Two Pairs of New Bisabolane-Type Sesquiterpenoids from Aspergillus sydowii.

Two pairs of new bisabolane-type sesquiterpenoids, (+)-aspersydowin A (7S) [(+)-1], (-)-aspersydowin A (7R) [(-)-1], (+)-aspersydowin B (7S,11S) [(+)-2], (-)-aspersydowin B (7R,11R) [(-)-2], along with six known compounds (1-8) were isolated from the fungus Aspergillus sydowii. Compounds 1 and 2 are enantiomers resolved by the Chiralpak IC, using a hexane- propan-2-ol mobile phase. The structure of 1 and 2 with absolute configuration were assigned tentatively by 1D (1 H, 13 C, and DEPT) & 2D (HSQC, 1 H-1 H COSY, HMBC, and NOESY) NMR data analyses and ECD calculations. Compounds 1-8 were screened for the biological activities in vitro. The results showed that compounds 3, 4 and 8 exhibited immunosuppressive activities with IC50 values of 10.9, 17.6 and 13.4 µM, respectively.

Trichodermatides A-D, four new polyketides from Trichoderma sp. XM-3.

Four new polyketides named trichodermatides A-D (1-4), along with five known analogues (5-9), were isolated from the fungus Trichoderma sp. XM-3. Their structures were elucidated on the basis of HRESIMS and NMR analyses, and their absolute configurations were determined by ECD comparison, 1H and 13C NMR calculation, DP4+ analysis, modified Mosher's method, and X-ray crystallography. Trichodermaketone D (9) showed mild antibacterial activity against Pseudomonas aeruginosa.

Genomic analysis of host gene responses to cerebral Plasmodium falciparum malaria.

INTRODUCTION: A vaccine for malaria is urgently required but no vaccine has yet shown satisfactory protective efficacy especially for Plasmodium falciparum. P. falciparum infection can progress to cerebral malaria (CM), a neurological syndrome with exceedingly high mortality. Designing effective P. falciparum vaccines require more understanding of the protective immune response while the host immune response to CM and the mechanisms are still elusive. Here, we aim to identify host gene responses to CM and host gene networks associated with CM pathogenesis. METHODS: An innovative genomic analysis strategy, the weighted gene coexpression network analysis (WGCNA) combined with differential gene expression analysis, was used in this study. Data for analysis contain 93 whole blood samples, derived from two previous public transcriptome datasets. RESULTS: This approach led to the identification of numerous differentially expressed human transcripts and dozens of coexpression gene modules. We further identified nine key genes, including MBP, SAMSN1, PSMF1, SLC39A8, EIF3B, SMPDL3A, FABP5, SPSB3, and SHARPIN, of which the last four genes were first identified to be related to CM in the present study. CONCLUSION: The results provided a comprehensive characterization of host gene expression profiles in CM and offered some new insight into malaria vaccine design. These identified key genes could be potential targets or immune modulators for novel therapeutic interventions of CM.

One new spirocyclic lactone and one new benzopyran derivative from Aspergillus terreus.

One new spirocyclic lactone, terreinlactone C (1), and one new benzopyran derivative, 2,2-dimethyl-3-hydroxychroman-6-aldehyde (2), were discovered from the fungus Aspergillus terreus. The chemical structures of compounds 1 and 2 were elucidated by detailedly analyzing NMR and HRESIMS data. Compound 1 is the first natural product with a 1-oxaspiro[4.5]decan-2-one ring system and a possible biogenetic pathway is proposed. Two compounds were tested for their cytotoxic activities against five human cancer cell lines.[Formula: see text].

Anti-BACE1 and anti-AchE activities of undescribed spiro-dioxolane-containing meroterpenoids from the endophytic fungus Aspergillus terreus Thom.

Spiroterreusnoids A-F, six undescribed spiro-dioxolane-containing adducts bearing 3,5-dimethylorsellinic acid-based meroterpenoid and 2,3-butanediol moieties were isolated from the endophytic fungus Aspergillus terreus Thom from Tripterygium wilfordii Hook. f. (Celastraceae). The structures of these adducts were established by spectroscopy, single-crystal X-ray diffraction, and experimental electronic circular dichroism (ECD) measurements. Spiroterreusnoids A-F represent the first examples of adducts composed of 3,5-dimethylorsellinic acid-based meroterpenoids. It is noteworthy that spiroterreusnoids A-F possessing a spiro-dioxolane moiety exhibited potential abilities in inhibiting BACE1 (IC50 values ranging from 5.86 to 27.16 µM) and AchE (IC50 values ranging from 22.18 to 32.51 µM), while the other analogues without this fragment displayed no such activities. Taken together, spiroterreusnoids A-F represent the first multitargeted natural adducts that could inhibit BACE1 and AchE, and might provide a new template for the development of new anti-Alzheimer's disease drugs.

