Chemistry and Biological Activities of Cannflavins of the Cannabis Plant.

Throughout history, Cannabis has had a significant influence on human life as one of the earliest plants cultivated by humans. The plant was a source of fibers used by the oldest known civilizations. Cannabis was also used medicinally in China, India, and ancient Egypt. Delta-9-tetrahydrocannabinol (Δ-THC), the main psychoactive compound in the plant was identified in 1964 followed by more than 125 cannabinoids. More than 30 flavonoids were isolated from the plant including the characteristic flavonoids called cannflavins, which are prenylated or geranylated flavones. In this review, the methods of extraction, isolation, identification, biosynthesis, chemical synthesis, analysis and pharmacological activity of these flavonoids are described. The biosynthetic routes of the cannflavins from phenylalanine and malonyl CoA as well as the microbial biotransformation are also discussed. Details of the chemical synthesis are illustrated as an alternative to the isolation from the plant materials along with other possible sources of obtaining cannflavins. Detailed methods discussing the analysis of flavonoids in cannabis are presented, including the techniques used for separation and detection. Finally, the various biological activities of cannflavins are reviewed along with the available molecular docking studies. Despite the low level of cannflavins in cannabis hamper their development as naturally derived products, efforts need to be put in place to develop high yield synthetic or biosynthetic protocols for their production in order for their development as pharmaceutical products.