Two New Isocoumarins Isolated from the Marine-Sponge-Derived Fungus Setosphaeria sp. SCSIO41009

Two new dihydroisocoumarins, exserolides L and M (1 and 2), along with six known compounds (3-8) were isolated from the extract of the marine-sponge-derived fungus Setosphaeria sp. SCSIO41009. Their structures were established by spectroscopic analyses. The absolute configurations of two new compounds were determined by modified Mosher's method and ECD data. Compounds 1 and 4 showed significant antiviral activities against A/Puerto Rico/8/34 H274Y (H1 N1) with IC50 values of 4.07±0.76 μM and 20.06±4.85 μM, respectively.

Genome Mining Uncovers a Flavoenzyme-Catalyzed Isomerization Process during the Maturation of Pyrenophorol Dilactones

The biosynthetic gene cluster responsible for the production of C2-asymmetric 16-membered dilactones, including pyrenophorol and its derivatives, was discovered through genome mining of polyketides from a sponge-derived fungus. The biosynthetic pathway of the pyrenophorol dilactones was subsequently elucidated. A distinctive flavoenzyme PylE was identified to catalyze the isomerization of the 4-alcohol-2,3-unsaturated moiety within the dilactone scaffold, resulting in the formation of a 1,4-diketone. Further insights into the catalytic mechanism of PylE were obtained through mutagenesis experiments combined with molecular docking.

Effects of secukinumab combined with tretinoin on metabolism, liver enzymes, and inflammatory factors in patients with moderate to severe psoriasis vulgaris

Introduction

Psoriasis is a T cell-mediated polygenic chronic inflammatory disease. Interleukin (IL)-17A plays a major role in psoriasis pathogenesis. Secukinumab is a high-affinity human monoclonal antibody against IL-17A.

Aim

This article explored efficacy and safety of secukinumab plus tretinoin in moderate to severe psoriasis (MSP) vulgaris, and assessed metabolism, liver function, and inflammation.

Material and methods

A total of 135 patients diagnosed with moderate or severe psoriasis vulgaris were enrolled and randomized into three groups at a 1 : 1 : 1 ratio, receiving treatment with rretinoin, secukinumab, or combination therapy for a duration of 16 weeks. Psoriasis area and severity index (PASI) scores, serum T lymphocyte subsets, glucose, lipid, and uric acid (UA) metabolism, liver enzymes, and inflammatory factors (IFs) were measured.

Results

Following the therapy, subjects had decreased PASI scores, increased serum CD3+, CD4+, and CD4+/CD8+, decreased serum CD8+, and decreased serum UA and IL-2, IL-6, IL-23, interferon-γ (IFN-γ), and tumor necrosis factor (TNF)-α (p < 0.05). Total cholesterol, triglycerides, low-density lipoprotein, high-density lipoprotein, apolipoproteins A1, B, fasting blood glucose, alanine transaminase, aspartate transaminase, and alkaline phosphatase had no obvious differences among the subjects (p > 0.05). As against the Tretinoin and the Secukinumab groups, the PASI score was visiblysmaller, the changes in serum T lymphocyte subsets were more obvious, and serum UA and IFs were lower in the Combination group following the therapy (p < 0.05).

Conclusions

Secukinumab combined with tretinoin is more effective in MSP vulgaris, which can visibly reduce inflammatory response without affecting glucose and lipid metabolism and liver function.

Secondary Metabolites from the Coral-Derived Fungus Aspergillus austwickii SCSIO41227 with Pancreatic Lipase and Neuraminidase Inhibitory Activities

The coral-derived fungus Aspergillus austwickii SCSIO41227 from Beibu Gulf yielded four previously uncharacterized compounds, namely asperpentenones B-E (1-4), along with twelve known compounds (5-16). Their structures were elucidated using HRESIMS and NMR (1H and 13C NMR, HSQC, HMBC), among which the stereo-structure of compounds 1-3 was determined by calculated ECD. Furthermore, compounds 1-16 were evaluated in terms of their enzyme (acetylcholinesterase (AChE), pancreatic lipase (PL), and neuraminidase (NA)) inhibitory activities. These bioassay results revealed that compounds 2 and 14 exerted noticeable NA inhibitory effects, with IC50 values of 31.28 and 73.64 μM, respectively. In addition, compound 3 exhibited a weak inhibitory effect against PL. Furthermore, these compounds showed the potential of inhibiting enzymes in silico docking analysis to demonstrate the interactions between compounds and proteins.

