Natural neuro-inflammatory inhibitors from Caragana turfanensis

A critical appraisal on the involvement of plant-based extracts as neuroprotective agents (2012-2022): an effort to ease out decision-making process for researchers

The purpose of this review study is to provide a condensed compilation of 164 medicinal plants that have been investigated for their neuroprotective aspects by researchers between the years 2012 and 2022 which also includes a recent update of 2023-2024. After using certain keywords to retrieve the data from SCOPUS, it was manually sorted to eliminate any instances of duplication. The article is streamlined into three major segments. The first segment takes a dig into the current global trend and attempts to decrypt vital information related to plant names, families, plant parts used, and neurological disorders investigated. The second segment of the article makes an attempt to present a comprehensive insight into the various mechanistic pathways through which phytochemicals can intervene to exert neuroprotection. The final segment of the manuscript is a bibliometric appraisal of all researches conducted. The study is based on 256 handpicked articles based on decided inclusion criteria. Illustrative compilation of various pathways citing their activation and deactivation channels are also presented with possible hitting points of various phytochemicals. The present study employed Microsoft Excel 2019 and VOS viewer as data visualisation tools.

Polyoxygenated cyclohexene derivatives and other constituents of Uvaria rufa stem

Six undescribed compounds, uvarirufols D and E, (+)-uvarigranol B, (-)-uvarigranol E, 6-acetoxy-5-hydroxy-7-methoxyflavanone and cherrevenaphthalene D, along with twelve known compounds, including polyoxygenated cyclohexenes, flavonoids, and lignans, were isolated from the methanol extract of Uvaria rufa stems. Their structures were elucidated by spectroscopic analyses and the absolute configurations were determined using electronic circular dichroism. Several isolates were evaluated for cytotoxic, antitubercular and anti-inflammatory potentials. (-)-6-Acetylzeylenol showed moderate inhibitory activity against Mycobacterium tuberculosis, with MIC value of 47.10 μg/mL. Cherrevenaphthalene D exhibited weak antimycobacterial activity and potent inhibitory effect on lipopolysaccharide-induced nitric oxide (NO) production in RAW 264.7 cells (EC50 = 8.54 μM). 8-Hydroxy-5,7-dimethoxyflavanone displayed moderate level of NO inhibition (EC50 = 43.62 μM) with little cytotoxicity. The polyoxygenated cyclohexenes and lignans were inactive against HCT 116 and 22Rv1 cancer cells (IC50 > 100 μM).

Phytochemical Study on Seeds of Paeonia clusii subsp. rhodia-Antioxidant and Anti-Tyrosinase Properties

In this study, the black fertile (BSs) and the red unfertile seeds (RSs) of the Greek endemic Paeonia clusii subsp. rhodia (Stearn) Tzanoud were studied for the first time. Nine phenolic derivatives, trans-resveratol, trans-resveratrol-4'-O-β-d-glucopyranoside, trans-ε-viniferin, trans-gnetin H, luteolin, luteolin 3'-O-β-d-glucoside, luteolin 3',4'-di-O-β-d-glucopyranoside, and benzoic acid, along with the monoterpene glycoside paeoniflorin, have been isolated and structurally elucidated. Furthermore, 33 metabolites have been identified from BSs through UHPLC-HRMS, including 6 monoterpene glycosides of the paeoniflorin type with the characteristic cage-like terpenic skeleton found only in plants of the genus Paeonia, 6 gallic acid derivatives, 10 oligostilbene compounds, and 11 flavonoid derivatives. From the RSs, through HS-SPME and GC-MS, 19 metabolites were identified, among which nopinone, myrtanal, and cis-myrtanol have been reported only in peonies' roots and flowers to date. The total phenolic content of both seed extracts (BS and RS) was extremely high (up to 289.97 mg GAE/g) and, moreover, they showed interesting antioxidative activity and anti-tyrosinase properties. The isolated compounds were also biologically evaluated. Especially in the case of trans-gnetin H, the expressed anti-tyrosinase activity was higher than that of kojic acid, which is a well-known whitening agent standard.

Anti-Inflammatory Activity of Cajanin, an Isoflavonoid Derivative Isolated from Canavalia lineata Pods

The bioactive components of Canavalia lineata (Thunb.) DC pods were investigated using bioactivity-guided isolation, and the chemical structures of flavonoids 1–3, isoflavonoid derivatives 4–11, and phenolic compounds 12 and 13 were identified by comparing NMR, MS, and CD spectral data with previously reported spectroscopic data. Compounds 1–13 were evaluated for their anti-inflammatory effects on LPS-stimulated RAW264.7 macrophages. Among these compounds, the isoflavonoid derivative cajanin (7) exhibited the most potent anti-inflammatory activity (IC₅₀ of NO = 19.38 ± 0.05 µM; IC₅₀ of IL-6 = 7.78 ± 0.04 µM; IC₅₀ of TNF-α = 26.82 ± 0.11 µM), exerting its anti-inflammatory effects by suppressing the activation and nuclear translocation of the transcription factor NF-κB by phosphorylating IκB and p65. These results suggested that cajanin (7) may be a potential candidate for improving the treatment of inflammatory diseases.

