Patumantanes A-D, seco-Polycyclic Polyprenylated Acylphloroglucinols with Diverse Carbon Skeletons from Hypericum patulum.

Patumantanes A-D (1-4), four new seco-polycyclic polyprenylated acylphloroglucinols (PPAPs) were isolated from Hypericum patulum. Patumantane A (1) was an unprecedented 1,2-seco-homoadamantane-type PPAP bearing a new 3,7-dioxatetracyclo[7.7.0.01,6.111,15]heptadecane architecture based on a 6/7/5/6 ring system. Patumantane B (2) was a unique 1,9-seco-adamantane-type PPAP with a tricyclo[4.4.4.0.02,12]tridecane core formed by a 6/6/6 carbon skeleton, and the further breakage between C-5 and C-9 decorated patumantane C (3) with the 9-nor-adamantane skeleton. More importantly, compounds 2 and 3 exhibited moderate immunosuppressive activity on Con A-induced T-lymphocyte proliferation in vitro, with IC50 values of 5.6 ± 1.2 and 11.2 ± 1.2 µM, respectively.

Cryptic piperazine derivatives activated by knocking out the global regulator LaeA in Aspergillus flavipes.

Genome sequencing on an intertidal zone-derived Aspergillus flavipes strain revealed its great potential to produce secondary metabolites. To activate the cryptic compounds of A. flavipes, the global regulator flLaeA was knocked out, leading to substantial up-regulation of the expression of two NRPS-like biosynthetic gene clusters in the ΔflLaeA mutant. With a scaled-up fermentation of the ΔflLaeA strain, five compounds, including two previously undescribed piperazine derivatives flavipamides A and B (1 and 2), along with three known compounds (3-5), were obtained by LC-MS guided isolation. The new compounds were elucidated by spectroscopic analysis and electronic circular dichroism (ECD) calculations, and the biosynthetic pathway was proposed on the bias of bioinformatic analysis and 13C isotope labeling evidence. This is the first report to access cryptic fungi secondary metabolites by inactivating global regulator LaeA and may provide a new approach to discovering new secondary metabolites by such genetic manipulation.

Discovery of Cytotoxic Nitric Oxide-Releasing Piperlongumine Derivatives Targeting Wnt/ß-Catenin in Colon Cancer Cells.

Piperlongumine (1) increases reactive oxygen species (ROS) levels and induces apoptosis in cancer cells through various pathways. Nitric oxide (NO) donors have demonstrated potent anticancer activities with exogenous NO being oxidized by ROS in the tumor microenvironment to form highly reactive N-oxides (RNOS). This amplifies oxidative stress cascade reactions, ultimately inducing cancer cell apoptosis. To exploit this synergy, a series of NO-releasing piperlongumine derivatives (2-5) were designed and synthesized. These compounds were expected to release NO in cancer cells, simultaneously generating piperlongumine derivative fragments to enhance the anticancer effects. Compound 6, structurally similar to compounds 2-5 but not releasing NO, served as a control. Among these derivatives, compound 5 exhibited the most potent antiproliferative activity against HCT-116 cells and efficiently released NO in this cell line. Further investigation revealed that compound 5 inhibited colon cancer cell proliferation by modulating ß-catenin expression, which is a pivotal protein in the Wnt/ß-catenin signaling pathway. These findings highlight compound 5 as a promising candidate for colon cancer treatment targeting the Wnt/ß-catenin pathway.

Maydistacins A-G, Terpestacin-type Sesterterpenoids with Anti-inflammatory Activity from the Phytopathogenic Fungus Bipolaris maydis.

