Cellulose coating and chelation of antibacterial compounds for the protection of flax yarns against natural soil degradation.

Natural cellulosic fibres such as flax fibres present interesting mechanical properties as well as biodegradability, and by-products, such as short flax fibres, could be used to produce geotextiles to stabilise soils. Today, geotextiles are often made of coir fibres, which have a high lignin percentage leading to their slow degradation in soil. Fibres with a high cellulosic content, such as those of flax, exhibit lower resistance to soil degradation. This study investigates solutions to improve this parameter with a view to increasing their service life and therefore their credibility compared to coir fibres for geotextile applications. For this purpose, a cellulose coating of yarns made of short flax fibres was performed and its stability under a water flow was assessed. The ability to form a cellulose sheath was estimated by chromaticity measurements of flax fibres after applying a dye specific to lignin. Infrared spectrometry analysis to monitor the level of protection against degradation by cellulolytic enzymes was also carried out. It appears that the cellulose coating provides an efficient physical protection, preventing access of these enzymes to their fibrous substrate. Then, the possibility of conferring antibacterial properties on the cellulose coating by chelating phytoalexin molecules such as gramine on it was assayed and proven to be effective against soil cellulolytic bacteria such as Cellvibrio fulvus and Cellvibrio vulgaris. This study therefore establishes that coating flax yarns with cellulose associated with antibacterial molecules could contribute to obtaining a longer service life in soil for geotextiles manufactured from flax fibres

Single Laboratory Validation of a Quantitative Core Shell-Based LC Separation for the Evaluation of Silymarin Variability and Associated Antioxidant Activity of Pakistani Ecotypes of Milk Thistle (Silybum Marianum L.)

Fruits of Silybum marianum (L.) Gaernt are the main source of taxifolin derived flavonolignans. Together, these molecules constitute a mixture called silymarin with many useful applications for cosmetic and pharmaceutic industries. Here, a validated method for the separation of the silymarin constituents has been developed to ensure precision and accuracy in their quantification. Each compound was separated with a high reproducibility. Precision and repeatability of the quantification method were validated according to the AOAC recommendations. The method was then applied to study the natural variability of wild accessions of S. marianum. Analysis of the variation in the fruits composition of these 12 accessions from Pakistan evidenced a huge natural diversity. Correlation analysis suggested a synergistic action of the different flavonolignans to reach the maximal antioxidant activity, as determined by cupric ion reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) assays. Principal component analysis (PCA) separated the 12 accessions into three distinct groups that were differing from their silymarin contents, whereas hierarchical clustering analysis (HCA) evidenced strong variations in their silymarin composition, leading to the identification of new silybin-rich chemotypes. These results proved that the present method allows for an efficient separation and quantification of the main flavonolignans with potent antioxidant activities

Nettle (Urtica dioica L.) as a source of antioxidant and anti-aging phytochemicals for cosmetic applications

Nettle (Urtica dioica L.) is a herbaceous perennial that has been used for centuries in folk medicine. More recently, nettle extracts have also been used in cosmetics because of the many benefits of their topical application for skin health. Their potential anti-aging action is of particular interest and is primarily ascribed to their antioxidant capacity. Here, using an experimental design approach and a clustering analysis, we linked the phytochemical composition of nettle extracts to their biological activities. This approach confirmed the antioxidant capacity of nettle extracts as well as providing the first evidence of another mechanism for their anti-aging potential involving the inhibition of enzyme activities, such as elastase and collagenase. We attributed these inhibitory effects to ursolic acid and quercetin present in the nettle extracts. Our results also demonstrated the possibility of extracting ursolic acid, quercetin and other phenolic compounds differentially to obtain an extract with a strong antioxidant capacity and anti-aging activities toward both elastase and collagenase. This could be of particular interest for cosmetic applications of nettle extracts.L'ortie (Urtica dioica L.) est une plante herbacée vivace utilisée depuis des siècles en médecine traditionnelle. Plus récemment, les extraits d'ortie ont été également utilisés dans des produits cosmétiques en raison des nombreux effets bénéfiques de leurs applications topiques sur la santé de la peau. En particulier, leur potentielle action anti-âge présente un fort intérêt et a été essentiellement attribuée à leur fort pouvoir antioxydant. Dans cette étude, en utilisant un plan d'expérience et une analyse hiérarchisée, nous avons connecté la composition phytochimique d'extraits d'ortie à leurs activités biologiques. Cette approche nous a permis de confirmer la capacité antioxydante des extraits d'ortie, mais aussi de proposer la première preuve d'un autre mécanisme de leur potentiel anti-âge impliquant l'inhibition d'activités enzymatiques. En effet, nos travaux montrent que ce second mécanisme implique l'inhibition d'enzymes de dégradation de la matrice extracellulaire telles que l'élastase et de la collagénase, et ces effets inhibiteurs ont été attribuables principalement à l'acide ursolique et la quercétine présents dans les extraits d'ortie. Nos résultats ont également mis en évidence la possibilité d'extraire de manière différentielle l'acide ursolique, la quercétine et d'autres composés phénoliques pour obtenir un extrait avec une forte capacité antioxydante et une activité anti-âge au travers de l'inhibition à la fois de l'élastase et de la collagénase, ce qui pourrait être d'un intérêt particulier pour les applications cosmétiques des extraits d'ortie

