Inubritantrimers A-D: Trimerized Sesquiterpenoid [4 + 2] Adducts Featuring a Distinctive Spiro-Polycyclic Scaffold from Inula britannica

Inubritantrimer A (1), a trace trimerized sesquiterpenoid [4 + 2] adduct featuring an unusual exo-exo type spiro-polycyclic scaffold, together with three new endo-exo [4 + 2] adducts, inubritantrimers B-D (2-4), were discovered from the flowers of Inula britannica. Their structures were elucidated using 1D/2D NMR, X-ray diffraction, and ECD approaches. 1 is characterized as a novel exo-exo trimer, synthesized biogenetically from three sesquiterpenoid monomers, featuring a unique linkage of C-11/C-1', C-13/C-3' and C-13'/C-3″, C-11'/C-1″ through a two-step exo [4 + 2] cycloaddition process. Compounds 1-4 exhibited modest cytotoxicity against breast cancer cells with IC50 values in the range of 5.84-12.01 μM.

Biomimetic Synthesis of Lavandiolides H, I, and K and Artematrolide F via Diels-Alder Reaction

The biomimetic synthesis of guaianolide dimers lavandiolides H, I, and K and artematrolide F containing a spirolactone moiety has been accomplished for the first time from naturally abundant arglabin in four to six steps with an overall yield up to 60%, and a series of natural product-like guaianolide dimers, trimer, and tetramer were also successfully synthesized. Notably, the trimeric compound exhibited antihepatoma cytotoxicity more potent than that of sorafenib with IC₅₀ values of 6.2 μM (HepG2), 6.8 μM (Huh7), and 7.2 μM (SK-HEP-1).

1,10-seco guaianolide-type sesquiterpenoids from Chrysanthemum indicum

ABSTACTA chemical investigation of the whole plant of traditional Chinese medicine, Chrysanthemum indicum L., led to the discovery of six guaianolide-type sesquiterpenoids 1-6 with a 1,10-splited skeleton. The structure of the new compound 1 was established by extensive analysis of UV, IR, MS, NMR and ECD data. Compounds 3-6 are mutually stereoisomers with four chiral centers and their absolute configurations were determined by comparison of ECD spectra. The anti-inflammatory effects of these isolates on lipopolysaccharide (LPS)-induced nitric oxide (NO) were investigated in RAW 264.7 cells. Results showed that most of the compounds displayed NO production inhibitory activities with IC₅₀ values ranged from 3.54 to 8.17 μM.

Chemistry and Pharmacological Activity of Sesquiterpenoids from the Chrysanthemum Genus

Plants from the Chrysanthemum genus are rich sources of chemical diversity and, in recent years, have been the focus of research on natural products chemistry. Sesquiterpenoids are one of the major classes of chemical constituents reported from this genus. To date, more than 135 sesquiterpenoids have been isolated and identified from the whole genus. These include 26 germacrane-type, 26 eudesmane-type, 64 guaianolide-type, 4 bisabolane-type, and 15 other-type sesquiterpenoids. Pharmacological studies have proven the biological potential of sesquiterpenoids isolated from Chrysanthemum species, reporting anti-inflammatory, antibacterial, antitumor, insecticidal, and antiviral activities for these interesting molecules. In this paper, we provide information on the chemistry and bioactivity of sesquiterpenoids obtained from the Chrysanthemum genus which could be used as the scientific basis for their future development and utilization.

Sesquiterpenoids from Chrysanthemum indicum with Inhibitory Effects on NO Production

Three new guaianolide lactones (1-3) and four new 9-oxonerolidol glucosides (5-8) together with 20 known compounds were isolated from the MeOH extract of the flowers of Chrysanthemum indicum. Their structures were elucidated based on the interpretation of NMR, HRESIMS, and electronic circular dichroism (ECD) data along with acid hydrolysis. Of the isolates, sesquiterpenoids 1-4 and 15 and flavones 17 and 18 exhibited inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide production in RAW 264.7 cells with IC₅₀ values in the range 0.2-27.0 μM.