Seven undescribed terpestacin-type sesterterpenoids, maydistacins A-G (1-7), along with two known congeners (8 and 9), were isolated from the phytopathogenic fungus Bipolaris maydis collected from the leaves of Hypericum longistylum. The structures of 1-7 were elucidated based on extensive spectroscopic analysis, chemical methods, NMR calculations with DP4+ probability analysis, and comparison of experimental and calculated electronic circular dichroism (ECD) calculations. In vitro anti-inflammatory effects of these compounds were tested in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Compound 1 exhibited inhibition of the production of nitric oxide in LPS-induced macrophages, with an IC50 value of 19 ± 2 µM. A dexamethasone control displayed an IC50 value of 6.7 ± 0.6 µM. Compound 1 is the first terpestacin-type sesterterpenoid reported to display anti-inflammatory activity and may provide a novel chemical scaffold for the discovery of new anti-inflammatory drugs.

Discovery of 23,24-diols containing ergosterols with anti-neuroinflammatory activity from Penicillium citrinum TJ507.

Citristerones A-E (1-5), five new 23,24-diols containing ergosterols, along with three known analogues, were isolated from the endophytic fungus Penicillium citrinum TJ507 obtained from Hypericum wilsonii N. Robson. Their structures and absolute configurations were determined by NMR, HRESIMS, Snatzke's method, X-ray diffraction analyses and ECD calculation. Subsequently, the anti-neuroinflammatory effects of these isolates were screened using lipopolysaccharide (LPS)-induced BV-2 microglial cells, and citristerone B (2) showed outstanding anti-neuroinflammatory activity, with IC50 value of 0.60 ± 0.04 µM. Moreover, immunofluorescence and western blot analysis suggested that citristerone B not only reduced the release of nitric oxide (NO) and proinflammatory cytokines in LPS-induced BV-2 microglial cells, but also significantly inhibited the expression of TNF-α, iNOS and NF-κB, along with the production of cellular ROS.

Discovery of adamantane-type polycyclic polyprenylated acylphloroglucinols that can prevent concanavalin A-induced autoimmune hepatitis in mice.

Hyperadamans A-G (1-7), seven new adamantane type polycyclic polyprenylated acylphloroglucinols (PPAPs), were isolated from Hypericum wilsonii N. Robson. Structurally, 1-4 were the first adamantanes bearing an unusual 2,7-dioxabicyclo-[2.2.1]-heptane fragment, and compound 5 was the first adamantane with a rare 1,6-dioxaspiro[4.4]nonane section. Importantly, 1-7 exhibited significant immunosuppressive activity on Con A-induced T-lymphocyte proliferation in vitro, with IC50 values ranging from 3.97 ± 0.10 to 18.12 ± 1.07 µM. Pretreatment with 1 in Con A-challenged autoimmune hepatitis mice could dramatically ameliorate the levels of hepatic injury indexes (ALT and AST) and reduce the product of proinflammatory cytokines (COX-2, IL-6, IL-1ß, IL-18, IL-23A and TNF-α). Furthermore, the protective effect of 1 on the Con A-induced liver injury was corroborated by the histological analysis and the immunohistochemistry.

Bioactive Indole Alkaloid from Aspergillus amoenus TJ507 That Ameliorates Hepatic Ischemia/Reperfusion Injury.

Hepatic ischemia/reperfusion injury (IRI) is a major factor contributing to the failure of hepatic resection and liver transplantation. As part of our ongoing investigation into bioactive compounds derived from fungi, we isolated eight indole alkaloids (1-8) from the endophytic fungus Aspergillus amoenus TJ507. Among these alkaloids, one previously undescribed compound, amoenamide D (1), was identified. The planar structure of 1 was elucidated by extensive spectroscopic analysis, including HRESIMS and NMR spectra. The absolute configuration of 1 was elucidated by using electronic circular dichroism calculations. Notably, in the CoCl2-induced hepatocyte damage model, notoamide Q (3) exhibited significant anti-hypoxia injury activity. Furthermore, in a murine hepatic ischemia/reperfusion injury model, treatment with 3 prevents IRI-induced liver damage and hepatocellular apoptosis. Consequently, 3 might serve as a potential lead compound to prevent hepatic ischemia/reperfusion injury.

