Anti-coronavirus and anti-pulmonary inflammation effects of iridoids, the common component from Chinese herbal medicines for the treatment of COVID-19.

The practice of Chinese herbal medicines for the treatment of COVID-19 in China played an essential role for the control of mortality rate and reduction of recovery time. The iridoids is one of the main constituents of many heat-clearing and detoxifying Chinese medicines that were largely planted and frequently used in clinical practice. Twenty-three representative high content iridoids from several staple Chinese medicines were obtained and tested by a SARS-CoV-2 pseudo-virus entry-inhibition assay on HEK-293 T/ACE2 cells, a live HCoV-OC43 virus infection assay on HRT-18 cells, and a SARS-CoV-2 3CL protease inhibitory FRET assay followed by molecular docking simulation. The anti-pulmonary inflammation activities were further evaluated on a TNF-α induced inflammation model in A549 cells and preliminary SARs were concluded. The results showed that specnuezhenide (7), cornuside (12), neonuezhenide (15), and picroside III (21) exhibited promising antiviral activities, and neonuezhenide (15) could inhibit 3CL protease with an IC50 of 14.3 µM. Docking computation showed that compound 15 could bind to 3CL protease through a variety of hydrogen bonding and hydrophobic interactions. In the anti-pulmonary inflammation test, cornuside (12), aucubin (16), monotropein (17), and shanzhiside methyl ester (18) could strongly decrease the content of IL-1ß and IL-8 at 10 µM. Compound 17 could also upregulate the expression of the anti-inflammatory cytokine IL-10 significantly. The iridoids exhibited both anti-coronavirus and anti-pulmonary inflammation activities for their significance of existence in Chinese herbal medicines, which also provided a theoretical basis for their potential utilization in the pharmaceutical and food industries.

[A new benzopyran glycoside from Gentiana macrophylla].

Thirteen compounds were isolated and identified from 70% ethanol extract of the roots of Gentiana macrophylla by multi-chromatographic methods, including microporous resin, silica gel, and C_(18) reversed-phase column chromatography, as well as HPLC as follows: macrophylloside G(1), macrophylloside D(2), 5-formyl-2,3-dihydroisocoumarin(3),(+)-medicarpin(4),(+)-syringaresinol(5), liquiritigenin(6),(3R)-sativanone(7),(3R)-3'-O-methylviolanone(8), 4,2',4'-trihydroxychalcone(9), latifolin(10), gentioxepine(11), 6α-hydroxycyclonerolidol(12), and ethyl linoleate(13). Compound 1 was a new benzopyran glycoside. Compounds 4, 6-10, 12, and 13 were isolated for the first time from Gentiana plants. Compounds 1 and 2 showed promising hepatoprotective activity against D-GalN-induced AML12 cell damage at the concentration of 10 µmol·L~(-1), and compound 2 exhibited more significant activity than silybin at the same concentration.

Isolation, structure modification, and anti-rheumatoid arthritis activity of isopimarane-type diterpenoids from Orthosiphon aristatus.

Orthosiphon aristatus is a well-known folkloric medicine and herb for Guangdong soup for the treatment of rheumatism in China. Eight isopimarane-type and migrated pimarane-type diterpenoids (1-8), including a new one with a rarely occurring α,ß-unsaturated diketone C-ring, were isolated from O. aristatus. Their structures were determined by spectroscopic methods and quantum chemical calculations. Furthermore, the most abundant compound, orthosiphol K, was structurally modified by modern synthetic techniques to give seven new derivatives (9-15). The anti-rheumatoid arthritis activity of these diterpenoids were evaluated on a TNF-α induced MH7A human rheumatoid fibroblast-like synoviocyte model. Compound 10 showed the most potent activity among these compounds. Based on their inhibitory effects on the release levels of IL-1ß, the preliminary structure-activity relationships were concluded. Furthermore, western blot analysis revealed that 10 could increase the expression of IκBα and decrease the expression of NF-κB p65, and the expression levels of COX-2 and NLRP3 proteins were consequently down-regulated.

Lignan glucosides from Gentiana macrophylla with potential anti-arthritis and hepatoprotective activities.

