New meroterpenoids and polyketides from the endophytic fungus Paraphaeosphaeria sp. C-XB-J-1 and their anti-inflammatory and SARS-CoV-2 Mpro inhibitory activities.

Seven new meroterpenoids, paraphaeones A-G (1-7), and two new polyketides, paraphaeones H-I (8-9), along with eight known compounds (10-17), were isolated from the endophytic fungus Paraphaeosphaeria sp. C-XB-J-1. The structures of 1-9 were identified through the analysis of 1H, 13C, and 2D NMR spectra, assisted by HR-ESI-MS data. Compounds 1 and 7 exhibited a dose-dependent decrease in lactate dehydrogenase levels, with IC50 values of 1.78 µM and 1.54 µM, respectively. Moreover, they inhibited the secretion of IL-1ß and CASP-1, resulting in a reduction in the activity levels of NLRP3 inflammasomes. Fluorescence microscopy results indicated that compound 7 concentration-dependently attenuated cell pyroptosis. Additionally, compounds 4 and 7 showed potential inhibitory effects on the severe acute respiratory syndrome coronavirus-2 main protease (SARS-CoV-2 Mpro), with IC50 values of 10.8 ± 0.9 µM and 12.9 ± 0.7 µM, respectively.

Three Undescribed Protoilludane-type Sesquiterpene Aryl Esters from Armillaria gallica.

Three previously undescribed protoilludane-type sesquiterpene aryl esters, armillanals A-C (1-3), along with seven known ones (4-10) were obtained from Armillaria gallica Marxm. & Romagn. Compounds 1 and 2 were a rare class of sesquiterpenes featuring the Δ2(3) and Δ12(13)-protoilludane skeleton. Their structures were established by extensive spectroscopic methods. Based on electronic circular dichroism (ECD) calculations, the absolute configurations of three new compounds (1-3) were determined. The anti-inflammatory activity of compounds 1-10 was screened and compound 3 could dose-dependently decrease the level of lactate dehydrogenase, showing IC50 value of 4.525 µM.

Two new oleanane triterpenes from Maytenus hookeri.

Two new triterpenes mayteneri A (1), mayteneri B (2), and seven known compounds (3-9) were isolated from stems of Maytenus hookeri Loes. The chemical structures of compounds 1 and 2 were established by 1D, 2D NMR, HRESIMS analysis, and calculating electronic circular dichroism (ECD). The structures of known compounds 3-9 were determined by comparison of their spectral with those reported. Compounds 4-7 showed significant inhibitory activity for NLRP3 inflammasome, with the IC50 values of 2.36-3.44 µM.

Abietane diterpenoids from Orthosiphon wulfenioides with NLRP3 inflammasome inhibitory activity.

Wulfenioidones A - K (1-11) were abietane diterpenoids with highly oxidized 6/6/6 aromatic tricyclic skeleton isolated from the whole plant of Orthosiphon wulfenioides, and their planar structures and absolute configurations were elucidated by spectroscopic data interpretation, electronic circular dichroism calculation as well as X-ray crystallography analysis. Bioactivity screening indicated that compounds 1-4, 6 and 8 exhibited lactate dehydrogenase (LDH) inhibition effect with IC50 values ranging from 0.23 to 3.43 µM by preventing the mononuclear macrophage cell pyroptosis induced by double signal stimulation of LPS and nigericin. Western Blot analyses of Caspase-1 and IL-1ß down-regulation exhibited that compound 1 could selectively inhibit NLRP3 inflammasome, and the cell morphological observation further supported that compound 1 prevented macrophage cell pyroptosis.

Chemical Constituents of the Branches and Leaves of Picrasma chinensis P.Y. Chen and Tyrosinase Inhibiting Activity.

One new alkaloid, picrasine A, two new quassinoids, picralactones A-B, together with eleven known compounds were isolated from Picrasma chinensis P.Y. Chen. The structures of these compounds were determined using 1D and 2D NMR, HR-ESI-MS, and IR spectroscopic data, and by comparison with published data. Some compounds were tested for tyrosinase inhibiting activity, however, none of them exhibited strong inhibitory effects.

Three New Clerodane Diterpenoids and Their NLRP3 Inflammasome Activation Inhibitory Activity from Callicarpa arborea Roxb.

Three new compounds callicarpenoids A-C (1-3), were isolated from the stems of Callicarpa arborea Roxb together with fifteen known compounds (4-18). The structures of these compounds were elucidated using advanced spectroscopic techniques, including 1D and 2D NMR, UV, IR, HR-ESI-MS, ECD, ORD, and quantum chemical calculations. Compound 3, a rare rearranged diterpenoid with a fused 5/6-ring system demonstrated strong potential as an inhibitor of the NLRP3 inflammasome activation with an IC50 value of 3.153 µM. It effectively reduced GSDMD-NT production, inhibited caspase-1 activation, and suppressed IL-1ß secretion, thereby mitigating NLRP3 inflammasome-induced pyroptosis in J774A.1 cells. These findings suggest that compound 3 warrants further research and development as a promising NLRP3 inflammasome inhibitor.

