Dracaena cochinchinensis stemwood extracts inhibit amyloid-β fibril formation and promote neuronal cell differentiation

Herbal medicines in Alzheimer's disease and the involvement of gut microbiota

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by memory loss and cognitive impairment. It severely affects the quality of life of victims. The prevalence of AD has been increasing in recent years. Therefore, it is of great importance to elucidate the pathogenic mechanism of AD and search for effective therapeutic approaches. Gut microbiota dysbiosis, an altered state of gut microbiota, has been well known for its involvement in the pathogenesis of AD. Much effort has been made in searching for approaches capable of modulating the composition of gut microbiota in recent years. Herbal medicines have attracted extensive attention in recent decades for the prevention and treatment of AD. Here, we gave an overview of the recent research progress on the modulatory effects of herbal medicines and herbal formulae on gut microbiota as well as the possible beneficial effects on AD, which may provide new insights into the discovery of anti-AD agents and their therapeutic potential for AD through modulating the composition of gut microbiota.

Synergy of botanical drug extracts from Dracaena cochinchinensis stemwood and Ardisia elliptica fruit in multifunctional effects on neuroprotection and anti-inflammation

Combination therapy is one of the promising approaches in developing therapeutics to cure complex diseases, such as Alzheimer's disease (AD). In Thai traditional medicines, the clinical application often comprises multiple botanical drugs as a formulation. The synergistic interactions between botanical drugs in combination therapies are proposed to have several advantages, including increased therapeutic efficacy, and decreased toxicity and/or adverse effects. This study aimed to explore the therapeutic functions of a botanical hybrid preparation (BHP) of two botanical drugs within a traditional multi-herbal formulation. The synergistic actions of BHP of Dracaena cochinchinensis stemwood (DCS) and Ardisia elliptica fruit (AEF) at a specific ratio of 1:9 w/w were illustrated in neuroprotection and anti-inflammation. In cultured PC12 cells, BHP of DCS and AEF showed synergistic functions in inducing neuronal differentiation, characterized by neurofilament expression and neurite outgrowth. In addition, BHP of DCS and AEF exhibited a synergistic effect in inhibiting the aggregation of Aβ, a hallmark of AD pathology. The activated BV2 microglial cells induced by LPS were synergistically suppressed by the BHP of DCS and AEF, as evaluated by the expression of pro-inflammatory markers, including TNF-α, IL-1β, and iNOS, as well as the morphological change of microglial cells. The findings suggested that the effects of BHP of DCS and AEF were greater than individual botanical drugs in a specific ratio of 1:9 w/w to enhance neuroprotective and anti-inflammatory functions.

Phenolic profiles and in vitro biochemical properties of Thai herb ingredients for chronic diseases prevention

Traditional remedies using natural ingredients have been handed down over generations, providing collective information for the development of modern therapeutics. These natural products have a long history of safe consumption with curative effects but lack of scientific-based evidence hinders the mass production of new remedies containing active ingredients with particular medicinal properties. This research investigated the phenolic profiles and biochemical properties of 29 herbal ingredients identified in two traditional Thai remedies, Prasachandaeng (PSCD) and Chantaharuethai (CHRT), and their effectiveness in combating chronic diseases. These two traditional remedies are used to reduce fever but some ingredients have been previously reported to possess other health-related properties. Statistical analysis by TOPSIS indicated that Biancaea sappan (L.) Tod. extract exhibited the highest overall closeness coefficient (C) score analyzed from all variables including total phenolic contents, antioxidant potentials, and enzyme inhibitions. Bouea macrophylla Griff. extract showed potential as an effective agent against diabetes through inhibition of two carbohydrate degrading enzymes, α-glucosidase and α-amylase, while Dischidia major (Vahl) Merr. showed strong properties as an anti-angiotensin-converting enzyme, leading to the control of hypertension. Dracaena cochinchinensis (Lour.) S.C. Chen effectively controlled the progression of Alzheimer's disease through the inhibition of cholinergic and β-amyloid formation enzymes. These results can be used as preliminary data for the development of new remedies to prevent or treat particular chronic diseases.

The dual face of microglia (M1/M2) as a potential target in the protective effect of nutraceuticals against neurodegenerative diseases

