Discovery of P450-Modified Sesquiterpenoids Levinoids A-D through Global Genome Mining.

Cytochrome P450-modified bacterial terpenoids remain in a vast chemical space to be explored. In the present study, we conducted global genome mining of 223,829 bacterial genomes and identified 2892 bacterial terpenoid biosynthetic gene clusters (BGCs) with cytochrome P450 genes. Among these, we selected 562 with multiple P450 enzymes, which were further clustered as 355 gene cluster families by sequence similarity analysis. We then chose lev, a BGC from Streptomyces levis MCCC1A01616, for heterologous expression and discovered four new α-amorphene-type sesquiterpenoids, levinoids A-D (1-4). The structures and absolute configurations of these four new compounds were determined by employing extensive NMR analysis, NMR chemical shift calculations with DP4+, and ECD calculations. Furthermore, levinoid C (3) exhibited a moderate level of neuroprotective activity (EC50 = 21 µM) in the glutamate-induced excitotoxicity cell model. Our findings highlight the untapped chemical diversity of P450-modified bacterial terpenoids, opening new avenues for further exploration and discovery.

Discovery of Natural Potent HMG-CoA Reductase Degraders for Lowering Cholesterol.

Exploitation of key protected wild plant resources makes great sense, but their limited populations become the major barrier. A particular strategy for breaking this barrier was inspired by the exploration of a resource-saving fungal endophyte Penicillium sp. DG23, which inhabits the key protected wild plant Schisandra macrocarpa. Chemical studies on the cultures of this strain afforded eight novel indole diterpenoids, schipenindolenes A-H (1-8), belonging to six diverse skeleton types. Importantly, semisyntheses suggested some key nonenzymatic reactions constructing these molecules and provided targeted compounds, in particular schipenindolene A (Spid A, 1) with low natural abundance. Remarkably, Spid A was the most potent HMG-CoA reductase (HMGCR) degrader among the indole diterpenoid family. It degraded statin-induced accumulation of HMGCR protein, decreased cholesterol levels and acted synergistically with statin to further lower cholesterol. Mechanistically, transcriptomic and proteomic profiling suggested that Spid A potentially activated the endoplasmic reticulum-associated degradation (ERAD) pathway to enhance the degradation of HMGCR, while simultaneously inhibiting the statin-activated expression of many key enzymes in the cholesterol and fatty acid synthesis pathways, thereby strengthening the efficacy of statins and potentially reducing the side effects of statins. Collectively, this study suggests the potential of Spid A for treating cardiovascular disease.

Mechanistic Insight into the Inhibitory Activity of Elasnin-Based Coating against Early Marine Biofilms.

Marine biofilms are multispecies microbial communities on surfaces that are crucial to the marine environment. They cause marine corrosion, biofouling, and transmission of marine pathogens and thus pose a great threat to public health and the maritime industry. To control marine biofilms, effective and environmentally friendly antibiofilm compounds are highly needed. Elasnin is a potent antibiofilm compound that exhibits high efficiency in inhibiting marine biofilms and biofouling, but its mode of action remains unclear. In the present study, multiomic analysis combined with quorum-sensing assays and in silico study revealed that elasnin acted as a signaling molecule in the microbial community. Elasnin promoted the growth of dominant species in the biofilm but deprived their ability of sensing and responding to environmental changes by disturbing their regulations of the two-component system, i.e., the ATP-binding cassette transport system and the bacterial secretion system. Consequently, biofilm maturation and subsequent biofouler settlement were inhibited. Elasnin also exhibited higher antibiofilm efficiency than dichlorooctylisothiazolinone and had low toxicity potential on the embryos and adults of marine medaka fish. Overall, this study provided molecular and ecological insights into elasnin's mode of action, highlighting its application potential in controlling marine biofilms and the feasibility and advantages of using signal molecules to develop eco-friendly technologies.

Aspcandine: A Pyrrolobenzazepine Alkaloid Synthesized by a Fungal Nonribosomal Peptide Synthetase-Polyketide Synthase Hybrid.