Two New Prostaglandin-Like Compounds from Callicarpa arborea Roxb and Their NLRP3 Inflammasome Activation Inhibitory Activity.

Two new prostaglandin-like compounds callicarboric acids A-B (1-2), along with six known compounds (3-8) were isolated from the stems of Callicarpa arborea Roxb. Their structures were determined with the help of modern spectroscopic techniques such as NMR, UV, IR, HR-ESI-MS, ECD, and ORD with the assistance of quantum chemical calculations. Compound 1 exhibited remarkable anti-NLRP3 inflammasome activation potential, demonstrating an IC50 value of 0.74 µM. Additionally, by reducing GSDMD-NT production, inhibiting caspase-1 activation, and suppressing IL-1ß secretion, it effectively mitigated NLRP3 inflammasome-induced pyroptosis in J774A.1 cells. These findings indicate that compound 1 possesses the capability to be a valuable candidate for further research and development as an NLRP3 inflammasome inhibitor.

Highly Oxygenated Labdane Diterpenoids from Stevia rebaudiana and Their Anti-Atherosclerosis Activities.

Five unknown labdane diterpenoids Stevelins A-E (1-5), three known labdane diterpenoids (6-8) and three labdane norditerpenoids (9-11) were isolated from the Stevia rebaudiana. The structures were determined primarily via NMR spectroscopic data and HR-ESI-MS experiments. X-ray crystallography using CuKα radiation was used to determine the absolute configurations of 1, and the absolute configurations of 2-5 were deduced by electronic circular dichroism (ECD) calculations. The potential anti-atherosclerosis activities of all compounds were evaluated by measuring their inhibitory effects on the macrophage foam cell formation. As a result, most isolated compounds could significantly inhibit oxidized low-density lipoprotein (ox-LDL)-induced macrophage foam cell formation, which suggests that these compounds may be promising candidates in the treatment for atherosclerosis.

Callicarpanes A-L, Twelve New Clerodane Diterpenoids with NLRP3 Inflammasome Inhibitory Activity from Callicarpa integerrima.

Twelve new clerodane diterpenoids named callicarpanes A-L (1-12), together with eight known compounds (13-20), were isolated from Callicarpa integerrima. Their structures were determined by comprehensive spectroscopic data. The calculated chemical shifts were used to identify relative configurations using DP4+ analysis. The absolute configurations (AC) were assigned based on quantum chemical calculations and X-ray single-crystal diffraction methods. Compounds 1, 3, 5, 9, 10, 12, 15, 16, and 19 showed significant inhibitory activity for NLRP3 inflammasome activation, with the IC50 against lactate dehydrogenase (LDH) release ranging from 0.08 to 4.78 µM. Further study revealed that compound 10 repressed IL-1ß secretion and caspase-1 maturation in J774A.1 cell as well as blocked macrophage pyroptosis.

Chemical constituents from the twigs and leaves of Picrasma quassioides.

Two new compounds, including a norsesquiterpenoid, annuionone H (1), and a quassinoid, picraqualide G (2), along with eleven known compounds (3-13), were isolated from the twigs and leaves of Picrasma quassioides. Comprehensive spectroscopic analyses and NMR calculation with DP4+ analysis were used to identify their structures. Moreover, of all these compounds, compound 4 showed a week inhibition rate in the anti-inflammatory screening results against mouse macrophage J774A.1 cell.

Two new compounds from Verbena bonariensis.

Two new compounds verboncin A (1) and verboncin B (4) and 14 known compounds (2-3 and 5-16) were isolated from Verbena bonariensis, and these 14 compounds were first obtained from this plant. Their chemical structures were established by one and two-dimensional NMR and HRESIMS analysis and the results were compared with literature values. The absolute configuration of 1 was determined by calculating electronic circular dichroism (ECD). The cytotoxicity of some of the compounds against MCF-7, HCT-116, MDA-MB-231, and SW620 human cancer cell lines were evaluated, in which compound 4 showed negligible cytotoxic activity with an IC50 value of 68.08 ± 0.35 µM against the MCF-7 cell line.

Aspulvins A-H, Aspulvinone Analogues with SARS-CoV-2 Mpro Inhibitory and Anti-inflammatory Activities from an Endophytic Cladosporium sp.

