The organosulfur compounds (OSCs), present in garlic, are studied for their protective effect against human cancers. P-glycoprotein (P-gp) and multidrug resistance protein 2 (Mrp2) are two transporters involved in the defense of cells and in the development of multidrug resistance. Whereas OSCs increase glutathione S-transferase activity (GST), Mrp2 plays a role in the transport of glutathione (GSH)-conjugates. In this study, we have investigated the effect of two OSCs, diallyl disulfide (DADS) and S-allyl cysteine (SAC), on P-gp and Mrp2 expression in renal brush-border membranes. By Western blot analysis, our results show that DADS induces Mrp2-expression (by 7-fold), which correlates with the rise of GST activity and GSH levels. Surprisingly, a co-administration of OSC with cisplatin, an anticancer drug, significantly increased Mrp2 gene and protein expression (by 30-fold), suggesting that DADS could potentiate the effects of cisplatin. Interestingly, SAC and cisplatin in co-treatment decreased P-gp protein expression and mdr1b isoform mRNA levels. In addition, modulation of the mdr1b isoform and Mrp2 by cisplatin was completely abolished by a glutathione precursor, N-acetyl cysteine. These results indicate that OSCs present in a garlic-rich diet might alter chemotherapeutic treatments using P-gp or Mrp2 substrates. (C) 2004 Elsevier Inc. All rights reserved.