Highly oxygenated meroterpenoids from the Antarctic fungus Aspergillus terreus.

Eleven highly oxygenated meroterpenoids, named terreustoxins A-K, along with five known analogues, were isolated from the Antarctic fungus Aspergillus terreus. The structures and absolute configurations of these undescribed compounds were characterized by NMR spectroscopy, single-crystal X-ray crystallography, and ECD experiments. Terreustoxins A-D are the first examples of meroterpenoids with two ortho-hydroxy groups at C-6 and C-7 in the terretonins family. Terreustoxin C and terretonin inhibited the proliferation of Con A-induced murine T cells at the concentration of 10 µM.

New 3,5-dimethylorsellinic acid-based meroterpenoids with BACE1 and AchE inhibitory activities from Aspergillus terreus.

Chemical investigation of the extracts of Aspergillus terreus resulted in the identification of terreusterpenes A-D (1-4), four new 3,5-dimethylorsellinic acid-based meroterpenoids. The structures and absolute configurations of 1-4 were elucidated by spectroscopic analyses including HRESIMS and 1D- and 2D-NMR, chemical conversion, and single crystal X-ray diffraction. Terreusterpenes A (1) and B (2) featured 2,3,5-trimethyl-4-oxo-5-carboxy tetrahydrofuran moieties. Terreusterpene D (4) was characterized by a 4-hydroxy-3-methyl gamma lactone fragment that was generated by accident from the rearrangement of 3 in a mixed tetrahydrofuran-H2O-MeOH solvent. All these compounds were evaluated for the ß-site amyloid precursor protein-cleaving enzyme 1 (BACE1) and acetylcholinesterase (AchE) inhibitory activities. Among them, compounds 1 and 2 showed potentially significant BACE1 inhibitory activity, with IC50 values of 5.98 and 11.42 µM, respectively. Interestingly, compound 4 exhibited promising BACE1 and AchE inhibitory activities, with IC50 values of 1.91 and 8.86 µM, respectively, while 3 showed no such activity. Taken together, terreusterpenes A and B could be of great importance for the development of new BACE1 inhibitors, while terreusterpene D could serve as the first dual-targeted 3,5-dimethylorsellinic acid-based meroterpenoid for the treatment of Alzheimer's disease.

Butenolides from a marine-derived fungus Aspergillus terreus with antitumor activities against pancreatic ductal adenocarcinoma cells.

Chemical study on the extract of a marine-derived fungus Aspergillus terreus yielded twelve butenolide derivatives, including three new compounds, namely asperlides A-C (1-3) and nine known butenolides (4-12). The structures of 1-3 were confirmed by comprehensive spectroscopic analysis, including HRESIMS, NMR spectroscopy, and calculated electronic circular dichroism (ECD). The cytotoxicity of the compounds was evaluated using PANC-1, HCC1806, HepG2, BEAS-2B and HT-29 cancer cells. The results showed that (+)-3',3'-di-(dimethylallyl)-butyrolactone II (4) and versicolactone B (6) exhibited the most potent cytotoxin of PANC-1 cell line, with the IC50 values of 5.3 and 9.4 µM, respectively. Morphological features of apoptosis were observed in 4 and 6-treated PANC-1 cells, including apoptotic body formation, membrane blebbing, cell shrinkage and nuclear condensation. Cell cycle analysis with propidium iodide staining exhibited that 4 inhibits proliferation of PANC-1 cells via the induction of G2/M and S phase arrest, while 6 could retard the PANC-1 cells via the induction of S phase arrest. Flow cytometric analysis suggested that treatment with 4 and 6 significantly induced PANC-1 cells apoptosis. These findings indicated that 4 and 6 might serve as a starting point for the development of an anticancer drug for the treatment of pancreatic ductal adenocarcinoma.

Brasilane sesquiterpenoids and dihydrobenzofuran derivatives from Aspergillus terreus [CFCC 81836].

