Publications

Dec 09, 2019

First Total Synthesis of (β-5)-(β-O-4) Dihydroxytrimer and Dihydrotrimer of Coniferyl Alcohol (G): Advanced Lignin Model Compounds

First Total Synthesis of (β-5)-(β-O-4) Dihydroxytrimer and Dihydrotrimer of Coniferyl Alcohol (G): Advanced Lignin Model Compounds

To investigate lignin degradation, scientists commonly use model compounds. Unfortunately, these models are most of the time simple β-O-4 dimers and do not sufficiently mimic the wide complexity of lignin structure (i.e., aliphatic side chains and robust C-C bonds).

Herein, we present a methodology to access advanced lignin models through the first synthesis of two trimers of monolignol G—possessing side-chains and both robust β-5 bond and labile β-O-4 bond—via a chemo-enzymatic pathway. Key steps were (1) the C-C coupling via laccase-mediated oxidation, (2) the C-O coupling via a simple SN2 between a phenolate and a bromoketoester, and (3) a modified Upjohn dihydroxylation or a palladium-catalyzed hydrogenation. (β-5)-(β-O-4) dihydroxytrimer and dihydrotrimer of coniferyl alcohol (G) were obtained in good global yield, 9 and 20%, respectively, over nine steps starting from ferulic acid.

Dec 03, 2019

(S)-γ-hydroxymethyl-α,β-butenolide (aka HBO), a Valuable Chiral Synthon: Syntheses, Reactivity and Applications

(S)-γ-hydroxymethyl-α,β-butenolide (aka HBO), a Valuable Chiral Synthon: Syntheses, Reactivity and Applications

Chirality is greatly sought for pharmaceutical compounds or fragrance and flavors. (S)-γ-hydroxymethyl-α,β-butenolide, aka HBO, is a chiral (5H)-furanone providing a polarized double bond, a lactone ring and a primary alcohol as playground for synthetic chemists. This molecule has been used for forty years in a wide range of synthetic pathways to natural and/or bioactive molecules. Its own synthesis, always from biosourced product, has also significantly evolved and could be now achieved both at large scale and by applying Green Chemistry principles. This review will explore the syntheses, the reactivity and the uses of HBO.

Nov 20, 2019

Identification of microalgae biorefinery scenarios and development of mass and energy balance flowsheets

Identification of microalgae biorefinery scenarios and development of mass and energy balance flowsheets

The notion of bioeconomy is at the basis of recent European strategies aiming at conciliating economic growth and sustainability. Consequently, extensive research has been conducted on biobased solutions such as microalgae products. Numerous initiatives to commercialize microalgae have been launched but few of them were successful. Algae biofuel is the most obvious illustration with its promises as energy supply but faces many challenges to become economically competitive. Consequently, it was recently proposed to develop microalgae biorefineries for an optimal biomass valorisation, to dilute the overall costs within a wide range of products.

Herein, the energy demand for different microalgae biorefinery scenarios is investigated and critical steps identified. Each scenario is modelled using information from literature and process engineering principles. The production of lipids, proteins, methane, fertilizers and dried biomass are considered. Once defined, the scenarios are modelled and their energy inputs are discussed. We also investigate the impact of using a biobased solvent for lipid extraction instead of a conventional one. On top of that, each scenario is assessed for two cells disruption methods.

In both cases, the study starts with dewatering the growth medium of the microalgae Chlorella vulgaris (240 kg DW h−1) and ends with the recovery of the products. The results vary from 20.07 to 66.53 MJ kg−1 input DW and highlight the importance of the cell disruption method in the total energy demand. While lipid extraction presents adverse impacts on proteins extraction due to solvent recovery, proteins extraction has beneficial effects on further methane production step. Our study concludes with the comparison of microalgae biomass with soy, for proteins and lipids production, and demonstrates quantitatively that microalgae-based technologies are still inefficient compared to present alternatives.