Discovery of ergosterol derivative from Aspergillus sp. TJ507 that protects against hepatic ischemia/reperfusion injury.

Hepatic ischemia/reperfusion injury is a major cause of hypohepatia after surgical procedures such as hypovolemic shock, transplantation, and so on. In our continuous study of bioactive natural products from fungus, eight ergosterol-type sterides (1-8), including two undescribed compounds, sterolaspers A (1) and B (2), were isolated from Aspergillus sp. TJ507. Structure elucidation was accomplished by extensive spectroscopic analysis and comparison with the reported NMR data as well as X-Ray single crystal diffraction tests. Activity screen of these isolates showed 5α-stigmast-3,6-dione (3) possessing anti-hypoxia injury effects against CoCl2-induced hypoxia damage in hepatocytes. More importantly, compound 3 could improve liver function, alleviate liver damage, and restrain the hepatocellular apoptosis in hepatic ischemia/reperfusion injury murine model. As such, this ergosterol-type steride, 5α-stigmast-3,6-dione (3), might serve as lead structure for the development of novel hepatoprotective agents in the clinical treatment of hepatic ischemia/reperfusion injury.

Norprzewalsone A, a Rearranged Polycyclic Polyprenylated Acylphloroglucinol with a Spiro[cyclopentane-1,3'-tricyclo[7.4.0.01,6]tridecane] Core from Hypericum przewalskii.

Norprzewalsone A (1), a rearranged polyprenylated polycyclic acylphloroglucinol (PPAP) with a new carbon skeleton, along with a new congener, norprzewalsone B (2), were isolated from Hypericum przewalskii. Compound 1 possessed a new 5/6/5/6/6 pentacyclic ring system based on a spiro[cyclopentane-1,3'-tricyclo[7.4.0.01,6]tridecane] core, which might be derived from the common [3.3.1]-type bicyclic polyprenylated acylphloroglucinol (BPAP) via the key retro-Claisen, intramolecular cyclization, and Diels-Alder cyclization reactions. Their structures and absolute configurations were confirmed by spectroscopic data, calculated 1D NMR data with DP4+ probability analyses, and electronic circular dichroism calculations and comparison. More significantly, compound 1 exhibited a moderate inhibitory effect on NO production in lipopolysaccharide-stimulated RAW264.7 cells.

Discovery of 13,15-nor-polycyclic polyprenylated acylphloroglucinols from Hypericum longistylum with anti-inflammatory activity.

Spihyperglucinols A (1) and B (2), the first 13,15-nor-polycyclic polyprenylated acylphloroglucinols (PPAPs) featuring a 7/6/5 tricyclic ring system based on an unexpected bicyclo[3.2.2]nonane core, along with three new congeners, spihyperglucinols C-E (3-5), were isolated from Hypericum longistylum. Importantly, 1 and 2 displayed potential inhibitory effects on the production of nitric oxide in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages, with IC50 values of (8.70 ± 1.18) and (9.23 ± 1.26) µM, respectively, comparable to the positive control, dexamethasone, with an IC50 value of (9.76 ± 1.13) µM.

(±)-Walskiiglucinol A, a pair of rearranged acylphloroglucinol derivative enantiomers from Hypericum przewalskii.

(±)-Walskiiglucinol A (1a/1b), a pair of rearranged acylphloroglucinol derivatives with a new carbon skeleton, was obtained from Hypericum przewalskii. Compounds 1a/1b were the first examples of naturally occurring acylphloroglucinol derivatives possessing a unique 1-oxaspiro[4.4]nonane core bearing a new 5/5 ring system. Their planar and relative structures were identified by extensive spectroscopic analysis and NMR chemical shift calculations with DP4+ probability analysis, and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. A plausible biogenetic pathway of 1a/1b was proposed in which the breakage of the C-2/C-3 linkage via a retro-Claisen reaction and the cyclization between C-3 and C-1 were proposed as key steps. The isolates were evaluated for cytotoxic activities against a panel of cancer cell lines and anti-inflammatory activities against lipopolysaccharide (LPS)-induced NO production, and compounds 1a/1b showed moderate cytotoxic activities with IC50 values ranging from 9.72 to 36.75 µM.