Ten lignans, including six previously undescribed phenolic ester glycosyl lignans (1-6), were isolated from a well-known traditional Chinese medicine, Qin-Jiao, which is the dry root of Gentiana macrophylla Pall. (Gentianaceae). Their structures were determined by spectroscopic and chemical methods, especially 2D NMR techniques. Quantum chemical calculations of theoretical ECD spectra allowed the determination of their absolute configurations. Refer to its traditional applications for the treatment of rheumatic arthralgia and hepatopathy, these compounds were evaluated on a TNF-α induced MH7A human synoviocyte inflammation model and a D-GalN induced AML12 hepatocyte injury model. Compounds 1, 2, 5, and 6 significantly reduced the release of proinflammatory cytokine IL-1ß in MH7A cells at 15 µM and they also could strongly protect AML12 cells against D-GalN injury at 30 µM. Flow cytometry and Western blot analysis showed that compound 5 ameliorated D-GalN induced AML12 cell apoptosis by upregulating the expression of anti-apoptotic Bcl-2 protein and down-regulating the expression of pro-apoptotic Bax protein.

Terpenoid Glucosides from Gentiana macrophylla That Attenuate TNF-α Induced Pulmonary Inflammation in A549 Cells.

Four previously undescribed terpenoid glucosides, including one sesquiterpenoid di-glucoside (1), two new iridoid glucosides (2, 3), and a new triterpenoid tri-glucoside (4), were isolated from a 70% ethanol extract of the root of Gentiana macrophylla (Gentianaceae), along with eight known terpenoids. Their structures were determined by spectroscopic techniques, including 1D, 2D NMR, and HRMS (ESI), as well as chemical methods. The absolute configuration of compound 1 was determined by quantum chemical calculation of its theoretical electronic circular dichroism (ECD) spectrum. The sugar moieties of all the new compounds were confirmed to be D-glucose by GC analysis after acid hydrolysis and acetylation. Anti-pulmonary inflammation activity of the iridoids were evaluated on a TNF-α induced inflammation model in A549 cells. Compound 2 could significantly alleviate the release of proinflammatory cytokines IL-1ß and IL-8 and increase the expression of anti-inflammatory cytokine IL-10.

Rare diphenylheptanoid-phenylheptanoid hybrids with α-glucosidase inhibitory effects from the pollen of Typha angustifolia.

Two rarely occurring diphenylheptanoid-phenylheptanoid hybrid dimers (1 and 2) and one new oxygenated fatty acid (3), as well as two known fatty acid analogues (4 and 5), were isolated from the 70% EtOH extract of the pollen of Typha angustifolia. Their planar structures were established by interpretation of MS and NMR spectroscopic data, and the absolute configurations of 1 and 2 were determined by Mosher's method and quantum chemical TD-DFT calculations of ECD spectra. An in vitro anti-diabetic evaluation of these isolates revealed that compounds 1 and 2 exhibited promising inhibitory activity against α-glucosidase with IC50 values of 11.85 ± 0.69 and 17.06 ± 3.08 µM, respectively. It is the first report on both diphenylheptanoid constituents and α-glucosidase inhibitors from the title plant, which represents a significant phytochemical progress of this herbal species and may serve as a reference for its future medicinal applications.

Enantiomeric N-acetyldopamine trimers from Cicadae Periostracum and their absolute configurations.

Six previously undescribed N-acetyldopamine (NADA) trimmer racemates, percicamides A-F (1-6), were isolated from a 70% ethanol extract of Cicadae Periostracum. Subsequent chiral-phase separation afforded six pairs of enantiomers, (+)- and (-)-percicamides A-F (1a/1b-6a/6b). Their structures including absolute configurations were elucidated by combined extensive spectroscopic data and quantum chemical calculations. Compounds 1-6 represent the first examples of NADA trimmers with a cis-relationship of H-7'/H-8' or H-7''/H-8''. Bioassays verified that all isolated compounds showed weak inhibitory effects on nitric oxide production in RAW 264.7 cells.

Six pairs of phenylpropanoid enantiomers from Cinnamomum mollifolium.

