Characterization and Antimicrobial Activity of Lignin-Derived Compounds in Ground Hurd Tissue of Cannabis sativa L. (Hemp) Cultivars

Objectives Characterize lignin-derived compounds from the hurd of 10 fiber/grain Cannabis sativa L. cultivars and investigate the antimicrobial activity of select compounds on the wasteful ruminant bacterium, Acetoanaerobium sticklandii SR. Methods Hurd was processed using an aqueous ethanol solvent system and analyzed via GC-MS to identify and characterize lignin derivatives. Antimicrobial activity of the hurd and three monomers was assessed using solid (hurd) and liquid medium (monomers) bioassays against SR. Results 27 compounds were identified, most as monomers but a few were dimers, ethylated derivatives, and organic acids. There were approximately equal G- and S-units with substantially fewer H-units. Several derivatives were present across cultivars, but their abundance appeared varied. Generally, syringaldehyde, vanillin, and syringic acid were most prominent, whereas vanillic acid and p-coumaric acid were less so, and syringaresinol was largely variable. Antimicrobial activity of ground hurd, as well as vanillin, vanillic acid, and p-coumaric acid were tested against SR. Only vanillin exhibited antimicrobial activity (1 mg mL−1) under the testing conditions. Conclusions The current work primarily contributes to the characterization and identification of lignin-derivatives in hemp hurd across fiber/grain cultivars with secondary contributions identifying hemp hurd as a potential source of plant-derived antimicrobials for amino-acid fermenting bacteria.