Chemical constituents of Equisetum debile

Phenolics and terpenoids with good anti-inflammatory activity from the fruits of Amomum villosum and the anti-inflammatory mechanism of active diterpene

The fruits of Amomum villosum are often considered a medicinal and food homologous material and have been found to have therapeutic effects in chronic enteritis, gastroenteritis, and duodenal ulcer. The aim of this study is to discover the anti-inflammatory active ingredients from dried ripe fruits of A. villosum and to elucidate the molecular mechanisms. We verified that the inhibitory activity of the ethyl acetate extract was superior to Dexamethasone (Dex), so we ultimately chose to study the ethyl acetate extract from the fruits of A. villosum. A total of 33 compounds were isolated from its ethyl acetate extract, including nine known diterpenoids (compounds 1-9), twelve known sesquiterpenoids (compounds 10-21), ten known phenolics (compounds 22, 23, 25-29, 31-33) and two new phenolics (24 and 30). On the basis of chemical evidences and spectral data analysis (UV, ECD, Optical rotation data, 1D and 2D-NMR, HR-ESI-MS, NMR chemical shift calculations), the structures of new compounds were elucidated. Among these compounds, isocoronarin D (5) was found to have good anti-inflammatory activity. Further research has found that isocoronarin D can down-regulate the protein levels of COX2 and NOS2, activate Nrf2/Keap1 and suppress NF-κB signaling pathway in LPS-induced RAW264.7 cells. In addition, isocoronarin D inhibited inflammasome assembly during inflammasome activation by hampering the binding of NLRP3 and ASC. Further evidence revealed that isocoronarin D suppressed the assembly of the NLRP3 inflammasome via blocking the formation of ASC specks. From these results, isocoronarin D may be the important bioactive compound of A. villosum and exhibits anti-inflammatory effects by regulating the NF-κB/Nrf2/NLRP3 axis in macrophages.

Apocarotenoids from Equisetum debile Roxb. ex Vaucher regulate the lipid metabolism via the activation of the AMPK/ACC/SREBP-1c signaling pathway

Sixteen undescribed apocarotenoids (1-16), along with 22 known analogues, were isolated from the aerial parts of Equisetum debile. Their structures, including absolute configurations, were elucidated by NMR, HRESIMS, X-ray diffraction analysis, the modified Mosher's method and the quantum-chemical calculation of electronic circular dichroism (ECD) spectra. Compounds 1-9, 11-12 are the first example of C16-apocarotenoids appeared in nature. The plausible biosynthetic pathway of 1-16 was proposed. Moreover, the isolates were evaluated for their lipid-lowering activity, and the results showed that 13, 14, 15, 22, 31, 32 and 33 could remarkably decrease the levels of both TC and TG in FFA induced HepG2 cells at 20 μM. The oil red staining assay further demonstrated the lipid-lowering effects of 13, 14 and 15. The western blot results indicated that compounds 13, 14 and 15 could regulate the lipid metabolism via the activation of the AMPK/ACC/SREBP-1c signaling pathway. A preliminary structure-activity relationship (SAR) study of the isolates indicated that the apocarotenoids with 6/5 ring system displayed more potent lipid-lowering effects.

Genus Equisetum L: Taxonomy, toxicology, phytochemistry and pharmacology

INTRODUCTION

The genus Equisetum (Equisetaceae) is cosmopolitan in distribution, with 41 recognized species. Several species of Equisetum are widely used in treating genitourinary and related diseases, inflammatory and rheumatic problems, hypertension, and wound healing in traditional medicine practices worldwide. This review intends to present information on the traditional uses, phytochemical components, pharmacological activities, and toxicity of Equisetum spp. and to analyze the new insights for further study.

METHODS

Relevant literature has been scanned and collected via various electronic repositories, including PubMed, Science Direct, Google Scholar, Springer Connect, and Science Online, from 1960 to 2022.

RESULTS

Sixteen Equisetum spp. were documented as widely used in traditional medicine practices by different ethnic groups throughout the world. A total of 229 chemical compounds were identified from Equisetum spp. with the major group of constituents being flavonol glycosides and flavonoids. The crude extracts and phytochemicals of Equisetum spp. exhibited significant antioxidant, antimicrobial, anti-inflammatory, antiulcerogenic, antidiabetic, hepatoprotective, and diuretic properties. A wide range of studies have also demonstrated the safety of Equisetum spp.

CONCLUSION

The reported pharmacological properties of Equisetum spp. support its use in traditional medicine, though there are gaps in understanding the traditional usage of these plants for clinical experiments. The documented information revealed that the genus is not only a great herbal remedy but also has several bioactives with the potential to be discovered as novel drugs. Detailed scientific investigation is still needed to fully understand the efficacy of this genus; hence, very few Equisetum spp. were studied in detail for phytochemical and pharmacological investigation. Moreover, its bioactives, structure-activity connection, in vivo activity, and associated mechanism of action ought to be explored further.

The untapped potential of spermidine alkaloids: Sources, structures, bioactivities and syntheses

Spermidine alkaloids are a kind of natural products possessing an aliphatic triamine structure with three or four methylene groups between two N-atoms. Spermidine alkaloids exist in plants, microorganisms, and marine organisms, which usually form amide structures with cinnamic acid or fatty acid derivatives. Their unique structures showed a wide range of biological activities such as neuroprotective, anti-aging, anti-cancer, antioxidant, anti-inflammatory, and antimicrobial. In order to better understand the research status of spermidine alkaloids and promote their applications in human health, this paper systematically reviewed the biological sources, structures, pharmacological actions, and synthetic processes of spermidine alkaloids over the past two decades. This will help to open up new pharmacological investigation fields and better drug design based on these spermidine alkaloids.

