Weiguang Sun

Filicinic Acid Based Meroterpenoids with Anti-Epstein–Barr Virus Activities from Hypericum japonicum

Seven filicinic acid-based meroterpenoids (1-7), possessing 6/6/11, 6/6/7/5, or 6/6/10 ring systems, were isolated from Hypericum japonicum. All of them have novel skeletons with the incorporation of sesquiterpenoid moieties to an acylated filicinic acid. Compounds 2a and 4 exhibited significant efficacy on anti-Epstein-Barr virus, with EC50 values of 0.57 and 0.49 μM, respectively. Furthermore, compounds 2a and 4 were well accommodated to the binding pocket of 2GV9 predicted by the molecular docking.

Phomopsterones A and B, Two Functionalized Ergostane-Type Steroids from the Endophytic Fungus Phomopsis sp. TJ507A

Two new functionalized ergostane-type steroids, phomopsterones A (1) and B (2), were isolated from the plant-derived Phomopsis sp. TJ507A. Their structures were determined on the basis of spectroscopic data, a modified Moshers method, X-ray crystallographic analysis, and quantum chemical calculations. Compound 1 is an unprecedented ergosteroid featuring a rearranged bicyclo[3.3.1]nonane motif resulting from B-ring scission and a subsequent 180° rotation of the ring A during biosynthesis. Compound 2 exhibited anti-inflammatory activity.

Fungal naphtho-γ-pyrones: Potent antibiotics for drug-resistant microbial pathogens.

Four naphtho-γ-pyrones (fonsecinones A and C and aurasperones A and E) were identified as potential antibacterial agents against Escherichia coli, extended-spectrum β-lactamase (ESBL)-producing E. coli, Pseudomonas aeruginosa, Enterococcus faecalis, and methicillin-resistant Staphylococcus aureus (MRSA) in an in vitro antibacterial screen of 218 fungal metabolites. Fonsecinone A (2) exhibited the most potent antibacterial activity, with minimum inhibitory concentrations (MICs) of 4.26, 17.04, and 4.26 μg/mL against ESBL-producing E. coli, P. aeruginosa, and E. faecalis, respectively. The inhibitory effects of fonsecinones A (2) and C (3) against E. coli and ESBL-producing E. coli were comparable to those of amikacin. Molecular docking-based target identification of naphtho-γ-pyrones 1–8 revealed bacterial enoyl-acyl carrier protein reductase (FabI) as an antibacterial target, which was further validated by FabI affinity and inhibition assays. Fonsecinones A (2) and C (3) and aurasperones A (6) and E (7) bound FabI specifically and produced concentration-dependent inhibition effects. This work is the first report of anti-drug-resistant bacterial activities of naphtho-γ-pyrones 1–8 and their possible antibacterial mechanism of action and provides an example of the successful application of in silico methods for drug target identification and validation and the identification of new lead antibiotic compounds against drug-resistant pathogens.

Novel small molecule 11β-HSD1 inhibitor from the endophytic fungus Penicillium commune

Two new phenone derivatives penicophenones A (1) and B (2), a new cyclic tetrapeptide penicopeptide A (3), and five known compounds were isolated from the culture broth of Penicillium commune, an endophytic fungus derived from Vitis vinifera. Compounds 1–3 were elucidated by extensive spectroscopic analyses including 1D and 2D NMR and HRESIMS. The absolute configurations of 1 and 3 were determined by comparing its ECD with related molecules and modified Marfey’s analysis, respectively. Penicophenone A (1) possesses a rare benzannulated 6,6-spiroketal moiety, which is a new member of the unusual structural class with peniphenone A as the representative. Compound 3 exhibited significant inhibition activities against 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in vitro and showed strong binding affinity to 11β-HSD1. Moreover, compound 3 treatments decreased the lipid droplet accumulation associate with the inhibition of 11β-HSD1 expression in differentiate-induced 3T3-L1 preadipocytes. Furthermore, the molecular docking demonstrated that compound 3 coordinated in the active site of 11β-HSD1 is essential for the ability of diminishing the enzyme activity.

(±)-Japonones A and B, two pairs of new enantiomers with anti-KSHV activities from Hypericum japonicum

Two pairs of new enantiomers with unusual 5,5-spiroketal cores, termed (±)-japonones A and B [(±)-1 and (±)-2], were obtained from Hypericum japonicum Thunb. The absolute configurations of (±)-1 and (±)-2 were characterized by extensive analyses of spectroscopic data and calculated electronic circular dichroism (ECD) spectra, the application of modified Mosher’s methods, and the assistance of quantum chemical predictions (QCP) of 13C NMR chemical shifts. Among these metabolites, (+)-1 exhibited some inhibitory activity on Kaposi’s sarcoma associated herpesvirus (KSHV). Virtual screening of (±)-1 and (±)-2 were conducted using the Surflex-Dock module in the Sybyl software, and (+)-1 exhibited ability to bind with ERK to form key interactions with residues Lys52, Pro56, Ile101, Asp165, Gly167 and Val99.

A New Breviane Spiroditerpenoid from the Marine-Derived Fungus Penicillium sp. TJ403-1

Marine-derived fungi are a promising and untapped reservoir for discovering structurally interesting and pharmacologically active natural products. In our efforts to identify novel bioactive compounds from marine-derived fungi, four breviane spiroditerpenoids, including a new compound, brevione O (1), and three known compounds breviones I (2), J (3), and H (4), together with a known diketopiperazine alkaloid brevicompanine G (5), were isolated and identified from an ethyl acetate extract of the fermented rice substrate of the coral-derived fungus Penicillium sp. TJ403-1. The absolute structure of 1 was elucidated by HRESIMS, one- and two-dimensional NMR spectroscopic data, and a comparison of its electronic circular dichroism (ECD) spectrum with the literature. Moreover, we confirmed the absolute configuration of 5 by single-crystal X-ray crystallography. All the isolated compounds were evaluated for isocitrate dehydrogenase 1 (IDH1) inhibitory activity and cytotoxicity, and compound 2 showed significant inhibitory activities against HL-60, A-549, and HEP3B tumor cell lines with IC50 values of 4.92 ± 0.65, 8.60 ± 1.36, and 5.50 ± 0.67 µM, respectively.

