2019 ASHS Annual Conference

Polyprenols, are a long-chain isoprenoid alcohols with the formula (C5H8)n. In the human body, polyprenols are transformed into dolichols, which play a significant role in immune function, liver regeneration, suppression of cancer, antimicrobial and antiviral activity and Alzheimer’s disease prevention. Polyprenols are promising compounds for pharmaceutical sector. The aim of this study to develop supercritical carbon dioxide (SC-CO₂) extraction of polyprenols and other bioactive compounds (antioxidants, polyphenolics and flavonoids) from needles of Picea pungens (blue spruce), Taxus bacatta (Irish yew), Pinus sylvestris (Scots pine) and leaves of Sorbus aucuparia (mountain ash). The SC-CO₂ extraction is a clean and environmentally friendly alternative to traditional solvent methods as it eliminates the use of toxic organic solvents and the expensive post-processing solvent elimination from the extracts. The experimental orthogonal array design L₂₄ (4⁵) was applied to optimise the SC-CO₂ extraction conditions: pressure (100–350 bar), temperature (40–70°C), percentage of modifier (ethanol absolute) and extraction time (up to 70 min). SC-CO₂ extraction of polyprenols was performed on P. pungens which were used as a model plant for optimisation. The SC-CO₂ extracts were compared with conventional solvent extracts (hexane/acetone, 1:1 and 4:1 v/v, and 70% ethanol). The detection and identification of polyprenos was performed by HPLC. Polyprenols were detected in P. pungens, P. sylvestris and S. aucuparia but not in T. bacatta. P. sylvestris was identified as the most promising source of polyprenols: it had the highest concentration of polyprenols with the widest range of isoprene oligomeric units. The SC-CO₂ extraction was an effective and promising method for the extraction of polyprenols. The higher yield of polyprenols were extracted by SC-CO then by traditional solvent extractions. Furthermore, wider range of short- and medium-chain polyprenol oligomers were observed in SC-CO₂ extracts. The optimum SC-CO₂ extraction conditions were also established. P. pungens, T. bacatta, P. sylvestris and S. aucuparia solvent and SC-CO₂ extracts were also analysed for the phenolics, flavonoids and antioxidants compounds. Antioxidant properties were evaluated by DPPH and FRAP assays. The extraction with 70% ethanol was identified as the most effective solvent for these bioactive compounds. All four plants demonstrated high level of bioactivities, with P. sylvestris having the highest concentration of phenolic, flavonoids and antioxidant. SC-CO₂ was not a very effective method for the extraction of phenolic, flavonoids and antioxidant compounds and in average ten times less effective than the extraction with 70% ethanol.