Characterization of an orphan biosynthetic gene cluster found in the fungus Aspergillus candidus CBS 102.13 resulted in the discovery of a pyrrolobenzazepine alkaloid, aspcandine (1). The unique molecular scaffold of 1 is synthesized by the nonribosomal peptide synthetase-polyketide synthase hybrid AcdB, which unusually incorporates 3-hydroxy-l-kynurenine as a building block. AcdB subsequently performs one round of chain elongation using malonyl-CoA, which is followed by the chain release to furnish the tricyclic system of 1.

Cytochalasans from the Endophytic Fungus Phomopsis sp. shj2 and Their Antimigratory Activities.

Cytochalasans from the endophytic fungi featured structure diversity. Our previous study has disclosed that cytochalasans from the endophytic fungus Phomopsis sp. shj2 exhibited an antimigratory effect. Further chemical investigation on Phomopsis sp. shj2 has led to the discovery of seven new cytochalasans (1-7), together with four known ones. Their structures were elucidated through extensive spectroscopic data interpretation and single-crystal X-ray diffraction analysis. Compounds 1-3 and 8-11 exhibited antimigratory effects against MDA-MB-231 in vitro with IC50 values in the range of 1.01-10.42 µM.

Biosynthesis and bioactivities of microbial genotoxin colibactins.

Covering: up to 2021Colibactin(s), a group of secondary metabolites produced by the pks island (clb cluster) of Escherichia coli, shows genotoxicity relevant to colorectal cancer and thus significantly affects human health. Over the last 15 years, substantial efforts have been exerted to reveal the molecular structure of colibactin, but progress is slow owing to its instability, low titer, and elusive and complex biosynthesis logic. Fortunately, benefiting from the discovery of the prodrug mechanism, over 40 precursors of colibactin have been reported. Some key biosynthesis genes located on the pks island have also been characterised. Using an integrated bioinformatics, metabolomics, and chemical synthesis approach, researchers have recently characterised the structure and possible biosynthesis processes of colibactin, thereby providing new insights into the unique biosynthesis logic and the underlying mechanism of the biological activity of colibactin. Early developments in the study of colibactin have been summarised in several previous reviews covering various study periods, whereas the two most recent reviews have focused primarily on the chemical synthesis of colibactin. The present review aims to provide an update on the biosynthesis and bioactivities of colibactin.

Discovery of ent-kaurane diterpenoids, characteristic metabolites of Isodon species, from an endophytic fungal strain Geopyxis sp. XY93 inhabiting Isodon parvifolia.

Isogeopyxins A-C (1-3), three new diterpenoids with ent-kaurane, ent-pimarane, and ent-abietane scaffolds, respectively, along with six known ent-kauranoids, were isolated from the fermentation culture of Geopyxis sp. XY93 inhabiting the leaves of Isodon parvifolia. Their structures were elucidated by interpretation of spectroscopic data, and single crystal X-ray diffraction. It marks the first time that ent-kauranoids, characteristic metabolites of Isodon species, have been isolated from an associated endophytic fungus.

Challenges of the establishment of rubber-based agroforestry systems: Decreases in the diversity and abundance of ground arthropods.

The global land area devoted to rubber plantations has now reached 13 million hectares, and the further expansion of these rubber plantations at the expense of tropical forests will have significant adverse effects on the ecological environment. Rubber-based agroforestry systems are considered a preferable approach for ameliorating the ecological environment. Many researchers have focused on the positive effects of rubber-based agroforestry systems on the ecological environment, while ignoring the risks involved in the establishment of rubber-based agroforestry systems. The present study investigated the effects of different-aged rubber-based agroforestry systems on the abundance and diversity of ground arthropods. It has been observed that the abundance and taxon richness of ground arthropods generally showed no difference when comparing young and mature rubber plantations. The rubber-based agroforestry systems significantly decreased the understory vegetation species, along with the abundance and taxon richness of ground arthropods compared to the same aged-rubber monoculture plantations. In addition, the change in the abundance and taxon richness of ground arthropods was greatly affected by the understory vegetation species and soil temperature. The abundance and taxon richness of ground arthropods decreased with the decrease in number of species of understory vegetation. The study results indicate that the establishment of rubber-based agroforestry systems have adversely affected the abundance and richness of ground arthropods to an extant greater than expected. Therefore, single, large rubber-based agroforestry systems are not recommended, and the intercropping of rubber and rubber-based agroforestry systems must be designed to promote the migration of ground arthropods between different systems.

