Protoilludane-Type and Related Nor-Sesquiterpenes from Phellinus hartigii and Their Anti-Hypertrophic Activities in Rat Cardiomyocytes.

Three nor-sesquiterpenes, phellinharts A-C (1-3), isolated from Phellinus hartigii, exhibited unprecedented protoilludane and cerapicane-type structures. The structures of compounds 1-3 were elucidated via spectroscopic analysis, quantum chemical calculations, and X-ray diffraction. Potential biogenic pathways involving demethylation, ring cleavage, and rearrangement were proposed. Compounds 1-3 displayed potent anti-hypertrophic activities with low cytotoxicity (CC50 > 50 µM) in rat cardiomyocytes, underscoring their therapeutic potential.

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.

Ketoreductase Domain-Catalyzed Polyketide Chain Release in Fungal Alkyl Salicylaldehyde Biosynthesis.

Alkyl salicylaldehyde derivatives are polyketide natural products, which are widely distributed in fungi and exhibit great structural diversity. Their biosynthetic mechanisms have recently been intensively studied; however, how the polyketide synthases (PKSs) involved in the fungal alkyl salicylaldehyde biosyntheses release their products remained elusive. In this study, we discovered an orphan biosynthetic gene cluster of salicylaldehyde derivatives in the fungus Stachybotrys sp. g12. Intriguingly, the highly reducing PKS StrA, encoded by the gene cluster, performs a reductive polyketide chain release, although it lacks a C-terminal reductase domain, which is typically required for such a reductive release. Our study revealed that the chain release is achieved by the ketoreductase (KR) domain of StrA, which also conducts cannonical ß-keto reductions during polyketide chain elongation. Furthermore, we found that the cupin domain-containing protein StrC plays a critical role in the aromatization reaction. Collectively, we have provided an unprecedented example of a KR domain-catalyzed polyketide chain release and a clearer image of how the salicylaldehyde scaffold is generated in fungi.

Strophioblachins A-K, Structurally Intriguing Diterpenoids from Strophioblachia fimbricalyx with Potential Anticardiac Hypertrophic Inhibitory Activity.

Three new rearranged diterpenoids, strophioblachins A-C (1-3), eight new diterpenoids, strophioblachins D-K (4-11), and seven previously described diterpenoids (12-18) were purified from the aerial parts of Strophioblachia fimbricalyx. Compounds 1 and 2 contain a rare 6/6/5/6 ring system, while 3 has an uncommon tricyclo[4.4.0.08,9]tridecane-bridged unit, and their diterpenoid skeletons are being reported for the first time. Utilizing spectroscopic and HRESIMS data analysis, the structures of the new compounds (1-11) were established, and ECD and 13C NMR calculations were used to confirm the relative and absolute configurations of 11 and 9. The absolute configurations of compounds 1, 3, and 10 were established using single-crystal X-ray diffraction. The results of testing for anticardiac hypertrophic activity demonstrated that compounds 10 and 15 dose-dependently lowered the mRNA expression of Nppa and Nppb. Protein levels were confirmed by Western blotting, which also demonstrated that compounds 10 and 15 lowered the expression of the hypertrophic marker ANP. The cytotoxic activity against neonatal rat cardiomyocytes was assayed in vitro by the CCK-8 and ELISA methods, and the results showed that compounds 10 and 15 were only very weakly active in the range.

Wulfenioidins D-N, Structurally Diverse Diterpenoids with Anti-Zika Virus Activity Isolated from Orthosiphon wulfenioides.

Eleven diterpenoids, wulfenioidins D-N (1-11), classified into five distinct carbon skeletons with one unreported framework, and four modified abietane diterpenoids were isolated from the whole plant of Orthosiphon wulfenioides. The structures and absolute configurations were characterized by spectroscopic methods, single-crystal X-ray diffraction, and electronic circular dichroism analyses. Compounds 3 and 5 exhibited activity against Zika virus (ZIKV) with EC50 values of 8.07 and 8.50 µM, respectively, and showed no significant cytotoxicity toward Vero cells at 100 µM. Western blot and immunofluorescence experiments showed that compounds 3 and 5 interfered with the replication of the ZIKV by inhibiting the expression of the ZIKV envelope (E) protein.

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.

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.

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.

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.

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.

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.

Design, synthesis and anti-breast cancer evaluation of biaryl pyridine analogues as potent RSK inhibitors.

In order to discover and develop the new RSK kinase inhibitor, 50 pyridyl biaryl derivatives were designed and synthesized with LJH685 as the lead compound and their anti-tumor ability was tested. The results showed that the ability of 7d compound to inhibit the phosphorylation of YB-1 was comparable to that of LJH685. Among them, after preliminary screening, compound 7d showed good activity in inhibiting cell proliferation. Therefore, we took 7d as an example and performed molecular docking analysis on it. Judging from the overlapping combination diagram with LJH685, the results have verified that compound 7d has a similar skeleton to LJH685 and has a similar docking effect with RSK. Therefore, compound 7d is in line with the RSK inhibitor we designed and could be developed to a promising anti-tumor drug in the future.

Spiroarborin, an ent-Clerodane Homodimer from Callicarpa arborea as an Inhibitor of the Eleven-Nineteen Leukemia (ENL) Protein by Targeting the YEATS Domain.

A spiro ent-clerodane homodimer with a rare 6/6/6/6/6-fused pentacyclic scaffold, spiroarborin (1), together with four new monomeric analogues (2-5), were isolated from Callicarpa arborea. Their structures were elucidated by comprehensive spectroscopic data analysis, quantum-chemical calculations, and X-ray diffraction. A plausible biosynthetic pathway of 1 was proposed, and a biomimetic synthesis of its derivative was accomplished. Compound 1 showed a potent inhibitory effect by directly binding to the YEATS domain of the 11-19 leukemia (ENL) protein with an IC50 value of 7.3 µM. This gave a KD value of 5.0 µM, as recorded by a surface plasmon resonance binding assay.

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.

C6-structural optimizations of 2-aryl-1H-pyrazole-S-DABOs: From anti-HIV to anti-DENV activity.

Both HIV and DENV are serious threats to human life, health and social economy today. So far, no vaccine for either HIV or DENV has been developed successfully. The research on anti-HIV or DENV drugs is still of great significance. In this study we developed a series of novel 2-Aryl-1H-pyrazole-S-DABOs with C6-strucutral optimizations as potent NNRTIs, among which, 8 compounds had low cytotoxicity and EC50 values in the range of 0.0508 âˆ¼ 0.0966 µM, and their selectivity index was SI > 1415 âˆ¼ 3940. In particular, two compounds 4a and 4b were identified to have good inhibitory effects on DENV of four serotypes. The EC50 of compound 4a and 4b against DENV-II (13.2 µM and 9.23 µM, respectively) were better than that of the positive control ribavirin (EC50 = 40.78 µM). In addition, the effect of C-6 substituents on the anti-HIV or anti-DENV activity of these compounds was also discussed.