Secondary Metabolites and Their Cytotoxic Activity of Artemisia nitrosa Weber. and Artemisia marschalliana Spreng.

As a promising source of biologically active substances, the Artemisia species from Kazakhstan have not been investigated efficiently. Considering the rich history, medicinal values, and availability of the Artemisia plants, systematic investigations of two Artemisia species growing in the East Kazakhstan region were conducted. In this study, one new germacrane-type sesquiterpene lactone (11), together with 10 known sesquiterpenes and its dimer, were characterized from A. nitrosa Weber. Additionally, one new chromene derivative (1') with another 12 known compounds, including coumarins, sesquiterpene diketones, phenyl propanoids, polyacetylenics, dihydroxycinnamic acid derivatives, fatty acids, naphthalene derivatives, flavones, and caffeic acid derivatives were isolated from A. marschalliana Spreng. All compounds were isolated and identified for the first time from these two Artemisia species. The structures of new compounds (11, 1') were established by using UV, TOFMS, LC-MS, 1D and 2D NMR spectroscopic analyses. The cytotoxicity of all isolated compounds was evaluated. As a result, all compounds did not show significant inhibition against HL-60 and A-549 cell lines. The sesquiterpenoids isolated from A. nitrosa were tested for their inhibitory activity against the LPS-induced NO release from the RAW624.7 cells, and neither of them exhibited significant activity.

Macrocephatriolides A and B: Two Guaianolide Trimers from Ainsliaea macrocephala as PTP1B Inhibitors and Insulin Sensitizers.

Macrocephatriolides A and B (1 and 2), two novel guaiane-type sesquiterpene lactone trimers possessing unique linkage patterns, were identified from the whole plant of Ainsliaea macrocephala. The trimeric architecture of 1 features a cyclohexene linkage and a methylene bridge, which were presumably constructed from three constitutive monomers via a Diels-Alder cycloaddition and a Michael addition, respectively. The three monomers of 2 were tethered by a 1,2-ethanediyl and a methylene linkage at the same time. Their complex structures were established by extensive analysis of spectroscopic data inclusive of band-selective CT-HSQC and CT-HMBC and time-dependent density functional theory (TDDFT) ECD calculations. Compound 2 showed potent inhibition against protein tyrosine phosphatase 1B (PTP1B) with an IC50 value of 26.26 ± 0.88 µM but not compound 1. In the kinetic study, compound 2 was disclosed as a competitive inhibitor of PTP1B with a Ki value of 16.34 ± 4.72 µM. In insulin-stimulated C2C12 myotubes, compound 2 dose-dependently enhanced glucose uptake by activating the insulin signaling pathway. Compound 2 might represent a new scaffold of insulin sensitizers.

Anti-inflammatory Eudesmane Sesquiterpenoids from Artemisia hedinii.

Fourteen new eudesmane sesquiterpenoids (1, 3-5, 7-16) and seven known analogues were isolated from the whole plant of Artemisia hedinii. Their structures were elucidated by spectroscopic data analysis and comparison with published NMR data, and their absolute configurations were confirmed by X-ray diffraction experiments and TDDFT ECD calculation. Compounds 1-15 were identified as eudesmane acids, which represent a kind of lactone ring-opening eudesmane-type sesquiterpenes with an acetoxyl or a hydroxy group attached to C-9. Compounds 1 and 2, 5 and 6, and 7 and 8 are three pairs of epimers isomerized at C-3, C-5, and C-11, respectively. Compounds 1-9, 11-13, 15-19, and 21 could influence the proinflammatory phenotype of the M1 macrophage. Among them, compounds 5, 8, 9, 12, 16, and 19 consistently exhibited anti-inflammatory effects, as evidenced by downregulating classic pro-inflammatory cytokines TNF-α, IL-12, IL-6, and IFN-γ in LPS-induced primary bone marrow derived M1 macrophages.

Sesquiterpene lactone dimers from Artemisia lavandulifolia inhibit interleukin-1ß production in macrophages through activating autophagy.

