Abstract
INTRODUCTION: As vitamin K(1) (phylloquinone, PK) displays vasoprotective effect, low dietary intake and poor bioavailability of PK may result in insufficient systemic levels for maintaining vascular health. This study aimed to test whether PK in hyaluronan-based nanocapsules (PK-Oil-HyC12) improves PK pharmacokinetics and endothelial function compared to PK in oil emulsion (PK-Oil). METHODS: PK pharmacokinetics in plasma, liver and aorta were analysed after single, oral administration of PK (10 mg/kg) in oil (PK-Oil) or encapsulated in hyaluronan-based nanocapsules with oil core (PK-Oil-HyC12) in mice using liquid chromatography-tandem mass spectrometry with atmospheric pressure chemical ionization method. PK-Oil-HyC12 absorption and nanocapsules distribution in lymphatic system was determined using a cycloheximide-based chylomicron flow blockage and intravital confocal microscopy. The endothelial function was analyzed in vivo by MRI in mice with dietary PK deficiency after 7-day supplementation with PK-Oil or PK-Oil-HyC12 (0.5 mg PK/kg). RESULTS: After a single, oral dose of PK-Oil-HyC12 in mice total exposure of PK (AUC values) was 2-4 times higher as compared to PK-Oil in plasma and liver, with no difference in PK content in the aorta. The efficient absorption and distribution of nanocapsules occurred mainly via a chylomicron-independent lymphatic route. Importantly, 7-day PK-Oil-HyC12 supplementation restored impaired endothelium-dependent vasodilation in the aorta of PK-deficient mice, while PK-Oil was ineffective. CONCLUSION: The improved bioavailability of PK, when administered in the form of hyaluronan-based nanocapsules, afforded the rapid replenishment of systemic PK and the reversal of endothelial dysfunction induced by low PK levels.