Insight into the Influence of Cultivar Type, Cultivation Year, and Site on the Lignans and Related Phenolic Profiles, and the Health-Promoting Antioxidant Potential of Flax (Linum usitatissimum L.) Seeds.

Flaxseeds are a functional food representing, by far, the richest natural grain source of lignans, and accumulate substantial amounts of other health beneficial phenolic compounds (i.e., flavonols, hydroxycinnamic acids). This specific accumulation pattern is related to their numerous beneficial effects on human health. However, to date, little data is available concerning the relative impact of genetic and geographic parameters on the phytochemical yield and composition. Here, the major influence of the cultivar over geographic parameters on the flaxseed phytochemical accumulation yield and composition is evidenced. The importance of genetic parameters on the lignan accumulation was further confirmed by gene expression analysis monitored by RT-qPCR. The corresponding antioxidant activity of these flaxseed extracts was evaluated, both in vitro, using ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and iron chelating assays, as well as in vivo, by monitoring the impact of UV-induced oxidative stress on the lipid membrane peroxidation of yeast cells. Our results, both the in vitro and in vivo studies, confirm that flaxseed extracts are an effective protector against oxidative stress. The results point out that secoisolariciresinol diglucoside, caffeic acid glucoside, and p-coumaric acid glucoside are the main contributors to the antioxidant capacity. Considering the health benefits of these compounds, the present study demonstrates that the flaxseed cultivar type could greatly influence the phytochemical intakes and, therefore, the associated biological activities. We recommend that this crucial parameter be considered in epidemiological studies dealing with flaxseeds.

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.

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.

Flaxseed (Linum usitatissimum L.) extract as well as (+)-secoisolariciresinol diglucoside and its mammalian derivatives are potent inhibitors of α-amylase activity.

Type 2 diabetes mellitus (T2DM) is one of the common global diseases. Flaxseed is by far the richest source of the dietary lignans (i.e., secoisolariciresinol diglucoside) which have been shown to delay the development of T2DM in animal models. Herein, we propose the first evidences for a mechanism of action involving the inhibition of the pancreatic α-amylase (EC 3.2.1.1) by flaxseed-derived lignans that could therefore constitute a promising nutraceutical for the prevention and the treatment of T2DM.

Podophyllotoxin and deoxypodophyllotoxin in Juniperus bermudiana and 12 other Juniperus species: optimization of extraction, method validation, and quantification.

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.

[Interest of lignans in prevention and treatment of cancers]. / Intérêt des lignanes dans la prévention et le traitement de cancers.

Lignans are diphenolic compounds widely distributed in the plant kingdom. They are mainly localised in lignified tissues, seeds and roots. These molecules are involved in plant defence mechanisms, but are also interesting for human health. Flax lignans belonging to the phytoestrogens are metabolised after ingestion into enterolignans that may offer a protection against the onset and development of hormono-dependant cancers. In vitro studies based on mammalian cellular models tend to confirm their beneficial effects observed during epidemiological studies and give us insights about their mechanisms of action. The most studied lignan, podophyllotoxin, and its semi-synthetic derivatives (etoposide, teniposide, etoposide phosphate), are particularly interesting at a curative level due to their cytotoxic properties. These semi-synthetic derivatives are used in chemotherapy of lung cancer for example. However, the extensive use of these anticancer drugs will lead to the problem of podophyllotoxin supply. This molecule is currently extracted from the rhizomes and roots of an Indian species Podophyllum hexandrum which has subsequently become endangered. Strategies are investigated to obtain economically viable alternative sources of Podophyllotoxin from plants and in vitro cultures of several species. Among them, north american Podophyllum peltatum, Linum wild species, Hyptis, Anthriscus, Juniperus or Dysosma species which accumulate Podophyllotoxin or closely related derivatives, are good candidates. double dagger.

Activity of a flax pectin methylesterase promoter in transgenic tobacco pollen.

The regulatory region of the flax Lupme3 gene, which codes for a pectin methylesterase, contains two sequences (PB box) that are putative cis-active sequence elements thought to regulate transcription in pollen. The Lupme3 promoter was fused to the beta-glucuronidase (gus) reporter gene. The chimeric gene fusion was introduced into tobacco via Agrobacterium-mediated transformation. Expression of the reporter gene was monitored using a histochemical X-Gluc assay at different stages of pollen maturation and germination. The Lupme3 promoter was found to be active in germination-competent mature pollen and in pollen tube.