Twelve new sesquiterpene lactone dimers, lavandiolides A-L (1-12), were isolated from the whole plants of Artemisia lavandulifolia. Among them, compounds 1-6 are 1,3-linked Diels-Alder adducts between two guaianolide monomers, and 7-12 are 2,4-linked sesquiterpene lactone dimers. Their structures were elucidated by comprehensive analysis of HRESIMS, 1D and 2D NMR spectra. Their absolute configurations were determined by ECD spectra and single-crystal X-ray diffraction analyses with Cu Kα radiation. The nitric oxide (NO) inhibitory effect of all the isolates was assessed on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Compounds 1, 3, 7 and 9 showed potent inhibitory effects on NO production, with IC50 values of 0.61 ± 0.15, 1.64 ± 0.04, 1.89 ± 0.16, and 1.40 ± 0.23 µM, respectively. Furthermore, compound 1 inhibited NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3) inflammasome-mediated interleukin-1ß (IL-1ß) production through activating autophagy.

Anti-SARS-CoV-2 activities in vitro of Shuanghuanglian preparations and bioactive ingredients.

Human infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19) and there is no cure currently. The 3CL protease (3CLpro) is a highly conserved protease which is indispensable for CoVs replication, and is a promising target for development of broad-spectrum antiviral drugs. In this study we investigated the anti-SARS-CoV-2 potential of Shuanghuanglian preparation, a Chinese traditional patent medicine with a long history for treating respiratory tract infection in China. We showed that either the oral liquid of Shuanghuanglian, the lyophilized powder of Shuanghuanglian for injection or their bioactive components dose-dependently inhibited SARS-CoV-2 3CLpro as well as the replication of SARS-CoV-2 in Vero E6 cells. Baicalin and baicalein, two ingredients of Shuanghuanglian, were characterized as the first noncovalent, nonpeptidomimetic inhibitors of SARS-CoV-2 3CLpro and exhibited potent antiviral activities in a cell-based system. Remarkably, the binding mode of baicalein with SARS-CoV-2 3CLpro determined by X-ray protein crystallography was distinctly different from those of known 3CLpro inhibitors. Baicalein was productively ensconced in the core of the substrate-binding pocket by interacting with two catalytic residues, the crucial S1/S2 subsites and the oxyanion loop, acting as a "shield" in front of the catalytic dyad to effectively prevent substrate access to the catalytic dyad within the active site. Overall, this study provides an example for exploring the in vitro potency of Chinese traditional patent medicines and effectively identifying bioactive ingredients toward a specific target, and gains evidence supporting the in vivo studies of Shuanghuanglian oral liquid as well as two natural products for COVID-19 treatment.

Cytotoxic Germacrane-Type Sesquiterpene Lactones from the Whole Plant of Carpesium lipskyi.

Ten new sesquiterpene lactones, carlipsines A-J (1-10), and 12 known analogues (11-22) were isolated from the whole plant of Carpesium lipskyi. Their structures were elucidated by using 1D and 2D NMR and HRESIMS analyses, and their absolute configurations were confirmed by X-ray diffraction studies. All compounds were identified as germacranolides with diverse substructural features. Compounds 1-4 are 2,5-hemiacetal-linked germacranolides. Compounds 5 and 6 possess a 1,2-epoxy moiety. Compounds 7 and 8 represent unusual 1,5-hemiacetal-linked germacranolides. Compounds 9 and 10 contain a tetrahydrofuran unit with the oxygen atom bridging C-1 and C-8. Compounds 6, 7, 8, 19, 20, 21, and 22 showed cytotoxicity against HL-60 and A-549 cell lines with IC50 values ranging from 2.8 to 10.3 µM.

Callistemonols A and B, Potent Antimicrobial Acylphloroglucinol Derivatives with Unusual Carbon Skeletons from Callistemon viminalis.