An unprecedented ergostane with a 6/6/5 tricyclic 13(14 → 8)abeo-8,14-seco skeleton from Talaromyces adpressus.

Talasterone A (1), an unprecedented 6/6/5 tricyclic 13(14 â†’ 8)abeo-8,14-seco-ergostane steroid, together with two known congeners dankasterone B (2) and (14ß,22E)-9,14-dihydroxyergosta-4,7,22-triene-3,6-dione (3), were characterized from Talaromyces adpressus. The structure of 1 with absolute configuration was elucidated based on NMR spectroscopic data and ECD calculation. Compound 2 belongs to a class of unconventional 13(14 â†’ 8)abeo-ergostanes, which have been renewed via the 1,2-migration of C-13-C-14 bond to C-8. In addition, compound 1 represents the first example of ergostane with a tricyclic 13(14 â†’ 8)abeo-8,14-seco-ergostane skeleton. The proposed biosynthetic pathway was established with the support of the coisolation of the known congeners from the producing organism. It is especially noteworthy that compound 1 exhibited potent anti-inflammatory activity with an IC50 value of 8.73 ± 0.66 µM, inhibiting the NF-κB pathway and thus reducing the production of proinflammatory cytokines.

A novel Gboxin analog induces OXPHOS inhibition and mitochondrial dysfunction-mediated apoptosis in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is an aggressive B-cell non-Hodgkin's lymphoma. Currently, moderate efficacy and limitations of approved drugs still exist, and it is necessary to develop newer and more effective drugs. Gboxin is a promising inhibitor of OXPHOS, which specifically inhibits the growth of many kinds of cancer cell lines. In the present study, 21 Gboxin analogs incorporating amide and ester moieties were designed and synthesized. Preliminary screening results show that 5d also has specific selectivity for cancer cells, particularly on the DLBCL cells, which is weaker than that of Gboxin but still good. Thus, the effect and underlying mechanism of 5d on DLBCL cells were further studied. The results showed that 5d exhibits potent proliferation inhibition and cell cycle arrest effects, and its IC50 to DLBCL cells is below 1 µM. In addition, 5d induces apoptosis of DLBCL cells in a time- and dose-dependent manner, and this effect is stronger than that of Gboxin and VP16. Mechanistically, 5d plays its role mainly through the stimulation of metabolic stress in DLBCL cell lines, which induces OXPHOS inhibition, inflammation, DNA damage and mitochondrial dysfunction. These data suggest that 5d has potential as a candidate agent for DLBCL alternative drug development.

Hypaluton A, an Immunosuppressive 3,4-nor-Polycyclic Polyprenylated Acylphloroglucinol from Hypericum patulum.

Hypaluton A (1), an unprecedented nor-polycyclic polyprenylated acylphloroglucinol (PPAP) bearing a new 8/6 bicyclic architecture, along with a new congener, hypaluton B (2), was obtained from Hypericum patulum. Their structures were confirmed by spectroscopic analyses, quantum-chemical 13C NMR calculations, electronic circular dichroism comparisons, and calculations. Hypaluton A is the first PPAP possessing an unparalleled 3,4-nor-bicyclic polyprenylated acylphloroglucinol (BPAP) scaffold, which might be derived from the common [5.3.1]-type-BPAP by losing seven carbons (C-3/4 of the acylphloroglucinol core and the isoprenyl at C-3) via the breakage at C-4-C-5 and C-2-C-3 bonds in the acylphloroglucinol core, together with the benzoyl migration through the hemiketalization/retro-Claisen cascade. More significantly, compound 1 is also the first discovered [6.3.0]-PPAP, which displayed pronounced inhibitory activity against lipopolysaccharide-induced B lymphocyte proliferation.