Eight new aspulvinone analogues, aspulvins A-H (1-8) and aspulvinones D, M, O, and R (9-12), were isolated from cultures of the endophytic fungus Cladosporium sp. 7951. Detailed spectroscopic analyses were conducted to determine the structures of the new compounds. All isolates displayed different degrees of inhibitory activity against the severe acute respiratory syndrome coronavirus 2 main protease (SARS-CoV-2 Mpro) at 10 µM. Notably, compounds 9, 10, and 12 showed potential SARS-CoV-2 Mpro inhibition with IC50 values of 10.3 ± 0.6, 9.4 ± 0.6, and 7.7 ± 0.6 µM, respectively. For all compounds except 3 and 4, the anti-inflammatory activity occurred by inhibiting the release of lactate dehydrogenase (LDH) with IC50 values ranging from 0.7 to 7.4 µM. Compound 10 showed the most potent anti-inflammatory activity by inhibiting Casp-1 cleavage, IL-1ß maturation, NLRP3 inflammasome activation, and pyroptosis. The findings reveal that the aspulvinone analogues 9, 10, and 12 could be promising candidates for coronavirus disease 2019 (COVID-19) treatment as they inhibit SARS-CoV-2 infection and reduce inflammatory reactions caused by SARS-CoV-2.

Callintegers A and B, Unusual Tricyclo[4.4.0.09,10]tetradecane Clerodane Diterpenoids from Callicarpa integerrima with Inhibitory Effects on NLRP3 Inflammasome Activation.

Callintegers A (1) and B (2), unprecedented clerodane norditerpenoids based on a novel carbon skeleton, were isolated from Callicarpa integerrima. Compounds 1 and 2 possess a novel 6/6/6-fused tricyclic ring system. Their structures and absolute configurations were determined by quantum chemical calculations, spectroscopic analysis, and single-crystal X-ray diffraction methods. Biological evaluation showed that compound 2 inhibited IL-1ß secretion in a dose-dependent manner with an IC50 value of 5.5 ± 3.2 µM. Caspase-1 maturation and IL-1ß secretion were also reduced, indicating that compound 2 impaired NLRP3 inflammasome activation.

The discovery of potentially active diterpenoids to inhibit the pyroptosis from Callicarpa arborea.

Pyroptosis is a programmed-inflammatory cell death, which leads to release of inflammatory cellular contents and formation of inflammation. Uncontrollable pyroptosis can result in serious immune diseases, such as cytokine release syndrome (CRS), sepsis, disseminated intravascular coagulation (DIC), and acute organ damage, including acute respiratory distress syndrome (ARDS) and acute kidney injury (AKI). Members of the Callicarpa genus are significant raw materials for traditional Chinese medicine, widely used for analgesia, hemostasis, and anti-inflammation. Previously, we have reported some ent-clerodane diterpenoids from Callicarpa arborea, shown potent inhibitory effects against pyroptosis. In this study, we went on investigating this kind of diterpenoids, and yielded 66 ent-clerodane diterpenoids, including 52 new compounds, from Callicarpa arborea. Their structures featured with a 5/6- (1-25) or a 6/6- (26-66)-fused double-ring scaffolds, were elucidated using spectroscopic data, electrostatic circular dichroism (ECD) and X-ray diffraction analyses. Screening for the inhibitory activity against pyroptosis by detecting of IL-1ß secretion in J771A.1 cells, revealed 28 compounds with an IC50 below 10.5 µM. Compound 1 was the most potent with an IC50 of 0.68 µM and inhibited the J774A.1 macrophage pyroptosis by blocking the NLR pyrin domain containing 3 (NLRP3) inflammasome activation. An in vivo study further revealed that compound 1 decreased infiltration of CD11b + F4/80 + macrophages into lung and attenuated the lipopolysaccharide (LPS)-induced lung injury. Taken together, this study indicated the potential of compound 1 as a candidate for pyroptosis-related inflammation treatment, as well as provided the chemical and pharmacological basis for the further development of Callicarpa genus as a herbal medicine.

Callicarpnoids A-C, structurally intriguing ent-Clerodane diterpenoid dimers with cytotoxicity against MCF-7 and HCT-116 cell lines from Callicarpa arborea Roxb.

Callicarpnoids A-C (1-3), three new ent-clerodane diterpenoid dimers formed via a [4 + 2] hetero Diels-Alder cycloaddition, appeared as a third example of this type of dimers, were isolated from the stems of Callicarpa arborea Roxb.. Their structures were elucidated by comprehensive spectroscopic analysis, and the absolute configurations were confirmed by single-crystal X-ray diffraction and electronic circular dichroism (ECD) calculations, as well as DP4 + analysis. Cytotoxicity test in two cell lines indicated that compounds 2 and 3 had significant cytotoxic effect against breast cancer cell (MCF-7) and colorectal cancer cell (HCT-116) with IC50 ranging from 5.2 to 7.2 µM, comparable to those of the positive control. Furthermore, the western blot analysis revealed that the protein expression levels of Bax were increased following compounds 2 and 3 treatment, whereas the expression levels of caspase 8, caspase 3, caspase 9 and Bcl2 were decreased in a dose-dependent manner, indicating that compounds 2 and 3 may induce apoptosis via both intrinsic and extrinsic pathways in MCF-7 and HCT-116 cells.

