Valorisation of the industrial hemp residue from essential oil production by recovery of cannabidiol and chemo-enzymatic conversion to cannabielsoin

Abstract

The production of essential oils by steam distillation is invariably associated with large amounts of organic waste which is normally disposed of or returned to the fields, although it may still contain some valuable components. In particular, Cannabis sativa essential oil produced by steam distillation of the apical part of industrial hemp plants yields a soaked biomass residue that may contain high-value cannabinoids. From the perspective of sustainable exploitation of agricultural resources, a method to extract cannabidiol (CBD) from such waste was demonstrated and scaled-up, using bioethanol as a renewable bio-based solvent and without requiring chromatographic separation, with an overall yield of 10.1 mg CBD per g waste. The work paves the way to an integrated complete utilisation of industrial hemp byproducts. Furthermore, two alternative lipase-mediated chemo-enzymatic derivatisations have been designed and optimised for the conversion of the recovered CBD into cannabielsoin (CBE), an underexploited cannabinoid with attractive bioactivity. The processes are practical and efficient, with 31–47% isolated yields and green metrics comparing well with the established chemical alternatives.