This work provides quantitative numbers for further evaluation of microalgae projects considering the current stage of the technology.

Oct 19, 2019

Towards symmetry driven and nature inspired UV filter design

Towards symmetry driven and nature inspired UV filter design

In plants, sinapate esters offer crucial protection from the deleterious effects of ultraviolet radiation exposure. These esters are a promising foundation for designing UV filters, particularly for the UVA region (400 – 315 nm), where adequate photoprotection is currently lacking. Whilst sinapate esters are highly photostable due to a cis-trans(and vice versa) photoisomerization, the cis-isomer can display increased genotoxicity; an alarming concern for current cinnamate ester-based human sunscreens. To eliminate this potentiality, here we synthesize a sinapate ester with equivalent cis- and trans- isomers. We investigate its photostability through innovative ultrafast spectroscopy on a skin mimic, thus modelling the as close to true environment of sunscreen formulas. These studies are complemented by assessing endocrine disruption activity and antioxidant potential. We contest, from our results, that symmetrically functionalized sinapate esters may show exceptional promise as nature-inspired UV filters in next generation sunscreen formulations.

May 02, 2019

Beating of hemp bast fibres: an examination of a hydro-mechanical treatment on chemical, structural, and nanomechanical property evolutions

Beating of hemp bast fibres: an examination of a hydro-mechanical treatment on chemical, structural, and nanomechanical property evolutions

In this study, a gradually increased hydro-mechanical treatments duration were applied to native hemp bast fibres with a traditional pulp and paper beating device (laboratory Valley beater). There is often a trade-off between the treatment applied to the fibres and the effect on their integrity. The multimodal analysis provided an understanding of the beating impact on the fibres at multiple scales and the experimental design made it possible to distinguish the effects of hydro- and hydro-mechanical treatment. Porosity analyses showed that beating treatment doubled the macroporosity and possibly reduced nanoporosity between the cellulose microfibrils.

The beating irregularly extracted the amorphous components known to be preferentially located in the middle lamellae and the primary cell walls rather than in the secondary walls, the overall increasing the crystallinity of cellulose from 49.3 to 59.1%, but a non-significant change in the indentation moduli of the cell wall was observed. In addition, beating treatments with two distinct mechanical severities showed a disorganization of the cellulose conformation, which significant dropped the indention moduli by 11.2 GPa and 8.4 GPa for 10 and 20 min of Valley beater hydro-mechanical treatment, respectively, compared to hydro-treated hemp fibres (16.6 GPa).

Pearson’s correlation coefficients between physicochemical features and the final indentation moduli were calculated. Strong positive correlations were highlighted between the cellulose crystallinity and rhamnose, galactose and mannose as non-cellulosic polysaccharide components of the cell wall.

Apr 19, 2019

Improvement of protein content and decrease of anti-nutritional factors in olive cake by solid-state fermentation: A way to valorize this industrial by-product in animal feed

Improvement of protein content and decrease of anti-nutritional factors in olive cake by solid-state fermentation: A way to valorize this industrial by-product in animal feed

The present work investigates the bioconversion of the olive cake (OC) generated by olive oil industries in Morocco through solid-state fermn. using selected filamentous fungi to increase its nutritional values for subsequent valorization as ruminants feed. The fungi -namely Beauveria bassiana, Fusarium flocciferum, Rhizodiscina cf. lignyota, and Aspergillus niger were cultured on OC for 15 days. Chem. compn. as well as enzymes activities were detd. Results showed (i) an increase in protein content of up to 94% for treated OC and (ii) significant (P < 0.05) decreases of phenolic compds., up to 43%, 70% and 42% for total phenolic content, total flavonoids content, and total condensed tannins, resp. Moreover, the RP-HPLC anal. of fermented OC confirmed the degrdn. of individual phenolic compds. by the strains.

These findings demonstrate that F. flocciferum and Rhizodiscina cf. lignyota are efficient enzymes producers leading to a nutritive enhancement of this byproduct.