Structural elucidation of spiro cyclohexandienonyl naphthalenes with potential anti-neuroinflammatory activities from Caragana acanthophylla Kom

Four undescribed spiro cyclohexandienonyl naphthalenes (acanthophyllas A-D) and a revised compound were isolated from the roots of Caragana acanthophylla Kom. (Fabaceae). They were identified using extensive spectroscopic data and via chemical methods. Three of them were resolved into their enantiomers, and their absolute configurations were confirmed by comparing the experimental and calculated electronic circular dichroism spectra. Moreover, the anti-inflammatory activities of the compounds were investigated by evaluating their inhibitory effects on nitric oxide production in lipopolysaccharide-stimulated BV-2 cells. Some compounds showed significant inhibitory activities with IC₅₀ values of 8.8-13.4 μM (minocycline, IC₅₀ 7.8 μM), indicating that they might serve as potential therapeutic agents for neurodegenerative diseases.

The antithrombotic activity of natural and synthetic coumarins

Thrombosis, which seriously endangers human health and life, is the leading cause of morbidity and mortality globally. Antithrombotic drugs can interfere with the occurrence and development of thrombotic diseases and play an important role in the treatment of thrombotic diseases. However, unsatisfactory efficacy and serious adverse effects of existing antithrombotic drugs increase the research for new, efficient and safer drugs. Natural and synthetic coumarins have been shown to possess antithrombotic activity, namely, anticoagulation and antiplatelet aggregation. Especially, coumarin-based warfarin, phenprocoumon and cloricromen have long been used in clinical treatment of thrombosis. Coumarin with low toxicity is the privileged structure for developing novel antithrombotic drugs with multiple mechanisms of action. The present review aims to compile current research on the development of coumarins against thrombosis, emphasizing the relationship between their chemical structures and therapeutic effectiveness. It is intended to provide promising ideas for the discovery of novel coumarin derivatives with high antithrombotic activity.

Characterization of growth phenotypes and gastrointestinal tract microbiota in sheep fed with caragana

AIMS

Using high-protein caragana as an unconventional feed supplement has promising application potential in livestock feeding programmes, and verifying its function is of great importance to guide efficient dietary management of livestock.

METHODS AND RESULTS

This study investigated the resulting changes in the growth, slaughter performance, serum physiological index, physical and chemical characteristics of meat, ruminal and intestine morphology and gastrointestinal tract microbiota in sheep fed with caragana (CAR), corn straw (COR) and alfalfa (ALF) diets. The CAR group showed an increased abundance of Christensenellaceae R-7 group, Marvinbryantia, Ruminococcaceae NK4A214, Lachnospiraceae UCG-002 and Desulfuromonas in the rumen compared with ALF, and CAR group mainly enhanced starch and sucrose metabolism, fructose and mannose metabolism, photosynthesis and d-alanine metabolism in the rumen compared with ALF.

CONCLUSIONS

CAR diet positively changed the fatty acid profile of longissimus dorsi muscle and significantly altered the composition and function of the microbiota in the rumen, ileum and cecum.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study systematically demonstrated the feasibility of CAR as an alternative to ALF for animal fattening in a complete formula granulated feed and provided a fundamental basis for further research and development of CAR as an unconventional feed source for ruminants.

Acutissimalignan B from traditional herbal medicine Daphne kiusiana var. atrocaulis (Rehd.) F. Maekawa inhibits neuroinflammation via NF-κB Signaling pathway

BACKGROUND

Emerging evidence indicates the important role of herbal medicine for neuroinflammation, which is closely associated with neurodegenerative diseases.

OBJECTIVE

To clarify the characteristics and primary mechanisms of action of the traditional herbal medicine Daphne kiusiana var. atrocaulis (Rehd.) F. Maekawa in neuroinflammation by phytochemistry and bioassays using both in vitro and in vivo assays.

METHODS

The chemical composition of D. kiusiana var. atrocaulis was clarified using multiple chromatography technologies and spectroscopic analysis. The anti-neuroinflammatory effects of the identified components were evaluated in LPS-induced BV-2 cells by monitoring the production of nitric oxide. C57BL/6 mice were used to construct a neuroinflammatory model by injecting LPS into the lateral ventricle of the brain. The most promising component was evaluated in vivo by measuring the number of Iba-1 cells and expression of inflammatory factors. Furthermore, the anti-neuroinflammatory mechanism involved in the activation of the NF-κB pathway was investigated using western blot and immunofluorescence.

