Cannabinoids : Extraction Methods, Analysis and Physicochemical Characterization
Cristina Lujan RAMIREZ, Maria Alejandra FANOVICH, Maria Sandra CHURIO.
Studies in Natural Products Chemistry, Chapter 4, 2019, Volume 61, 143-173 (1-44).
ABSTRACT : A new paradigm has been established in the application of cannabinoids in the last decade. The growing accessibility to different types of Cannabis products and the rise in concern about their health benefits have provoked a rapid expansion of the research interests in phytocannabinoids with promising pharmacological properties. The characterization of the diverse chemotypes of Cannabis sativa, the elucidation of their various structures, and quantification of cannabinoids in the complex biological matrices are still challenges for the field of analytical chemistry. Besides, several studies have focused on the chemical aspects of these molecules addressing their acid-base, redox and photochemical reactivities. This knowledge is relevant in relation to the stability of the components in Cannabis preparations and for understanding the molecular basis of the activity of the extracts, such as the antioxidant capacity. The evaluation of physicochemical properties together with the current state and most recent advances in extraction techniques, fractionation and characterization of bioactive compounds from Cannabis are reviewed here. Traditional processing methods and novel technologies, such as supercritical fluid extraction, are described. In addition, the most important characterization methods are critically compared.
Cannabinoids is the term given to the group of endogenous, natural, and synthetic compounds that interact with cannabinoid receptors in animals. Among them, phytocannabinoids is the family of plant derived terpenophenolic compounds typically found in Cannabis sativa, including their carboxylic acid analogs and transformation products. Unless otherwise indicated, the word cannabinoid will be used in this chapter to refer to the naturally occurring phytocannabinoids [1-2].
Cannabis sativa is one of the most controversial protagonists of phytomedicine. It has been widely used in ethnomedicine and as a source of textile fiber [3,4]. Its recreational use as well as psychoactive properties led the species to be classified as an illegal drug and this greatly hindered the study of its chemical components and pharmacological features. This annual herb native from Central Asia belongs to the Cannabaceae family and grows up to 5 m tall. The leaves are serrated and have a distinct vein pattern that extends to its tip. This pattern can change among varieties . Cannabis is a dioecious species having histaminate male and pistillate female flowers on separate plants. The inflorescences contain the active compounds for medicinal use, mostly concentrated in the trichomes. There are six kinds of trichomes with different morphology. Cannabinoids are accumulated in the glands of both capitate-stalked and -sessile trichomes, but mostly in this latter . In the early 1970’s, cultivators began to grow Cannabis without seeds (“sinsemilla”). This effect was achieved by eliminating staminate plants from the cultivars and allowing only unfertilized pistillate plants to mature for later harvest. Instead of placing seeds in the earliest flowers, the pistillate plants continue to produce additional flowers. These flowers develop high density of resin glands, increasing the content of cannabinoids and terpenes .