A phytochemical investigation on the leaves of Callistemon viminalis resulted in the isolation of two unusual compounds, callistemonols A (1) and B (2). Callistemonol A (1) possesses a novel skeleton of a furan ring fusing both an α,ß-triketone and a phloroglucinol unit, while callistemonol B (2) is an acylphloroglucinol derivative featuring two methyl substituents on a five-membered ring and an isovaleryl side chain. Their structures were fully characterized on the basis of extensive spectroscopic analysis, including 1D and 2D NMR parameters, as well as the IR and HRESIMS data. Callistemonol A (1) represents an example of a natural dibenzofuran with two phenyl moieties, and a plausible biogenetic pathway to generate this novel dibenzofuran through a C-C bond-forming radical SAM enzyme is proposed. Moreover, antimicrobial assays, in conjunction with time-killing and biophysical studies, revealed that 1 and 2 exert potent bactericidal activities against a panel of methicillin-resistant pathogenic microbes.

Pretreatment with broad-spectrum antibiotics alters the pharmacokinetics of major constituents of Shaoyao-Gancao decoction in rats after oral administration.

The influence of broad-spectrum antibiotics on the pharmacokinetics and biotransformation of major constituents of Shaoyao-Gancao decoction (SGD) in rats was investigated. The pharmacokinetic behaviors of paeoniflorin (PF), albiflorin (AF), liquiritin (LT), isoliquiritin (ILT), liquiritin apioside (LA), isoliquiritin apioside (ILA), and glycyrrhizic acid (GL), seven major constituents of SGD, as well as glycyrrhetinic acid (GA), a major metabolite of GL, were analyzed. A 1-week pretreatment with broad-spectrum antibiotics (ampicillin, metronidazole, neomycin, 1 g L-1; and vancomycin, 0.5 g L-1) via drinking water reduced plasma exposure of the major constituents. The AUC0-24 h of PF and LT was significantly decreased by 28.7% and 33.8% (P < 0.05 and P < 0.005), respectively. Although the differences were not statistically significant, the AUC0-24 h of AF, ILT, LA, ILA, and GL was decreased by 31.4%, 50.9%, 16.9%, 44.1%, and 37.0%, respectively, compared with the control group. In addition, the plasma GA exposure in the antibiotic-pretreated group was significantly lower (P < 0.005) than the control group. The in vitro stability of the major constituents of SGD in the rat intestinal contents with or without broad-spectrum antibiotics was also investigated. The major constituents were comparatively stable in the rat duodenum contents, and the biotransformation of GL mainly occurred in the rat colon contents. In summary, broad-spectrum antibiotics suppressed the absorption of the major constituents of SGD and significantly inhibited the biotransformation of GL to GA by suppressing the colon microbiota. The results indicated a potential clinical drug-drug interaction (DDI) when SGD was administered with broad-spectrum antibiotics.

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.

A Pair of Enantiomeric Bis- seco-abietane Diterpenoids from Cryptomeria fortunei.

(±)-Cryptomeriolide, a pair of racemic bis- seco-abietane diterpenoids, were isolated from the bark of Cryptomeria fortunei. The separation of enantiomers was achieved by using chiral stationary phase HPLC. Their structures including the absolute configuration and conformations in solution and solid state were determined by extensive analysis of spectroscopic data, single-crystal X-ray diffraction, and comparison of calculated and experimental electronic circular dichroism data. A bioinspired one-pot enantiomeric synthesis of 1a and 1b was accomplished via a readily made intermediate orthoquinone from sugiol. All compounds including the synthetic intermediates were assayed for their cytotoxic activities on human cancer cell lines HL-60, A549, and SGC7901.

Cucurbitane Glucosides from the Crude Extract of Siraitia grosvenorii with Moderate Effects on PGC-1α Promoter Activity.

