In Situ Decarboxylation-Pressurized Hot Water Extraction for Selective Extraction of Cannabinoids from Cannabis sativa. Chemometric Approach

Progress in the analysis of phytocannabinoids by HPLC and UPLC (or UHPLC) during 2020-2023

INTRODUCTION

Organic molecules that bind to cannabinoid receptors are known as cannabinoids. These molecules possess pharmacological properties similar to those produced by Cannabis sativa L. High-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC, also known as ultra-high-performance liquid chromatography, UHPLC) have become the most widely used analytical tools for detection and quantification of phytocannabinoids in various matrices. HPLC and UPLC (or UHPLC) are usually coupled to an ultraviolet (UV), photodiode array (PDA), or mass spectrometric (MS) detector.

OBJECTIVE

To critically appraise the literature on the application of HPLC and UPLC (or UHPLC) methods for the analysis of phytocannabinoids published from January 2020 to December 2023.

METHODOLOGY

An extensive literature search was conducted using Web of Science, PubMed, and Google Scholar and published materials including relevant books. In various combinations, using cannabinoid in all combinations, cannabis, hemp, hashish, C. sativa, marijuana, analysis, HPLC, UHPLC, UPLC, and quantitative, qualitative, and quality control were used as the keywords for the literature search.

RESULTS

Several HPLC- and UPLC (or UHPLC)-based methods for the analysis of phytocannabinoids were reported. While simple HPLC-UV or HPLC-PDA-based methods were common, the use of HPLC-MS, HPLC-MS/MS, UPLC (or UHPLC)-PDA, UPLC (or UHPLC)-MS, and UPLC (or UHPLC)-MS/MS was also reported. Applications of mathematical and computational models for optimization of protocols were noted. Pre-analyses included various environmentally friendly extraction protocols.

CONCLUSION

During the last 4 years, HPLC and UPLC (or UHPLC) remained the main analytical tools for phytocannabinoid analysis in different matrices.

Simple Extraction of Cannabinoids from Female Inflorescences of Hemp (Cannabis sativa L.)

The high interest in non-psychoactive cannabidiol increases the need for efficient and straightforward cannabidiol (CBD) extraction methods. The research aimed to compare simple methods of cannabinoid extraction that do not require advanced laboratory equipment. This work assesses the content of total CBD and Δ⁹-tetrahydrocannabinol (Δ⁹-THC) in popular solvents such as water and ethanol extracts. Hemp raw material was analyzed with Gas Chromatography with a Flame Ionization Detector (GC-FID), while extracts were tested by High-Performance Liquid Chromatography (HPLC). The female inflorescences of three varieties of industrial hemp were tested: Futura 75, KC Dora, and Tygra (different sowing and N fertilization densities). Tygra (T/10/30) showed the highest content of CBD (0.064%) in water extracts. However, in 80% tincture from Futura 75 (F/30/30), a higher CBD content of 1.393% was observed. The use of 96% ethanol for extraction and ultrasound enabled the highest CBD content to be obtained: 2.682% in Futura 75 (F/30/30). Cold water extraction showed no effect on Δ⁹-THC content, while hot water extraction increased content from 0.001% in KC Dora to 0.002% in Futura 75 (F/30/30) and Tygra, but the changes were statistically insignificant. Application of 80% ethanol revealed the significantly highest content of Δ⁹-THC in KC Dora, from 0.026% (K/30/90) to 0.057% (K/30/30), as well as in Tygra (T/30/30) (0.036%) and Futura 75 (F/30/30) (0.048%). The use of ethanol extraction in combination with ultrasound could be an efficient method of obtaining cannabinoids.

Terpenes and Cannabinoids Yields and Profile from Direct-Seeded and Transplanted CBD-Cannabis sativa

