Talaesthanes A-C, three new meroterpenoids from the endophytic fungus Talaromyces primulinus H21.

Three new meroterpenoids (1-3) and ten known ones (4-13) were obtained from the endophytic fungus Talaromyces primulinus H21 isolated from the plant of Euphorbia sikkimensis. Their structures including their absolute configurations were elucidated by extensive analysis of spectroscopic data such as HR-ESI-MS, 1D/2D NMR, and X-ray diffraction of single crystal together with comparison of experimental ECD with calculated ECD. All compounds were examined for their inhibitory effects on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in RAW264.7 cells, and compounds 3, 9, 12, and 13 exhibited certain inhibition on NO production, with IC50 values of 27.19, 41.55, 25.23, and 24.71 µM, respectively.

Chemical constituents of Penicillium ferraniaense GE-7 and their cytotoxicities.

Phytochemical investigation on the plant endophytic fungus Penicillium ferraniaense GE-7 led to the isolation of 18 compounds including one new α-pyrone derivative, peniferranige A (1). The structure including the absolute configuration of compound 1 was elucidated by NMR, HRMS, and ECD data. Demethoxyfumitremorgin C (16) and meleagrin (17) possessed moderate activities against the human lung cancer cell line H1975 with IC50 values of 28.52 ± 1.07 and 13.94 ± 1.92 µM, respectively.

Chemical constituents of Wikstroemia alternifolia and their neuroprotective activities.

Phytochemical investigation on the plant of Wikstroemia alternifolia led to the isolation of 26 compounds including two new ones, wikstralternifols A and B (1 and 7). Their structures including the absolute configuration were elucidated by spectroscopic data together with analysis of experimental and calculated ECD data. All compounds were isolated from this plant for the first time, and their main structural types were lignans, sesquiterpenoids, and flavonoids. In the sodium nitroprusside-induced rat pheochromocytoma PC-12 cell model, the neuroprotective activities of the selected sesquiterpenoids (1 and 4) and lignans (7 - 14) were screened at the concentration of 10 µM, and 7 - 14 displayed better activities than the positive control edaravone.

Discovery of a highly potent and orally available importin-ß1 inhibitor that overcomes enzalutamide-resistance in advanced prostate cancer.

Nuclear transporter importin-ß1 is emerging as an attractive target by virtue of its prevalence in many cancers. However, the lack of druggable inhibitors restricts its therapeutic proof of concept. In the present work, we optimized a natural importin-ß1 inhibitor DD1 to afford an improved analog DD1-Br with better tolerability (>25 folds) and oral bioavailability. DD1-Br inhibited the survival of castration-resistant prostate cancer (CRPC) cells with sub-nanomolar potency and completely prevented tumor growth in resistant CRPC models both in monotherapy (0.5 mg/kg) and in enzalutamide-combination therapy. Mechanistic study revealed that by targeting importin-ß1, DD1-Br markedly inhibited the nuclear accumulation of multiple CRPC drivers, particularly AR-V7, a main contributor to enzalutamide resistance, leading to the integral suppression of downstream oncogenic signaling. This study provides a promising lead for CRPC and demonstrates the potential of overcoming drug resistance in advanced CRPC via targeting importin-ß1.

Discovery of Ingenane Diterpenoids from Euphorbia hylonoma as Antiadipogenic Agents.

Thirteen new Euphorbia diterpenoids, euphylonanes A-M (1-13), and eight known ones were isolated from the whole plants of Euphorbia hylonoma. Compounds 1 and 2 are two rearranged ingenanes bearing a rare 6/6/7/3-fused ring system. Compound 3 represents the first example of a 9,10-epoxy tigliane, while 4-21 are typical ingenanes varying with substituents. Structures were elucidated using a combination of spectroscopic, computational, and chemical methods. Most ingenanes exerted a significant antiadipogenic effect in 3T3-L1 adipocytes, among which 4 was the most active with an EC50 value of 0.60 ± 0.27 µM. Mechanistic study revealed that 4 inhibited the adipogenesis and lipogenesis in adipocytes via activation of the AMPK signaling pathway.