Seven new cucurbitane glucosides, 11-oxomogrosides III E and IV (1 and 2), 11-oxoisomogroside V (3), 7-oxomogrosides III E and IV (4 and 5), and mogrosides VI A and VI B (6 and 7), were separated from the crude extract of Siraitia grosvenorii. The new structures were defined by analysis of their 1H and 13C NMR, 2D NMR, and HRESIMS data. Especially, the band-selective constant time HSQC and band-selective constant time HMBC techniques were recuited to elucidate the structures of the complex glucoside moieties. Using the PGC-1α promoter driven luciferase reporter assay, the isolated compounds were examined for PGC-1α promoter activity.

Novel Diterpenoids from the Twigs of Podocarpus nagi.

Phytochemical investigation of the twigs of Podocarpus nagi (Podocarpaceae) led to the isolation of two new abietane-type diterpenoids, named 1ß,16-dihydroxylambertic acid (1) and 3ß,16-dihydroxylambertic acid (2), along with two new ent-pimarane-type diterpenoids, named ent-2ß,15,16,18-tetrahydroxypimar-8(14)-ene (3) and ent-15-oxo-2ß,16,18-trihydroxypimar-8(14)-ene (4). Their respective structures were elucidated on the basis of spectroscopic analyses, including 1D- and 2D-NMR, IR, CD, and HR-ESI-MS. This is the first time ent-pimarane-type diterpenoids from the genus Podocarpus has been reported. All four new compounds were tested for cytotoxic activity. The MTT assay results showed that compounds 3 and 4 significantly inhibited the proliferation of human cervical cancer Hela cells, human lung cancer A549 cells, and human breast cancer MCF-7 cells at a concentration of 10 µM. Furthermore, using the lipopolysaccharide (LPS)-stimulated RAW264.7 cells, compounds 2 and 4 were found to significantly inhibit nitrogen oxide (NO) production with IC50 values of 26.5 ± 6.1 and 17.1 ± 1.5 µM, respectively.

Polyoxypregnane steroids from the stems of Marsdenia tenacissima.

A new polyoxypregnane aglycone, tenacigenin D (1), and seven new C21 steroid glycosides, tenacissimosides D-J (2-8), were isolated from the stems of Marsdenia tenacissima. Their structures were determined by interpretation of their 1D and 2D NMR and other spectroscopic data, as well as by comparison with published values for related known compounds. Compound 1 was found to circumvent P-glycoprotein (P-gp)-mediated multidrug resistance through an inhibitory effect on P-gp with a similar potency to verapamil. In addition, compound 1 potentiated the activity of erlotinib and gefitinib in epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI)-resistant non-small-cell lung cancer cells.

Germacrane-type sesquiterpenes from Pilea cavaleriei Levl. subsp. cavaleriei.

The first systematic investigation of germacrane-type sesquiterpenes from Pilea cavaleriei Levl. subsp. cavaleriei was conducted. Eleven undescribed germacrane analogues named cavalinols A-K were identified. Their planar structures were determined by extensive analysis of 1D and 2D NMR spectroscopic data, and the absolute configurations were further determined by X-ray single crystal diffraction, Mosher method, and time dependent density functional theory (TDDFT) electron circular dichroism (ECD) calculation, with the aid from DFT NMR calculation and NOESY experiment. Except for the common 10-memebered ring, ten new compounds contained a p-coumaroyl sidechain connected to C-8 of the nucleus skeleton. All the isolated compounds were screened for anti-inflammatory activity in LPS stimulated RAW 264.7 cells, and compounds 5 and 6 showed moderate activity.

ent-Labdane diterpenes from the stems of Mallotus japonicus.

Eight new ent-labdane diterpenoids, mallonicusins A-H (1-8), were isolated from the stems of Mallotus japonicus. Their structures, including the absolute configurations, were determined by extensive analyses of spectroscopic data and the ECD spectra of the Pr(FOD)3 complex of substrates in CCl4. The absolute configuration of compound 1 was confirmed by single-crystal X-ray crystallography using Cu Kα radiation.

Triterpenoids from the stem bark of Melia toosendan and determination of their absolute configurations at C(24).

