Synthesis and biological evaluation of lycoctonine derivatives with cardiotonic and calcium channels inhibitory activities.

In our previous study, a screening of a variety of lycotonine-type diterpenoid alkaloids were screened for cardiotonic activity revealed that lycoctonine had moderate cardiac effect. In this study, a series of structurally diverse of lycoctonine were synthesized by modifying on B-ring, D-ring, E-ring, F-ring, N-atom or salt formation on lycoctonine skeleton. We evaluated the cardiotonic activity of the derivatives by isolated frog heart, aiming to identify some compounds with significantly enhanced cardiac effects, among which compound 27 with a N-isobutyl group emerged as the most promising cardiotonic candidate. Furthermore, the cardiotonic mechanism of compound 27 was preliminarily investigated. The result suggested that the cardiotonic effect of compound 27 is related to calcium channels. Patch clamp technique confirmed that the compound 27 had inhibitory effects on CaV1.2 and CaV3.2, with inhibition rates of 78.52 % ± 2.26 % and 79.05 % ± 1.59 % at the concentration of 50 µM, respectively. Subsequently, the protective effect of 27 on H9c2 cells injury induced by cobalt chloride was tested. In addition, compound 27 can alleviate CoCl2-induced myocardial injury by alleviating calcium overload. These findings suggest that compound 27 was a new structural derived from lycoctonine, which may serve as a new lead compound for the treatment of heart failure.

Penicimides A and B, two novel diels-alder [4 + 2] cycloaddition ergosteroids from Penicillium herquei.

Two novel naturally occurring [4 + 2] Diels-Alder cycloaddition ergosteroids (1 and 2), three undescribed oxidized ergosteroids (3-5), and eleven known analogs (6-16) were isolated from Penicillium herquei. Compounds 1 and 2 represent the first reported cycloadducts of a steroid with 1,4,6-trimethyl-1,6-dihydropyridine-2,5-dione or 4,6-dimethyl-1,6-dihydropyridine-2,5-dione to date. Compound 3 is the C-15 epimer of (22E,24R)-9α,11ß-dihydroxyergosta-4,6,8(14),22-tetraen-3-one (14). The chemical structures of these compounds were elucidated through widespread spectroscopic analyses, mainly including HRESIMS and 1D and 2D NMR data, calculated 13C NMR-DP4+ analysis, and electronic circular dichroism (ECD) data analyses. Biological evaluations of Compounds 1-16 revealed that 3, 9-11, and 15 inhibited the production of NO in LPS-induced RAW264.7 cells with an IC50 value from 7.37 ± 0.69 to 38.9 ± 2.25 µM (the positive control dexamethasone IC50: 9.54 ± 0.71 µM). In addition, Compound 3 exhibited a potent inhibitory effect on the secretion of the proinflammatory cytokines TNF-α and IL-6, the transcription level of the proinflammatory macrophage markers TNF-α, and the expression of the iNOS protein.

Diterpenoid alkaloids from Delphinium trichophorum.

Three new hetisine type C20-diterpenoid alkaloids, named as trichophorines A-C (1-3), were isolated from Delphinium trichophorum, together with nine known alkaloids (4-12). Their structures were elucidated on the basis of spectroscopic data (1D, 2D NMR, single-crystal X-ray, and HR-ESI-MS). All compounds were evaluated for the inhibitory activities against LPS induced NO production in RAW 264.7 macrophage cells, and none of them showed considerable inhibitory activity.

Nine undescribed oxidized ergosterols from the endophytic fungus Penicillium herquei and their cytotoxic activity.