Brasilanones A-F and asperterreusines A-C, undescribed brasilane sesquiterpenoids and dihydrobenzofuran derivatives, were isolated from the marine-derived fungus Aspergillus terreus [CFCC 81836]. Their structures with absolute configurations were elucidated on the basis of spectroscopic data, X-ray crystallographic analyses, and electronic circular dichroism (ECD) calculations. Brasilanones A-F are unusual brasilane sesquiterpenoids with an α,ß-unsaturated ketone unit, interestingly, brasilanones B-D are stereo isomers. All of the isolates were evaluated for their inhibitory activities against NO production and cytotoxic activities against five human cancer cell lines (HL-60, SW-480, A-549, MCF-7, and SMMC-7721). Brasilanones A and E showed moderate inhibitory effect with NO inhibition rates of 47.7% (p < 0.001) and 37.3% (p < 0.001) at the concentration of 40 µM. Asperterreusines A showed cytotoxicity against HL-60 and SW-480 cell lines with IC50 values of 15.3 and 25.7 µM, respectively.

α-Glucosidase Inhibitors From the Coral-Associated Fungus Aspergillus terreus.

Nine novel butenolide derivatives, including four pairs of enantiomers, named (±)-asperteretones A-D (1a/1b-4a/4b), and a racemate, named asperteretone E (5), were isolated and identified from the coral-associated fungus Aspergillus terreus. All the structures were established based on extensive spectroscopic analyses, including HRESIMS and NMR data. The chiral chromatography analyses allowed the separation of (±)-asperteretones A-D, whose absolute configurations were further confirmed by experimental and calculated electronic circular dichroism (ECD) analysis. Structurally, compounds 2-5 represented the first examples of prenylated γ-butenolides bearing 2-phenyl-3-benzyl-4H-furan-1-one motifs, and their crucial biogenetically related metabolite, compound 1, was uniquely defined by an unexpected cleavage of oxygen bridge between C-1 and C-4. Importantly, (±)-asperteretal D and (4S)-4-decarboxylflavipesolide C were revised to (±)-asperteretones B (2a/2b) and D (4), respectively. Additionally, compounds 1a/1b-4a/4b and 5 were evaluated for the α-glucosidase inhibitory activity, and all these compounds exhibited potent inhibitory potency against α-glucosidase, with IC50 values ranging from 15.7 ± 1.1 to 53.1 ± 1.4 µM, which was much lower than that of the positive control acarbose (IC50 = 154.7 ± 8.1 µM), endowing them as promising leading molecules for the discovery of new α-glucosidase inhibitors for type-2 diabetes mellitus treatment.

BACE1 Inhibitory Meroterpenoids from Aspergillus terreus.

Sixteen 3,5-dimethylorsellinic acid-based (DMOA-based) meroterpenoids, including 10 new compounds, asperterpenes D-M (1-10), were obtained from Aspergillus terreus. The structures and absolute configurations of the new compounds were confirmed by extensive spectroscopy, single-crystal X-ray diffraction analysis, and experimental electronic circular dichroism (ECD) measurements. Compounds 2, 3, and 7 are the first 3,5-dimethylorsellinic acid-based meroterpenoids possessing a unique cis-fused A/B ring system. These new compounds were evaluated for their inhibitory activity against ß-site amyloid precursor protein-cleaving enzyme 1 (BACE1). Compounds 2, 3, and 7, the first 3,5-dimethylorsellinic acid-based meroterpenoids possessing cis-fused A/B rings, exhibited significant inhibitory activities against BACE1 with IC50 values of 3.3, 5.9, and 31.7 µM, respectively.

Terrusnolides A-D, new butenolides with anti-inflammatory activities from an endophytic Aspergillus from Tripterygium wilfordii.

Terrusnolides A-D (1-4), four butenolides were isolated from an endophytic Aspergillus from Tripterygium wilfordii. The structures of 1-4 were established by comprehensive spectroscopic analyses and electronic circular dichroism (ECD) calculation. It is interesting that 1 was a butenolide derived by a triple decarboxylation, while 2-4 were the metabolites with 4-benzyl-3-phenyl-5H-furan-2-one motif possessing an isopentene group fused to the benzene ring. In vitro anti-inflammatory effects of these isolates were evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. 1-4 exhibited excellent inhibitory effects on the production of interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), and nitric oxide (NO) in LPS-induced macrophages, comparable with the positive control (indomethacin). Those results indicated that, terrusnolides A-D might serve as new potential natural remedies for the treatment of inflammation.

Phenylacetylene-bearing 3,4-seco-cleistanthane diterpenoids from the roots of Phyllanthus glaucus.

Three new cleistanthane diterpenoids, phyllanglins A-C (1-3), a new natural product, 4-acetyl-bergenin (4), and three known compounds (5-7) were isolated from the roots of Phyllanthus glaucus. Their structures were elucidated by extensive spectroscopic data analyses and single-crystal X-ray diffraction. Phyllanglins A-C were unusual cleistanthane diterpenoids with phenylacetylene moieties, and a plausible biogenetic pathway was proposed to discuss the origins of them. All of the isolates were evaluated for their anti-inflammatory activities.