RESULTS

Thirty-two constituents (1-32), including five new compounds, were successfully identified from D. kiusiana var. atrocaulis. Compounds 3, 5, 12-15, and 20 (IC50 values from 5.41 to 57.27 μM) could considerably inhibit the LPS-induced production of NO in BV-2 cells, displaying stronger anti-neuroinflammatory activities than that of minocycline (IC50 = 67.08 μM). The concentration of the most potential compound 13 (IC50 5.41 μM) was 5.4% of the ethyl acetate fraction. Acutissimalignan B (13) could reduce the mRNA expression of iNOs, TNF-α, IL-1β, and IL-6, inhibit the phosphorylation of IκBα, and inhibit the nuclear translocation of NK-κB p65 in BV-2 cells induced by LPS. Moreover, in the LPS-induced mouse model, compound 13 was found to exert anti-neuroinflammatory activity by attenuating the activation of microglia in the cortex and hippocampus, repressing the phosphorylation of IκBα, inhibiting the nuclear translocation of NK-κB p65, and decreasing the mRNA expression of iNOs, TNF-α, IL-1β, and IL-6 in the cortex.

CONCLUSION

We found that D. kiusiana var. atrocaulis had an inhibitory activity on neuroinflammation. In addition, the main active component (-)-acutissimalignan B (13) showed anti-neuroinflammatory effects in both in vivo and in vitro assays. Its mechanism of action may be associated with the inhibition of the NF-κB signaling pathway. Our current findings provide new information on D. kiusiana var. atrocaulis in the treatment of neuroinflammation.

Secondary Metabolites with Antioxidant Activities for the Putative Treatment of Amyotrophic Lateral Sclerosis (ALS): "Experimental Evidences"

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disorder that is characterized by progressive loss of the upper and lower motor neurons at the spinal or bulbar level. Oxidative stress (OS) associated with mitochondrial dysfunction and the deterioration of the electron transport chain are factors that contribute to neurodegeneration and perform a potential role in the pathogenesis of ALS. Natural antioxidant molecules have been proposed as an alternative form of treatment for the prevention of age-related neurological diseases, in which ALS is included. Researches support that regulations in cellular reduction/oxidation (redox) processes are being increasingly implicated in this disease, and antioxidant drugs are aimed at a promising pathway to treatment. Among the strategies used for obtaining new drugs, we can highlight the isolation of secondary metabolite compounds from natural sources that, along with semisynthetic derivatives, correspond to approximately 40% of the drugs found on the market. Among these compounds, we emphasize oxygenated and nitrogenous compounds, such as flavonoids, coumarins, and alkaloids, in addition to the fatty acids, that already stand out in the literature for their antioxidant properties, consisting in a part of the diets of millions of people worldwide. Therefore, this review is aimed at presenting and summarizing the main articles published within the last years, which represent the therapeutic potential of antioxidant compounds of natural origin for the treatment of ALS.

Bioactive sesquiterpene coumarins from the resin of Ferula sinkiangensis targeted on over-activation of microglia

Nine undescribed (1-4, 6-10) sesquiterpene coumarins, together with a new natural one (5) and ten known ones (11-20), were isolated from the low polarity fraction of the 95% ethanol extract of the resin of Ferula sinkiangensis. Their structures were elucidated based on the comprehensive analysis of HRESIMS, 1D and 2D NMR data. The absolute configurations were determined by comparison of experimental and calculated ECD spectra. All the identified SCs were evaluated for their anti-neuroinflammatory activities in LPS-induced BV-2 cells. Ferusingensine G (8) displayed a significant inhibitory effect on nitric oxide (NO) production with an IC₅₀ value of 1.2 μM. The results suggested that natural SCs might be served as potential neuroinflammatory inhibitors.

PTP1B and α-glucosidase inhibitors from Selaginella rolandi-principis and their glucose uptake stimulation

