Construction of a Bifunctional Nanoelectrode for Intracellular Natural Product Delivery and Monitoring Anticancer Efficiency in Single Cells.

Natural products play a significant role in new drug discovery and anticancer therapy, making the evaluation of their anticancer efficiency crucial for clinical application. However, delivering natural products to single cells and in situ monitoring of induced signaling molecule fluctuation to evaluate anticancer efficiency remain significant challenges. Hence, we proposed a universal and straightforward strategy to construct a bifunctional nanoelectrode that integrates drug loading and monitoring of signal molecule fluctuations at the single-cell level. Platinum (Pt) nanoparticles/reduced graphene oxide (rGO) composites were first electrochemically deposited on the carbon fiber nanoelectrode (CFNE@Pt/rGO) to serve as electrocatalytic materials for the monitoring of natural-product-induced reactive oxygen species (ROS) generation. The GO/natural product complex, formed by π-π stacking and hydrophobic interactions, was further electrochemically reduced on the surface of CFNE@Pt/rGO to enable the CFNE drug-loading function. Using this bifunctional functional nanoelectrode, a series of natural products (such as capsaicin, curcumin, and chrysin) were delivered into single cancer cells, and their anticancer efficiency was evaluated by measuring ROS generation. The results showed that intracellular ROS production induced by chrysin was 1.5-fold greater than that of curcumin and 2.1-fold greater than that of capsaicin. This work proposes an effective tool to evaluate the anticancer efficiency of various natural products. Additionally, this nanotool can be expanded to monitor the fluctuation of other biomolecules (such as RNS, GSH, NADH, etc.) by replacing Pt nanoparticles with other electrocatalytic materials, which is significant for comprehensively exploring the anticancer efficiency of new drugs and for the clinical treatment of various diseases.

Microscopic and Transcriptomic Analyses to Elucidate Antifungal Mechanisms of Bacillus velezensis TCS001 Lipopeptides against Botrytis cinerea.

Botrytis cinerea is an important fungal pathogen that causes gray mold disease in plants. Previously, Bacillus velezensis TCS001 live culture presented broad-spectrum antifungal activity against various plant pathogenic fungi and oomycetes, particularly B. cinerea. Here, the bioactivity of lipopeptides produced by TCS001 against B. cinerea was investigated. The IC50 values of the crude lipopeptide extract (CLE) from TCS001 to suppress mycelial growth and conidial germination were 14.20 and 49.39 mg/L, respectively. SEM and TEM imaging revealed that CLE caused morphological deformities and ultrastructural changes in the mycelium. Transcriptomic analyses combined with ΔBcpsd mutant construction demonstrated that the CLE could confer antifungal activity via suppressing Bcpsd expression in the pathogen. In addition, the CLE activated the plant immune system by increasing the content of defense-related enzymes and the expression of marker genes in immunity signaling pathways in cucumber plants. Therefore, TCS001 CLE could be potentially developed into biopesticides for the biocontrol of gray mold disease.

Two new aromatic tenvermectins from mutant Streptomyces avermitilis HU02-06.

Two new aromatic tenvermectins (TVMs), 13-oleandrosyl-oleandrosyloxy ST906 (1) and aromatic TVM B (2), were isolated from the fermentation broth of Streptomyces avermitilis HU02-06. Their structures were established by extensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS data. Bioassay test showed that these two new tenvermectins exhibited weak nematocidal activity against Bursaphelenchus xylophilus and moderate cytotoxic activity against tumor cell lines HepG2 and HCT116.

Electrochemical Monitoring of Sphingosine-1-phosphate-Induced ATP Release Using a Microsensor Based on an Entropy-Driven Bipedal DNA Walker.

Neuropathic pain is a chronic and severe syndrome for which effective therapy is insufficient and the release of ATP from microglia induced by sphingosine-1-phosphate (S1P) plays a vital role in neuropathic pain. Therefore, there is an urgent demand to develop highly sensitive and selective ATP biosensors for quantitative monitoring of low-concentration ATP in the complex nervous system, which helps in understanding the mechanism involved in neuropathic pain. Herein, we developed an electrochemical microsensor based on an entropy-driven bipedal DNA walker. First, the microsensor specifically recognized ATP via ATP aptamers, initiating the entropy-driven bipedal DNA walker. Subsequently, the bipedal DNA walker autonomously traversed the microelectrode interface, introducing methylene blue to the electrode surface and achieving cascade signal amplification. This microsensor showed excellent selectivity, stability, and a low limit of detection at 1.13 nM. The S1P-induced ATP release from BV2 cells was successfully monitored, and it was observed that dicumarol could inhibit this release, suggesting dicumarol as a potential treatment for neuropathic pain. The microsensor's small size exhibited significant potential for monitoring ATP level changes in neuropathic pain in vivo, which provides a new strategy for in situ and quantitative monitoring of nonelectroactive biomolecules associated with neurological diseases.

