The effect of ascorbigen and 1'-methylascorbigen as a model compound pair was studied on the phytopathogenic bacterium Pseudomonas savastanoi pv. phaseolicola in the BioArena experimental system after overpressured layer chromatography. Results showed a characteristic, strong antibacterial effect of 1'-methylascorbigen and weak effect of ascorbigen present on the adsorbent layer as chromatographic spot. Addition of formaldehyde capture compounds (L-arginine, glutathione, dimedone) partially or totally reduced the antibacterial effect of 1'-methylascorbigen and ascorbigen. On adding Cu(II) ions--which mobilize and coordinate formaldehyde--to the culture medium, the antibacterial effect of both compounds became stronger. It is supposed that the weak antibacterial effect of ascorbigen may have originated from the 1'-methylascorbigen formed in situ on the adsorbent layer by partial enzymatic methylation of ascorbigen.