Current cannabis studies mainly focused on flowers, however, each part of the plant has a wide range of indications, primarily related with pain and inflammation, as ancient herbal medicines in various cultures. One previous published study by scientists from PBG BioPharma profiled cannabinoids, terpenoids, flavonoids, sterols, and triterpenoids, not only in cannabis flowers, but also in leaves, stem bark, and roots. By profiling these compounds in each cannabis plant part and associating them with therapeutic benefits, cannabis plant material that is currently treated as waste has potential to be developed into natural health products or medications. These groups of identified bioactive compounds may underpin the traditional applications indicated for each plant part, but most of the therapeutic properties for these individual compounds have been studied in other herbal medicine and not in cannabis.
The pharmaceutical values and the potential synergies of these bioactive compounds need to be directly investigated using cannabis material. One recent study investigated the antioxidant capacity of the phenolic rich extracts from non-psychoactive residual biomass - cannabis stems and leaves. Maximum total phenolic content (TPC) and total antioxidant capacity (TAC) were achieved by optimizing extraction time, particle size, and solid-solvent ratio during extraction using ethanol as solvent. Phenolic compounds are compounds containing hydroxylated aromatic rings (e.g., phenolic acids, flavonoids, tannins, stilbenes, lignans, etc.) and are important plant constituents with redox properties responsible for antioxidant activity, which helps to fight and prevent cancer and other diseases. A coefficient of correlation of 0.7034 was found between TPC and TAC, which indicated that around 70% of the TPC contribute to the TAC of the extracts. Some phenolic compounds were degraded by using high temperatures or long extraction times.
The study concluded that extraction time, particle size, and solid-solvent ratio have a great influence on the total phenolic compounds content and the total antioxidant capacity. This research showed that cannabis stems and leaves can be used as an alternative source of phenolic compounds with antioxidant capacity comparable or higher to other plants that have medicinal properties.
Reference:
Jin, D., Dai, K., Xie, Z. & Chen, J. Secondary Metabolites Profiled in Cannabis Inflorescences, Leaves, Stem Barks, and Roots for Medicinal Purposes. Scientific Reports 10, 3309 (2020). https://pubmed.ncbi.nlm.nih.gov/32094454/