Herbicidal Activity of Secondary Metabolites Isolated from Streptomyces sp. NEAU-HV44 on Selected Weeds and Crops.

Streptomyces is an effective source of new natural bioherbicides. In this study, a novel isolated strain NEAU-HV44 showed strong inhibitory activity against Amaranthus retroflexus L. and was concluded to the genus Streptomyces. Strain NEAU-HV44 fermentation conditions were optimized to maximize the herbicidal activity. The supernatant of strain NEAU-HV44 could significantly control the growth of weeds (A. retroflexus L., Setaria viridis, Portulaca oleracea L., and Chenopodium album) and crops (maize, soybean, wheat, Chinese cabbage, cucumber, tomato, and romaine lettuce) with dose-dependent in preemergence. Notably, weeds were more sensitive to a low-concentration supernatant extract than crops in preemergence. In postemergence, the 2 mg mL-1 supernatant extract could significantly reduce the height and >50% biomass (fresh weight) of tested weeds. The supernatant extract could cause cell membrane destabilization and the cell death of weeds. In addition, the growth of tomato was also inhibited at a high concentration, but no obvious symptoms were observed on soybean and romaine lettuce after spraying the supernatant extract. Then two novel julichrome monomers, julichromes Q12 (1) and Q13 (2), and two known julichromes, julichrome Q3.3 (3) and julichrome Q3.5 (4), were isolated from the supernatant extract of strain NEAU-HV44 by bioactivity-guided approach. This is the first report of the herbicidal activity of julichromes. These four herbicidal compounds could inhibit the shoot and root growth of weeds at 0.2 mg mL-1, and compound 4 could completely inhibit the growth of P. oleracea L. Thus, julichromes (Q12, Q13, Q3.3, Q3.5 1-4) may be new bioherbicidal candidates.

Anulamycins A-F, Cinnamoyl-Containing Peptides from a Lake Sediment Derived Streptomyces.

Bioinformatics analysis of a whole genome sequence coupled with HPLC-DAD analysis revealed that Streptomyces sp. Hu103 has the capacity to produce skyllamycin analogues. A subsequent chemical investigation of this strain yielded four new cinnamoyl-containing cyclopeptides, anulamycins A-D (1-4), two new cinnamoyl-containing linear peptides, anulamycins E and F (5 and 6), and two known cyclopeptides, skyllamycins A (7) and B (8). Their structures including absolute configurations were elucidated by detailed analysis of NMR and HRESIMS/MS spectroscopic data and the advanced Marfey's method. Compounds 1-4 exhibited antibacterial activity comparable to those of skyllamycins A and B.

A new ß-class milbemycin derivative from a mutant of genetically engineered strain Streptomyces avermitilis AVE-H39.

A new ß-class milbemycin, 13α-hydroxy milbemycin ß6 (1), was isolated from the fermentation broth of a mutant of genetically engineered strain Streptomyces avermitilis AVE-H39. Its structure and absolute configuration were elucidated by extensive spectroscopic methods and confirmed by single crystal X-ray diffraction.

Confirmation of the absolute configuration of tenvermectin B by single-crystal X-ray diffraction analysis of its furan formate derivative.

Tenvermectins A and B are a kind of 16-membered macrocyclic lactone antibiotics with potent insecticidal property, which have been obtained from two genetically engineered strains Streptomyces avermitilis MHJ1011 and S. avermitilis AVE-H39. Aiming at confirming the absolute configuration of tenvermectin B by X-ray diffraction method, 4″, 5 -di-(2-furoyloxyl) tenvermectin B (1) was prepared and a suitable crystal of 1 was obtained from MeOH. The absolute configuration of 1 was unambiguously established by single-crystal X-ray diffraction analysis. The determination of the stereochemistry of tenvermectin B could promote its chemical and biological studies as agricultural and veterinary agents. In addition, compound 1 displayed weak acaricidal and nematocidal activities against Tetranychus cinnabarinus and Bursaphelenchus xylophilus respectively.

A novel spiro-heterocycle milbemycin metabolite from a genetically engineered strain of Streptomyces bingchenggensis.

Milbemycin R, a novel spiro-heterocycle milbemycin, was obtained from the metabolites produced by the mutant strain S. bingchenggensis BCJ60B11. Its structure was determined by spectroscopic and spectrometric analyses including 1 D, 2 D NMR, IR, HR-ESI-MS data. The acaricidal and nematicidal activities of milbemycin R against Tetranychus cinnabarinus and Bursaphelenchus xylophilus were tested. Milbemycin R possessed better acaricidal activity than milbemycins A3/A4.