3-Hydroxy-4-methyldecanoic Acid-Containing Cyclotetradepsipeptides from an Endolichenic Beauveria sp.

An investigation of an endolichenic Beauveria sp. led to the discovery of seven new cyclotetradepsipeptides, beauveamides A-G (2-8), along with the known beauverolide Ka (1). All incorporate a 3-hydroxy-4-methyldecanoic acid (HMDA) moiety in their structures. Their configuration was determined through Marfey's, J-based configuration analysis, and NMR computational methods, representing the first time that the stereostructures of HMDA-moiety-containing cyclotetradepsipeptides have been established. Compounds 1 and 2 exhibited protecting effects on HEI-OC1 cells at 10 µM, while 1, 4, and 5 could stimulate glucose uptake in cultured rat L6 myoblasts at 50 µM. Compound 1 showed dose-dependent activity in both L6 myoblasts and myotubes.

Chaetolactam A, an Azaphilone Derivative from the Endophytic Fungus Chaetomium sp. g1.

Chaetolactam A (1), an unprecedented azaphilone derivative bearing a unique 9-oxa-7-azabicyclo[4.2.1]octan-8-onering system, together with two new compounds, 11-epi-chaetomugilide B (2) and chaetomugilide D (3) was isolated from an endophytic fungus, Chaetomium sp. g1. Notably, extensive NMR data analyses, NMR calculations with DP4 and DP4+ analyses, ECD calculations, and the RDC method were employed to establish the structure of 1. Furthermore, 2 exhibited potent apoptosis induction activity by mediating caspase-3 activation and PARP degradation at 3 µM in HL-60.

Nomograms for predicting survival in early-onset esophageal cancer.

Background: This study aimed to develop nomograms predicting the overall survival (OS) of patients younger than 50 years old with esophageal cancer.Methods: We selected patients included 2004-2015 in the Surveillance, Epidemiology, and End Results (SEER) database. Nomograms were constructed using significant variables from multivariable Cox analyses. The discrimination and calibration power of the models were evaluated using concordance indexes (C-indexes) and calibration curves. Decision curve analysis was used to assess the clinical net benefits of the nomograms.Results: Of 1,997 selected patients, 53.2% had advanced-stage tumor. Race, grade, T stage, N stage, and treatment were independent factors affecting OS in early-stage patients. The C-indexes of the corresponding nomogram were 0.710 (95% CI = 0.684-0.736) and 0.681 (95% CI = 0.640-0.722) in training and validation sets, respectively. Grade, marital status, and treatment were independent factors affecting OS in advanced-stage patients. The C-indexes of the corresponding nomogram were 0.677 (95% CI = 0.653-0.701) and 0.675 (95% CI = 0.638-0.712) in training and validation sets, respectively. Calibration curves demonstrated high consistency between predicted and actual survival.Conclusion: We constructed and verified nomograms that could accurately predict the survival rate of esophageal cancer in patients younger than 50 years old. This may help clinicians better understand prognostic factors.

Discovery of Pyranoviolin A and Its Biosynthetic Gene Cluster in Aspergillus violaceofuscus.

