Oral microemulsion of phytoconstituent found in licorice as chemopreventive against benzo(a)pyrene induced forestomach tumors in experimental mice model

Dibenzoylmethane (DBM), a minor phytoconstituent found in roots of licorice (Glycyrhiza glabra) has been reported to exhibit antioxidant and chemopreventive effects. It suffers from a problem of poor aqueous solubility and permeability leading to low oral bioavailability. Microemulsion, a novel colloidal carrier was proposed to improve its solubility in order to achieve enhanced oral biodistribution and efficacy. The microemulsion was prepared using peppermint oil and Tween 20 as oil phase and surfactant respectively. The spherical globules of microemulsion depicted a mean globule size of 157 nm and polydispersity index (PDI) of 0.715. The results of exvivo intestinal permeation using non everted intestinal sac technique demonstrated 5.7 time enhancement in intestinal permeability from microemulsion. During the invivo chemopreventive evaluations using benzo(a)pyrene [B(a)P] induced forestomach tumors in mice model, the treatment with DBM microemulsion, resulted in almost 100% reduction in tumor incidence after the last dose of B(a)P. The histopathological studies suggested the regression of stomach tumors after treatment with DBM microemulsion. Also, the biochemical estimations for oxidative stress markers depicted its improved efficacy in chemoprevention. The above results suggested that oral microemulsion formulation augmented the permeability and effectiveness of DBM as potential chemopreventive agent. (C) 2017 Elsevier B.V. All rights reserved.