New Fusarin Derivatives from the Marine Algicolous Fungus Penicillium steckii SCSIO41040

Five new fusarin derivatives, steckfusarins A-E (1-5), and two known natural products (6, 7), were isolated and identified from the marine algicolous fungus Penicillium steckii SCSIO 41040. The new compounds, including absolute configurations, were determined by spectroscopic analyses and calculated electronic circular dichroism (ECD). All new compounds were evaluated for their antioxidant, antibacterial, antifungal, antiviral, cytotoxic, anti-inflammatory, antioxidant, cholesterol-lowering, acetyl cholinesterase (AChE) enzyme and 6-phosphofructo-2-kinase (PFKFB3) and phosphatidylinositol-3-kinase (PI3K) inhibitory activities. The biological evaluation results revealed that compound 1 exhibited radical scavenging activity against 2,2-diphenyl-1-picrylhydrazylhydrate (DPPH), with an IC50 value of 74.5 µg/mL. In addition, compound 1 also showed weak anti-inflammatory activity at a concentration of 20 µM.

A new quinolone and acetylcholinesterase inhibitors from a sponge-associated fungus Penicillium sp. SCSIO41033

The chemical investigation of the EtOAc extract from the solid rice medium cultured with a sponge-associated fungus Penicillium sp. SCSIO41033 led to the isolation of two quinolones including a new one, penicinolone (1), three xanthone derivatives (3-5), and four anthraquinones (6-9). Their structures were determined by comprehensive analysis of 1H and 13C NMR, COSY, HSQC, and HMBC spectroscopic, and HRESIMS mass spectrometric data. The bioactive assays revealed that compounds 1 and 2 showed no antimicrobial activities against five bacteria and eight fungi, and compounds 5, 8 and 9 exhibited inhibition against AChE with IC50 values of 45.9, 42.5 and 40.5 μg/mL. Molecular docking analysis was performed to explore the interactions between active molecules and AChE protein, which indicated that xanthone and anthraquinone derivatives had the potential for developing AChE inhibitors.

Cytotoxic pyridine alkaloids from a marine-derived fungus Arthrinium arundinis exhibiting apoptosis-inducing activities against small cell lung cancer

Small cell lung cancer (SCLC) is a kind of high-grade neuroendocrine carcinoma, which is characterized by a higher proliferative rate, earlier metastasis and more poor outcomes compared to non-small cell lung cancer (NSCLC). Under the guidance of MS/MS based molecular networking, three undescribed pyridone alkaloids, namely, arthpyrones M-O (1-3), together with two known pyridone derivatives, arthpyrones C (4) and G (5), were isolated from a sponge-derived Arthrinium arundinis. Their structures were determined through extensive spectroscopic analysis, ECD calculations, and X-ray single-crystal diffraction. Arthpyrone M (1) possessed a novel cage structure bearing an ether bridge functionality rarely reported in this class of metabolites. All isolated compounds were evaluated for their cytotoxicities against five cancer cell lines. As a result, compounds 1-5 showed cytotoxicity against some or all of the five cancer cell lines with IC₅₀ values ranging from 0.26 to 6.43 μM. Among them, arthpyrone O (3) not only exhibited potent efficacy against the proliferative activity of SCLC cells and induced apoptosis in vitro, but also significantly inhibited the growth of xenograft tumor based on SCLC cells in vivo, which indicated 4-hydroxy-2-pyridone alkaloids might been revised as privileged scaffolds in drug discovery.

Tanzawaic Acid Derivatives from the Marine-Derived Penicillium steckii as Inhibitors of RANKL-Induced Osteoclastogenesis

Seven new tanzawaic acid derivatives, steckwaic acids E-K (1-7), and one new benzene derivate (8), together with seven known tanzawaic acid analogues (9-16) were isolated from the marine algicolous fungus Penicillium steckii SCSIO 41040. The structures and absolute configurations of these new compounds (1-8) were determined by spectroscopic analyses, X-ray diffraction, and comparison of ECD spectra to calculations. Compounds 2, 10, and 15 inhibited lipopolysaccharide (LPS)-induced nuclear factor kappa-B (NF-κB) with IC₅₀ values of 10.4, 18.6, and 15.2 μM, respectively. Compound 2 could suppress the receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophage cells (BMMCs). To the best of our knowledge, this is the first report of osteoclastogenesis inhibitory activity for tanzawaic acid derivatives.