Six pairs of undescribed phenylglycerol benzoate enantiomers, (±)-mollifolines A-F, which can also be categorized into three two-pairs of epimers, were isolated from Cinnamomum mollifolium H. W. Li (Lauraceae). The relative configurations (threo or erythro) of the epimers were determined by conformational searching of the lowest energy conformers and analyses of the relationship between the dihedral angle of H-7'─C-7'─C-8'─H-8' and the 3JH-7', H-8' coupling constant according to the Karplus equation. Furthermore, intramolecular hydrogen bonds were proved to play an important role in stabilizing the lowest conformations by using reduced density gradient (RDG) method for noncovalent interactions. Chiral resolutions of these enantiomer pairs were accomplished by immobilized polysaccharide derivative-based chiral HPLC columns. Absolute configurations of the 12 optically pure isomers were finally determined by quantum chemical time-dependent density functional theory (TDDFT) calculations of their electronic circular dichroism (ECD) spectra.

(±)-Heterocageflavone, anti-inflammatory isoprenylated flavonoids with a tricyclo[5.3.1.03,8]undecane moiety from Artocarpus heterophyllus.

(±)-Heterocageflavone (1), a pair of enantiomeric isoprenylated flavonoids, were isolated from Artocarpus heterophyllus. Compound 1 incorporates an unusual tricyclo[5.3.1.03,8]undecane moiety, forming a unique caged polycyclic system. The structures of the pair were determined by spectroscopic analysis, ECD calculations, and single-crystal X-ray diffraction. Compound 1 showed significant inhibitory activity against LPS-induced NO production in RAW264.7 cells with an IC50 value of 49.2 µM.

α-Pyrones with glucose uptake-stimulatory activity from the twigs of Cryptocarya wrayi.

Five new α-pyrones, cryptowratones A-E (1-5), and five known congeners (6-10), together with four other known compounds 11-14 were isolated from the twigs of Cryptocarya wrayi. The structures of the new compounds were elucidated on the basis of extensive spectroscopic data analysis and ECD calculations. All α-pyrones except 6 were evaluated for their stimulatory effects on glucose uptake in vitro with CHO-K1/GLUT4 cells. The positive control insulin displayed an approximate 42 ± 0.14% promotion on glucose uptake at 25 µM, compared with the CHO-K1/GLUT4 group. Compounds 1a/2a, 2, 3, and 10 showed a more significant stimulation of glucose uptake than insulin (25 µM) by 36 ± 0.08%, 27 ± 0.12%, 28 ± 0.12%, and 25 ± 0.12% at 1.5 µM, respectively. Immunofluorescence assays indicated the glucose uptake-stimulatory activity of α-pyrones might be correlated with increased GLUT4 translocation.

Two new isoquinoline alkaloids from Cryptocarya wrayi and their biological activities.

Two new isoquinoline alkaloids, cryptowrayines A (1) and B (2), along with one known pavine alkaloid (-)-12-hydroxyeschscholtzidine (3), were isolated from the twigs of Cryptocarya wrayi. The structures of new compounds were elucidated by extensive spectroscopic data analysis and electronic circular dichroism (ECD) calculations. Both compounds 1 and 2 exhibited moderate quinone reductase inducing activity in Hepa 1c1c7 cells.

A Cryptic Plant Terpene Cyclase Producing Unconventional 18- and 14-Membered Macrocyclic C25 and C20 Terpenoids with Immunosuppressive Activity.

A versatile terpene synthase (LcTPS2) producing unconventional macrocyclic terpenoids was characterized from Leucosceptrum canum. Engineered Escherichia coli and Nicotiana benthamiana expressing LcTPS2 produced six 18-/14-membered sesterterpenoids including five new ones and two 14-membered diterpenoids. These products represent the first macrocyclic sesterterpenoids from plants and the largest sesterterpenoid ring system identified to date. Two variants F516A and F516G producing approximately 3.3- and 2.5-fold, respectively, more sesterterpenoids than the wild-type enzyme were engineered. Both 18- and 14-membered ring sesterterpenoids displayed significant inhibitory activity on the IL-2 and IFN-γ production of T cells probably via inhibition of the MAPK pathway. The findings will contribute to the development of efficient biocatalysts to create bioactive macrocyclic sesterterpenoids, and also herald a new potential in the well-trodden territory of plant terpenoid biosynthesis.