New halimane and clerodane diterpenoids from Croton cnidophyllus.

Three new halimane furanoditerpenoids (1-3) and three new clerodane furanoditerpenoids (4-6), along with seven known terpenoids including four pimarane diterpenoids (7-10) and three norisoprenoids (11-13) were isolated from the 95% EtOH extracts of the plants of Croton cnidophyllus. The 2D structures including absolute configuration of new furanoditerpenoids (1-6) were elucidated by analysis of their HRMS and NMR data as well as comparison of experimental and calculated ECD curves. Bioassay revealed that two compounds (8 and 9) possessed certain inhibitory effects against NO production stimulated by LPS, with IC50 values of 19.00 ± 1.76 and 21.61 ± 1.11 µM, respectively.

Discovery of the First Raptor (Regulatory-Associated Protein of mTOR) Inhibitor as a New Type of Antiadipogenic Agent.

Raptor, a regulatory-associated protein of mTOR, has been genetically proved to be an important regulator in lipogenesis. However, its druggable potential is rarely investigated, largely due to the lack of an inhibitor. In this study, the antiadipogenic screening of a daphnane diterpenoid library followed by target fishing led to the identification of a Raptor inhibitor, 1c (5/7/6 carbon ring with orthoester and chlorine functionalities). Pharmacodynamic studies verified that 1c is a potent and tolerable antiadipogenic agent in vitro and in vivo. Mechanistic studies revealed that the targeting of Raptor by 1c could block the formation of mTORC1 and then downregulate the downstream S6K1- and 4E-BP1-mediated C/EBPs/PPARγ signaling, eventually retarding adipocyte cell differentiation at the early stage. These findings suggest that Raptor can be explored as a novel therapeutic target for obesity and its related complications, and 1c as the first Raptor inhibitor may provide a new therapeutic option for these conditions.

Discovering a New Okadaic Acid Derivative, a Potent HIV Latency Reversing Agent from Prorocentrum lima PL11: Isolation, Structural Modification, and Mechanistic Study.

Marine toxins (MTs) are a group of structurally complex natural products with unique toxicological and pharmacological activities. In the present study, two common shellfish toxins, okadaic acid (OA) (1) and OA methyl ester (2), were isolated from the cultured microalgae strain Prorocentrum lima PL11. OA can significantly activate the latent HIV but has severe toxicity. To obtain more tolerable and potent latency reversing agents (LRAs), we conducted the structural modification of OA by esterification, yielding one known compound (3) and four new derivatives (4-7). Flow cytometry-based HIV latency reversal activity screening showed that compound 7 possessed a stronger activity (EC50 = 46 ± 13.5 nM) but was less cytotoxic than OA. The preliminary structure-activity relationships (SARs) indicated that the carboxyl group in OA was essential for activity, while the esterification of carboxyl or free hydroxyls were beneficial for reducing cytotoxicity. A mechanistic study revealed that compound 7 promotes the dissociation of P-TEFb from the 7SK snRNP complex to reactivate latent HIV-1. Our study provides significant clues for OA-based HIV LRA discovery.

Prenylated dihydroflavones from the root barks of Morus alba.

Three new prenylated dihydroflavones, moralbaflavones A-C (1-3), together with four known ones (4a/4b, 5, and 6) were isolated from the root barks of Morus alba L. Their structures including the absolute configurations were determined by the analysis of HRMS, NMR, and ECD data. The neuroprotective properties of these prenylated dihydroflavones were screened at the concentration of 10 µM in the sodium nitroprusside-induced rat pheochromocytoma PC-12 cells, and the results showed moralbaflavone C (3) possessed significant neuroprotective activity, being more potent than the positive control edaravone.