(±)-Terreinlactone A, a Pair of 3-Substituted δ-Lactone Enantiomers Derived from Terrein from the Fungus Aspergillus terreus.

Terreinlactone A (1a/1b), a pair of 3-substituted δ-lactone enantiomers, and terreinlactone B (2), a new biosynthetic intermediate of 1a/1b, were isolated from Aspergillus terreus, along with their biosynthetic precursor (+)-terrein (3) and (+)-isoterrein (4). Compounds 1a and 1b were separated by using a Daicel chiral-pak ASH column eluting with n-hexane-EtOH (80 : 20). The structures of 1a/1b with absolute configurations were determined by comprehensive spectroscopic analyses and electronic circular dichroic (ECD) calculations. Terreinlactone A (1) represents the first example of 1,5-seco-terrein and a biogenetic pathway is proposed from the precursor terrein via the intermediated terreinlactone B (2).

Anti-inflammatory butenolide derivatives from the coral-derived fungus Aspergillus terreus and structure revisions of aspernolides D and G, butyrolactone VI and 4',8''-diacetoxy butyrolactone VI.

Chemical investigation of the coral-derived fungus Aspergillus terreus led to the discovery of ten butenolide derivatives (1-10), including four new ones (1-4). The new structures were characterized on the basis of comprehensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS data. Compounds 1 and 2 were a pair of rare C-8'' epimers with vicinal diol motifs. The absolute configurations of 1-4 were determined via [Mo2(AcO)4] induced circular dichroism (ICD) spectra and comparison of their experimental ECD spectra. Importantly, the structures of reported aspernolides D and G, butyrolactone VI and 4',8''-diacetoxy butyrolactone VI have been correspondingly revised via a combined strategy of experimental validations, 13C NMR predictions by ACD/Labs software, and 13C NMR calculations. Herein we provide valuable referenced 13C NMR data (C-7'', C-8'', and C-9'') for the structure elucidations of butenolide derivatives with 1-(2-hydroxyphenyl)-3-methylbutane-2,3-diol, 2-(2,3-dihydrobenzofuran-2-yl)propan-2-ol, or 2,2-dimethylchroman-3-ol motifs. Additionally, all the isolates (1-10) were assessed for anti-inflammatory activity by measuring the amount of NO production in lipopolysaccharide (LPS)-induced RAW 264.7 mouse macrophages, and compound 10 showed an even stronger inhibitory effect than the postive control indomethacin, presenting it as a promising lead compound for the development of new anti-inflammatory agents.

6,8-Di-C-methyl-flavonoids with neuroprotective activities from Rhododendron fortunei.

Six 6,8-di-C-methyl-flavonoids, (2R,3R)-6,8-di-C-methyl-5,7,4'-trihydroxyflavanonol 7-O-ß-d-gluco-pyranoside (1), (2R,3R)-6,8-di-C-methyl-5,7,4'-trihydroxyflavanonol 7-O-ß-d-xylopyranosyl(1→6)-ß-d-glucopyranoside (2), 6,8-di-C-methylkaempferol 7-O-ß-d-glucopyranoside (3), (2R)-farrerol (4a), (2R/2S)-farrerol 7-O-ß-d-glucopyranoside (5), and (2R/2S)-farrerol 7-O-ß-d-xylopyranosyl(1→6)-ß-d-glucopyranoside (6), and four known analogues, farrerol (4b), (2R,3R)-6,8-di-C-methyldihydrokae-mpferol (7), 6,8-di-C-methylkaempferol 7-O-ß-d-glucopyranoside (8), and 6,8-di-C-methylkaempferol (9), were isolated from the twigs and leaves of Rhododendron fortunei. The structures of compounds 1-9 were determined by spectroscopic analyses (HRESIMS, 1D and 2D NMR, and CD) and chemical methods. Compounds 1-9 were evaluated for their neuroprotective effects on the human neuroblastoma SH-SY5Y cells apoptosis induced by hydrogen peroxide (H2O2) and amyloid ß peptide (Aß), respectively. Compounds 1-3 and 5-9 exhibited significant neuroprotective effects against H2O2-induced SH-SY5Y cell apoptosis, and compound 8 exhibited the strongest activity with a improvement of cell viability by about 30% at the concentration of 10µM. Compounds 1-9 showed significant neuroprotective effects against Aß-induced SH-SY5Y cell apoptosis.

Enantiomeric Lignans and Neolignans from Phyllanthus glaucus: Enantioseparation and Their Absolute Configurations.

