2,8-Decadiene-1,10-Diol Inhibits Lipopolysaccharide-Induced Inflammatory Responses Through Inactivation of Mitogen-Activated Protein Kinase and Nuclear Factor-κB Signaling Pathway

Correlations Between Amelioration of Rotenone-Induced Parkinson's Symptoms by Amomum tsaoko Flavonoids and Gut Microbiota in Mice

Parkinson's disease (PD) is the second most common neurodegenerative disease, but the existing therapeutic drugs for PD have limitations; thus, there is an urgent need to discover new methods of prevention and treatment. Amomum tsaoko Crevost et Lemarie (AT) is a classic traditional Chinese medicine and food. Its main pharmacological effect is the regulation of the gastrointestinal tract. To date, no studies on the use of AT or its extracts to treat PD have been reported. In this study, a rotenone-induced PD mouse model was utilized to evaluate the protective effect of Amomum tsaoko flavonoids (ATFs) and to elucidate the role of the gut microbiota in this effect. The results demonstrated that ATFs not only ameliorated the motor and constipation symptoms but also reduced the loss of nigrostriatal dopaminergic neurons. Furthermore, ATFs reduced the expression of inflammation-related genes (TNF-α, IL-1β, IL-6, COX-2, and MCP-1) and increased the expression of gut barrier-related genes (Muc-2, ZO-1, Occludin, Claudin3, and Claudin4) in the colon. Notably, ATFs were able to reverse rotenone-induced gut dysbiosis, including a significant decrease in the abundance of conditionally pathogenic bacteria (Desulfovibrio, Provotellaceae UCG-001, the Lachnospiraceae_NK4A136_group, norank_f_Erysipelotrichacea, and the Eubacterium nodatum group) and an increase in the abundance of probiotics (Bifidobacterium and Faecalibaculum). Interestingly, these genera were found to be significantly associated with PD motor symptoms and constipation indicators. This suggests that ATFs have the potential to alleviate PD symptoms through the modulation of gut microbes. These findings provide a solid foundation for further investigations into the anti-PD mechanism of ATFs and their potential in the prevention and treatment of PD.

Anti-Microbial Activity of Aliphatic Alcohols from Chinese Black Cardamom (Amomum tsao-ko) against Mycobacterium tuberculosis H37Rv

The fruits of Amomun tsao-ko (Chinese black cardamom; Zingiberaceae) contain an abundance of essential oils, which have previously demonstrated significant antimicrobial activity. In our preliminary search for natural anti-tuberculosis agents, an acetone extract of A. tsao-ko (AAE) exhibited strong antibacterial activity against Mycobacterium tuberculosis H37Rv. Therefore, the aim of this study was to find the principal compounds in an AAE against M. tuberculosis. Nine aliphatic compounds (1−9) including a new compound (1, tsaokol B) and a new natural unsaturated aliphatic diester (6), together with three acyclic terpenoids (10−12), were isolated from an AAE by repetitive chromatography. The structures of the isolates were determined by spectroscopic data analysis. All isolates were evaluated for activity against M. tuberculosis H37Rv. Isolated compounds 1−6, and 11 had MICs ranging from 0.6−89 µg/mL. In contrast, compounds 7 to 10, and 12 had MICs that were >100 µg/mL. Tsaokol A (3) was the most active compound with MICs of 0.6 µg/mL and 1.4 µg/mL, respectively, against replicating and nonreplicating M. tuberculosis. These results are the first to illustrate the potency of tsaokol A (3) as a natural drug candidate with good selectivity for treating tuberculosis.

Tetracera loureiri Extract Regulates Lipopolysaccharide-Induced Inflammatory Response Via Nuclear Factor-κB and Mitogen Activated Protein Kinase Signaling Pathways

