CBGA-rich Cannabis sativa subcritical water vs supercritical CO2 and organic solvent extraction: Cannabinoids, volatiles and antioxidant activity

Subcritical water extraction (SWE) was evaluated as an alternative to conventional and modern extraction methods for the recovery of cannabinoids, volatile compounds and antioxidants from CBGA-rich hemp (Cannabis sativa L.). A 2^3 full factorial design of experiments (DoE) was applied to optimize the SWE conditions. The extraction yield was determined gravimetrically, and antioxidant activity and total polyphenol content were analysed using spectrophotometric methods. HPLC was used to quantify cannabinoids, while GC-MS was applied for the volatile compound analysis of the essential oil and condensed aqueous phase obtained through Clevenger distillation. SWE achieved a yield of 35.9 % and a high antioxidant activity, which is comparable to Soxhlet and high-pressure ethanol extraction methods. The temperature and the drug-to-solvent ratio were identified as significant factors affecting the yield, with Soxhlet extraction yielding the highest CBG content (36.1 %) and high-pressure ethanol extraction yielding the highest CBGA content (17.4 %). GC-MS analysis revealed that the essential oil was rich in sesquiterpenes (82.5 %), while the aqueous phase contained predominantly oxygenated monoterpenes (35.0 %). In conclusion, SWE is a promising method for obtaining hemp extracts with a high antioxidant activity and favourable yields, making it a potential sustainable alternative to conventional extraction methods.