Anti-arthritic activity of Fu-Fang-Lu-Jiao-Shuang on collagen-induced arthritis in Balb/c mice and its underlying mechanisms.

Background: Rheumatoid arthritis (RA) is a common, autoimmune disorder characterized by progressive multiple joint destruction, deformity, disability and premature death in most patients. Fu-Fang-Lu-Jiao-Shuang (FFLJS) is an effective traditional Chinese medicine, which has long been used clinically to treat RA patients. Objective: The objective of this study is aimed to evaluate the anti-rheumatic effects of FFLJS on collagen induced arthritis (CIA) model, as well as the underlying mechanisms, which have not previously been explored. Materials and Methods: CIA was induced by immunization with type II collagen (CII) in male Balb/c mice. The mice in the onset of arthritis were treated daily with FFLJS (125 or 500 mg/kg) or 1% carboxymethyl cellulose-Na for 28 days. Paw thickness and arthritic score were evaluated to confirm the anti-arthritic effect of FFLJS on CIA in mice. Levels of anti-CII antibody, proinflammatory cytokines interleukin-1 (IL-1) β, IL-17, and tumor necrosis factor-α (TNF-α) as well as prostaglandin E-2 (PGE-2) in serum and histological changes in the ankle joint were also analyzed. In addition, expressions of matrix metalloproteinases-1 (MMP-1), MMP-3 and tissue inhibitors of matrix metalloproteases-1 (TIMP-1) in synovial tissue were also detected to further study the molecular mechanism of the anti-arthritic effects of FFLJS. Results: During therapeutic treatment, FFLJS significantly reduced paw thickness and arthritic score in CIA mice, decreased the amounts of TNF-α, IL-1 β, IL-17, PGE-2 and anti-CII antibody in serum. In addition, FFLJS treatment could prevent the bone destruction by reducing the expression of MMP-1 and MMP-3, increasing the expression of TIMP-1 in synovial tissue of CIA mice. Conclusion: These findings offer the convincing evidence for the first time that the anti-rheumatic effects of FFLJS might be related to down-regulation of TNF-α, IL-1 β, IL-17 and PGE-2 levels for acute arthritis, and regulation of MMP-1, MMP-3 and TIMP-1 protein expression for chronic arthritis.

Aspermerodione, a novel fungal metabolite with an unusual 2,6-dioxabicyclo[2.2.1]heptane skeleton, as an inhibitor of penicillin-binding protein 2a

Rising drug resistance limits the treatment options infected by methicillin-resistant Staphylococcus aureus (MRSA). A promising solution for overcoming the resistance of MRSA is to inhibit the penicillin-binding protein 2a (PBP2a). A novel terpene-polyketide hybrid meroterpenoid, aspermerodione (1), characterized by an unusual 2,6-dioxabicyclo[2.2.1]heptane core skeleton, and a new heptacyclic analogue, andiconin C (2), were isolated and identified from the liquid cultures of endophytic fungus Aspergillus sp. TJ23. The structures and their absolute configurations of all chiral centers were elucidated via extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations and determined via single-crystal X-ray diffraction analysis. Aspemerodione (1) was found to be a potential inhibitor of PBP2a, and work synergistically with the β-lactam antibiotics oxacillin and piperacillin against MRSA.

Bioactive secondary metabolites from the marine-associated fungus Aspergillus terreus

Three new compounds, including a prenylated tryptophan derivative, luteoride E (1), a butenolide derivative, versicolactone G (2), and a linear aliphatic alcohol, (3E,7E)-4,8-dimethyl-undecane-3,7-diene-1,11-diol (3), together with nine known compounds (4-12), were isolated and identified from a coral-associated fungus Aspergillus terreus. Their structures were elucidated by HRESIMS, one- and two-dimensional NMR analysis, and the absolute configuration of 2 was determined by comparison of its electronic circular dichroism (ECD) spectrum with the literature. Structurally, compound 1 featured an unusual (E)-oxime group, which occurred rarely in natural products. Compounds 1-3 were evaluated for the α-glucosidase inhibitory activity, and compound 2 showed potent inhibitory potency with IC50 value of 104.8 ± 9.5 μM, which was lower than the positive control acarbose (IC50 = 154.7 ± 8.1 µM). Additionally, all the isolated compounds were evaluated for the anti-inflammatory activity against NO production, and compounds 1-3, 5-7, and 10 showed significant inhibitory potency with IC50 values ranging from 5.48 to 29.34 μM.

Citrinal B, natural 11 beta-hydroxysteroid dehydrogennase type 1 inhibitor identified from structure-based virtual screening

Citrinal B, a tricyclic compound from endophytic fungus Colletotrichum capsici in our previous studies, exhibited significant inhibitory activity against 11β-hydroxysteroid dehydrogenase type 1 (11 β-HSD1) in vitro and showed strong binding affinity to 11β-HSD1. Moreover, citrinal B treatments decreased the lipid droplet accumulation associate with the inhibition of 11β-HSD1 expression in differentiate induced 3T3-L1 preadipocytes. Furthermore, the molecular docking demonstrated that citrinal B coordinated in the active site of 11β-HSD1 is essential for the ability of diminishing the enzyme activity.