A chemical investigation of the EtOAc extract of the endophytic fungus Penicillium herquei led to the isolation of nine undescribed oxidized ergosterols, penicisterols A-I (1-9), along with ten known analogs (10-19). Their structures and absolute configurations were elucidated by a combination of spectroscopic data analysis, quantum-chemical electronic circular dichroism (ECD) calculations and comparisons, [Rh2(OCOCF3)4]-induced ECD experiments, DFT-calculated 13C chemical shifts and DP4+ probability analysis. Compound 1 was a rare example of ergosterol in which the bond between C-8 and C-9 was cleaved to form an enol ether. Moreover, compound 2 possessed a rare (2,5-dioxo-4-imidazolidinyl)-carbamic acid ester group substituted at C-3. All undescribed oxidized ergosterols (1-9) were evaluated for their cytotoxic activity against five cancer cell lines including 4T1 (mouse breast carcinoma), A549 (human pulmonary carcinoma), HCT-116 (human colorectal carcinoma), HeLa (human cervical carcinoma) and Hepg2 (human hepatoma carcinoma) cells. Compounds 2 and 3 displayed moderate cytotoxic activity against 4T1, A549 and HeLa cells, with IC50 values ranging from 17.22 to 31.35 µM.

New secondary metabolites from the endophytic fungus Aspergillus sp. from Tripterygium wilfordii.

One new 3,5-dimethylorsellinic acid (DMOA)-based meroterpenoid (1), one prenylated tryptophan derivative (2), together with ten known compounds (3-12) were isolated from the endophytic fungus Aspergillus sp. from Tripterygium wilfordii. Their structures and absolute configurations were determined by NMR spectroscopic data, HRESIMS data, UV and IR data as well as electronic circular dichroism (ECD) calculation. In structure, compound 1 was a rare example of DMOA-based meroterpenoid with a cis-fused C/D ring system, and compound 2 possessed an unusual (E)-oxime group. In bioactivity, the lovastatin analogues 5, 6, 9 and 10 showed potential immunosuppressive activity against anti-CD3/anti-CD28 monoclonal antibodies (mAbs)-irritated murine splenocytes proliferation, with IC50 values ranging from (5.30 ± 0.51) µM to (16.51 ± 1.62) µM.

Isolation, absolute configurations and bioactivities of pestaphilones A-I: Undescribed methylated side chain containing-azaphilones from Pestalotiopsis oxyanthi.

Nine undescribed side chain containing azaphilones, pestaphilones A-I, were isolated from the Anoectochilus roxburghii endophytic fungus Pestalotiopsis oxyanthi. The structures of these isolates were identified by spectroscopic data, electronic circular dichroism (ECD) calculations and comparisons, quantum-chemical 13C NMR calculations with DP4+ probability analysis, Rh2(OCOCF3)4-induced ECD, acetonide formation, selective oxidation reaction and X-ray crystallographic data. Structurally, pestaphilones A-I were the first azaphilones characteristically formed via a methyl group at C-9 in the C7 side chain. More importantly, a selective oxidation reaction was firstly set up to resolve the absolute configuration of flexible side chain containing azaphilones, and an acetonide formation based Rh2(OCOCF3)4-induced ECD experiment was performed to identify the configurations of the oxygenated pyranoquinone core in the azaphilones. In bioassay, pestaphilones A-F displayed potential immunosuppressive activity in concanavalin A (Con A)-induced T lymphocyte proliferation, with IC50 values ranging from (9.36 ± 1.14) µM to (35.21 ± 3.25) µM.

New immunosuppressive secondary metabolites from the endophytic fungus Aspergillus sp.

Six new metabolites, including two diphenolic derivatives (1 and 2), one pseurotin (3), one butenolide derivative (4), one benzopyran (5) and one isochromane lactone (6), together with ten known compounds (7-16) were isolated from an endophytic fungus Aspergillus sp. Their planar structures and absolute configurations were established based on techniques of MS, NMR, IR, UV, [Rh2(OCOCF3)4] complex-induced ECD, quantum chemical electronic circular dichroism (ECD) calculations, and single crystal X-ray diffraction. Structurally, compound 2 represents the first example of diphenolic derivative possessing an unusual 1-oxaspiro[2.4]heptane core bearing a 5/3 bicyclic skeleton; compound 3 represents the first example of pseurotin type natural products that only one hydroxy group is substituted at side chain. In bioassay, compounds 3, 7 and 8 exhibited potential inhibitory effect on the proliferation of anti-CD3/anti-CD28 monoclonal antibodies (mAbs) induced murine T cells, with IC50 values of (7.81 ± 0.71), (8.25 ± 0.78) and (8.84 ± 0.81) µM, respectively.

