KR-33493

KR-33493 is a potent, orally active Fas-associated factor 1 (FAF1) inhibitor. KR-33493 inhibits the recruitment of FAF1 to the Fas death domain and the amplification of Fas-mediated apoptotic signaling. KR-33493 can be used in neuroprotection and cardiovascular research for Parkinson's disease and myocardial ischemia/ischemic injury^[1-4].

In vitro, HCT116 colon cancer cells was co-treated with KR-33493 (20μM) and Dendrobium huoshanense polysaccharide (DHP; 600μg/ml) in for 24h. KR-33493 blocked the Fas receptor-dependent anti-proliferative effect of DHP, inhibited DHP-induced activation of the Fas-FasL signaling pathway (characterized by suppressed upregulation of FADD and blockade of caspase-8/caspase-3 cascade activation), attenuated DHP-triggered mitochondrial membrane potential decline, tBid/Bid ratio elevation, and apoptosis, thereby restoring the proliferative capacity of HCT116 cells^[5]. KR-33493 (20μM) was pre-incubated with rheumatoid arthritis synovial fibroblasts (RA FLS) for 1h, followed by either continued incubation alone or co-incubation with Danggui Niantong Decoction (DGNTD)-containing serum for up to 48h. When used alone, KR-33493 did not affect the basal apoptotic morphology of FLS; in combination with DGNTD, KR-33493 reduced apoptosis, decreased the protein expression levels of Fas, FADD, caspase-8, and caspase-3, and reversed the pro-apoptotic effect of DGNTD on FLS^[6]. KR‑33493 (10μM) was applied to Aβ1‑42‑injured C8D1A astrocyte‑like cells. KR‑33493 suppressed the upregulation of Fas/FasL‑VDAC1 signaling‑related proteins, accompanied by enhanced expression of autophagy‑related molecules and reduced expression of apoptosis‑related molecules^[7].

In vivo, KR-33493 (50, 150, 500mg/kg/day) was administered orally to Sprague-Dawley rats for 28 consecutive days. KR-33493 maintained 100% survival at all doses and caused no test item-related abnormal clinical signs, disturbances in body weight or weight gain, alterations in food consumption, ophthalmic abnormalities, abnormalities in hematological or serum biochemical parameters, urinalysis abnormalities, or histopathological lesions, no test item-related changes in organ weights were observed, except for a mild reduction in body weight gain and isolated fur loss in one female rat in the 500mg/kg/day group^[8].

References:
[1] Yoo SE, Yu C, Jung S, et al. Design and synthesis of fluorescent and biotin tagged probes for the study of molecular actions of FAF1 inhibitor. Bioorg Med Chem Lett. 2016 Feb 15;26(4):1169-72.
[2] Tosato M, Di Marco V. Metal Chelation Therapy and Parkinson's Disease: A Critical Review on the Thermodynamics of Complex Formation between Relevant Metal Ions and Promising or Established Drugs. Biomolecules. 2019 Jul 9;9(7):269.
[3] Pockle RD, Masareddy RS, Patil AS, et al. A comprehensive review on pharmaceutical excipients. Ther Deliv. 2023 Jul;14(7):443-458.
[4] Reinares-Sebastián A, Esteban-García N, Takada M, et al. Drug discovery and development for Parkinson's disease: are preclinical models good enough? Front Aging Neurosci. 2025 Oct 28;17:1692592.
[5] Yao L, Gu C, Ge R, et al. Acetylated Dendrobium huoshanense polysaccharide: a novel inducer of apoptosis in colon cancer cells via Fas-FasL pathway activation and metabolic reprogramming. Front Oncol. 2025 Mar 4;15:1529868.
[6] Zhao F, Li J, Lu Q, Chen E, Yuan L. Danggui Niantong decoction induces apoptosis by activating Fas/caspase-8 pathway in rheumatoid arthritis fibroblast-like synoviocytes. Nan Fang Yi Ke Da Xue Xue Bao. 2020 Aug 30;40(8):1119-1126.
[7] Wang S, Yang Y, Lin J, et al. Astragalin actives autophagy and inhibits apoptosis of astrocytes in AD mice via down-regulating Fas/Fasl-VDAC1 pathway. Free Radic Biol Med. 2025 May;232:72-85.
[8] Jeong JW, Yu C, Lee JH, et al. Subacute toxicity evaluation of KR-33493, FAF1 inhibitor for a new anti-parkinson's disease agent, after oral administration in rats and dogs. Regul Toxicol Pharmacol. 2016 Nov;81:387-396.