Six new triterpenoids, meliasenins S-X (1-6, resp.), were isolated from the stem bark of Melia toosendan. Their structures were elucidated by mass spectrometry, NMR experiments, and comparison with the known compounds. Particularly, the absolute configuration at C(24) in new compounds was determined through their CD spectra of the [Pr(FOD)3 ] complex (fod=1,1,1,2,2,3,3,7,7,7-decafluoroheptane-4,6-dione) in CCl4 , as well as by using Mosher's method.

The first phytochemical investigation of Artemisia nujianensis: Eight new guaianolides and their anti-inflammatory activity.

The first phytochemical investigation of Artemisia nujianensis resulted in the isolation of eight new guaianolides (1-8) and six known analogs. Their structures were determined by extensive analysis of 1D and 2D NMR data, HRESIMS data, DFT NMR calculations, and X-ray diffraction studies. Some compounds were evaluated for their anti-inflammatory activities in LPS-stimulated RAW 264.7 cells. Compounds 5, 7 and 9 showed moderate inhibitory effects on LPS-induced NO production in RAW 264.7 cells, with IC50 values of 12.50 ± 0.21, 9.53 ± 0.14 and 6.85 ± 0.11 µM, respectively.

Ten undescribed cadinane-type sesquiterpenoids from Eupatorium chinense.

Ten undescribed cadinane-type sesquiterpenes (1-10) were isolated from the whole plant of Eupatorium chinense. Their planar structures were mainly elucidated by extensive analysis of spectroscopic data and DFT NMR calculations. The absolute configurations of 1, 2, and 3 were determined by TDDFT ECD calculations while those of compounds 4-7 and 9 were confirmed by single crystal X-ray diffraction experiments. Compounds 2 and 3 are a pair of C-10 epimers, compounds 4 and 5 a pair of C-1 epimers, and compounds 9 and 10 a pair of compounds isomerized at both C-1 and C-10. A possible biosynthetic pathway for these new sesquiterpenes was proposed.

Withaphysalins from Medicinal and Edible Physalis minima and Their Anti-inflammatory Activities.

Physalis minima is a medicinal and edible plant in China. In this study, 22 new withaphysalins, including a novel 1(10 → 6)abeo-14ß-hydroxy one (1) and other 15 unusual 14ß-hydroxy ones (3-4, 6-17, 19), were isolated from the whole herbs of P. minima together with two known analogues (23-24). Their structures were established by extensive analysis of high-resolution electrospray ionization mass spectrometry, IR, and 1D and 2D NMR spectroscopic data. Their absolute configurations were determined by electronic circular dichroism (ECD) spectra and single-crystal X-ray crystallographic analyses, together with DFT NMR calculations. All isolated compounds were evaluated for their anti-inflammatory activity via measuring the colorimetric reporter of the secreted embryonic alkaline phosphatase gene driven by an IFN-ß minimal promoter fused to five copies of the NF-κB consensus transcriptional response element and three copies of the c-Rel binding site in LPS-stimulated human THP1-Dual cells. Compounds 2, 5, 6, 9, 10, 11, and 20 showed significant anti-inflammatory effects with IC50 values in the range of 3.01-13.39 µM. Among them, compounds 2 and 10 showed better anti-inflammatory effects to inhibit the secretion of IL-6, IL-1ß, and TNF-α in LPS-stimulated THP1-Dual cells.

Anti-inflammatory sesquiterpenoid dimers from Artemisia atrovirens.

Eight new sesquiterpenoid dimers, artatrovirenolides A-H (1-8), along with three known analogues (9-11), were isolated from Artemisia atrovirens by using the LC-MS guided isolation. Compound 1 was a compound dimerized from a guaianolide and a 1,10-seco-guaianolide unit while others were from two guaianolide units. Their structures were established by comprehensive analysis of spectroscopic data, and their absolute configurations were determined by the aid of time-dependent density functional theory electronic circular dichroism (TDDFT ECD) calculation. Compound 8 showed anti-inflammatory effect in LPS-stimulated BV-2 microglial cells at 1 µM, while compounds 1, 2, 5, and 6 inhibited microglial inflammation at 10 µM.