A new polyketide-non-ribosomal peptide hybrid molecule, pyranoviolin A (1), was discovered from the genome-sequenced fungus Aspergillus violaceofuscus CBS 115571 and was characterized to be the first pyranonigrin analog harboring the C-3 methoxy group. Examination of the genome sequence of the fungus identified a putative biosynthetic gene cluster of 1, which was designated as the pyv cluster. The gene deletion experiment of the polyketide synthase (PKS)-non-ribosomal peptide synthetase (NRPS) hybrid gene in the cluster confirmed the involvement of the pyv cluster in the pyranoviolin A biosynthesis. Finally, a plausible biosynthetic route leading to 1 has been proposed based on the bioinformatic analysis. Our study indicates that metabolite analysis of genome-sequenced microorganisms whose metabolites have been largely unexplored facilitates the discovery of new secondary metabolites along with their biosynthetic gene clusters.

Serum microRNA expression profiling revealing potential diagnostic biomarkers for lung adenocarcinoma.

BACKGROUND: Recent studies have demonstrated that microRNAs (miRNAs) in the blood circulation can serve as promising diagnostic markers for cancers. This four-stage study aimed at finding serum miRNAs as potential biomarkers for lung adenocarcinoma (LA) diagnosis. METHODS: The study was carried out between 2016 and 2017. The Exiqon miRNA qPCR panel (3 LA vs. 1 normal control [NC] pooled serum samples) was used for initial screening to acquire miRNA profiles. Thirty-five dysregulated miRNAs were further evaluated in the training (24 LA vs. 24 NCs) and testing stages (110 LA vs. 110 NCs) using quantitative real-time polymerase chain reaction assays. RESULTS: Four serum miRNAs (miR-133a-3p, miR-584-5p, miR-10b-5p, and miR-221-3p) were significantly overexpressed in LA patients compared with NCs. The diagnostic value of the four-miRNA panel was validated by an external cohort (36 LA vs. 36 NCs). The areas under the receiver operating characteristic curve of the four-miRNA panel in the training, testing, and external validation stages were 0.734, 0.803, and 0.894 respectively. Meanwhile, the expression level of miR-221-3p was much higher in LA tumor samples than that in the adjacent normal tissues (19 LA vs. 19 NCs). The expression level of miR-10b-5p was also elevated in the serum-derived exosomes samples (18 LA vs. 18 NCs). The expression of miR-133a-3p, miR-584-5p, and miR-10b-5p was significantly elevated in LA patients with epidermal growth factor receptor mutation compared with NCs. CONCLUSION: The study established a four-miRNA signature in serum that could improve the diagnostic capability of LA.

Arthrinins E-G, Three Botryane Sesquiterpenoids from the Plant Endophytic Fungus Arthrinium sp. HS66.

Arthrinins E-G (1-3), three new sesquiterpenoids possessing non-isoprenoid botryane skeleton, were isolated from the fermentation of an endophytic fungus named Arthrinium sp. HS66 which colonized in the stems of Isodon xerophilus. Their structures were determined by extensive spectroscopic methods. Furthermore, the structure of 1 was unambiguously confirmed by X-ray diffraction, while those of 2 and 3 were verified through quantum chemical calculation of NMR data and ECD spectra.

Discovery of isopenicin A, a meroterpenoid as a novel inhibitor of tubulin polymerization.

Microtubules are involved in celluar processes of movement, intracellular trafficking and mitosis, thus microtubule-targeting agents have been widely used in cancer therapy. Herein, we report isopenicin A, a novel meroterpenoid isolated from the plant endophytic fungus of Penicillium sp. sh18, as a novel microtubule binding molecule that efficiently depolymerizes microtubule polymerization to evoke G2/M cell cycle arrest and subsequent cell apoptosis, contributing to proliferation inhibition of human tumor cell lines. The discovery of isopenicin A provides a new chemotype for discovery and development of promising microtubule inhibitors.

Structural determination of eleven new preschisanartane-type schinortriterpenoids from two Schisandra species and structural revision of preschisanartanin J using NMR computation method.

