Application of supercritical CO2 for extraction of polyisoprenoid alcohols and their esters from plant tissues

Medium-chain-length polyprenol (C45-C55) formation in chloroplasts of Arabidopsis is brassinosteroid-dependent

Brassinosteroids are important plant hormones influencing, among other processes, chloroplast development, the electron transport chain during light reactions of photosynthesis, and the Calvin-Benson cycle. Medium-chain-length polyprenols built of 9-11 isoprenoid units (C45-C55 carbons) are a class of isoprenoid compounds present in abundance in thylakoid membranes. They are synthetized in chloroplast by CPT7 gene from Calvin cycle derived precursors on MEP (methylerythritol 4-phosphate) isoprenoid biosynthesis pathway. C45-C55 polyprenols affect thylakoid membrane ultra-structure and hence influence photosynthetic apparatus performance in plants such as Arabidopsis and tomato. So far nothing is known about the hormonal or environmental regulation of CPT7 gene expression. The aim of our study was to find out if medium-chain-length polyprenol biosynthesis in plants may be regulated by hormonal cues.We found that the CPT7 gene in Arabidopsis has a BZR1 binding element (brassinosteroid dependent) in its promoter. Brassinosteroid signaling mutants in Arabidopsis accumulate a lower amount of medium-chain-length C45-C55 polyprenols than control plants. At the same time carotenoid and chlorophyll content is increased, and the amount of PsbD1A protein coming from photosystem II does not undergo a significant change. On contrary, treatment of WT plants with epi-brassinolide increases C45-C55 polyprenols content. We also report decreased transcription of MEP enzymes (besides C45-C55 polyprenols, precursors of numerous isoprenoids, e.g. phytol, carotenoids are derived from this pathway) and genes encoding biosynthesis of medium-chain-length polyprenol enzymes in brassinosteroid perception mutant bri1-116. Taken together, we document that brassinosteroids affect biosynthetic pathway of C45-C55 polyprenols.

Strategy of Coniferous Needle Biorefinery into Value-Added Products to Implement Circular Bioeconomy Concepts in Forestry Side Stream Utilization

Sustainable development goals require a reduction in the existing heavy reliance on fossil resources. Forestry can be considered a key resource for the bioeconomy, providing timber, energy, chemicals (including fine chemicals), and various other products. Besides the main product, timber, forestry generates significant amounts of different biomass side streams. Considering the unique and highly complex chemical composition of coniferous needle/greenery biomass, biorefinery strategies can be considered as prospective possibilities to address top segments of the bio-based value pyramid, addressing coniferous biomass side streams as a source of diverse chemical substances with applications as the replacement of fossil material-based chemicals, building blocks, food, and feed and applications as fine chemicals. This study reviews biorefinery methods for coniferous tree forestry biomass side streams, exploring the production of value-added products. Additionally, it discusses the potential for developing further biorefinery strategies to obtain products with enhanced value.

Compositional Analysis and Potent Insecticidal Activity of Supercritical CO2 Fluid Extracts of Alcea nudiflora L. Leaves

To mitigate potentially severe food shortages due to the exponential growth of the global population, it is of paramount importance to improve the yield and quality of globally harvested food crops. As pest control contributes to both these aspects, the development of safe and effective pesticides is one of the main strategies pursued in this direction in the context of agricultural chemistry. During our investigation of natural pesticides, a supercritical CO₂ fluid extract of Alcea nudiflora L. was found to exert extremely potent insecticidal activity against aphids (Macrosiphum euphorbiae) and cowpea seed beetles (Callosobruchus maculatus) with LC₅₀ values of 0.03 mg/mL (24 h exposure, contact method). The facts that their insecticidal activity is in the most potent class among the essential oils known to date, and that the extract did not show any toxicity toward beneficial insects such as ladybugs (Coccinella magnifica) and European honeybees (Apis mellifera Linnaeus), indicate that this extract could be a good, natural, and safe new pesticide candidate. A compositional analysis of this extract was carried out using GC/MS.

Supercritical-CO2 extraction, identification and quantification of polyprenol as a bioactive ingredient from Irish trees species

