Lignans are plant-derived biphenolic compounds with multiple hydroxyl groups, which, upon ingestion, are metabolized by gut microbiota into enterolignans—enterolactone and enterodiol. These mammalian metabolites exhibit structural similarity to estradiol, enabling lignans to modulate hormonal balance and exert estrogen-like effects. A growing body of evidence highlights their broad spectrum of health-promoting properties, including antioxidant, anti-inflammatory, and hormone-regulating effects. Lignans have shown potential in alleviating menopausal symptoms, preventing estrogen-dependent cancers, and mitigating conditions such as cardiovascular disease, diabetes, and metabolic syndrome. Additionally, their antimicrobial activity against bacteria, fungi, and viruses is being increasingly recognized. This review provides a comprehensive and up-to-date synthesis of current knowledge. It uniquely integrates the latest insights into lignan biosynthesis, gut microbiota-mediated metabolism, and clinically relevant outcomes. Importantly, this review incorporates recent findings from prospective cohort studies and meta-analyses and sheds light on emerging therapeutic applications, including antifungal activity—an area rarely covered in earlier literature. By presenting a holistic perspective, this review advances our understanding of lignans as multifaceted compounds with significant potential in preventive and therapeutic health strategies.

Fusarium culmorum is a ubiquitous soil pathogen with a wide host range. In flax (Linum ussitatissimum), it causes foot and root rot and accumulation of mycotoxins in flax products. Fungal infections lead to huge losses in the flax industry. Moreover, due to mycotoxin accumulation, flax products constitute a potential threat to the consumers. We discovered that the defense against this pathogen in flax is based on early oxidative burst among others. In flax plants infected with F. culmorum, the most affected genes are connected with ROS production and processing, callose synthesis and ABA production. We hypothesize that ABA triggers defense mechanism in flax and is a significant player in a successful response to infection.

Polyamines (PAs) are small aliphatic compounds that participate in the plant response to abiotic stresses. They also participate in nitric oxide (NO) production in plants; however, their role in this process remains unknown. Therefore, the study aimed to investigate the role of putrescine (Put) in NO production in the roots of cucumber seedlings subjected to salt stress (120 mM NaCl) for 1 and 24 h. In salinity, exogenous Put can regulate NO levels by managing NO biosynthesis pathways in a time-dependent manner. In cucumber roots exposed to 1 h of salinity, exogenous Put reduced NO level by decreasing nitrate reductase (NR)-dependent NO production and reduced nitric oxide synthase-like (NOS-like) activity. In contrast, during a 24 h salinity exposure, Put treatment boosted NO levels, counteracting the inhibitory effect of salinity on the NR and plasma membrane nitrate reductase (PM-NR) activity in cucumber roots. The role of endogenous Put in salt-induced NO generation was confirmed using Put biosynthesis inhibitors. Furthermore, the application of Put can modulate the NR activity at the genetic and post-translational levels. After 1 h of salt stress, exogenous Put upregulated CsNR1 and CsNR2 expression and downregulated CsNR3 expression. Put also decreased the NR activation state, indicating a reduction in the level of active dephosphorylated NR (dpNR) in the total enzyme pool. Conversely, in the roots of plants subjected to 24 h of salinity, exogenous Put enhanced the NR activation state, indicating an enhancement of the dpNR form in the total NR pool. These changes were accompanied by a modification of endogenous PA content. Application of exogenous Put led to an increase in the amount of Put in the roots and reduced endogenous spermine (Spm) content in cucumber roots under 24 h salinity. The regulatory role of exogenous Put on NO biosynthesis pathways may link with plant mechanisms of response to salt stress.

Background: Flax (Linum usitatissimum L.) is an economically important crop that is highly susceptible to Fusarium oxysporum f. sp. lini (Foln). While phytohormones are key regulators of defence, their interaction with polyamines during infection remains poorly understood. This study aimed to characterise hormonal dynamics in flax under Foln infection and the modulatory role of spermidine (Spd). Methods: Targeted UPLC–MS/MS profiling quantified over 30 hormone-related compounds, including auxins, cytokinins, gibberellins, jasmonates, salicylic acid, and abscisic acid, in shoots and roots of healthy, infected, and Spd-treated plants. Two Spd concentrations (10 and 100 mM) were applied under controlled in vitro conditions. Results: Foln infection triggered tissue- and time-specific hormonal shifts, with early activation of jasmonate and auxin metabolism in shoots and later accumulation of salicylic acid and gibberellins in roots. Spd, particularly at 10 mM, reshaped these responses by reinforcing cytokinin and salicylic acid responses, stabilising auxin homeostasis, and enhancing jasmonate and abscisic acid responses. Conclusions: Spermidine coordinates hormone crosstalk, enabling balanced and efficient defence activation. The results highlight its potential as a priming agent enhancing flax resilience to F. oxysporum.