Nineteen preschisanartane-type schinortriterpenoids (SNTs), among which eleven ones were previously undescribed, were isolated from two Schisandra species, S. sphaerandra and S. rubriflora. Their structures were determined using 1D and 2D NMR spectroscopic analyses, NMR data comparison, quantum chemical calculation of NMR parameters, electronic circular dichroism (ECD), X-ray single crystal diffraction, and chemical derivation. Furthermore, structural re-examination of a few previously reported preschisanartane-type SNTs led to the structural revision of preschisanartanin J. Besides, it is suggested that the reported structures of arisanlactone D and schilancidilactone W should be re-checked. Finally, a few isolated SNTs were found to possess neurite outgrowth-promoting activities, and protective activities against neural injuries.

(+)- and (-)-Alternarilactone A: Enantiomers with a Diepoxy-Cage-like Scaffold from an Endophytic Alternaria sp.

The enantiomers (+)- and (-)-alternarilactone A (1), the first examples of dibenzo-α-pyrones bearing a diepoxy-cage-like moiety, were isolated from the endophytic fungus Alternaria sp. hh930. The deficiency in 1H-1H COSY and HMBC correlations caused by the highly oxidized caged system of 1 and the deceptive and ambiguous signals such as "W" couplings in NMR data increased the risk of structure misassignment of 1. By performing a quantum chemical calculation of the NMR chemical shifts together with a DP4+ probability analysis and single-crystal X-ray crystallographic experiment, their structures were unambiguously determined, and their absolute configurations were determined by ECD calculations.

Isopenicins A-C: Two Types of Antitumor Meroterpenoids from the Plant Endophytic Fungus Penicillium sp. sh18.

Isopenicins A-C (1-3), three novel meroterpenoids possessing two types of unprecedented terpenoid-polyketide hybrid skeletons, were isolated from the cultures of Penicillium sp. sh18. Their structures were determined through synergetic use of extensive spectroscopic analysis, quantum-chemical calculation with ANN-PRA analysis, and X-ray crystallographic analysis. Additionally, the inhibitory activities of these compounds on the Wnt/ß-catenin signaling pathway were evaluated, and 1 was identified as a potent inhibitor of the Wnt signaling pathway.

Introduction of a leguminous shrub to a rubber plantation changed the soil carbon and nitrogen fractions and ameliorated soil environments.

The conversion of monoculture rubber (Hevea brasiliensis) plantations into rubber-based agroforestry systems has become a common trend in forestry management in the past few decades. Rubber-Flemingia macrophylla (a leguminous shrub) systems are popular in southwestern China's Xishuangbanna region. The biogeochemical cycles of soil carbon and nitrogen in forests are mainly affected by their fractions. This study investigated the effect of introducing Flemingia macrophylla to rubber plantations of different ages on soil carbon and nitrogen fractions. The experimental treatments included R1 (young rubber plantation), RF1 (young rubber-Flemingia macrophylla system), R2 (mature rubber plantation) and RF2 (mature rubber-Flemingia macrophylla system). The results showed that the introduction of Flemingia macrophylla to rubber plantations of different ages significantly changed soil carbon and nitrogen fractions, improved soil labile organic carbon and nitrogen contents, and ameliorated soil environments. The average soil microbial biomass organic carbon, nitrogen and nitrate-nitrogen in the 0-10 cm soil layer during the experimental period was 38.9%, 55.5%, and 214.7% higher in RF1 than R1, respectively, and 22.1%, 22.2%, and 652.2% higher in RF2 than R2, respectively. Therefore, Flemingia macrophylla can be used as an alternative interplanted tree species within rubber plantations in similar environments of southeastern Asia.

Secondary Metabolites from the Endophytic Fungus Xylaria sp. hg1009.

A detailed chemical investigation of the secondary metabolites produced by the endophytic fungus Xylaria sp. isolated from the stems of Isodon sculponeatus afforded six new compounds, xylariahgins A-F (1-6), two new natural products (7 and 8), along with two known compounds (9 and 10) (Fig. 1). The structures of all compounds were unambiguously established by analyzing their spectroscopic data or referring to pertinent literature. Compounds 1-8 were tested for their cytotoxic activity against five human tumor cell lines.