Tetracera loureiri (T. loureiri) is a woody climber inhabiting open deciduous or evergreen forests in Southeast Asia. A decoction comprising its stem and other herbs is a traditional Thai remedy for fatigue and jaundice, as well as to promote overall health. Anti-inflammatory effects induced by T. loureiri extract have not been reported. In this study, we investigated the anti-inflammatory effect of an ethanol extract of T. loureiri (ETL) on lipopolysaccharide (LPS)-induced inflammatory response in RAW264.7 macrophages. We found that ETL treatment inhibited the production of nitric oxide (NO) in LPS-stimulated RAW264.7 cells, without affecting cell viability. The effect of ETL on the expression of various pro-inflammatory mediators was analyzed using reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and enzyme-linked immunosorbent assay (ELISA). We observed that ETL inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the mRNA and protein levels and decreased the production of prostaglandin E₂ (PGE₂) by COX-2 in RAW264.7 macrophages. ETL dose-dependently reduced the production of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in LPS-induced RAW264.7 cells, in a dose-dependent manner. Furthermore, ETL suppressed the LPS-induced nuclear translocation of the nuclear factor, NF-κB. Additionally, ETL was found to inhibit the activation of mitogen-activated protein kinases (MAPK), such as extracellular signal-regulated kinase, c-Jun-N-terminal kinase, and p38 MAPK. In conclusion, our findings demonstrate that ETL inhibits the expression of pro-inflammatory mediators and cytokines, thereby downregulating NF-κB and MAPK signaling pathways in LPS-stimulated macrophages, Consequently, ETL is a potential therapeutic agent for the treatment of inflammatory diseases.

Flavonoid constituents of Amomum tsao-ko Crevost et Lemarie and their antioxidant and antidiabetic effects in diabetic rats - in vitro and in vivo studies

Amomum tsao-ko Crevost et Lemarie (A. tsao-ko) is a well-known dietary spice and traditional Chinese medicine. This study aimed to identify the flavonoids in A. tsao-ko and evaluate their antioxidant and antidiabetic activities in in vitro and in vivo studies. A. tsao-ko methanol extracts possessed a high flavonoid content (1.21 mg QE per g DW) and a total of 29 flavonoids were identified by employing UPLC-MS/MS. In vitro, A. tsao-ko demonstrated antioxidant activity (ORAC value of 34276.57 μM TE/100 g DW, IC₅₀ of ABTS of 3.49 mg mL^-1 and FRAP value of 207.42 μM Fe²⁺ per g DW) and α-amylase and α-glucosidase inhibitory ability with IC₅₀ values of 14.23 and 1.76 mg mL^-1, respectively. In vivo, type 2 diabetes mellitus (T2DM) models were induced by a combined high-fat diet (HFD) and streptozotocin (STZ) injection in rats. Treatment with the A. tsao-ko extract (100 mg freeze-dried powder per kg bw) for 6 weeks could significantly improve impaired glucose tolerance, decrease the levels of fasting blood glucose (FBG), insulin, and malondialdehyde (MDA), and increase the superoxide dismutase (SOD) level. Histopathology revealed that the A. tsao-ko extract preserved the architecture and function of the pancreas. In conclusion, the flavonoid composition of A. tsao-ko exhibits excellent antioxidant and antidiabetic activity in vitro and in vivo. A. tsao-ko could be a novel natural material and developed as a related functional food and medicine in T2DM management.

Amomum tsao-ko Crevost & Lemarié: a comprehensive review on traditional uses, botany, phytochemistry, and pharmacology

Tsaoko Fructus, the dried ripe fruit of Amomum tsao-ko Crevost & Lemarié, is used as both medicinal material and food additive. This review summarized the traditional uses, botany, phytochemistry, and pharmacological progress on Tsaoko Fructus. One classical prescription and the other 11 representative prescriptions containing Tsaoko Fructus were reviewed. The indications of these prescriptions are major in treating spleen and stomach disorders and epidemic febrile diseases including malaria. At least 209 compounds have been isolated and identified from Tsaoko Fructus, most of which belong to terpenoids, phenylpropanoids, and organic acids. Essential oil, crude extract, and some compounds were observed to have pharmacological activities such as anti-biotics, anti-inflammation, antioxidant, mostly via in vitro experiments. However, the mechanism of its medicinal uses remains unclear. This review provides a comprehensive understanding of Tsaoko Fructus, which will be beneficial to exploring the mechanism and potential medicinal applications of Tsaoko Fructus, as well as developing a rational quality control system for Tsaoko Fructus as a medicinal material in the future.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11101-021-09793-x.

Chemistry and bioactivity of plants from the genus Amomum

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Amomum belonging to the family Zingiberaceae, is mainly distributed in tropical regions of Asia and Oceania. Their fruits and seeds are valuable traditional medicine and used extensively, particularly in South China, India, Malaysia, and Vietnam. The genus Amomum has long been used for treating gastric diseases, digestive disorder, cancer, hepatopathy, malaria, etc. AIMS OF THE REVIEW: The main purpose of this review is to provide the available information on the traditional medicinal uses, phytochemistry, and pharmacology aspects of the genus Amomum in order to explore the trends and perspectives for further studies on its non-volatile constituents.

