The indane diastereoisomers, PH2 and PH5: divergence between their effects in delayed-type hypersensitivity models and a model of colitis

OBJECTIVES: Compounds PH2 and PH5 are distereoisomers of novel indane compounds, synthesised as analogues of secondary metabolites of the fern, Onychium. In this study, we compare their effects on a variety of inflammatory models. METHODS: In an effort to extend our knowledge of their anti-inflammatory profile, we have investigated their activity in two models of delayed-type hypersensitivity (DTH); the methylated bovine serum albumin model (mBSA) and the oxazolone contact hypersensitivity (CHS) model, on IL2 release from Jurkat cells and in the dextran sulphate sodium (DSS) murine model of inflammatory bowel disease. KEY FINDINGS: Both diastereoisomers are equipotent in reducing paw swelling in the mBSA model and in inhibiting interleukin (IL) 2 release from Jurkat cells. They are equally ineffective in the oxazolone contact hypersensitivity model (CHS). Only the diastereoisomer, PH5, protects against DSS-induced colitis and of its two enantiomers, only the S,S-enantiomer, PH22, possesses this activity. PH2 is ineffective in the DSS model. CONCLUSIONS: The results suggest that the beneficial effect of PH5, and its enantiomer PH22, in the DSS model is a consequence of an action on a target specific to the colitis model. The implications of such data suggest an unknown target in this disease model that may be exploited to therapeutic advantage.