Design, Synthesis, and Anticancer Activity of Novel 3,6-Diunsaturated 2,5-Diketopiperazines

Based on the marine natural products piperafizine B, XR334, and our previously reported compound 4m, fourteen novel 3,6-diunsaturated 2,5-diketopiperazine (2,5-DKP) derivatives (1, 2, 4-6, 8-16), together with two known ones (3 and 7), were designed and synthesized as anticancer agents against the A549 and Hela cell lines. The MTT assay results showed that the derivatives 6, 8-12, and 14 had moderate to good anticancer capacities, with IC₅₀ values ranging from 0.7 to 8.9 μM. Among them, compound 11, with naphthalen-1-ylmethylene and 2-methoxybenzylidene functions at the 3 and 6 positions of 2,5-DKP ring, respectively, displayed good inhibitory activities toward both A549 (IC₅₀ = 1.2 μM) and Hela (IC₅₀ = 0.7 μM) cancer cells. It could also induce apoptosis and obviously block cell cycle progression in the G2/M phases in both cells at 1.0 μM. The electron-withdrawing functions might not be favorable for the derivatives with high anticancer activities. Additionally, compared to piperafizine B and XR334, these semi-N-alkylated derivatives have high liposolubilities (>1.0 mg mL^-1). Compound 11 can be further developed, aiming at the discovery of a novel anticancer candidate.

Novel Biomass-Based Polymeric Dyes: Preparation and Performance Assessment in the Dyeing of Biomass-Derived Aldehyde-Tanned Leather

High-performance chrome-free leather production is currently one of the most concerning needs to warrant the sustainable development of the leather industry due to the serious chrome pollution. Driven by these research challenges, this work explores using biobased polymeric dyes (BPDs) based on dialdehyde starch and reactive small-molecule dye (reactive red 180, RD-180) as novel dyeing agents for leather tanned using a chrome-free, biomass-derived aldehyde tanning agent (BAT). FTIR, ¹H NMR, XPS, and UV-visible spectrometry analyses indicated that a Schiff base structure was generated between the aldehyde group of dialdehyde starch (DST) and the amino group of RD-180, resulting in the successful load of RD-180 on DST to produce BPD. The BPD could first penetrate the BAT-tanned leather efficiently and then be deposited on the leather matrix, thus exhibiting a high uptake ratio. Compared with the crust leathers prepared using a conventional anionic dye (CAD), dyeing, and RD-180 dyeing, the BPD-dyed crust leather not only had better coloring uniformity and fastness but it also showed a higher tensile strength, elongation at break, and fullness. These data suggest that BPD has the potential to be used as a novel sustainable polymeric dye for the high-performance dyeing of organically tanned chrome-free leather, which is paramount to ensuring and promoting the sustainable development of the leather industry.

Hydrothermal conversion of biomass to fuels, chemicals and materials: A review holistically connecting product properties and marketable applications

Biomass is a renewable and carbon-neutral resource with good features for producing biofuels, biochemicals, and biomaterials. Among the different technologies developed to date to convert biomass into such commodities, hydrothermal conversion (HC) is a very appealing and sustainable option, affording marketable gaseous (primarily containing H₂, CO, CH₄, and CO₂), liquid (biofuels, aqueous phase carbohydrates, and inorganics), and solid products (energy-dense biofuels (up to 30 MJ/kg) with excellent functionality and strength). Given these prospects, this publication first-time puts together essential information on the HC of lignocellulosic and algal biomasses covering all the steps involved. Particularly, this work reports and comments on the most important properties (e.g., physiochemical and fuel properties) of all these products from a holistic and practical perspective. It also gathers vital information addressing selecting and using different downstream/upgrading processes to convert HC reaction products into marketable biofuels (HHV up to 46 MJ/kg), biochemicals (yield >90 %), and biomaterials (great functionality and surface area up to 3600 m²/g). As a result of this practical vision, this work not only comments on and summarizes the most important properties of these products but also analyzes and discusses present and future applications, establishing an invaluable link between product properties and market needs to push HC technologies transition from the laboratory to the industry. Such a practical and pioneering approach paves the way for the future development, commercialization and industrialization of HC technologies to develop holistic and zero-waste biorefinery processes.