[A new phenylethanol glycoside from Baphicacanthis Cusiae Rhizoma et Radix].

The 95% ethanol extract of Baphicacanthis Cusiae Rhizoma et Radix was purified by multi-chromatographic methods including microporous resin, silica gel, Sephadex LH-20, and C_(18) reversed-phase column chromatography. Fourteen compounds were isolated and structurally identified, including five phenylethanoid glycosides, five phenylpropanoids, one lupinane triterpene, two alkaloids, and one flavonoid, listed as follows: 2-(4-hydroxy-3-methoxyphenyl)-3-(2-hydroxy-5-methoxyphenyl)-3-oxo-1-propanol B(1), threo-2,3-bis-(4-hydroxy-3-methoxybenzene)-3-methoxypropanol(2), 2-(3-hydroxy-4-methoxyphenyl)-ethanol-1-O-[3,4-O-di-acetyl-(1→3)-O-α-L-rhamnopyranosyl]-ß-D-glucopyranoside(3), verbascoside(4), 2″,3″-di-O-acetyl martynoside(5),(+)-pinore-sinol(6), diospyrosin(7), daidzein(8), wiedemannioside B(9), buddlenol A(10), 2″-O-acetyl martyonside(11), lupeol(12), indirubin(13), and tryptanthrin(14). Compound 3 was a new phenylethanoid glycoside, and the other 10 compounds were isolated for the first time from Baphicacanthis Cusiae Rhizoma et Radix except compounds 12, 13, and 14.

Discovery of a Potential Liver Fibrosis Inhibitor from a Mushroom Endophytic Fungus by Genome Mining of a Silent Biosynthetic Gene Cluster.

Liver fibrosis has accounted for liver diseases and overall mortality, but no relevant drug has been developed. Filamentous fungi are important resources of natural products for pharmaceutical development. Calcarisporium arbuscula is a mushroom endophytic fungus, which primarily produces aurovertins. Here, in an aurovertin null-production mutant, one silent gene cluster (mca17) was activated by overexpression of a pathway-specific zinc finger transcriptional regulator, and a tetramic acid-type compound (1, MCA17-1) was identified. Along with detailed structural characterization, its biosynthesis was proposed to be produced from the core PKS-NRPS hybrid enzyme. Moreover, 1 suppressed the activation of LX-2 upon transforming growth factor-ß (TGF-ß) challenge and had stronger bioactivity than the positive control obeticholic acid (OCA) against liver fibrosis. Our work suggested that this engineered fungus could be a producer of 1 for promising pharmaceutical development, and alternatively, it would be developed as a mushroom ingredient in dietary therapy to prevent liver fibrosis.

Pseudosterins A-C, Three 1-Ethyl-3-formyl-ß-carbolines from Pseudostellaria heterophylla and Their Cardioprotective Effects.

Pseudostellaria heterophylla is used in China not only as a functional food but also as an herb to tonify the spleen, enhance immunity, and treat palpitation. Our previous investigation showed that a fraction enriched in glycosides obtained from the roots of P. heterophylla possessed pronounced protective effects on H9c2 cells against CoCl2-induced hypoxic injury. However, the active compounds responsible for the observed effects were still unknown. In the current investigation, pseudosterins A-C (1-3), three new alkaloids with a 1-ethyl-3-formyl-ß-carboline skeleton, together with polydatin, have been isolated from the active fraction. Their structures were elucidated on the basis of spectroscopic analysis and quantum chemical calculations. The four compounds showed cardioprotective effects against sodium hydrosulfite-induced hypoxia-reoxygenation injury in H9c2 cells, with the three alkaloids being more potent. This is also the first report of alkaloids with a ß-carboline skeleton isolated from P. heterophylla as cardioprotective agents.

Structural Elucidation of Three 9,11-Seco Tetracyclic Triterpenoids Enables the Structural Revision of Euphorol J.