Biscroyunoid A, an Anti-Hepatic Fibrotic 19-nor-Clerodane Diterpenoid Dimer with a C-16-C-12' Linkage from Croton yunnanensis.

Biscroyunoid A (1), a 19-nor-clerodane diterpenoid dimer featuring a unique C-16-C-12' linkage and containing an unusual 4,7-dihydro-5H-spiro[benzofuran-6,1'-cyclohexane] motif, together with its biosynthetic precursor, croyunoid A (2), were isolated from Croton yunnanensis. Their structures were determined by spectroscopic, computational, and single-crystal X-ray diffraction methods. Compound 1 exerted an antihepatic fibrosis effect in LX-2 cells via inhibition of TGFß-Smad2/3 signaling.

Acupoint catgut embedding improves learning and memory impairment in vascular dementia rats.

Background: Vascular dementia (VD) is a disease that affects brain function through cerebrovascular disease. Due to its complex pathogenesis, there is no effective drug treatment for VD. The present study aimed to evaluate the role of acupoint catgut embedding in the treatment of rats with VD and its possible molecular mechanism. Methods: A modified 4 vessel occlusion (4-VO) method was used to establish a VD model rat, and spatial learning and memory ability was assessed using the Morris water maze (MWM) test. The protein expression levels were detected by Western blot. Hematoxylin and eosin (HE) staining was used for histological analysis and enzyme-linked immunosorbent assay (ELISA) was applied for analysis of serum inflammatory factors. Results: We successfully constructed VD model rats with spatial learning and memory impairment, hippocampus injury, and high inflammatory response. Treatment of VD rats with acupoint catgut embedding significantly reduced escape latency and increased the time in the target quadrant and platform crossing times. VD-mediated hippocampal tissue damage and inflammatory reaction [down-regulating interleukin-1ß (IL-1ß), interleukin-6 (IL-6)] were significantly alleviated by acupoint catgut embedding treatment. In addition, further mechanism exploration found that acupoint catgut embedding treatment could improve the activity of the toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-κB (NF-κB) signaling pathway. In summary, acupoint catgut embedding treatment improved spatial learning and memory loss, alleviated pathological damage of the hippocampus, and inhibited inflammation response in VD rats, which was probably related to the inhibition of the TLR4/MyD88/NF-κB signaling pathway. Conclusions: Acupoint catgut embedding may warrant further study as an adjuvant therapy for the treatment of VD.

Five new limonoids isolated from Walsura robusta.

Five new toosendanin limonoids with highly oxidative furan ring walsurobustones A-D (1-4), and one new furan ring degraded limonoid walsurobustone E (5) together with one known compound toonapubesic acid B (6) were isolated from the leaves of Walsura robusta. Their structures were elucidated by NMR and MS data. Especially, the absolute configuration of toonapubesic acid B (6) was confirmed by X-ray diffraction study. Compounds 1-6 exhibited good cytotoxicity against the cancer cell lines HL-60, SMMC-7721, A-549, MCF-7, and SW480.

Diversity of sesquiterpenoids from Stellera chamaejasme with neuroprotective effects.

Chromatographic fractionation of the 95% EtOH extract of the roots of Stellera chamaejasme yielded 20 sesquiterpenoids of four different types, guaiane-, carotane-, sesquicarane-, and alpiniane-types. Among them, sesquistrachanoids A-F were previously undescribed ones, whose structures including absolute configurations were elucidated by spectroscopic methods, the Mo2(OAc)4-induced ECD experiment, and analysis of experimental and calculated 1D NMR and ECD data. Sesquistrachanoid A is a 2,3-seco-guaiane-type sesquiterpenoid with a α-pyrone core and sesquistrachanoid B is the first example of 8,9-seco-guaiane-type sesquiterpenoid featured with an 1,8-δ-lactone core. Sesquistrachanoid C is a guaiane sesquiterpenoid characterized by a peroxide bridge between C-8 and C-10. All sesquiterpenoids were evaluated for their neuroprotective effects on cell damage induced by sodium nitroprusside in PC-12 cells. The bioassay results showed that six compounds at 10 µM could restore the cell viability, being comparable to that of the positive control edaravone. The mechanistic study on the most pronounced activity compound, stelleraguaianone B, demonstrated that it played a neuroprotective role by promoting the mRNA expression of antioxidant enzymes to reduce oxidative stress.

