Secoisolariciresinol diglycoside, a flaxseed lignan, exerts analgesic effects in a mouse model of type 1 diabetes: Engagement of antioxidant mechanism

The antidiabetic properties of lignans: a comprehensive review

BACKGROUND

Diabetes mellitus (DM) is a chronic metabolic disease with a high global prevalence. Lignans, a class of plant natural compounds found in commonly consumed foods, are well-tolerated by humans and have demonstrated promising potential in the management of DM. Consumption of lignan-rich foods has been associated with improved overall health and quality of life.

PURPOSE

The clinical and preclinical evidence on the role of lignans in managing DM are critically examined.

METHODS

A thorough literature search was conducted across major scientific databases, focusing on studies that reported the effects of individual lignans on key diabetes indicators, such as glucose utilisation and insulin sensitivity, in both human and animal models, as well as in cell-based studies.

RESULTS

A total of 180 lignans were included in the review. Out of these, only three were investigated in randomised clinical trials in humans and 31 in animal models. The reviewed evidence suggests some beneficial effects of lignans in preventing the development of obesity-related diabetes. Their therapeutic benefits in preventing diabetes-related complications, particularly diabetic nephropathy, in both type 1 and type 2 diabetes, are also supported. Metabolites of various lignans, produced by microbial metabolism in the gut and serum enzymes, appear to be key bioactive forms, highlighting the need for detailed pharmacodynamic studies, optimised dosage designs, and the use of the appropriate lignan molecules for cell-based screening.

CONCLUSION

Lignans and their microbial metabolites show promise in preventing obesity-related diabetes and mitigating diabetes-related complications such as diabetic nephropathy, though further clinical studies are needed to optimize their therapeutic potential.

Spinal neuron-glial crosstalk and ion channel dysregulation in diabetic neuropathic pain

Diabetic neuropathic pain (DNP) is one of the most prevalent complications of diabetes, characterized by a high global prevalence and a substantial affected population with limited effective therapeutic options. Although DNP is closely associated with hyperglycemia, an increasing body of research suggests that elevated blood glucose levels are not the sole inducers of DNP. The pathogenesis of DNP is intricate, involving the release of inflammatory mediators, alterations in synaptic plasticity, demyelination of nerve fibers, and ectopic impulse generation, yet the precise mechanisms remain to be elucidated. The spinal dorsal horn coordinates dynamic interactions between peripheral and central pain pathways, wherein dorsal horn neurons, microglia, and astrocytes synergize with Schwann cell-derived signals to process nociceptive information flow. Abnormally activated neurons can alter signal transduction by modifying the local microenvironment, compromising myelin integrity, and diminishing trophic support, leading to neuronal sensitization and an amplifying effect on peripheral pain signals, which in turn triggers neuropathic pain. Ion channels play a pivotal role in signal conduction, with the modulation of sodium, potassium, and calcium channels being particularly crucial for the regulation of pain signals. In light of the rising incidence of diabetes and the current scarcity of effective DNP treatments, a thorough investigation into the interactions between neurons and glial cells, especially the mechanisms of ion channel function in DNP, is imperative for identifying potential drug targets, developing novel therapeutic strategies, and thereby enhancing the prospects for DNP management.

Medicinal Plants for the Treatment of Neuropathic Pain: A Review of Randomized Controlled Trials

Neuropathic pain is a disabling condition caused by various diseases and can profoundly impact the quality of life. Unfortunately, current treatments often do not produce complete amelioration and can be associated with potential side effects. Recently, herbal drugs have garnered more attention as an alternative or a complementary treatment. In this article, we summarized the results of randomized clinical trials to evaluate the effects of various phytomedicines on neuropathic pain. In addition, we discussed their main bioactive components and potential mechanisms of action to provide a better view of the application of herbal drugs for treating neuropathic pain.

Synthetic Secoisolariciresinol Diglucoside Attenuates Established Pain, Oxidative Stress and Neuroinflammation in a Rodent Model of Painful Radiculopathy

Painful cervical radiculopathy is characterized by chronic neuroinflammation that lowers endogenous antioxidant responses leading to the development of oxidative stress and pain after neural trauma. Therefore, antioxidants such as secoisolariciresinol diglucoside (SDG), that promote antioxidant signaling and reduce oxidative damage may also provide pain relief. This study investigated if repeated systemic administration of synthetic SDG after a painful root compression reduces the established pain, oxidative stress and spinal glial activation that are typically evident. SDG was administered on days 1-3 after compression and the extent of oxidative damage in the dorsal root ganglia (DRG) and spinal cord was measured at day 7 using the oxidative stress markers 8-hydroxguanosine (8-OHG) and nitrotyrosine. Spinal microglial and astrocytic activation were also separately evaluated at day 7 after compression. In addition to reducing pain, SDG treatment reduced both spinal 8-OHG and nitrotyrosine, as well as peripheral 8-OHG in the DRG. Moreover, SDG selectively reduced glial activation by decreasing the extent of astrocytic but not microglial activation. These findings suggest that synthetic SDG may attenuate existing radicular pain by suppressing the oxidative stress and astrocytic activation that develop after painful injury, possibly identifying it as a potent therapeutic for painful radiculopathies.

