Cell experiment:

Cells are plated at a density of 1×105 cells/well in microtiter plates and treated with different concentrations of iberin (1, 2.5, 10 and 25 μM). Then 20 μL of 5 mg/mL MTT in PBS, is added to each well and allowed to incubate for a further 4 h. After 4 h of incubation, 100 μL of DMSO is added to each well to dissolve the formazan crystals. Absorbance values at 550 nm are measured with a microplate reader[2].

Animal experiment:

Rats: Groups of five rats are dosed by oral intubation with the test compounds, as solutions in soybean oil, each day for 5 days. This doses used are 4.0 mg/kg/day for AITC, 5.9 mg/kg/day for iberverin, 6.5 mg/kg/day for iberin, 6.4 mg/kg/day for erucin, 7.1 mg/kg/day for sulforaphane, and 7.2 mg/kg/day for cheirolin. The volume of solution administered is 2 mL/kg in all cases. Ten control rats are dosed with soybean oil alone[5]. Mice: Iberin is diluted in 96% ethanol to a concentration of 32 mg/mL followed by a 40x dilution in 0.9% NaCl. The mice are injected with 0.2 mL of the final solution, corresponding to 8 μg/g of body weight. The placebo group is injected with a 2.4% ethanol solution (96% ethanol–0.9% NaCl) corresponding to the amount of ethanol that the iberin-treated group received. Mice are treated every 12 h from day 2 preinsertion to day 2 postinsertion, and treatment is continued until 12 h before the mice are euthanized[4].

Iberin is a phase II detoxification enzyme inducer.

Phase II enzymes are found to protect against chemical carcinogenesis, and the selectivity of isothiocyanates in inducing such enzymes is of interest in view of recent epidemiological studies showing a decreased incidence of cancer.

In vitro: Previous study fhound that the treatment of neuroblastoma cells with iberin led to a dose- and time-dependent growth inhibition, increased cytotoxicity, and G1 or G2 cell cycle arrest. The iberin-induced cell cycle arrest was related to the inhibition of Cdk2, Cdk4, and Cdk6 protein expression. DNA-staining pattern analyses revealed an increase in apoptotic cell death in iberin-treated cells, and FLICA staining founf that iberin could induce apoptosis, which was associated with the activation of PARP, caspase-9, and caspase-3 [1].

In vivo: In animal study, the ability of iberin was tested to increase tissue levels of the phase II enzymes quinone reductase (QR) and glutathione S-transferase (GST). At the low dose level employed (40 μmol/kg/day), cheirolin was without effect in any tissue. Results showed that iberin was able to increase the activities of GST and QR in the forestomach, duodenum, and/or the urinary bladder of the rats, with the greatest effects being observed in the urinary bladder. However, little difference was observed in the inductive activity of iberin and its various isothiocyanate analogs [2].

Clinical trial: Up to now, Iberin is still in the preclinical development stage.

References:
[1] Jadhav U, Ezhilarasan R, Vaughn SF, Berhow MA, Mohanam S.  Iberin induces cell cycle arrest and apoptosis in human neuroblastoma cells. Int J Mol Med. 2007 Mar;19(3):353-61.
[2] Munday R, Munday CM.  Induction of phase II detoxification enzymes in rats by plant-derived isothiocyanates: comparison of allyl isothiocyanate with sulforaphane and related compounds. J Agric Food Chem. 2004 Apr 7;52(7):1867-71.