Two new 22-membered macrolides from Streptomyces sp. HU210.

Two new 22-membered macrolide metabolites, phthoramycins B (1) and C (2), were isolated from the fermentation broth of Streptomyces sp. HU210. Their structures were elucidated based on extensive spectroscopic techniques including 1D, 2D NMR and HRESIMS data. Compounds 1 and 2 showed moderate cytotoxic activity against human leukemia cell line K562 and lung carcinoma cell line A549.

An entropy-driven three-dimensional multipedal-DNA walker for ultrasensitive detection of cancer cells.

Sensitive and accurate detection of cancer cells is of great significance for the early diagnosis and treatment of cancer. In this work, we developed a simple fluorescent signal amplification biosensor based on an entropy-driven three-dimensional (3D) multipedal-DNA walker for highly sensitive detection of cancer cells. Firstly, DNA tetrahedron nanostructures (DTNs) combined with AS1411 aptamer were used as the capture probe to achieve efficient capture of cancer cells. Then, the bipedal hairpin fuel chain hybridized with DTNs and exposed two catalytic "legs" to form a walker probe. Finally, the walker probe autonomously walked on polystyrene microspheres (PS) via entropy-driven catalytic reaction. DTNs rolled on the PS to achieve multipedal walking, realizing fluorescence signal amplification due to fluorescence recovery of DNA-CdTe quantum dots on the PS surface. This fluorescence signal amplification strategy showed excellent selectivity and sensitivity toward cancer cells with the detection limit of 7 cell mL-1. This entropy-driven 3D multipedal DNA walker fluorescence exhibited great potential in detecting circulating tumor cells and tumor markers used for early diagnosis and clinical treatment of cancer.

Aptamer-mediated DNA concatemer functionalized magnetic nanoparticles for reversible capture and release of circulating tumor cells.

Effectively capturing, releasing, and reanalyzing circulating tumor cells (CTCs) are critical in cancer diagnosis and individualized treatment. Traditional immunomagnetic separation has disadvantages of low sensitivity and specificity, and is time-consuming and costly in CTCs capture. It is also easily disturbed by the microenvironment in releasing and analyzing CTCs. Here, we proposed an aptamer-mediated DNA concatemer functionalized magnetic nanoparticles (MNPs-AMDC) for the reversible capture and release of CTCs. In this study, aptamers were used both for efficiently capturing CTCs without complicated assembly steps and stimulus-response switch for releasing CTCs with little influence on cellular activity. The MNPs-AMDC was demonstrated to effectively capture (83%) and release CTCs with a good viability rate (92%). Moreover, this device was also tested in clinical blood samples, which would provide a universal tool for diagnosing cancer and treating individuals.

Two new cyclopentenone metabolites from Streptomyces sp. HU119.

Two previously undescribed cyclopentenone metabolites, (S)-2-(3-acetylamino-2-methyl)propyl-3-butyl-2-cyclopenten-1-one (1) and (S)-2-(3-acetylamino-2-ethyl)propyl-3-butyl-2-cyclopenten-1-one (2), were isolated from the fermentation broth of the strain Streptomyces sp. HU119. The structures of 1 and 2 were determined by the comprehensive spectroscopic analysis, including 1 D, 2 D NMR, MS spectral analysis and the comparison with data from the literature. The absolute configurations were elucidated by experimental and calculated optical rotations (OR). Compounds 1 and 2 displayed weak cytotoxic activity.

Sarubicinols A-C, Cytotoxic Benzoxazoles from a Streptomyces.

A chemical investigation of Streptomyces sp. Hu186 afforded two known quinone antibiotics, sarubicin A (1) and sarubicin B (2), together with three unusual variants, sarubicinols A-C (3-5), and two new 1,4-naphthoquinone metabolites, sarubicin B1 (6) and sarubicin B2 (7). Compounds 3-5 possess a rare 2-oxabicyclo [2.2.2] substructure and a benzoxazole ring system. Their structures were elucidated using 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry data. The absolute configurations of the side-chain moieties in 4 and 5 were solved by electronic circular dichroism calculations. Compounds 1-7 showed moderate cytotoxic activity against four tumor cell lines.

Two new threonine-containing metabolites from fungus Curvularia inaequalis strain HS-FG-257.

Two new threonine-containing metabolites, N-[4-hydroxy-3-prenyl-benzoyl]-L-threonine (1) and N-[2,2-dimethyl-2H-chromene-6-carbonyl]-L-threonine (2), were isolated from the fermentation broth of the soil fungus Curvularia inaequalis strain HS-FG-257. Their structures were elucidated through the interpretation of HR-ESIMS and extensive NMR spectroscopic data. Both compounds exhibited no cytotoxic activity against the test cell lines A549 and HCT-116.