Microwave-Assisted Extraction of Herbacetin Diglucoside from Flax (Linum usitatissimum L.) Seed Cakes and Its Quantification using an RP-HPLC-UV System

Flax (Linum usitatissimum L.) seeds are widely used for oil extraction and the cold-pressed flaxseed (or linseed) cakes obtained during this process constitute a valuable by-product. The flavonol herbacetin diglucoside (HDG) has been previously reported as a constituent of the flaxseed lignan macromolecule linked through ester bonds to the linker molecule hydroxymethylglutaric acid. In this context, the development and validation of a new approach using microwave-assisted extraction (MAE) of HDG from flaxseed cakes followed by quantification with a reverse-phase HPLC system with UV detection was purposed. The experimental parameters affecting the HDG extraction yield, such as microwave power, extraction time and sodium hydroxide concentration, from the lignan macromolecule were optimized. A maximum HDG concentration of 5.76 mg/g DW in flaxseed cakes was measured following an irradiation time of 6 min, for a microwave power of 150 W using a direct extraction in 0.1 M NaOH in 70% (v/v) aqueous methanol. The optimized method was proven to be rapid and reliable in terms of precision, repeatability, stability and accuracy for the extraction of HDG. Comparison with a conventional extraction method demonstrated that MAE is more effective and less time-consuming

Investigation of the Lignan Content in Extracts from Linum, Callitris and Juniperus Species in Relation to Their In Vitro Antiproliferative Activities

Podophyllotoxin, a lignan still extracted from the rhizomes of Podophyllum hexandrum (Berberidaceae), is the starting molecule for the semisynthesis of widely used anticancer drugs such as etoposide. However, this source is threatened by the over-collection of P. hexandrum. Plants belonging to the Linaceae and Cupressaceae families could be attractive alternative sources with species that contain the lignan podophyllotoxin or its precursors and derivatives. Wild flax species, such as Linum flavum, as well as some Juniperus and Callitris species were investigated for their lignan content, and the in vitro antiproliferative capacity of their extracts was assayed on four tumor cell lines. Some of the lignans were detected by LC-HRMS for the first time in these extracts. In addition, lignans purified from these plants and compounds semisynthesized from commercially available podophyllotoxin were tested in terms of their in vitro antiproliferative activity. The genus Juniperus was the most promising given its in vitro antiproliferative effects, which were also observed with extracts from L. flavum and Callitris species. The in vitro antiproliferative effect of the plant extracts studied here appears to correlate well with the contents of the aryltetralin lignan podophyllotoxin and its glycoside as well as with deoxypodophyllotoxin and 6-methoxypodophyllotoxin. The strongest correlation between the lignan content of the extracts and the antiproliferative activity was observed for 6-methoxypodophyllotoxin. Regarding the possibility of producing large renewable amounts of 6-methoxypodophyllotoxin, this molecule could be of interest to produce new anticancer drugs and to bypass the resistance mechanisms against podophyllotoxin-derived drugs.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Kinetics of glucosylated and non-glucosylated aryltetralin lignans in Linum hairy root cultures

International audienceDue to their pronounced cytotoxic activity, a number of aryltetralin lignans (ATLs), such as podophyllotoxin (PTOX), are used as antitumor compounds. The production of such molecules from entire plants or plant cell-tissue-organ cultures is thus of interest to the pharmaceutical industry. Hairy root cultures constitute a good tool not only for phytochemical production but also for investigating plant secondary metabolism. This work reports on the growth and ATL biosynthesis in two hairy root cultures of Linum album Kotschy ex Boiss. and Linum flavum. The kinetics of accumulation of the intermediates of MPTOX biosynthesis and of their glucosylated forms are described over a 21-day period of growth. An accumulation of non-glucosylated forms of the ATLs during the exponential phase of the cultures is followed by an accumulation of the glucosylated forms during the stationary phase. Our results show a strong coordination of the biosynthetic paths derived from deoxypodophyllotoxin via deoxypodophyllotoxin 6-hydroxylase and deoxypodophyllotoxin 7-hydroxylase, and a coordinated glucosylation of podophyllotoxin, methoxypodophyllotoxin, and 5'-demethoxymethoxypodophyllotoxin. Furthermore, our results suggest an important role of β-peltatin-6-glucoside formation in the control of ATL accumulation in Linum hairy root cultures