As part of an ongoing search for new protein tyrosine phosphatase 1B inhibitors and glucose uptake stimulators from nature, a new coumarin, selaginolide A (1) and four known isoflavones (2‒5) were isolated from the ethanol extract of a Vietnamese medicinal plant Selaginella rolandi-principis. The chemical structures of the isolates were elucidated by extensive analysis of spectroscopic and physicochemical data. Compounds 3‒5 have been identified from Selaginella genus for the first time. The antidiabetic properties of the isolates (1‒5) were investigated using in vitro assay on 2-NBDG uptake in 3T3-L1 adipocytes and against PTP1B and α-glucosidase enzyme activities as well. Compounds 1 exhibited the most potency with inhibitory IC₅₀ values of 7.40 ± 0.28 and 7.52 ± 0.37 µM against PTP1B and α-glucosidase, respectively. Compounds 3 and 5 possessed potential inhibitions on PTP1B enzyme with IC₅₀ values of 23.02 ± 1.29 and 11.08 ± 0.92 µM and moderate inhibitions on α-glucosidase with IC₅₀ values of 36.47 ± 1.87 and 55.73 ± 2.58 µM, respectively. Compounds 2 and 4 showed weak PTP1B inhibitory activity (IC₅₀ > 30 µM) but displayed remarkable α-glucosidase inhibition with IC₅₀ values of 3.39 ± 0.87 and 9.72 ± 0.62 µM, respectively. Furthermore, ursolic acid as a positive control (IC₅₀ 3.42 ± 0.26 µM) and compounds 1 and 5 acted as mixed-competitive inhibitors against PTP1B enzyme with K_i values of 6.46, 10.28, and 15.01 µM, respectively. In addition, compounds 1 and 5 also showed potent stimulatory effects on 2-NBDG uptake at a concentration of 10 µM. The obtained result might suggest the potential of new coumarin (1) as a new type of natural PTP1B and α-glucosidase inhibitor for further research and development of antidiabetic and obese agents.Graphic abstract.

Phenylpropanoids and lignoids from the whole plant of Vaccinium emarginatum and their cytotoxicity against prostate cancer cells

One new naturally occurring quinone, 3',4'-dihydroxy-1,2,6-trimethoxy-[1,1'-biphenyl]-4(1H)-one (1), one new diarylpropane, emarginone A (2), and one new neolignan, emarginone B (3), along with eighteen known compounds have been isolated from the chemical investigation of the EtOAc-soluble fraction of the Vaccinium emarginatum whole plant methanolic extract. The new structures were elucidated by combined analysis of spectroscopic analytical methods and comparison with the literature data obtained from known analogues. In addition, the cytotoxicity of compounds 2, 4, and 14-20 against Du145 and PC-3 prostate cancer cell lines using MTT cell proliferation assay was evaluated. Compounds 2 and 19 showed most potent cytotoxicity against Du145 with IC₅₀ values of 7.53 and 6.63 μg/mL, respectively. Furthermore, compounds 2, 17, and 19 also exhibited significant cytotoxicity against PC-3 with IC₅₀ values ranging from 3.44-6.64 μg/mL.

Natural Inhibitors on Over-Activation of Microglia from Herbals

Neuroinflammation manifested by over-activation of microglial cells plays an essential role in neurodegenerative diseases. Short-term activation of microglia can be beneficial, but chronically activated microglia can aggravate neuronal dysfunction possibly by secreting potentially cytotoxic substances such as tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO), which can result in dysfunction and death of neurons. Therefore inhibiting over-activation of microglia and the production of cytotoxic intermediates may become an effective therapeutic approach for neuroinflammation. In this paper, we review our continuous research on natural inhibitors of over-activated microglia from traditional herbals, including flavonoids, lignans, sesquiterpene coumarins, and stilbenes.

Prenylated Flavonoids from the Roots and Rhizomes of Sophora tonkinensis and Their Effects on the Expression of Inflammatory Mediators and Proprotein Convertase Subtilisin/Kexin Type 9

Seven new prenylated flavonoids (1-7) and one new prenylated phenylpropiophenone (8) were isolated from roots and rhizomes of Sophora tonkinensis, along with nine known compounds (9-17). The structures 1-8 were elucidated by spectroscopic data analysis and comparison with reported values. Compounds 8 and 12 (7-methoxyebenosin) showed inhibitory activities against nitric oxide production in lipopolysaccharide-induced RAW264.7 cells, with IC₅₀ values of 8.1 and 6.2 μM, respectively. They also significantly lowered expression of CSF2, TNF, and IL-1β. Lonchocarpol A (10) and erybraedin D (16) at concentrations of 20 μM downregulated proprotein convertase subtilisin/kexin type 9 (PCSK9) mRNA expression in HepG2 cells. Moreover, erybraedin D (16) inhibited PCSK9 protein synthesis (IC₅₀ 7.8 μM), while simultaneously activating AMP-activated protein kinase and acetyl-CoA carboxylase.

Terpenoids from the roots of Leontopodium longifolium and their inhibitory activity on NO production in RAW264.7 cells

Phytochemical investigation of the roots of Leontopodium longifolium, led to the isolation of a novel norsesquiterpene, named as longifolactone (1), along with three known diterpenes. The structures of these compounds were elucidated by analysis of HR-ESI-MS, UV, IR and 1D and 2D NMR spectroscopic data. The absolute configuration of the new compound was determined by electronic circular dichroism (ECD) using both experimental and calculated ECD spectra. Furthermore, their anti-inflammatory effects were evaluated in LPS-activated RAW264.7 cells to determine their effects on the release of NO. Longifolactone (1) showed weak cytotoxicity towards two human cancer cell lines.