Differential Accumulation of Metabolites and Transcripts Related to Flavonoid, Styrylpyrone, and Galactolipid Biosynthesis in Equisetum Species and Tissue Types

Three species of the genus Equisetum (E. arvense, E. hyemale, and E. telmateia) were selected for an analysis of chemical diversity in an ancient land plant lineage. Principal component analysis of metabolomics data obtained with above-ground shoot and below-ground rhizome extracts enabled a separation of all sample types, indicating species- and organ-specific patterns of metabolite accumulation. Follow-up efforts indicated that galactolipids, carotenoids, and flavonoid glycosides contributed positively to the separation of shoot samples, while stryrylpyrone glycosides and phenolic glycosides were the most prominent positive contributors to the separation of rhizome samples. Consistent with metabolite data, genes coding for enzymes of flavonoid and galactolipid biosynthesis were found to be expressed at elevated levels in shoot samples, whereas a putative styrylpyrone synthase gene was expressed preferentially in rhizomes. The current study builds a foundation for future endeavors to further interrogate the organ and tissue specificity of metabolism in the last living genus of a fern family that was prevalent in the forests of the late Paleozoic era.

Phytochemistry and Pharmacology of the Genus Equisetum (Equisetaceae): A Narrative Review of the Species with Therapeutic Potential for Kidney Diseases

The Equisetum genus, Equisetaceae family, is widely distributed worldwide and may be the oldest nonextinct genus on Earth. There are about 30 known species, which are very often used in traditional medicine with diverse applications. This review aimed to compile scientific reports about Equisetum species with relevant pharmacological properties and/or therapeutic potential for kidney diseases. Our bibliographic survey demonstrates that the most widespread traditional use of Equisetum is as a diuretic, followed by the treatment of genitourinary diseases (kidney diseases, urethritis, kidney stones, and others), inflammation, wound healing, rheumatic diseases, prostatitis, and hypertension. The most popular species from the Equisetum genus with medicinal use is E. arvense L., whose diuretic effect was confirmed in animal models and clinical trials. The species E. bogotense Kunth also demonstrated the beneficial effect of inducing diuresis in both experimental and clinical assays. Several other species have also been studied regarding their therapeutic potential, showing different biological actions. Regarding the chemical composition, it contains many active constituents, such as alkaloids, flavonoids, phenol, phytosterols, saponins, sterols, silicic acid, tannin, triterpenoids, and volatile oils. However, despite the widespread traditional use, many species need to be explored in detail for scientific validation of popular use. Indeed, the species of the Equisetum genus have great potential in the management of kidney disorders.

Laxative Metabolites from the Leaves of Moringa oleifera

Three new flavonoids, quercetin-3-O-6-[methyl-(S)-3-hydroxy-3-methylglutaroyl(1→6]-β-d-glucopyranoside (1), kaempferol-3-O-[methyl-(S)-3-hydroxy-3-methylglutaroyl(1→6)]-β-d-glucopyranoside (2), and quercetin-3-O-6-[(E)-4-methoxy-5-methylhexa-2,4-dienoatyl(1→6)]-β-d-glucopyranoside (3), and two new alkaloids, 5-dehydroxymethyl-pyrrolemarumine 4″-O-α-l-rhamnopyranoside (4) and N¹-methyl-N²-((4-O-α-l-rhamnopyranoside)benzyl) oxalamide (5), together with 45 known compounds (6-50) were isolated from the leaves of Moringa oleifera Lam. Among those compounds, 1-octacosanol (50), a straight-chain 28-carbon alcohol, exhibited good activity against diphenoxylate-induced constipation in mice, which is obtained as a laxative constituent from the plant for the first time. In order to have an accurate understanding of the content of compound 50, a quantification with gas chromatography-tandem mass spectrometry (GC-MS/MS) was carried out. The anti-inflammatory and α-glucosidase inhibitory activity of some compounds also was assessed.

Antioxidant and cytotoxic lignans from the roots of Bupleurum chinense

In the search for biologically active compounds from the roots of Bupleurum chinense D C., phytochemical investigation of its ethanol extract led to the isolation and identification of a new 8-O-4' neolignan glucoside, saikolignanoside A (1), along with eight known lignans (2-9). Their structures were determined on the basis of IR, UV, HRESIMS, and NMR spectroscopic analyses. The antioxidant and cytotoxic effects of isolated compounds were evaluated in vitro. The isolated compounds (IC₅₀ > 200 μM) did not display 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Whereas compounds 1-2, 5, 7, and 9 exhibited potent 2, 2'-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging properties with IC₅₀ values ranging from 8.34 to 15.24 μM, while compounds 3-4, 6, 8 showed moderate properties. In addition, all compounds were evaluated for cytotoxicities against A549, HepG2, U251, Bcap-37, and MCF-7 cell lines. Compounds 5 and 9 (IC₅₀< 51.62 μM) possessed stronger cytotoxic activities against all the tested tumor cell lines, compared with the positive control 5-Fluorouracil.