Flaxseed accumulates in its seedcoat a macromolecular complex composed of lignan (secoisolariciresinol diglucoside, SDG), flavonol (herbacetin diglucoside, HDG) and hydroxycinnamic acids (p-couramic, caffeic and ferulic acid glucosides). Their antioxidant and/or cancer chemopreventive properties support their interest in human health and therefore, the demand for their extraction. In the present study, ultrasound-assisted extraction (UAE) of flaxseed phenolic compounds was investigated. Scanning Electron Microscopy imaging and histochemical analysis revealed the deep alteration of the seedcoat ultrastructure and the release of the mucilage following ultrasound treatment. Therefore, this method was found to be very efficient for the reduction of mucilage entrapment of flaxseed phenolics. The optimal conditions for UAE phenolic compounds extraction from flaxseeds were found to be: water as solvent supplemented with 0.2N of sodium hydroxide for alkaline hydrolysis of the SDG-HMG complex, an extraction time of 60 min at a temperature of 25°C and an ultrasound frequency of 30 kHz. Under these optimized and validated conditions, highest yields of SDG, HDG and hydroxycinnamic acid glucosides were detected in comparison to other published methods. Therefore, the procedure presented herein is a valuable method for efficient extraction and quantification of the main flaxseed phenolics. Moreover, this UAE is of particular interest within the context of green chemistry in terms of reducing energy consumption and valuation of flaxseed cakes as by-products resulting from the production of flax oil.

Rose Bengal, a dye sensitizer, was found to be active as a visible light photoredox catalyst for the direct enantioselective α-alkylation of aldehydes in environmentally benign and simple conditions. Starting from a SOMO converse mechanism, the catalytic activity of the imidazolidinone organocatalyst was improved using an electrophilic cocatalyst. The resulting methodology and optimal conditions led to efficient and transition-metal-free direct photoredox organocatalysis.Scheme 1 Previous laboratory work showing the competitive pathways in the photo-oxidation of tertiary amines. † Electronic supplementary information (ESI) available: General procedures, experimental data, photosensitizers properties, spectroscopic data. See

The lignans podophyllotoxin and deoxypodophyllotoxin are secondary metabolites with potent pharmaceutical applications in cancer therapy. However, the supply of podophyllotoxin from its current natural source, Podophyllum hexandrum, is becoming increasingly problematic, and alternative sources are therefore urgently needed. So far, podophyllotoxin and deoxypodophyllotoxin have been found in some Juniperus species, although at low levels in most cases. Moreover, extraction protocols deserve optimization. This study aimed at developing and validating an efficient extraction protocol of podophyllotoxin and deoxypodophyllotoxin from Juniperus species and applying it to 13 Juniperus species, among which some had never been previously analyzed. Juniperus bermudiana was used for the development and validation of an extraction protocol for podophyllotoxin and deoxypodophyllotoxin allowing extraction yields of up to 22.6 mg/g DW of podophyllotoxin and 4.4 mg/g DW deoxypodophyllotoxin, the highest values found in leaf extract of Juniperus. The optimized extraction protocol and HPLC separation from DAD or MS detections were established and validated to investigate podophyllotoxin and deoxypodophyllotoxin contents in aerial parts of 12 other Juniperus species. This allowed either higher yields to be obtained in some species reported to contain these two compounds or the occurrence of these compounds in some other species to be reported for the first time. This efficient protocol allows effective extraction of podophyllotoxin and deoxypodophyllotoxin from aerial parts of Juniperus species, which could therefore constitute interesting alternative sources of these valuable metabolites.