A comparative analysis of the proanthocyanidins from fruit and non-fruit trees and shrubs of Northern Europe: Chemical characteristics and biological activity

The comparative analysis of the chemical composition and biological activity of extracts and proanthocyanidins (PACs) isolated from harvesting and pruning agro-waste of fruit shrub-trees (Hippophae rhamnoides L. and Aronia melanocarpa) and forest cleaning waste of non-fruit trees and shrubs (Alnus incana L., Alnus glutinosa and Salix caprea) of Northern Europe was carried out. Aronia melanocarpa and Hippophae rhamnoides L. biomass had the highest proanthocyanidins content (up to 12%) on dry biomass. Fruit trees-derived purified PACs which contained structures with higher polymerization degree had slightly higher antioxidant activity. Both fruit and non-fruit trees PACs can be successfully used in antimicrobial preparations and as antioxidants, and could be interchangeable in the compositions of the antimicrobial preparations, especially against E. coli, P. aeruginosa and S. aureus. Salix caprea, which contained wider range of gallocatechin subunits, and Alnus spp., which contained diarylheptanoids, had shown better anti-microbial activity against B. cereus. Non-fruit trees PACs are desirable in the preparations against C. albicans. PACs from Hippophae rhamnoides L. and Aronia melanocarpa inhibited biofilm formation to 50%, but the extract from Hippophae rhamnoides L. showed the most significant MRSA biofilm growth inhibition (onto 80%). Preparations on the basis of waste biomass-derived compounds will contribute to sustainable pharmacy since their application will allow to diminish the use of antibiotics and to have less toxic side effects both for humans and the environment.