New cytotoxic secondary metabolites against human pancreatic cancer cells from the Hypericum perforatum endophytic fungus Aspergillus terreus.

Four new compounds, including two lovastatin analogues, terrstatins A and B (1 and 2), and a pair of butenolide derivatives, (±)-asperteretone F (3a/3b), along with eleven known compounds (4-14), were isolated from the Hypericum perforatum endophytic fungus Aspergillus terreus. Their structures and absolute configurations were determined based on extensive spectroscopic analysis, experimental and calculated electronic circular dichroism (ECD) analysis. All isolates were evaluated for cytotoxic activities against five human cancer cell lines, and compounds 3a/3b and 6 showed potential cytotoxic activities against human pancreatic cancer cells, including AsPC-1, SW1990 and PANC-1 cells, with IC50 values ranging from 1.2 to 15.6 µM.

New secondary metabolites with immunosuppressive activity from the phytopathogenic fungus Bipolaris maydis.

Three previously undescribed compounds, including a meroterpenoid, guignardone T (1), and two ophiobolin-type sesterterpenoids, maydispenoids A and B (2 and 3), along with four known compounds (4-7), were isolated from the phytopathogenic fungus Bipolaris maydis collected from Anoectochilus roxburghii (Wall.) Lindl leaves. The structures of all undescribed compounds were elucidated by spectroscopic analysis, electronic circular dichroism (ECD) calculations and single-crystal X-ray diffraction. Structurally, maydispenoids A was characterized by a fascinating decahydro-3-oxacycloocta[cd]pentalene fragment. It is notable that the compounds 2 and 3 exhibited potential inhibitory activity in anti-CD3/anti-CD28 monoclonal antibodies (mAbs) stimulated murine splenocytes proliferation, with IC50 values of 5.28 and 9.38 µM, respectively, and also suppress the murine splenocytes proliferation activated by lipopolysaccharide (LPS), with IC50 values of 7.25 and 16.82 µM, respectively. This is the first report of ophiobolin-type sesterterpenoids as immunosuppressor, and may provide new chemical templates for the development of new immunosuppressive drugs for autoimmune disease treatment.

New bioactive secondary metabolites from the Anoectochilus roxburghii endophytic fungus Aspergillus versicolor.

Six new compounds, including two new isochromane lactones, versicoisochromanes A and B (1 and 2), two new benzolactones, versicobenzos A and B (3 and 4), one furancarboxylic derivate, asperfuran A (6) and one ergosterol-type steroid, asperergoster A (7), along with five known steroids (8-12), were isolated from the Anoectochilus roxburghii endophytic fungus Aspergillus versicolor. The structures of these new compounds were determined by extensive spectroscopic techniques and electronic circular dichroism (ECD) calculations. It is notable that the new compound 7 exhibited obvious IL-1ß, NO and TNF-α inhibitory activity in LPS-stimulated RAW264.7 macrophages, with IC50 values of 35.5, 33.9 and 31.3 µM, respectively. Furthermore, compounds 7 and 8 displayed potential inhibitory effects on murine splenocytes proliferation stimulated by anti-CD3/anti-CD28 monoclonal antibodies (mAbs), meanwhile suppress the lipopolysaccharide (LPS) irritated murine splenocytes proliferation.

Przewalcyrones A-F, epoxychromene-containing polycyclic polyprenylated acylphloroglucinols with immunosuppressive activity from Hypericum przewalskii Maxim.

