Characterisation of components of an extract of hemp and preliminary assessment of anti-inflammatory activity in an ex vivo model of bovine endometritis

Abstract

Hemp products are currently enjoying much commercial interest as potential anti-inflammatory preparations. However, evidence for efficacy is lacking for some clinical conditions and for crude extracts and mixtures of cannabinoids. Uterine inflammation (endometritis) is a major cause of subfertility in livestock. The aim was to assess whether a commercially important crude hemp extract (extracted with supercritical CO₂) and a commercial CBG:CBD (cannabigerol:cannabidiol) cannabinoid mixture have anti-inflammatory properties, using an ex vivo bovine tissue culture model of endometritis. LC-MS² (liquid chromatography-tandem mass spectrometry) analysis of the crude extract allowed identification of twelve cannabinoids (cannabidiolic acid (CBDA), cannabidiol (CBD), cannabidivarinic acid (CBDVA), cannabidivarin (CBDV), cannabielsoic acid A (CBEA-A), cannabielsoic acid B (CBEA-B), cannabichromene (CBC), cannabinoloic acid (CBNA), cannabinol (CBN), cannabiripsol (CBR), cannabicoumarononic acid (CBCONA), cannabicoumaronone (CBCON)) in the extract, along with isomers, an alkaloid and three polyunsaturated fatty acids. Fragmentation pathways, some including 6-π-electron pericyclic processes, are proposed. Tissue explants, from uteri from heifers at stage I or IV of the oestrous cycle, were treated with control, LPS (lipopolysaccharide), crude hemp extract, or with LPS + crude hemp extract for 24 h. The CBG:CBD mixture was assessed similarly. Inflammatory responses were measured as concentrations of PGF_2α, PGE₂ and IL-6 in culture supernatants. Secretion of IL-6 from tissue explants was abrogated by the hemp extract (50 μg mL^-1), compared to LPS alone, but it had no effect on secretion of PGF_2α. The CBG:CBD mixture had no effect on any of the markers. The crude hemp extract was not cytotoxic towards MDBK bovine kidney cells whereas the CBG:CBD mixture (50 μg mL⁻¹) caused cell death. The hemp extract warrants further investigation for anti-inflammatory effects using a broader range of inflammatory markers, whereas the CBG:CBD mixture is not recommended for further study in the context of bovine endometritis.