In vitro activity: Chelerythrine interacts with the catalytic domain of PKC, is a competitive inhibitor with respect to the phosphate acceptor (histone IIIS) with Ki value of 0.7 μM and a non-competitive inhibitor with respect to ATP. Chelerythrine shows potent cytotoxic effects against L-1210 cells with IC50 of 0.53 μM. Chelerythrine does not alter any activity of PKA, TPK and Ca/CM-PK, and the Chelerythrine inhibitory effect on PKC activity does not vary among the various substrates including GS, MLC, MBP and Fibrinogen. Chelerythrine inhibits PKC activity in crude cell extracts from SQ-20B cells in a dose dependent manner. Chelerythrine decreases cell viability as determined by the MTT assay in a dose-dependent manner in SCC35, JSQ3, SQ20B and SCC61 cells. Chelerythrine chloride (5 μM) suppresses VEGF-induced expression of ICAM-1, VCAM-1, and E-selectin in HUVECs. Chelerythrine chloride (5 μM) suppresses VEGF-induced NF-κB activity in HUVECs. Chelerythrine chloride (5 μM) all suppresses basal and VEGF-induced leukocyte adhesiveness in HUVECs. Chelerythrine (6 mM-30 mM) rapidly induces pyknosis, shrinkage and subsequent cell death in cardiac myocytes. Chelerythrine(30 μM)-induced myocyte death is accompanied by nuclear fragmentation and activation of caspase-3 and -9 in primary culture of neonatal rat ventricular myocytes. Chelerythrine (10 μM) causes cytochrome c release from mitochondria, suggesting that ROS mediates chelerythrine-induced cytochrome c release in cardiac myocytes. Chelerythrine displaces the fluorescently labeled BH3 domain peptide from a recombinant GST-BcLXL fusion protein with IC50 of 1.5 μM. Chelerythrine at 2.5 μM and 5 μM for 16 hours induces a substantial decrease in mitochondrial potential as indicated by an increase in JC-1 green fluorescence in human neuroblastoma SH-SY5Y cells. Chelerythrine (5 μM) also induces the appearance of sub-G1 DNA that is indicative of apoptosis in SH-SY5Y cells. Chelerythrine (10 μM) induces mitochondrial potential change, CytC release from the mitochondria in SH-SY5Y cells.

Kinase Assay: purified protein kinase C was prepared from rat brain. Briefly, the incubation mixture (200 μL) contains 20 mM Tris/HCl buffer (pH 7.5), 10 mM MgCl2, 200 μg/mL histones, micelles makes with 700 μM phosphatidyl serine and 180 μM 1,2-dioleine in 0.3% triton X100, 0.2 mM CaCl2, 100 μM ATP, [γ-32P ]-ATP (105 dpm), Chelerythrine to be tested (solubilized in dimethylsulphoxyde) and the enzyme (0.5 μg protein). After incubation at 30℃ for 3 minutes, the reaction is terminated by the addition of 3 mL of 20% trichloroacetic acid. Acid-precipitable materials are collected on Whatman GFE filters and extensively washed with ice-cold 20% trichloroacetic acid. The radioactivity on the filters is measured using a liquid scintillation counter. Protein kinase C activity is corrected for non-specific activity by assaying in the absence of micelles and CaCl2.

Cell Assay: Cell viability is evaluated via MTT assay. Cells (2×103 HEK-293 cells/well and 3×103 SW-839 cells/well) in 100 μL medium are seeded into 96-well plates, and incubated for 12 h. Next, the medium in each well is replaced with medium containing various concentrations of Chelerythrine Chloride, and the cells are incubated at 37°C for an additional 24 and 48 h. Subsequently, 20 μL MTT (5 mg/mL) is added to each well. Following an additional incubation at 37°C for 4 h, the supernatant is removed, and 100 μL DMSO is added to each well. The absorbance values (read at 540 nm) are determined using the iMark(TM) Microplate Absorbance Reader.