Trimeric and dimeric sesquiterpenoids from Artemisia atrovirens and their cytotoxicities

Two sesquiterpenoid trimers and two sesquiterpenoid dimers possessing unprecedented scaffolds with a methylene-bridged connection were identified from Artemisia atrovirens. Compound 3 showed obvious cytotoxicity against HepG2 and Huh7 cell lines.

Natural Products: Review for Their Effects of Anti-HBV

Hepatitis B is a global infectious disease, seriously endangering human health. Currently, there are mainly interferons and nucleoside analogues treatment of hepatitis B in the clinic, which have certain therapeutic effects on hepatitis B, but their side effects and drug resistance are increasingly prominent. Therefore, it is urgently needed to discover and develop new anti-HBV drugs, especially natural products, which have novel, high efficiency, and low toxicity anti-HBV compounds with novel antiviral mechanisms. In this manuscript, the natural products (polysaccharides and 165 compounds) with the activity of antihepatitis B virus are discussed according to their chemical classes, including 14 phenylpropanoids, 8 flavonoids,12 xanthones, 13 anthroquinones, 47 terpenoids, 6 alkaloids, 15 enediynes, 11 aromatics, 18 phenylalanine dipeptides compounds, and 13 others. In addition, the anti-HBV mechanism and targets of natural product were also discussed. The aim of this review is to report new discoveries about anti-HBV natural products and to provide reference for researchers.

Chrysanthemum indicum L.: A Comprehensive Review of its Botany, Phytochemistry and Pharmacology

Chrysanthemum indicum L. (C. indicum L.), a member of the Compositae family, is a perennial plant that has been used as a traditional medicine for more than 2000 years in China and is widely used for the treatment of Pemphigus, swelling, pain, and scrofula. To date, more than 190 chemical constituents have been isolated and identified from this plant, including flavonoids, terpenoids, phenylpropanoids, and phenolic acids. Numerous modern studies have shown that extracts or monomeric compounds from C. indicum L. have several pharmacological activities, such as anti-inflammatory anti-oxidation, antipathogenic microorganism, anticancer, immune regulation, and hepatoprotective effects. However, resource availability, the research on the mechanism, and quality control are still insufficient, which deserves further efforts. In this paper, the advances in botany, phytochemistry, and pharmacology of C. indicum L were reviewed. We hope that this review can provide important information for traditional Chinese medicine, phytochemistry, synthetic and medicinal chemistry researchers for making full use of C. indicum L. resource.

Natural disesquiterpenoids: an update

This review highlights the progress on the isolation, bioactivity, biogenesis and total synthesis of dimeric sesquiterpenoids since 2010.

Tetramerized Sesquiterpenoid Ainsliatetramers A and B from Ainsliaea fragrans and Their Cytotoxic Activities

Two guaianolide sesquiterpenoid tetramers named ainsliatetramers A and B were separated from Ainsliaea fragrans. Through spectroscopic analyses, especially the band-selective CT-HSQC and CT-HMBC techniques, the complex skeleton was constructed from four sesquiterpene units via three different linkages. A biosynthetic pathway was proposed featuring a Michael addition and a regular and a hetero-Diels-Alder cycloaddition. Both exhibited potent cytotoxicity against human cancer cell lines with IC₅₀ values ranging from 2 to 15 μM.

Monomeric and Dimeric Cytotoxic Guaianolide-Type Sesquiterpenoids from the Aerial Parts of Chrysanthemum indicum

Twelve new guaianolide-type sesquiterpenoids (1-12) and five known guaianolide derivatives (13-17) were isolated from an aqueous ethanol extract of the aerial parts of Chrysanthemum indicum. Their structures were determined through spectroscopic data analysis. The absolute configurations of the new compounds were assigned by X-ray crystallography and electronic circular dichroism. Compound 5 shows multiple cytotoxic activities against four human naso-pharyngeal carcinoma (NPC) cell lines (CNE1, CNE2, SUNE-1, and HONE-1) and one human intestinal epithelial cell line (HT-29) with IC₅₀ values of 4.6, 6.0, 3.5, 4.3, and 9.6 μM, respectively. Compound 16 exhibits weak cytotoxicity against four NPC cell lines, CNE1 (IC₅₀ = 7.3 μM), CNE2 (IC₅₀ = 7.4 μM), HONE-1 (IC₅₀ = 7.6 μM), and SUNE-1 (IC₅₀ = 5.6 μM), but no cytotoxicity against HT-29 (IC₅₀ > 10 μM).

