Determination of cranberry proanthocyanidin A2 in human plasma and urine using LC‐MS/MS

Abstract

A‐type proanthocyanidins (PAC) exhibit anti‐adhesion activity against uropathogenic Escherichia coli in vitro, putatively protecting against urinary tract infections. However, data on PAC bioavailability in humans has not been established due to lack of a method for their quantification. We conducted a single‐dose pharmacokinetic study to quantify PAC A2 (A2) in urine and plasma of 10 healthy adults. Fasted subjects consumed 237 mL low‐calorie, low‐sugar 54% cranberry juice cocktail (CJC). Blood and urine samples were collected at specified intervals before and up to 24 h following CJC consumption. Prior to LC‐MS/MS analysis of urinary A2, liquid‐liquid extraction using ethyl acetate and solid phase extraction (SPE) were sequentially employed to extract A2 and minimize matrix‐induced MS signal depression. A2 was extracted from plasma using SPE only. The limit of quantitation (LOQ) for A2 was 1.25 ng/mL in urine and 2.5 ng/mL in plasma. The recovery rate of A2 spiked into urine was 12%. The intra‐ and inter‐assay CV for A2 spiked into urine were 9.8% and 10.6%, respectively. The maximal concentration of A2 in urine was 24.4 ng/mg creatinine at 11.0 h post ingestion, while A2 was detected in plasma at concentrations below the LOQ. This study demonstrates for the first time the bioavailability of A2 following CJC consumption. The detected A2 in urine may be derived from the beverage and via metabolism by gut microflora.