Following recent legalization, the production of hemp (Cannabis sativa L.) for high-value plant compounds became a major crop in many countries across the world. In this study, we profiled popular plant compounds being extracted for emerging markets, terpenes and cannabinoids, developed in two different planting systems of a single, high-cannabidiol (CBD), low-Δ⁹-tetrahydrocannabinol (Δ⁹-THC), dioecious hemp cultivar 'Culver' in central Oregon, U.S.A. One system is the current conventional system of an open, all-female, clonal transplant (OFCT) production system. This is compared to a dioecious, densely seeded (DDS) production system. Overall, the essential oil (EO, chiefly terpenes) and cannabinoid profiles of plants harvested from the two systems were comparable. In comparison to the DDS plots, the EO obtained from colas of the OFCT plots had higher concentrations of α-pinene, myrcene, limonene, β-bisabolene, γ-cadinene, caryophyllene oxide, guaiol, 10-epi-γ-eudesmol, β-eudesmol, bulnesol, epi-α-bisabolol, α-humulene, and CBD, although lower concentrations of 1,8-cineole, (E)-caryophyllene, γ-elemene, α-selinene, selina-4(15),7(11)-diene, selina-3,7(11)-diene, and germacrene B. Of the various plant parts (female leaves and chaff, male flowers) tested in the DDS plots, the highest EO yield was obtained from the chaff. The main EO constituents of female leaves were (E)-caryophyllene (14-21%), caryophyllene oxide (13-16%), α-humulene (5-6%), humulene epoxide II (3.5-3.8%), epi-α-bisabolol (2.7-5.5%), CBD, and α-eudesmol (1.1-2.6%). The principal EO constituents of female chaff from the DDS system were (E)-caryophyllene (∼21%), α-humulene (6.6%), β-selinene (4.5%), α-selinene (3.6%), selina-3,7(11)-diene (9.8%), selina-4(15),7(11)-diene (6.3%), caryophyllene oxide (5.2%), and cannabichromene (3.1%). The major EO constituents of the male flowers were CBD (19.3%), caryophyllene oxide (11%), α-humulene (4.1%), epi-α-bisabolol (3.9%), selina-3,7(11)-diene (3.4%), and β-selinene (3.4%). Cannabinoids were not detected in the EO distilled for 30 min, but they were present in the EO from 240 min of distillation. The EO content of female leaves and male flowers was relatively low, whereas the EO content of the female chaff from the DDS system was significantly greater. Breaking with conventional knowledge, the EO of male flowers may accumulate up to 19% CBD. Distillation of plants from both production systems converted CBD-A to CBD, CBDV-A to CBDV, CBG-A to CBG, and THC-A to THC as a result of the thermal decarboxylation of acidic cannabinoids but otherwise did not affect the total cannabinoid content. Most of the cannabinoids remained in the distilled biomass after the extraction of terpenes (EO). Therefore, the distilled, terpene-free biomass represents a high-value product that could be further extracted for cannabinoids or used as a component in various products.

Postharvest Operations of Cannabis and Their Effect on Cannabinoid Content: A Review

In recent years, cannabis (Cannabis sativa L.) has been legalized by many countries for production, processing, and use considering its tremendous medical and industrial applications. Cannabis contains more than a hundred biomolecules (cannabinoids) which have the potentiality to cure different chronic diseases. After harvesting, cannabis undergoes different postharvest operations including drying, curing, storage, etc. Presently, the cannabis industry relies on different traditional postharvest operations, which may result in an inconsistent quality of products. In this review, we aimed to describe the biosynthesis process of major cannabinoids, postharvest operations used by the cannabis industry, and the consequences of postharvest operations on the cannabinoid profile. As drying is the most important post-harvest operation of cannabis, the attributes associated with drying (water activity, equilibrium moisture content, sorption isotherms, etc.) and the significance of novel pre-treatments (microwave heating, cold plasma, ultrasound, pulse electric, irradiation, etc.) for improvement of the process are thoroughly discussed. Additionally, other operations, such as trimming, curing, packaging and storage, are discussed, and the effect of the different postharvest operations on the cannabinoid yield is summarized. A critical investigation of the factors involved in each postharvest operation is indeed key for obtaining quality products and for the sustainable development of the cannabis industry.

Analytical Techniques for Phytocannabinoid Profiling of Cannabis and Cannabis-Based Products-A Comprehensive Review

Cannabis is gaining increasing attention due to the high pharmacological potential and updated legislation authorizing multiple uses. The development of time- and cost-efficient analytical methods is of crucial importance for phytocannabinoid profiling. This review aims to capture the versatility of analytical methods for phytocannabinoid profiling of cannabis and cannabis-based products in the past four decades (1980–2021). The thorough overview of more than 220 scientific papers reporting different analytical techniques for phytocannabinoid profiling points out their respective advantages and drawbacks in terms of their complexity, duration, selectivity, sensitivity and robustness for their specific application, along with the most widely used sample preparation strategies. In particular, chromatographic and spectroscopic methods, are presented and discussed. Acquired knowledge of phytocannabinoid profile became extremely relevant and further enhanced chemotaxonomic classification, cultivation set-ups examination, association of medical and adverse health effects with potency and/or interplay of certain phytocannabinoids and other active constituents, quality control (QC), and stability studies, as well as development and harmonization of global quality standards. Further improvement in phytocannabinoid profiling should be focused on untargeted analysis using orthogonal analytical methods, which, joined with cheminformatics approaches for compound identification and MSLs, would lead to the identification of a multitude of new phytocannabinoids.