Effects of peppermint tea consumption on the activities of CYP1A2, CYP2A6, Xanthine Oxidase, N-acetyltranferase-2 and UDP-glucuronosyltransferases-1A1/1A6 in healthy volunteers

- Peppermint tea consumption reduces NAT2 activity in humans.
- Peppermint tea consumption possibly reduces CYP1A2 activity in humans.
- Peppermint tea does not affect CYP2A6, Xanthine Oxidase and UDP-glucuronosyltransferases 1A1/1A6 activity in humans.

Peppermint leaves are widely used for the symptomatic treatment of digestive disorders. Previous studies have shown significant effects of its natural products on human enzyme activity; however, there is no study available concerning the effects of peppermint tea on metabolizing enzymes in humans. Aim of the present study was to investigate the effect of peppermint tea on CYP1A2, CYP2A6, Xanthine Oxidase (XO), N-acetyltranferase-2 (NAT2) and UDP-glucuronosyltransferases-1A1/1A6 (UGT1A1/1A6) activities in healthy subjects. Four males and five females consumed peppermint tea (2 g of dry leaves/200 mL water, twice daily) for six days. CYP1A2, CYP2A6, XO, NAT2 and UGT1A1/1A6 activities were determined before and at the end of the study period, using the following caffeine and paracetamol metabolic ratios: CYP1A2: 17MX/137MX (saliva) and (AFMU+1MU+1MX)/17MU (urine); CYP2A6: 17MU/(17MU + 17MX), XO: 1MU/(1MU+1MX), NAT2, AFMU/(AFMU+1MU+1MX) and UGT1A1/1A6 glucuronidated/total paracetamol, all determined in urine. NAT2 metabolic ratio was significantly reduced following peppermint consumption (0.15 ± 0.13 vs 0.14 ± 0.13; p < 0.05). CYP1A2 urine and saliva indices were reduced, yet not significantly, following peppermint consumption (urine: 3.17 ± 1.08 vs 2.91 ± 0.76, saliva: 0.56 ± 0.12 vs 0.50 ± 0.12; p > 0.05). Peppermint had no influence on CYP2A6, XO and UGT1A1/1A6 indices. Daily ingestion of peppermint tea may alter pharmacokinetics of clinically administered drugs and promote cancer chemoprevention through NAT2 inhibition.