Bioactive Polyketide-Terpenoid Hybrids from a Soil-Derived Fungus Bipolaris zeicola.

Nine novel polyketide-terpenoid hybrids (1-9), characterized by a 1-alkylated-3,5-dihydroxyphenyl derivative coupled with a modified farnesyl pyrophosphate (FPP) unit, were isolated from a soil-derived fungus Bipolaris zeicola. Their structures were determined by comprehensive spectroscopic data, single-crystal X-ray diffraction analyses, and electronic circular dichroism calculations. Structurally, compounds 1, 2, 5, and 6 possess a rare thiazole moiety; compounds 3 and 4 are the first examples of meroterpenoids featuring an undescribed 6/6/6/6/5 pentacyclic system and bearing a tetrahydrofuran ring fused to a polyketide and a sesquiterpenoid subunit; compounds 7 and 8 possess a rare 2H-1,4-thiazin-3(4H)-one moiety; and compound 9 represents the first example of meroterpenoid having an unusual thiazol-2(3H)-one moiety. The bioactivity assays revealed that compounds 1, 2, 5, 6, and 9 exhibited a significant immunosuppressive effect against concanavalin A (ConA)-induced T lymphocyte proliferation with IC50 values ranging from 5.6 to 8.8 µM, and compounds 1, 2, and 4 exhibited moderate cytotoxic activities with IC50 values ranging from 18.4 to 29.4 µM.

Bioassay-Guided Isolation of an Abetiane-Type Diterpenoid from Prunella vulgaris That Protects against Concanavalin A-Induced Autoimmune Hepatitis.

Prunella vulgaris is a widely used edible Chinese medicinal plant. In the present study, two new abietane-type diterpenoids, abietoquinones A (1) and B (2), were isolated from this plant by an immunosuppressive bioassay-guided isolation procedure. Their structures were elucidated unambiguously by NMR spectroscopic analysis, single-crystal X-ray crystallography, and electronic circular dichroism calculations. Compounds 1 and 2 bear a cyclohex-2-ene-1,4-dione moiety, which is uncommon among abietane diterpenes. Also, abietoquinone A (1) suppressed murine splenocyte proliferation and decreased the production of proinflammatory cytokines induced by concanavalin A (Con A) in vitro. In Con A-challenged mice, preinjection with 1 significantly ameliorated liver injury. Additionally, abietoquinone A (1) exhibited inhibitory activities against the proliferation of murine splenocytes and human T cells induced by anti-CD3/anti-CD28 monoclonal antibodies (mAbs).

Polycyclic polyprenylated acylphloroglucinols with immunosuppressive activity from Hypericum perforatum and absolute configurations assignment of previously reported analogues.

Hyperformitins A-I (1-9), nine undescribed polycyclic polyprenylated acylphloroglucinols (PPAPs) with double-bond migration, along with four new isomers hyperformitins J-M (10-13), were isolated from Hypericum perforatum. Their structures and absolute configurations were determined by spectroscopic analyses including HRESIMS, IR, UV, NMR, and ECD, as well as optical rotation (OR) calculations. The absolute configurations of previously reported analogues, garsubellins D and C as well as garcinielliptones L and M, were assigned for the first time by NMR spectra and specific rotations analyses assisting with OR calculations. Selected compounds were tested for their immunosuppressive activities against lipopolysaccharide (LPS)-induced B lymphocyte proliferation. Compounds 1, 3, 4, 5, 7, and 11 showed inhibition activities against the proliferation of B lymphocyte with IC50 values ranging from 4.1 to 9.7 µM. Furthermore, the neuroprotective activities of the isolates against corticosterone (CORT)-induced injury in PC12 cells were also tested, and compounds 1, 12, and 13 exhibited neuroprotective effects with cell viabilities of 68.0%, 71.3%, and 68.4%, respectively under the concentration of 10 µM.