Artemisianins A-D, new stereoisomers of seco-guaianolide involved heterodimeric [4+2] adducts from Artemisia argyi induce apoptosis via enhancement of endoplasmic reticulum stress

Artemisianins A-D (1-4), four stereoisomers of sesquiterpenoid dimers, forming via [4+2] cycloaddition from a 1, 10-seco-guaianolide dienophile and a guaianolide diene, along with two biosynthetically related precurors 5 and 6, were isolated from the famous traditional Chinese medicine Artemisia argyi. The structures of 1-4, including their absolute configurations, were elucidated by extensive spectroscopic data and ECD/TDDFT calculation analysis. Compounds 1-4 exhibited cytotoxicity with IC₅₀ values ranging from 7.2 to 23.3 μM. The accumulation of Ca²⁺ in cytoplasm and enlarged endoplasmic reticulum (ER) indicated that 1 mediated HT-29 cancer cell apoptosis through improvement of ER-stress, which was further proved by unfolded protein response (UPR) pathway on basis of the upregulation of IRE1α, p-PERK, ATF6, and CHOP.

Ainsliatriolides A and B, Two Guaianolide Trimers from Ainsliaea fragrans and Their Cytotoxic Activities

Ainsliatriolides A (1) and B (2), two guaianolide sesquiterpenoid trimers possessing an unprecedented skeleton, were isolated from Ainsliaea fragrans. Their structures were elucidated through extensive analysis of spectroscopic data and confirmed by single-crystal X-ray diffraction experiment. Ainsliatriolides A and B are first examples of compound trimerized from guaianolide sesquiterpenoids through two different C-C linkages (type A, 4-2'/15-14'; type B, 15'-15″). Ainsliatriolide A displayed potent cytotoxicity with an averaged IC₅₀ value of 1.17 μM against four cancer cells.

Insights into the importance of dietary chrysanthemum flower (Chrysanthemum morifolium cv. Hangju)-wolfberry (Lycium barbarum fruit) combination in antioxidant and anti-inflammatory properties

Dietary chrysanthemum flower and wolfberry alone or together are widely consumed as a health beverage on a daily basis for centuries. The study aims to evaluate combinative effects of flower heads of Chrysanthemum morifolium cv. Hangju (C) and Lycium barbarum fruit (wolfberry, W) served as tea on chemical compounds, antioxidant and anti-inflammatory activities in RAW 264.7 macrophages. Eight phenolics were mainly detected in chrysanthemum flowers, whereas polysaccharides were dominant in wolfberry. The infusion of five combinations showed significantly antioxidant activities positively associated with the chrysanthemum flower content in chemical methods (ORAC and FRAP). However, the cellular-based CAA assay exhibited the highest antioxidant activities of the infusion at C:W = 1:1, indicating a synergistic interaction (CI = 0.11, P < .01). Additionally, the anti-inflammatory effect of infusion, specifically at a combination of C:W = 1:1, was observed by reducing the LPS-induced nitric oxide production, and inhibiting the expression of iNOS, TNF-α, IL-1β, and IL-6 mRNA (P < .05). The infusion prepared at a C:W = 1:1 was found to inactivate MAPKs (ERK and JNK) and NF-κB. The antioxidant and anti-inflammatory mechanisms might be attributed to acacetin-7-O-rutinoside, luteolin-7-O-glucoside and chlorogenic acid from chrysanthemum flower, and wolfberry polysaccharide via multiple inflammatory pathways.