New benzofuran neolignans with neuroprotective activity from Phyllanthodendron breynioides.

A pair of undescribed dihydrobenzofuran neolignan enantiomers, (+/-)-phybrenan A (1a/1b), two new benzofuran neolignans, phybrenan B and C (2 and 3), along with four known neolignans (4 - 7) were obtained from the plants of Phyllanthodendron breynioides P. T. Li. The planar structures of all isolates were demonstrated by the analysis of detailed spectroscopic evidence (NMR, HRMS, and IR), and the absolute configurations of novel neolignans were elucidated by combined calculated and experimental ECD data analysis. The neuroprotective activities of all benzofuran neolignans against sodium nitroprusside (SNP)-induced cell death were examined in rat pheochromocytoma PC12 cells. The results exhibited that three compounds (4 - 6) possessed remarkable neuroprotective activities at 10 µM, better than the positive drug edaravone.

Euphylonoids A and B, Two Highly Modified Jatrophane Diterpenoids with Potent Lipid-Lowering Activity from Euphorbia hylonoma.

Euphylonoids A (1) and B (2), two highly modified jatrophane diterpenoids, were isolated from Euphorbia hylonoma. 1 represents a new 9(10→18)-abeo-8,12-cyclojatrophane skeleton containing a cage-like 3,8-dioxatricyclo[5.1.2.04,9]decane core, while 2 is a 14(13→20)-abeo-8,12-cyclojatrophane featuring an unusual 17-oxatetracyclo[12.2.1.01,5.09,13]heptadecane framework. Their structural elucidation was completed by spectroscopic, chemical, computational, and single-crystal X-ray diffraction means. 2 significantly inhibited early adipogenesis in 3T3-L1 adipocytes via activating AMP-activated protein kinase signaling.

Mulberry Diels-Alder-type adducts: isolation, structure, bioactivity, and synthesis.

Mulberry Diels-Alder-type adducts (MDAAs) are unique phenolic natural products biosynthetically derived from the intermolecular [4 + 2]-cycloaddition of dienophiles (mainly chalcones) and dehydroprenylphenol dienes, which are exclusively distributed in moraceous plants. A total of 166 MDAAs with diverse skeletons have been isolated and identified since 1980. Structurally, the classic MDAAs characterized by the chalcone-skeleton dienophiles can be divided into eight groups (Types A - H), while others with non-chalcone dienophiles or some variations of classic MDAAs are non-classic MDAAs (Type I). These compounds have attracted significant attention of natural products and synthetic chemists due to their complex architectures, remarkable biological activities, and synthetic challenges. The present review provides a comprehensive summary of the structural properties, bioactivities, and syntheses of MDAAs. Cited references were collected between 1980 and 2021 from the SciFinder, Web of Science, and China National Knowledge Internet (CNKI).

Discovery of Highly Potent Daphnane Diterpenoids Uncovers Importin-ß1 as a Druggable Vulnerability in Castration-Resistant Prostate Cancer.

Importins are overexpressed in many cancers and mediate the abnormal nuclear transport of oncogenic factors. The druggable potential of importins still remains unclear, largely because of the lack of potent inhibitors. Herein, the anti-castration-resistant prostate cancer (CRPC) screening of a Euphorbiaceae diterpenoid library followed by target fishing led to the identification of a highly potent importin-ß1 inhibitor, daphnane diterpenoid DD1. DD1 selectively inhibited the growth and survival of CRPC cells at subnanomolar concentrations and completely blocked tumor growth in preclinical models at an extremely low dosage. Mechanistic studies revealed that targeting of importin-ß1 by DD1 significantly reduced the nuclear accumulation of key CRPC drivers, shutting down their downstream oncogenic signaling. Disruption of the predicted binding sites of DD1 on importin-ß1 abolished this anti-CRPC effect. These findings suggest that importin-ß1 is an effective therapeutic target in CRPC and that DD1 as the most potent importin-ß1 inhibitor to date can be developed as therapeutics for treatment of this disease.

