PHA 408

PHA-408 is a highly selective, orally active and ATP-competitive IKK-2 inhibitor with an IC₅₀ of 40 nM. PHA-408 blocks NF-κB signaling by suppressing IκBα phosphorylation and degradation, p65 phosphorylation, and pro-inflammatory cytokine production, and prevents TNF-α-induced premature senescence in HUVECs. PHA-408 alleviates LPS-and cigarette smoke-triggered pulmonary inflammation, reduces LPS-stimulated serum TNF-α release, and ameliorates joint damage in SCW-induced arthritis in rats. PHA-408 is applicable for the research of rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), and Duchenne muscular dystrophy^[1][2][3][4]. In Vitro:PHA-408 (2 μM; 6 days co-treatment with TNF-α) prevents TNF-α-induced premature senescence in HUVECs, as evidenced by reduced p16 and p21 expression, restored Ki-67 levels, and decreased senescence-associated secretory phenotype (SASP) markers including E-selectin, ICAM-1, IL-6, and IL-8^[1].
PHA-408 (0-10000 nM) inhibits recombinant human IKK-2 homodimer and IKK-2/IKK-1 heterodimer with IC₅₀ values of 10-40 nM, weakly suppresses IKK-1 (IC₅₀ = 14 μM, > 350-fold selectivity), and displays no obvious activity against a panel of 30 tyrosine and serine/threonine kinases except PIM1, with a 15-fold selectivity over PIM1 relative to IKK-2^[3].
PHA-408 (0.001-3 μM; 1 h preincubation; 20 min LPS stimulation) suppresses LPS-induced IKK-2 activity in immunoprecipitated IKK complexes from PBMCs and blocks LPS-triggered IκBα phosphorylation as well as p65 phosphorylation at Ser536 in PBMCs^[3].
PHA-408 (0.001-3 μM; 1 h preincubation; 18 h LPS stimulation) inhibits LPS-induced TNF-α, IL-6 and IL-8 production in PBMCs and human whole blood in a concentration-dependent manner^[3].
PHA-408 (0.001-3 μM; 1 h preincubation; 18 h IL-1β stimulation) inhibits IL-1β-induced IL-8, PGE2 production, and NF-κB-dependent SEAP reporter activity in RASFs without affecting cell viability^[3].
PHA-408 (0.001-3 μM; 1 h preincubation; 45 min IL-1β stimulation) shows no effect on IL-1β-induced JNK and p38 MAPK pathways in RASFs^[3].
PHA-408 (10 μM; 1 h preincubation; 20 min LPS stimulation) maintains inhibition of IKK-2 activity for up to 4 h following extensive washing of PBMCs^[3].
PHA-408 (20 μM; 6 h) increases cytosolic IκB-α expression and reduces nuclear p65 expression in freshly isolated adult mdx costal diaphragm^[4].
PHA-408 (20 μM; 52 h) reduces nuclear p65 immunofluorescence intensity in cultured mdx myotubes^[4].
PHA-408 (1, 10 μM; 6 h) shows no significant effect on cytosolic IκB-α or nuclear p65 expression at lower concentrations in freshly isolated adult mdx costal diaphragm^[4]. In Vivo:PHA-408 (15 and 45 mg/kg; p.o.; once daily for 3 days) dose-dependently reduces LPS- and cigarette smoke-induced lung inflammation in male Sprague-Dawley rats (280 g), including neutrophil influx and elevated CINC-1, IL-6, TNF-α, IL-1β, and GM-CSF levels in BAL fluid/lung homogenates, and suppresses NF-κB activation (IκBα degradation, p65 nuclear translocation, and NF-κB DNA binding) in lung tissues at 1 h post-exposure^[2].
PHA-408 (0.5-50 mg/kg; p.o.; single dose) inhibits LPS-induced serum TNF-α production, with an EC₅₀ of approximately 27-29 mg/kg and an IC₅₀ of approximately 2-3.4 μM based on plasma concentration in male Lewis rats^[3].
PHA-408 (10 mg/kg; p.o.; t.i.d. for 11 days) reduces paw swelling, suppresses IKK-2 activity in immunoprecipitates from paw tissues and blocks bone destruction in streptococcal cell wall (SCW)-induced chronic arthritis in female Lewis rats (125-140 g)^[3].
PHA-408 (15-60 mg/kg/day; p.o.; t.i.d. for 14 days) exhibits good tolerability at efficacious doses with an ED₉₀ of 30 mg/kg/day and a corresponding NOAEL of 30 mg/kg/day, induces mild and reversible adverse responses including transient body weight loss, neutrophilia, reduced liver enzyme levels and lymphoid depletion (45-60 mg/kg/day) in female Lewis rats (approximately 200 g)^[3].
PHA-408 (50 mg/kg; p.o.; once daily for 30 days) in mdx mice (1 month old, male) slightly increases cytosolic IκB-α expression in costal diaphragm, but does not significantly reduce nuclear p65 expression^[4].
PHA-408 (100 mg/kg; p.o.; single dose) in mdx mice shows no reduction in nuclear p65 expression at 5 h post-administration^[4].
PHA-408 (0.8 mg/kg/day; i.p.; twice daily for 30 days) in mdx mice (1 month old, male) significantly reduces nuclear p65 expression by approximately 50% in costal diaphragm^[4].