Chemical investigation of the extracts of the aerial parts of Hypericum przewalskii Maxim. resulted in the isolation and identification of six new epoxychromene-containing polycyclic polyprenylated acylphloroglucinols (PPAPs), named przewalcyrones A-F (1-6), and one known analogue (7). All of the structures were determined based on extensive spectroscopic analyses, X-ray crystallographic analysis, modified Mosher's method, [Rh2(OCOCF3)4]-induced ECD, and electronic circular dichroism (ECD) comparison. Structurally, przewalcyrones A-F represent the first examples of PPAPs containing an unexpected 8,8-dimethyl-3,9-epoxychromene moiety. All these compounds were evaluated for the immunosuppressive activity in anti-CD3/anti-CD28 monoclonal antibody (mAb)-stimulated human T cells. Among them, przewalcyrones C and D exhibited potential in vitro immunosuppressive activity, with IC50 values of (5.01 ± 0.52) µM and (5.26 ± 0.56) µM, respectively, highlighting those compounds as a promising starting point for the development of new immunosuppressive agents.

Asperversiamides, Linearly Fused Prenylated Indole Alkaloids from the Marine-Derived Fungus Aspergillus versicolor.

Asperversiamides A-H (1-8), eight linearly fused prenylated indole alkaloids featuring an unusual pyrano[3,2- f]indole unit, were isolated from the marine-derived fungus Aspergillus versicolor. The structures and absolute configurations of these compounds were elucidated by extensive spectroscopic analyses, single-crystal X-ray diffraction, electronic circular dichroism (ECD) calculations, and optical rotation (OR) calculations. The relative configuration of C-21 of iso-notoamide B was herein revised, and a new methodology for preliminarily determining if the relative configuration of the bicyclo[2.2.2]diazaoctane moiety of a spiro-bicyclo[2.2.2]diazaoctane-type indole alkaloid is syn or anti was developed. The anti-inflammatory activities of the isolated compounds were all tested, and of these compounds, 7 exhibited a potent inhibitory effect against iNOS with an IC50 value of 5.39 µM.

Asperversins A and B, Two Novel Meroterpenoids with an Unusual 5/6/6/6 Ring from the Marine-Derived Fungus Aspergillus versicolor.

Asperversins A (1) and B (2), two novel meroterpenoids featuring an uncommon 5/6/6/6 ring system, along with five new analogues (3⁻7) and a known compound asperdemin (8), were obtained from the marine-derived fungus Aspergillus versicolor. Their structures and absolute configurations were confirmed by extensive spectroscopic analyses, single-crystal X-ray diffraction studies, and electronic circular dichroism (ECD) calculation. All new compounds were tested for their acetylcholinesterase enzyme (AChE) inhibitory activities and cytotoxic activities, of which compound 7 displayed moderate inhibitory activity against the AChE with an IC50 value of 13.6 μM.

Anti-inflammatory Grayanane Diterpenoids from the Leaves of Rhododendron molle.

Thirteen new grayanane diterpenoids (1-13), a new dimeric grayanane diterpenoid, bimollfoliagein A (14), and 15 known analogues (15-29) were isolated from the leaves of Rhododendron molle. The structures of the new compounds (1-14) were determined by extensive spectroscopic data interpretation. The absolute configurations of 1-3, 7, 8, 16, 18, and 24 were defined by single-crystal X-ray diffraction analysis. Mollfoliagein A (1) represents the first example of a 2,3:11,16-diepoxy grayanane diterpenoid, featuring a cis/trans/cis/cis/trans-fused 3/5/7/6/5/5 hexacyclic ring system with a 7,13-dioxahexacyclo[10.3.3.01,11.04,9.06,8.014,17]octadecane scaffold. Diterpenoids 1-29 were evaluated for their anti-inflammatory activities in vitro, and 15, 16, 18, 19, 23-26, 28, and 29 exhibited significant inhibitory activities against nitric oxide production in lipopolysaccharide-induced RAW264.7 mouse macrophages with IC50 values ranging from 2.8 to 35.4 µM. A preliminary structure-activity relationship for the anti-inflammatory activity of diterpenoids 1-29 is discussed.