Exploring the chemical space around Cannabis sativa L. leaves as a source of bioactive compounds of pharmaceutical interest

In the field of Cannabis sativa L. derived products, the attention has been usually focused on plant inflorescences as a source of cannabinoids, with stems and seeds also utilized, while leaves are typically discharged. Although previous studies have examined the composition of C. sativa leaves to evaluate their antioxidant potential, their full value remains largely unknown. In this perspective, this study aims to reveal the hidden potential of C. sativa leaves to reposition them from a waste material to an alternative source of bioactive compounds. To this purpose, the leaves of four non-psychotropic C. sativa (hemp) varieties, including a cannabinoid-free one, were comprehensively characterized for their composition for the first time. The most relevant outcome of the present work was the first identification and characterization of squalene in hemp leaves, along with the development of a suitable extraction and analytical method for this bioactive triterpenoid. Among cannabinoids, cannabinoic acids were the most abundant compounds, complemented by the detection of several minor compounds having either the cannabidiol (CBD) or cannabigerol (CBG) scaffold. As for the other chemical constituents, cannflavins were the predominant non-cannabinoid phenolic compounds. The analysis also addressed to policosanols and terpenes, revealing some variety-specific volatile compounds, beside the most common ones. Overall, hemp leaves showed a rich chemical composition to be exploited in the pharmaceutical field, perfectly aligning with a circular economy perspective.