MATERIALS AND METHODS

The present review collected the literatures published prior to 2020 on the traditional medicinal uses, phytochemistry, and pharmacology of the genus Amomum. The available literatures were extracted from scientific databases, such as Sci-finder, PubMed, Web of Science, Google Scholar, Baidu Scholar, and CNKI, books, and others.

RESULTS

Herein, we summarize all 166 naturally occurring non-volatile compounds from 16 plants of the genus Amomum reported in 171 references, including flavonoids, terpenoids, diarylheptanoids, coumarins, etc. Triterpenes and flavonoids are the main constituents among these compounds and maybe play an important role in the activities directly or indirectly. As traditional medicine, the plants from the genus Amomum have been usually used in some traditional herbal prescriptions, and pharmacological researches in vitro and in vivo revealed that the extracts possessed significant antioxidant, anti-inflammatory, anti-allergic activities, etc. CONCLUSION: The review systematically summarizes current studies on traditional medicinal uses, phytochemistry, pharmacological activity on the plants from the genus Amomum. To date, the majority of publications still focused on the research of volatile constituents. However, the promising preliminary data of non-volatile constituents indicated the research potential of this genus in phytochemical and pharmacological aspects. Furthermore, the further in-depth investigations on the safety, efficacy, as well as the stereo-chemistry and structure-activity relationships of pure compounds from this genus are essential in the future.

Monoterpenoids from the Fruits of Amomum tsao-ko Have Inhibitory Effects on Nitric Oxide Production

In our search for novel plant-derived inhibitors of nitric oxide (NO) with potential for treating inflammatory diseases, the phytochemicals of Amomum tsao-ko fruits were investigated, leading to the isolation of one bicyclic nonane (1), three menthene skeleton monoterpenoids (2-4), and two acyclic monoterpenoids (5 and 6). Their structures were identified using one- and two-dimensional nuclear magnetic resonance spectroscopy, and mass spectrometry. To the best of our knowledge, compounds 2-5 were obtained from the genus Amomum for the first time. All isolates were tested for their ability to inhibit lipopolysaccharide-stimulated NO overproduction in RAW264.7 cells. Compound 4 was found to inhibit NO production. Western blotting analysis indicated that active compound 4 can regulate inducible NO synthase expression. In addition, lipopolysaccharide-induced interleukin 1 beta and interleukin-6 overproduction was reduced in a concentration-dependent manner.

Anti-inflammatory effect of tribulusamide D isolated from Tribulus terrestris in lipopolysaccharide-stimulated RAW264.7 macrophages

Tribulus terrestris (T. terrestris) has been used as a traditional medicine for the treatment of a variety of diseases, including inflammation, edema and hypertension. The aqueous and ethanol extracts of T. terrestris contain alkaloids, flavonoids, tannins, quinines and phenolic compounds. Tribulusamide D is a compound that has been isolated from the ethanol extract of T. terrestris. The present study investigated the anti‑inflammatory effect of tribulusamide D on lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. Tribulusamide D inhibited the production of LPS‑induced nitric oxide and prostaglandin E2, by reducing the expression of inducible nitric oxide synthase and cyclooxygenase‑2 expression, respectively. The expression of these genes associated with inflammation was determined using reverse transcription‑polymerase chain reaction and western blot analysis. Furthermore, tribulusamide D reduced the expression of LPS‑induced inflammatory cytokines, including interleukin (IL)‑6, IL‑10 and tumor necrosis factor‑α. They were quantified using an enzyme‑linked immunosorbent assay. In addition, the present study confirmed that the inhibitory effects of tribulusamide D on the inflammatory response were mediated through inactivation of mitogen‑activated protein kinase p38 and inhibition of nuclear localization of nuclear factor‑B, which were also determined by western blot analysis. To the best of our knowledge, the current study is the first to demonstrate that tribulusamide D exerts anti‑inflammatory activity by altering the expression of inflammatory mediators and cytokines, indicating that tribulusamide D could be developed as a potential therapeutic agent for the treatment of inflammatory disorders.