This study ascertained the accumulation of polyprenol from four Irish conifer species Picea sitchensis, Cedrus atlantica ‘Glauca’, Pinus sylvestris and Taxus baccata and one flowering tree Cotoneaster hybrida using supercritical fluid extraction with carbon dioxide (SFE-CO₂) and solvent extraction. The effects of SFE-CO₂ parameters such as temperature (ranged from 40 to 70 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ{\rm C}$$\end{document}∘C), pressure (ranged from 100 to 350 bars) and dynamic time (from 70 min to 7 h) were analysed on the extraction efficiency of polyprenol. Qualitative and quantitative analysis of polyprenol was examined using high-performance liquid chromatography. Results showed that P. sylvestris accumulated the highest polyprenol yield of 14.00  ± \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0.4$$\end{document}0.4mg g⁻¹ DW when extracted with hexane:acetone (1:1 v/v). However, with SFE-CO₂ conditions of 200 bars, 70 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^\circ{\rm C}$$\end{document}∘C, 7 h, with absolute ethanol as a cosolvent with a flow rate of 0.05 ml min⁻¹, P. sitchensis accumulated the highest polyprenol yield of 6.35 ± \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0.4$$\end{document}0.4 mg g⁻¹DW. This study emphasised the potential application of SFE-CO₂ in the extraction of polyprenol as an environmentally friendly method to be used in pharmaceutical and food industries.

Supercritical Carbon Dioxide Extraction of Allium ursinum: Impact of Temperature and Pressure on the Extracts Chemical Profile

The aim of this study was to extract Allium ursinum L. for the first time by supercritical carbon dioxide (SC-CO₂ ) as green sustainable method. The impact of temperature in the range from 40 to 60 °C and pressure between 150 and 400 bar on the quality of the obtained extracts and efficiency of the extraction was investigated. The highest extraction yield (3.43 %) was achieved by applying the extraction conditions of 400 bar and 60 °C. The analysis of the extracts was performed by gas chromatography and mass spectrometry (GC/MS). The most dominant sulfur-containing constituent of the extracts was allyl methyl trisulfide with the highest abundance at 350 bar and 50 °C. In addition, the presence of other pharmacologically potent sulfur compounds was recorded including S-methyl methanethiosulfinate, diallyl trisulfide, S-methyl methylthiosulfonate, and dimethyl trisulfide. Multivariate data analysis tool was utilized to investigate distributions of the identified compounds among the extracts obtained under various extraction conditions and yields. It was determined that the SC-CO₂ extraction can by efficiently used for A. ursinum.

Identification of Abies sibirica L. Polyprenols and Characterisation of Polyprenol-Containing Liposomes

The needles of conifer trees are one of the richest sources of natural polyprenols. Polyprenol homologs from Abies sibirica L. lipophilic 80% purified extract were analyzed and quantified. In total, 10 peaks (Prenol-11 to Prenol-20) were observed in the ultra-high-performance liquid chromatography–diode array detector (UHPLC-DAD) chromatogram of Siberian fir with the most abundant compound being Prenol-15 (relative amount 37.23 + 0.56% of the total polyprenol yield). Abies sibirica L. polyprenol solubility and incorporation efficiency into liposomes were studied in various commercially available lecithin mixtures (Phosal IP40, Phosal 75SA, and Lipoid P45). The resulting multilamellar polyprenol liposomes were morphologically characterized by Light and Transmission Electron Microscopy, and the liposome size was discovered to be polymodal with the main peak at 1360 nm (90% of the volume). As polyprenols are fully soluble only in lipids, a liposomal formulation based upon co-solubilization and a modified ethanol injection method of polyprenols into the ethanol-phospholipid system was developed for the entrapment and delivery of polyprenols for potential commercial applications in food supplement and cosmetic industries.

Double bond stereochemistry influences the susceptibility of short-chain isoprenoids and polyprenols to decomposition by thermo-oxidation

Isoprenoid alcohols are common constituents of living cells. They are usually assigned a role in the adaptation of the cell to environmental stimuli, and this process might give rise to their oxidation by reactive oxygen species. Moreover, cellular isoprenoids may also undergo various chemical modifications resulting from the physico-chemical treatment of the tissues, e.g., heating during food processing. Susceptibility of isoprenoid alcohols to heat treatment has not been studied in detail so far. In this study, isoprenoid alcohols differing in the number of isoprene units and geometry of the double bonds, β-citronellol, geraniol, nerol, farnesol, solanesol and Pren-9, were subjected to thermo-oxidation at 80 °C. Thermo-oxidation resulted in the decomposition of the tested short-chain isoprenoids as well as medium-chain polyprenols with simultaneous formation of oxidized derivatives, such as hydroperoxides, monoepoxides, diepoxides and aldehydes, and possible formation of oligomeric derivatives. Oxidation products were monitored by GC-FID, GC-MS, ESI-MS and spectrophotometric methods. Interestingly, nerol, a short-chain isoprenoid with a double bond in the cis (Z) configuration, was more oxidatively stable than its trans (E) isomer, geraniol. However, the opposite effect was observed for medium-chain polyprenols, since Pren-9 (di-trans-poly-cis-prenol) was more susceptible to thermo-oxidation than its all-trans isomer, solanesol. Taken together, these results experimentally confirm that both short- and long-chain polyisoprenoid alcohols are prone to thermo-oxidation.