A combination of metabolite profiling and network pharmacology to explore the potential pharmacological changes of secoisolariciresinol-diglycoside

The prototypes and metabolites formed from the use of traditional Chinese medicines (TCM) are typically the cause of both side side-effects and therapeutic results. Therefore, the characterization of in vivo substances and the determination of functional changes are of great importance for clinical applications. Secoisolariciresinol-diglycoside (SDG), one major compound in flaxseeds, was used as a potential drug to treat tumors in the clinic; however, the metabolism information and functional changes of SDG in vivo were limited, which limited its application. In this study, an integrated strategy based on metabolite profiling and network pharmacology was applied to explore the metabolism feature and functional changes of SDG. As a result, a total of 28 metabolites were found in rats, including 14 in plasma, 22 in urine, 20 in feces, 7 in the heart, 14 in the liver, 8 in the spleen, 10 in the lungs, 14 in the kidneys, and 4 in the brain. Among them, M8, M13 and M26 were the main metabolites of SDG in rats and 24 were characterized for the first time. The metabolic reactions contained phase I reactions of demethylation, dehydroxylation, deglycosylation, arabinosylation and glycosylation, and phase II reactions of glucuronidation and sulfation were also observed. Notably, the arabinosylation and glycosylation were found in SDG for the first time. Meanwhile, 121 targets of SDG and its metabolites were found, PRKCB was the main target of SDG, and the metabolites of SDG mainly targeted HSP90A1, IL6, AKT1, MAPK3, MTOR, PIK3CA, SRC, ESR1, AR, PIK3CB, and PIK3CB. The difference of targets between SDG and its metabolites could result in its additional functional pathways of neurotrophin signaling pathway, PI3K-Akt signaling pathway, HIF-1 signaling pathway or indications of anti-prostate cancer. This work provided a new insight for exploring the mechanism and therapy indications of drugs.

The prototypes and metabolites formed from the use of traditional Chinese medicines (TCM) are typically the cause of both side side-effects and therapeutic results.

Flaxseed Lignans as Important Dietary Polyphenols for Cancer Prevention and Treatment: Chemistry, Pharmacokinetics, and Molecular Targets

Cancer causes considerable morbidity and mortality across the world. Socioeconomic, environmental, and lifestyle factors contribute to the increasing cancer prevalence, bespeaking a need for effective prevention and treatment strategies. Phytochemicals like plant polyphenols are generally considered to have anticancer, anti-inflammatory, antiviral, antimicrobial, and immunomodulatory effects, which explain their promotion for human health. The past several decades have contributed to a growing evidence base in the literature that demonstrate ability of polyphenols to modulate multiple targets of carcinogenesis linking models of cancer characteristics (i.e., hallmarks and nutraceutical-based targeting of cancer) via direct or indirect interaction or modulation of cellular and molecular targets. This evidence is particularly relevant for the lignans, an ubiquitous, important class of dietary polyphenols present in high levels in food sources such as flaxseed. Literature evidence on lignans suggests potential benefit in cancer prevention and treatment. This review summarizes the relevant chemical and pharmacokinetic properties of dietary polyphenols and specifically focuses on the biological targets of flaxseed lignans. The consolidation of the considerable body of data on the diverse targets of the lignans will aid continued research into their potential for use in combination with other cancer chemotherapies, utilizing flaxseed lignan-enriched natural products.

Seed coats as an alternative molecular factory: thinking outside the box

Seed coats as commodities. Seed coats play important roles in the protection of the embryo from biological attack and physical damage by the environment as well as dispersion strategies. A significant part of the energy devoted by the mother plant to seed production is channeled into the production of the cell layers and metabolites that surround the embryo. Nevertheless, in crop species these are often discarded post-harvest and are a wasted resource that could be processed to yield co-products. The production of novel compounds from existing metabolites is also a possibility. A number of macromolecules are already accumulated in these maternal layers that could be exploited in industrial applications either directly or via green chemistry, notably flavonoids, lignin, lignan, polysaccharides, lipid polyesters and waxes. Here, we summarize our knowledge of the in planta biosynthesis pathways of these macromolecules and their molecular regulation as well as potential applications. We also outline recent work aimed at providing further tools for increasing yields of existing molecules or the development of novel biotech approaches, as well as trial studies aimed at exploiting this underused resource.

Nitroxidative Signaling Mechanisms in Pathological Pain

Tissue injury can initiate bidirectional signaling between neurons, glia, and immune cells that creates and amplifies pain. While the ability for neurotransmitters, neuropeptides, and cytokines to initiate and maintain pain has been extensively studied, recent work has identified a key role for reactive oxygen and nitrogen species (ROS/RNS; nitroxidative species), including superoxide, peroxynitrite, and hydrogen peroxide. In this review we describe how nitroxidative species are generated after tissue injury and the mechanisms by which they enhance neuroexcitability in pain pathways. Finally, we discuss potential therapeutic strategies for normalizing nitroxidative signaling, which may also enhance opioid analgesia, to help to alleviate the enormous burden of pathological pain.