Bioavailability of Terpenes and Postprandial Effect on Human Antioxidant Potential. An Open-Label Study in Healthy Subjects

Scope: To assess bioavailability of terpenes in human plasma and their effect on oxidative stress biomarkers. Methods and results: In this open-label and single arm postprandial trial, seventeen healthy male volunteers (20-40 years old) follow a low-phytochemical diet for 5 days. Next, after overnight fasting, volunteers consume Mastiha powder (a natural resin rich in terpenes) dispersed in water. Blood samples are collected on time points 0 h (before ingestion) and 0.5, 1, 2, 4, 6, and 24 h (post-ingestion). Ultra-high-pressure liquid chromatography high-resolution MS (UHPLC-HRMS/MS) is applied for high throughput analysis of plasma. Serum resistance to oxidation and oxidized LDL (oxLDL) levels are measured. UHPLC-HRMS/MS analysis shows that major terpenes are bioavailable since 0.5 h after administration, reaching a peak between 2 h and 4 h. Serum resistance to oxidation, expressed as difference of tLAG (time point-0 h), starts to increase from 0.5 h. This increase reaches statistical significance at 4 h (402.3 +/- 65.0 s), peaks at 6 h (524.6 +/- 62.9 s), and remains statistically significant until 24 h (424.2 +/- 48.0 s). oxLDL levels, expressed as %change from 0 h, are reduced significantly from time point-1 h until time point-6 h. Conclusion: Results demonstrate the terpene bioavailability pattern after oral administration of Mastiha. Terpenes are potential mediators of antioxidant defense in vivo.