*2.1. Materials*

All HPLC-grade solvents were purchased from Carlo Erba (Milan, Italy) and Fluka (Milan, Italy), whereas chemical standards were supplied by Sigma-Aldrich (Milan, Italy).

Goji berries were generously gifted by Azienda Natural Goji® (Fondi, Italy), and by two local providers from Northwest Romania. Samples given by Azienda Natural Goji®, belonging to "Poland" and "Wild" varieties, P and W, were harvested at different commercial harvesting periods (2015: 6 July, 23 July, 3 August; 2016: 26 July; 4 August, P1–P5 and W1–W5) in Fondi (Italy) based on their stage maturity as determined by the producer. Samples given by the two local providers from Romania belonged to the Biglifeberry and Erma (B, E) varieties, were from only one collection (B1, E1), and were harvested at maturity in the summer of 2014 from two organic cultures from Ciuperceni (E variety, SM county) and Ploscos, (B variety, Cluj county). No specific permissions were requested for the plant sample collection, which did not involve endargered or protected species.

All samples were quickly frozen at −80 ◦C and stored at −18 ◦C until the analyses were performed, with no direct sunlight exposure.