The pathophysiology of different neurodegenerative illnesses is significantly influenced by the polarization regulation of microglia and macrophages. Traditional classifications of macrophage phenotypes include the pro-inflammatory M1 and the anti-inflammatory M2 phenotypes. Numerous studies demonstrated dynamic non-coding RNA modifications, which are catalyzed by microglia-induced neuroinflammation. Different nutraceuticals focus on the polarization of M1/M2 phenotypes of microglia and macrophages, offering a potent defense against neurodegeneration. Caeminaxin A, curcumin, aromatic-turmerone, myricetin, aurantiamide, 3,6'-disinapoylsucrose, and resveratrol reduced M1 microglial inflammatory markers while increased M2 indicators in Alzheimer's disease. Amyloid beta-induced microglial M1 activation was suppressed by andrographolide, sulforaphane, triptolide, xanthoceraside, piperlongumine, and novel plant extracts which also prevented microglia-mediated necroptosis and apoptosis. Asarone, galangin, baicalein, and a-mangostin reduced oxidative stress and pro-inflammatory cytokines, such as interleukin (IL)-1, IL-6, and tumor necrosis factor-alpha in M1-activated microglia in Parkinson's disease. Additionally, myrcene, icariin, and tenuigenin prevented the nod-like receptor family pyrin domain-containing 3 inflammasome and microglial neurotoxicity, while a-cyperone, citronellol, nobiletin, and taurine prevented NADPH oxidase 2 and nuclear factor kappa B activation. Furthermore, other nutraceuticals like plantamajoside, swertiamarin, urolithin A, kurarinone, Daphne genkwa flower, and Boswellia serrata extracts showed promising neuroprotection in treating Parkinson's disease. In Huntington's disease, elderberry, curcumin, iresine celosia, Schisandra chinensis, gintonin, and pomiferin showed promising results against microglial activation and improved patient symptoms. Meanwhile, linolenic acid, resveratrol, Huperzia serrata, icariin, and baicalein protected against activated macrophages and microglia in experimental autoimmune encephalomyelitis and multiple sclerosis. Additionally, emodin, esters of gallic and rosmarinic acids, Agathisflavone, and sinomenine offered promising multiple sclerosis treatments. This review highlights the therapeutic potential of using nutraceuticals to treat neurodegenerative diseases involving microglial-related pathways.

The extracts of Dracaena cochinchinensis stemwood suppress inflammatory response and phagocytosis in lipopolysaccharide-activated microglial cells

BACKGROUND

Neuroinflammation is a pivotal process in the brain that contributes to the development of neurodegenerative diseases, such as Alzheimer's disease (AD). During neuroinflammation, the over-activation of microglial cells can drive the pathological processes underlying AD, including an increase in amyloid β (Aβ) production and accumulation, ultimately leading to neuronal and synaptic loss. Dracaena cochinchinensis (Lour.) S.C. Chen, also known as "Chan-daeng" in Thai, belongs to the Asparagaceae family. In Thai traditional medicine, it has been used as an antipyretic, pain reliever, and anti-inflammatory agent. However, the effects of D. cochinchinensis on neuroinflammation are yet to be determined.

PURPOSE

We aimed to evaluate the anti-neuroinflammatory activities of D. cochinchinensis stemwood extract in activated microglia.

METHODS

In this study, lipopolysaccharide (LPS), a potent pro-inflammatory stimulus, was used to activate microglial BV2 cells, as a cell model of neuroinflammation. Our investigation included several techniques, including qRT-PCR, ELISA, Western blotting, phagocytosis, and immunofluorescence staining, to examine the potential anti-inflammatory effects of D. cochinchinensis stemwood.

RESULTS

D. cochinchinensis stemwood, named DCS, was extracted with ethanol and water. The extracts of DCS showed dose-dependent anti-inflammatory effects, markedly suppressing the LPS-mediated mRNA expression of pro-inflammatory factors, including IL-1β, TNF-α, and iNOS, while increasing expression of the anti-inflammatory biomarker Arg1 in both BV2 microglia and RAW264.7 macrophages. DCS extracts also decreased the protein levels of IL-1β, TNF-α, and iNOS. These findings were correlated with the suppression of phosphorylated proteins of p38, JNK, and Akt in the LPS-activated microglia. Moreover, DCS extracts significantly attenuated excessive phagocytosis of beads and Aβ fibrils during the LPS-mediated microglial activation.

CONCLUSION

Taken together, our results indicated that DCS extracts had anti-neuroinflammatory properties by suppressing the expression of pro-inflammatory factors, increasing the expression of the anti-inflammatory biomarker Arg1, and modulating excessive phagocytosis in activated microglia. These findings suggested that DCS extract could be a promising natural product for the treatment of neuroinflammatory and neurodegenerative diseases, like AD.

Two new alkaloids from Dendrobium nobile Lindl. exhibited neuroprotective activity, and dendrobine alleviated Aβ1-42 -induced apoptosis by inhibiting CDK5 activation in PC12 cells

Dendrobium nobile Lindl. is registered in the Chinese Pharmacopoeia as a traditional medicine. Phytochemical investigation of the ethanol extract of D. nobile Lindl. stems yielded three alkaloid compounds, including two new compounds dendroxine B (2) and denrine B (3) as well as one known compound dendrobine (1). Here, we identified the structure of these compounds using spectroscopic analyses and compared them with those described in previous studies. Compounds 1-3 were found to show protective effect against amyloid-β 1-42 (Aβ_1-42 )-induced neurotoxicity in rat pheochromocytoma (PC12) cells, among which dendrobine exhibited the most significant neuroprotective effect. Hoechst 33342/propidium iodide staining indicated that dendrobine ameliorated Aβ_1-42 -induced apoptosis. Moreover, quantitative real-time polymerase chain reaction and western blot analysis analysis demonstrated that dendrobine suppressed the activation of cyclin-dependent kinase 5 (CDK5), upregulated Bcl-2 expression, and downregulated Bax, cyto-c, and caspase-3 expression. Molecular docking analysis and surface plasmon resonance assay suggested that dendrobine directly bound to CDK5 protein with a KD value of 2.05 × 10^-4  M. In summary, alkaloids are the neuroprotective constituents of D. nobile Lindl., and dendrobine protected PC12 cells against Aβ_1-42 -induced apoptosis by inhibiting CDK5 activation.