Discovery of nor-bicyclic polyprenylated acylphloroglucinols possessing diverse architectures with anti-hepatoma activities from Hypericum patulum.

Five new 2-nor-bicyclic polyprenylated acylphloroglucinols (BPAPs), norhyperpalums A-E (1-5), three new 2,3-nor-BPAPs, norhyperpalums F-H (8-10), one new 2,3,4-nor-BPAP (13), and four known analogs (6, 7, 11 and 12) were obtained from Hypericum patulum. Their structures were confirmed by spectroscopic data, electronic circular dichroism (ECD) calculations and comparisons, quantum-chemical 13C NMR calculations with DP4 + probability analysis, the modified Mosher's method, Rh2(OCOCF3)4-induced ECD, and X-ray crystallographic data. Norhyperpalums A-E (1-5) are rare 2-nor-BPAPs bearing a 6/5/5 system based on a hexacyclic-fused 1,6-dioxaspiro[4.4]nonane core, and norhyperpalums F and G (8 and 9) exhibit an unusual 6-oxabicyclo[3.2.1]octane architecture. More significantly, compound 2 displayed pronounced cytotoxicities against hepatoma cell lines by the induction of S-phase cell cycle arrest and promotion of cell apoptosis.

Discovery of bioactive polycyclic polyprenylated acylphloroglucinols from Hypericum wilsonii.

Eleven new polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperwilsones A-K (1-11), along with five known PPAPs (12-16), were isolated from Hypericum wilsonii. Their structures were established via spectroscopic methods, the careful analysis of calculated and experimental electronic circular dichroism (ECD) spectra, single-crystal X-ray diffraction, the modified Mosher's method, and [Rh2(OCOCF3)4]-induced ECD. Hyperwilsone A (1) and hyperwilsone B (2) possessed the unique acetal functionality. Hyperwilsone C (3) was a rare example of [3.3.1]-type PPAP possessing a 3-isopropylfuran moiety. In bioassay, compounds 9 and 10 showed potent anti-inflammatory activity against LPS-induced NO production by inhibiting the nuclear translocation of NF-κB p65 and thus reducing the production of proinflammatory cytokines. Compounds 5, 8, 11, and 14 exhibited moderate inhibitory activity against SUDHL-4 and HL60 cancer cells with IC50 values in the range of 5.74-19.82 µM.

Discovery of GOT1 Inhibitors from a Marine-Derived Aspergillus terreus That Act against Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is a devastating digestive system carcinoma with high incidence and death rates. PDAC cells are dependent on the Gln metabolism, which can preferentially utilize glutamic oxaloacetate transaminase 1 (GOT1) to maintain the redox homeostasis of cancer cells. Therefore, small molecule inhibitors targeting GOT1 can be used as a new strategy for developing cancer therapies. In this study, 18 butyrolactone derivatives (1-18) were isolated from a marine-derived Aspergillus terreus, and asperteretone B (5), aspulvinone H (AH, 6), and (+)-3',3'-di-(dimethylallyl)-butyrolactone II (12) were discovered to possess significant GOT1-inhibitory activities in vitro, with IC50 values of (19.16 ± 0.15), (5.91 ± 0.04), and (26.38 ± 0.1) µM, respectively. Significantly, the molecular mechanism of the crystal structure of GOT1-AH was elucidated, wherein AH and the cofactor pyrido-aldehyde 5-phosphate competitively bound to the active sites of GOT1. More importantly, although the crystal structure of GOT1 has been discovered, the complex structure of GOT1 and its inhibitors has never been obtained, and the crystal structure of GOT1-AH is the first reported complex structure of GOT1/inhibitor. Further in vitro biological study indicated that AH could suppress glutamine metabolism, making PDAC cells sensitive to oxidative stress and inhibiting cell proliferation. More significantly, AH exhibited potent in vivo antitumor activity in an SW1990-cell-induced xenograft model. These findings suggest that AH could be considered as a promising lead molecule for the development of anti-PDAC agents.