Compounds 1-3, the rare examples of 9,11-seco euphane or lanostane triterpenoids featuring an enol-hemiacetal functionality, were isolated from Euphorbia stracheyi. Their structures were elucidated by a combination of spectroscopic, computational, chemical, and single-crystal X-ray diffraction means, which enables the structure of previously published euphorol J to be revised as 1. 1-3 showed significant cytotoxicities on the breast cancer cell line MDA-MB-468 with IC50 values in the range of 2.9-3.9 µM.

Horienoids A and B, Two Heterocoupled Sesquiterpenoid Dimers from Hedyosmum orientale.

Two eudesmane-guaiane/lindenane heterocoupled sesquiterpenoid dimers, horienoids A (1) and B (2) with new carbon skeletons, from Hedyosmum orientale were characterized by a combined method. Compound 1 featured a unique 2,10-dioxabicyclo[6.2.1]undecane core moiety with an anti-Bredt bridgehead double bond. Their biogenetic pathways were proposed to involve Diels-Alder and cascade rearrangement reactions as the key steps. Compound 2 exhibited a potent anti-inflammatory effect on LPS-induced BV-2 microglial cells.

An Efficient Regioselective Synthesis of 8-Formylhomoisoflavonoids with Neuroprotective Activity by Enhancing Autophagy.

6-Formylisoophiopogonone B (7a) and 8-formylophiopogonone B (7b), two natural products isolated from Ophiopogon japonicus, represent a subgroup of rare 6/8-formyl/methyl-homoisoflavonoid skeletons. Herein we report an efficient method for the synthesis of these formyl/methyl-homoisoflavonoids. The synthesized compounds were evaluated for their neuroprotective effects on the MPP+-induced SH-SY5Y cell injury model and showed marked activity. Exploration of the neuroprotective mechanisms of compound 7b led to an increased expression of autophagy marker LC3-II and down-regulation of autophagy substrate p62/SQSTM1. Molecular docking studies showed that 7b may prevent the inhibition of the classic PI3K-AKT-mTOR signaling pathway by interfering with the human HSP90AA1.

A Cell Factory of a Fungicolous Fungus Calcarisporiumarbuscula for Efficient Production of Natural Products.

Fungal natural products are rich sources of clinical drugs. Particularly, the fungicolous fungi have a large number of biosynthetic gene clusters (BGCs) to produce numerous bioactive natural products, but most BGCs are silent in the laboratory. We have shown that a fungicolous fungus Calcarisporiumarbuscula NRRL 3705 predominantly produces the highly reduced polyketide-type mycotoxins aurovertins. Here after evaluation of the aurovertin-null mutant ΔaurA as an efficient host, we further screened two strong promoters aurBp and A07068p based on RNA-Seq, and successfully activated an endogenous gene cluster from C. arbuscula as well as three additional exogenous BGCs from other fungi to produce polyketide-type natural products. Thus, we showed an efficient expression system from the fungicolous fungus C. arbuscula, which will be highly beneficial and complementary to the conventional Aspergillus and Penicillium fungal cell factories, and provides a useful toolkit for genome-wide mining of bioactive natural products from fungicolous fungi.

Acid/Base-Tunable Unimolecular Chirality Switching of a Pillar[5]azacrown Pseudo[1]Catenane.

Stimuli-responsive unimolecular chirality switching is a highly intriguing topic because the molecular structure as well as its function can be adjusted simultaneously by a switching process. Herein, a novel acid/base-tunable unimolecular chirality switching system based on a pillar[5]azacrown pseudo[1]catenane is reported. The bicyclic pillar[5]azacrown pseudo[1]catenane PN4 is synthesized through fusing an azacrown ring onto one repeating unit of a pillar[5]arene. Protonation and deprotonation can reversibly regulate the conformational transformations of PN4 between self-inclusion and self-exclusion structures, which results in the chiroptical inversions of the pseudo[1]catenane. NMR spectra, circular dichroism spectra, and single-crystal structures demonstrate these processes. This pseudo[1]catenane is a novel pillararene-based unimolecular chirality switching system driven by acid/base responsiveness and reveals a new perspective on the supramolecular chirality chemistry of macrocycles.