Tigliane and rhamnofolane glycosides from Euphorbia wallichii prevent oxidative stress-induced neuronal death in PC-12 cells.

Tigliane and rhamnofolane diterpenoids bearing glycosyl substituents are rarely found in nature. In the current study, seven new tigliane glycosides, euphorwallsides A - G (1-7), and five new rhamnofolane glycosides, euphorwallsides H - L (8-12), were isolated from the whole plants of Euphorbia wallichii. Their structures were elucidated by a combination of spectroscopic, computational, and chemical means. The aglycones of 1-5 represent a rare class of 13-deoxygenated tiglianes, while those of 8-12 represent the first examples of 4-deoxygenated rhamnofolanes. 2, 3, 5, 7, 8, and 12 showed significant neuroprotective effects on sodium nitroprusside (SNP)-induced neuronal death in pheochromocytoma cell line PC-12 at 10 µM, being more active than the clinical drug, edaravone. Mechanistic study revealed that the most active compound, 3, could inhibit reactive oxygen species (ROS) accumulation and restore the mitochondrial membrane potential via modulating the Nrf2 signaling pathway in PC-12 cells.

Crotonianoids A-C, Three Unusual Tigliane Diterpenoids from the Seeds of Croton tiglium and Their Anti-Prostate Cancer Activity.

Crotonianoids A-C (1-3), three unusual tigliane diterpenoids, were isolated from the seeds of Croton tiglium. Compound 1 is a 13,14:13,15-diseco-tigliane featuring a unique spiro[bicyclo[5.3.0]decane-2,5'-2'(3'H,4'H)-furanone] core; 2 is a 13,15-seco-tigliane incorporating a rare peroxide bridge between C-13 and C-15; and 3 is the first example of a phorbol ester with a 10R-configuration. Their structures were determined by spectroscopic, computational, and X-ray diffraction methods. Compounds 1 and 2 markedly inhibited the growth and survival of prostate cancer cell C4-2B at micromolar concentrations and induced cell apoptosis. Mechanistic study revealed that 1 and 2 could suppress androgen receptor (AR) signaling pathway by promoting the degradation of AR protein.

Homo/Hetero-Dimers of Aromatic Bisabolane Sesquiterpenoids with Neuroprotective Activity from the Fungus Aspergillus versicolor A18 from South China Sea

Chromatographic fractionation of the EtOH extracts of the marine-derived fungus Aspergillus versicolor A18 has led to the isolation of 11 homo/hetero-dimers of aromatic bisabolane sesquiterpenoids including eight diphenyl ether-coupled aromatic bisabolanes (1a/1b and 5−10) and three homodimers (2−4), together with their monomers including three aromatic bisabolanes (11−13) and two diphenyl ethers (14 and 15). Their structures and absolute configurations were elucidated by extensive spectroscopic analysis including HRESIMS, 1D/2D NMR, calculated ECD, and the optical rotatory data. Among the four new compounds, (+/−)-asperbisabol A (1a/1b), asperbisabol B (2), and asperbisabol C (3), the enantiomers 1a and 1b represent an unprecedented skeleton of diphenyl ether-coupled aromatic bisabolane sesquiterpenoids with a spiroketal core moiety. The neuroprotective effects of selected compounds against sodium nitroprusside (SNP)-induced injury were evaluated in PC12 cells by the MTT assay. Five compounds (1a, 6, and 8−10) showed remarkable neuroprotective activities at 10 µM, being more active than the positive control edaravone.