A facile preparation and crystal structure of romipeptide A.

A double disulfide tethering depsipeptide dimer, romipeptide A (1) was prepared by NaOH catalyzed dimerization of romidepsin. Its structure was determined by analysis of NMR and HR-ESI-MS data as well as single crystal X-ray diffraction. Bioassay results showed that 1 exhibited good cytotoxic activity against two tumor cell lines B16 and HCT116. This study reported the single crystal data of 1 for the first time. The facile preparation of 1 afforded enough amount for its further biological evaluations.

Tetrodecadazinone, a novel tetrodecamycin-pyridazinone hybrid with anti-liver fibrosis activity from Streptomyces sp. HU051.

Tetrodecadazinone (1), a novel tetrodecamycin-pyridazinone hybrid possessing a new 1,2-dimethyl-1-(2-methylnonyl)decahydronaphthalene skeleton, and 4-hydroxydihydrotetrodecamycin (2) were separated from a culture of Streptomyces sp. HU051, together with a known compound, dihydrotetrodecamycin (3). Diverse spectroscopic approaches were applied to assign the structures of 1-3, and the structure of 1 was further confirmed by single crystal X-ray diffraction analysis. Compound 1 is the first example of a pyridazinone-containing natural product. Biosynthetically, 1 is proposed to be derived from a Michael addition reaction of a PKS-derived tetrodecamycin and a piperazic-acid-derived pyridazinone. Biological evaluation revealed 1 could reduce the expressions of extracellular matrix proteins (fibronectin and collagen I) and α-smooth muscle actin (α-SMA) in transforming growth factor-ß (TGF-ß1)-activated LX-2 cells. Preliminary mechanism study showed 1 exerted its anti-liver fibrosis effect by regulating TGF-ß1/Smad2/3 signaling pathway.

Effects of High-Forage Diets Containing Raw Flaxseeds or Soybean on In Vitro Ruminal Fermentation, Gas Emission, and Microbial Profile.

Lipid metabolism plays an important role in the energy economy of ruminants. However, its interactions of fat, rumen fermentation, gas emission, and microorganisms are not yet clear. This study evaluated the effect of adding raw oilseeds to high-forage diets on in vitro ruminal fermentation, gas composition, and microbial profile. Three isoenergetic and isoproteic experimental diets were designed and used as fermentation substrate: control treatment (CON group) was the basal diet lacking oilseeds, the other two treatments were the basal diet supplemented by 100 g/kg dry matter (DM) raw whole soybean (S group) and 50 g/kg DM raw flaxseed (F group), respectively. Data showed that the acetate, butyrate, and total VFA concentration of culture fluids in the S group were lower (p < 0.05) than in the F group. There was a tendency to a higher level (p = 0.094) of propionate concentration in the F group compared with the other two groups. The gas production in the F group was higher (p < 0.05) than in the control group. There was a lower abundance of Sutterella (p < 0.05) and a greater abundance of Butyrivibrio (p < 0.05) in both of the two oilseed treatments. Methanobrevibacter (p = 0.078) in the F group was the lowest. Our results suggested that CH4 emission could be inhibited with flaxseed supplementation by propionate production metabolism, biohydrogenation of unsaturated fatty acid (FA), and toxicity to Methanobrevibacter, while regarding soybean seed supplementation, the emission of CH4 was more likely to be reduced through biohydrogenation of unsaturated FA modulated by Butyrivibrio.

Two new 13-hydroxylated milbemycin metabolites from the genetically engineered strain Streptomyces avermitilis AVE-H39.

Two new milbemycin metabolites, 13α-hydroxymilbemycin ß13 (1) and 26-methyl-13α-hydroxymilbemycin ß13 (2), were isolated from the fermentation broth of a genetically engineered strain Streptomyces avermitilis AVE-H39. Their structures were determined by the comprehensive spectroscopic data, including 1 D, 2 D NMR, MS spectral analysis and the comparison with data from the literature. Compounds 1 and 2 not only exhibited potent acaricidal activities against Tetranychus cinnabarinus, but also had nematocidal activity against Bursaphelenchus xylophilus.

Two new milbemycin derivatives from a genetically engineered strain Streptomyces bingchenggensis.

Two new milbemycin derivatives, milbemycin M (1) and milbemycin N (2), were isolated from the culture of a genetically engineered strain Streptomyces bingchenggensis BCJ60. Their structures were elucidated through the interpretation of NMR and HR-ESI-MS spectroscopic data, as well as comparison with previous reports. The acaricidal and nematicidal activities of them against Tetranychus cinnabarinus and Bursaphelenchus xylophilus were tested. The results showed that compounds 1-2 possessed potent acaricidal and nematocidal activities.