It induces apoptosis and autophagy in ER-negative Jurkat cells when used at a concentration of 0.4 µM.⁴ Ridaifen-B decreases nitric oxide (NO) production and protein levels of IL-1α and IL-6 in LPS-stimulated RAW 264.7 cells when used at a concentration of 1 µM.²

WARNING This product is not for human or veterinary use.

1. Guo, W.-Z., Wang, Y., Umeda, E., et al. Search for novel anti-tumor agents from ridaifens using JFCR39, a panel of human cancer cell lines. Biol. Pharm. Bull. 36(6), 1008-1016 (2013).

2. Franks, L.N., Ford, B.M., Fujiwara, T., et al. The tamoxifen derivative ridaifen-B is a high affinity selective CB₂ receptor inverse agonist exhibiting anti-inflammatory and anti-osteoclastogenic effects. Toxicol. Appl. Pharmacol. 353, 31-42 (2018).

3. Shiina, I., Sano, Y., Nakata, K., et al. Synthesis and pharmacological evaluation of the novel pseudo-symmetrical tamoxifen derivatives as anti-tumor agents. Biochem. Pharmacol. 75(5), 1014-1026 (2008).

4. Nagahara, Y., Takeyoshi, M., Sakemoto, S., et al. Novel tamoxifen derivative Ridaifen-B induces Bcl-2 independent autophagy without estrogen receptor involvement. Biochem. Biophys. Res. Commun. 435(4), 657-663 (2013).