Eight pairs of enantiomeric neolignans, norlignans, and sesquineolignans (1a/1b-8a/8b), together with five known neolignans (9a/9b and 10-12), have been isolated from 70% acetone extract of the whole plants of Phyllanthus glaucus Wall. (Euphorbiaceae). The racemic or partial racemic mixtures were successfully separated by chiral HPLC using different types of chiral columns with various mobile phases. Their structures were elucidated on the basis of extensive spectroscopic data. The absolute configurations of 2a/2b were determined by computational analysis of their electronic circular dichroism (ECD) spectrum, and the absolute configurations of other isolates were ascertained by comparing their experimental ECD spectra and optical rotation values with those of structure-relevant compounds reported in literatures. Compounds 4a/4b featured unique sesquineolignan skeletons with a novel 7-4'-epoxy-8'-8''/7'-2'' scaffold, consisting of an aryltetrahydronaphthalene and a dihydrobenzofuran moiety. The planar structures of compounds 2, 3, 7, and 8 were documented previously; however, their absolute configurations were established for the first time in this study. The antioxidant activities of 1a/1b-8a/8b were evaluated using DPPH free radical scavenging assay, and the results demonstrated that compounds 1b and 3b showed potent DPPH radical scavenging activities with IC50 values of 5.987 ± 1.212 and 9.641 ± 0.865 µg/mL, respectively.

Asperterpenes A and B, two unprecedented meroterpenoids from Aspergillus terreus with BACE1 inhibitory activities.

Asperterpenes A (1) and B (2), two 3,5-dimethylorsellinic acid-based meroterpenoids that contain a unique ß-oriented Me-21 with an unprecedented 1,2,5-trimethyl-4,9-dioxobicyclo[3.3.1]non-2-ene-3-carboxylic acid moiety, were obtained from Aspergillus terreus in very limited amounts of 3.6 mg and 1.8 mg, respectively. The absolute structure of 1 was determined using X-ray diffraction. Because of the low yield of 1, a comprehensive characterization of the BACE1 inhibitory activities of 1 was completed via molecular biological, cell and animal studies guided by in silico target confirmation (ISTC). ISTC assays suggested that compounds 1 and 2 might be BACE1 inhibitors. In cell-based tests, asperterpenes A and B, as natural products, exhibited promising inhibitory activities against BACE1, with IC50 values of 78 and 59 nM, respectively. LY2811376 (the positive control), one of the most potent clinical BACE1 inhibitors, has shown an IC50 value of 260 nM. In vivo, compound 1 exhibited activity similar to that of LY2811376 against Alzheimer's disease (AD) in 3xTg AD mice. Taken together, these findings demonstrate that asperterpene A, which contains a novel carbon skeleton, is the first terpenoid to exhibit effective BACE1 inhibitory activity. Moreover, 1 represents a potential lead compound and a versatile scaffold for the development of drugs for the treatment of AD.

Neolignans with a Rare 2-Oxaspiro[4.5]deca-6,9-dien-8-one Motif from the Stem Bark of Cinnamomum subavenium.

Two pairs of racemic spirodienone neolignans with a rare 2-oxaspiro[4.5]deca-6,9-dien-8-one motif, named (±)-subaveniumins A (1) and B (2), were isolated from the bark of Cinnamomum subavenium. The chiral separation of the (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers was accomplished via high-performance liquid chromatography on a chiral column. Their structures were elucidated using single-crystal X-ray diffraction and spectroscopic analyses (UV, IR, HRESIMS, and 1D and 2D NMR). The absolute configurations of the enantiomers were determined by comparing the experimental and calculated electronic circular dichroic spectra. The (+)-1, (-)-1, (+)-2, and (-)-2 enantiomers exhibited moderate inhibitory effects against NO production in RAW264.7 mouse macrophages induced by lipopolysaccharide, with IC50 values of 17.9, 5.6, 15.1, and 4.3 µM, respectively.

A new phenolic glycoside from the barks of Cinnamomum cassia.

A new phenolic glycoside (1), named methyl 2-phenylpropanoate-2-O-ß-D-apiofuranosyl-(1→6)-O-ß-D-glucopyranoside, was isolated from the barks of Cinnamomum cassia, along with three known phenolic glycosides and four known lignan glycosides. The structure of 1 was elucidated by extensive interpretation of spectroscopic data and chemical method. Selected compounds were evaluated for their immunosuppressive activities against murine lymphocytes. Compounds 1, 2, 6 and 8 exhibited differential inhibition against ConA-induced T cells proliferation.