Diterpenoids from Strophioblachia glandulosa and Their NLRP3 Inflammasome Inhibitory Effects.

Our study on the roots and leaves of the never-hitherto-chemically studied S. glandulosa led to the isolation of five new diterpenes, referred to as stroglandulons A-E (1-5), alongside 18 known constituents (6-23). The structures of the new compounds were elucidated on the basis of their spectroscopic data, while the known ones were determined based on the comparison of their data with the literature values. Compounds 1-5 were evaluated for their inhibitory effects against NLRP3 inflammasome activation; compound 5 showed inhibition by an IC50 value of 6.12±0.03 µM.

Ainslides A-F, Six Sesquiterpenoids Isolated from Ainsliaea pertyoides and Their NLRP3-Inflammasome Inhibitory Activity.

Six new sesquiterpenoids, named as ainslides A-F (1-6), including one carotene-type sesquiterpene (1), one eudesmane (2), four guaianolides (3-6), together with eight known sesquiterpenoids (7-14), were purified from the whole plants of Ainsliaea pertyoides. The structures of these sesquiterpenoids were characterized based on spectroscopic methods including 1D and 2D NMR, HR-ESI-MS, UV, and IR spectra, together with ECD calculations and X-ray diffraction experiments. The anti-inflammatory activity of all the isolated compounds was screened and compounds 3 and 7-13 exhibited NLRP3-inflammasome inhibitory activity with IC50 values of 1.80-4.33 µM.

Fluoro-functionalized ionic covalent organic frameworks (F-iCOFs) for highly selective enrichment and sensitive determination of perfluorinated sulfonates by MALDI-MS.

An easily prepared fluoro-functionalized ionic covalent organic framework (F-iCOF) has been implemented into MALDI-TOF MS, enabling the highly selective enrichment and sensitive determination of perfluorinated sulfonate (PFS) contaminants in a rapid and convenient manner. The good thermal stability and excellent optical absorption properties of F-iCOF makes it a brilliant matrix with no background noise. Moreover, benefitting from the large surface area, appropriate pore size, good water dispersibility, and abundant fluorine atom and cationic characteristic of F-iCOF, it exhibited superior adsorption capacity and enrichment selectivity towards PFSs. Good signal responses for PFSs were obtained in the presence of various interfering compounds such as BSA, HA, or even more than 100-fold excess of glutamic acid and similar in structure sodium alkyl sulfonates, highlighting the specific selectivity of F-iCOF. Calibration curves for potassium perflurobutane sulfonate (PFBSK) in tap water and whole blood were established with good linear correlation in the range 1-500 pg mL-1. The limits of detection and quantification for PFBSK were as low as 0.04 pg mL-1 and 0.05 pg mL-1, respectively, which are comparable or better than the existing methods for the determination of PFSs.

Centrantheroside F, a new ionone glycoside from Centranthera grandiflora.

One new ionone glycoside, named centrantheroside F (1), together with 9 known compounds (2-10), were isolated from the roots of Centranthera grandiflora. Their structures were determined by spectroscopic data analyses and comparing with the literature data. The absolute configuration of 1 was confirmed via 2 D NMR and electronic circular dichroism (ECD). All isolated compounds were evaluated for their inhibitory activity on lipopolysaccharide (LPS)-induced nitric oxide (NO) production.

Synthesis of nigranoic acid and manwuweizic acid derivatives as HDAC inhibitors and anti-inflammatory agents.

As a successful anti-tumor drug target, the family of histone deacetylases (HDACs) is also a critical player in immune response, making the research of anti-inflammatory HDAC inhibitors an attractive new focus. In this report, triterpenoids nigranoic acid (NA) and manwuweizic acid (MA) were identified as HDAC inhibitors through docking-based virtual screening and enzymatic activity assay. A series of derivatives of NA and MA were synthesized and assessed for their biological effects. As a result, hydroxamic acid derivatives of NA and MA showed moderately increased activity for HDAC1/2/4/6 inhibition (the lowest IC50 against HDAC1 is 1.14 µM), with no activity against HDAC8. In J774A.1 macrophage, compound 1-3, 13 and 17-19 demonstrated inhibitory activity against lactate dehydrogenase (LDH) and IL-1ß production, without affecting cell viability. Compound 19 increased the histone acetylation level in J774A.1 cells, as well as inhibited IL-1ß maturation and caspase-1 cleavage. These results indicated that compound 19 blocks the activation of NLRP3 inflammasome, probably related to HDAC inhibition. This work provided a natural scaffold for developing low-cytotoxic and anti-inflammatory HDAC inhibitors, as well as a class of tool molecules for studying the relationship between HDACs and NLRP3 activation.