Highly Oxidized Guaianolide Sesquiterpenoids with Potential Anti-inflammatory Activity from Chrysanthemum indicum

Ten new highly oxidized monomeric (1-8) and dimeric guaianolides (9 and 10), along with two known guaianolide derivatives (11 and 12), were isolated from the aerial parts of Chrysanthemum indicum using a bioassay-guided fractionation procedure. The new compounds were characterized by the basic analysis of the spectroscopic data obtained, and the absolute configurations were determined by both empirical approaches and ECD calculations. Inhibitory effects of 1-12 on nitric oxide production were investigated in lipopolysaccaride (LPS)-mediated RAW 264.7 cells, and most of them (1-8 and 11) displayed IC₅₀ values in the range 1.4-9.7 μM. Moreover, a mechanistic study revealed that the potential anti-inflammatory activity of compound 1 appears to be mediated via suppression of an LPS-induced NF-κB pathway and down-regulation of MAPK activation.

3,5-Diarylpyrazole Derivatives Obtained by Ammonolysis of the Total Flavonoids from Chrysanthemum indicum Extract Show Potential for the Treatment of Alzheimer's Disease

Four new 3,5-diarylpyrazole analogues (1-4) were isolated from an extract of the flowers of Chrysanthemun indicum using a combination of ammonolysis of the total flavonoid extract and an Aβ aggregation inhibitory activity guided purification procedure. All four compounds (1-4) showed moderate to potent activity against Aβ aggregation with EC50 values of 4.3, 15.8, 1.3, and 2.9 μM, respectively. Moreover, compound 3 showed low cytotoxicity and significant neuroprotective activity against Aβ-induced cytotoxicity in the SH-SY5Y cell line. This report is the first to show that 3,5-diarylpyrazole analogues can inhibit Aβ aggregation and exhibit neuroprotective activity with potential for the treatment of Alzheimer's disease. Taken together, the method presented here offers an alternative approach to yield bioactive compounds.

Neo-clerodane diterpenoids from Scutellaria barbata with activity against Epstein-Barr virus lytic replication

Bioassay-guided fractionation was conducted on an EtOAc-soluble extract of the whole plants of Scutellaria barbata, monitored by inhibition of Epstein-Barr virus (EBV) lytic replication. Twenty-six neo-clerodane diterpenoids were isolated, of which 13 are new (1-13, scutolides A-L) and 13 previously known (14-26). The structures of 1-13 were elucidated by analysis of their NMR and MS spectroscopic data. Furthermore, the configurations of the new compounds 1 and 11 were confirmed by single-crystal X-ray diffraction. All of the isolated compounds were evaluated for inhibitory effects against EBV lytic replication. Eleven compounds (3, 4, 6, 11, 12, 15, 16, 17, 20, 22, and 24) exhibited moderate to potent inhibition, with EC50 values from 3.2 to 23.6 μM and selective index (SI) values from 2.1 to 109.2. More specifically, the new compound 4 showed the most potent activity, with EC50 and SI values of 3.2 μM and 46.1, respectively, while compound 24 (EC50 = 16.4 μM) exhibited the highest SI of 109.2. This study is the first to report that neo-clerodane diterpenoids demonstrate significant inhibition against EBV lytic replication.

Potential antiviral lignans from the roots of Saururus chinensis with activity against Epstein-Barr virus lytic replication

Epstein-Barr virus (EBV) is a member of the γ-herpes virus subfamily and has been implicated in the pathogenesis of several human malignancies. Bioassay-guided fractionation was conducted on an EtOAc-soluble extract of the roots of Saururus chinensis and monitored using an EBV lytic replication assay. This led to the isolation of 19 new (1-19) and nine known (20-28) lignans. The absolute configurations of the new lignans were established by Mosher's ester, ECD, and computational methods. Eight lignans, including three sesquineolignans (19, 23, and 24) and five dineolignans (3, 4, 26, 27, and 28), exhibited inhibitory effects toward EBV lytic replication with EC50 values from 1.09 to 7.55 μM and SI values from 3.3 to 116.4. In particular, manassantin B (27) exhibited the most promising inhibition, with an EC50 of 1.72 μM, low cytotoxicity, CC50 > 200 μM, and SI > 116.4. This is the first study demonstrating that lignans possess anti-EBV lytic replication activity.