Ochrathinols A and B, two pairs of sulfur-containing racemates from an Antarctic fungus Aspergillus ochraceopetaliformis SCSIO 05702 inhibit LPS-induced pro-inflammatory cytokines and NO production

Ochrathinols A and B ((±)-1 and (±)-2), two undescribed sulfur-containing racemates, and ochracids A and B (3 and 4), two unprecedented pyrrolizidine alkaloids, were isolated from an Antarctic soil-derived fungus Aspergillus ochraceopetaliformis SCSIO 05702. Their structures including absolute configurations were determined through extensive spectroscopic analysis, chiral-phase HPLC analysis, quantum ECD calculations, and X-ray single-crystal diffraction. Ochrathinols A and B are unprecedented sulfur natural products featuring a novel 3-methylhexahydro-2H-cyclopenta [b]thiophene core. Interestingly, ochrathinol A ((±)-1) outstandingly suppressed the release of LPS-induced IL-1β, IL-6, and TNF-α inflammatory cytokines with concentration of 10 μM and alleviated the unbalanced NAD⁺/NADH ratio caused by LPS in RAW264.7 macrophages.

Structurally various p-terphenyls with neuraminidase inhibitory from a sponge derived fungus Aspergillus sp. SCSIO41315

Guided by Global Natural Products Social molecular networking, 14 new p-terphenyl derivatives, asperterphenyls A-N (1-14), together with 20 known p-terphenyl derivatives (15-34), were obtained from a sponge derived fungus Aspergillus sp. SCSIO41315. Among them, new compounds 2-8 and 15-17 were ten pairs of enantiomers. Comprehensive methods such as chiral-phase HPLC analysis, ECD calculations and X-ray diffraction analysis were applied to determine the absolute configurations. Asperterphenyls B (2) and C (3) represented the first reported natural p-terphenyl derivatives possessing a dicarboxylic acid system. Asperterphenyl A (1) displayed neuraminidase inhibitory activity with an IC₅₀ value of 1.77 ± 0.53 µM and could efficiently inhibit infection of multiple strains of H1N1 with IC₅₀ values from 0.67 ± 0.28 to 1.48 ± 0.60 µM through decreasing viral plaque formation in a dose-dependent manner, which suggested that asperterphenyl A (1) might be exploited as a potential antiviral compound in the pharmaceutical fields.

Liver Protection of a Low-Polarity Fraction from Ficus pandurata Hance, Prepared by Supercritical CO2 Fluid Extraction, on CCl4-Induced Acute Liver Injury in Mice via Inhibiting Apoptosis and Ferroptosis Mediated by Strengthened Antioxidation

Ficus pandurata Hance (FPH) is a Chinese herbal medicine widely used for health care. This study was designed to investigate the alleviation efficacy of the low-polarity ingredients of FPH (FPHLP), prepared by supercritical CO₂ fluid extraction technology, against CCl₄-induced acute liver injury (ALI) in mice and uncover its underlying mechanism. The results showed that FPHLP had a good antioxidative effect determined by the DPPH free radical scavenging activity test and T-AOC assay. The in vivo study showed that FPHLP dose-dependently protected against liver damage via detection of ALT, AST, and LDH levels and changes in liver histopathology. The antioxidative stress properties of FPHLP suppressed ALI by increasing levels of GSH, Nrf2, HO-1, and Trx-1 and reducing levels of ROS and MDA and the expression of Keap1. FPHLP significantly reduced the level of Fe²⁺ and expression of TfR1, xCT/SLC7A11, and Bcl2, while increasing the expression of GPX4, FTH1, cleaved PARP, Bax, and cleaved caspase 3. The results demonstrated that FPHLP protected mouse liver from injury induced by CCl₄ via suppression of apoptosis and ferroptosis. This study suggests that FPHLP can be used for liver damage protection in humans, which strongly supports its traditional use as a herbal medicine.

Secondary Metabolites from Coral-Associated Fungi: Source, Chemistry and Bioactivities

Our study of the secondary metabolites of coral-associated fungi produced a valuable and extra-large chemical database. Many of them exhibit strong biological activity and can be used for promising drug lead compounds. Serving as an epitome of the most promising compounds, which take the ultra-new skeletons and/or remarkable bioactivities, this review presents an overview of new compounds and bioactive compounds isolated from coral-associated fungi, covering the literature from 2010 to 2021. Its scope included 423 metabolites, focusing on the bioactivity and structure diversity of these compounds. According to structure, these compounds can be roughly classified as terpenes, alkaloids, peptides, aromatics, lactones, steroids, and other compounds. Some of them described in this review possess a wide range of bioactivities, such as anticancer, antimicrobial, antifouling, and other activities. This review aims to provide some significant chemical and/or biological enlightenment for the study of marine natural products and marine drug development in the future.

Three unusual hybrid sorbicillinoids with anti-inflammatory activities from the deep-sea derived fungus Penicillium sp. SCSIO06868

Under the guidance of MS/MS based molecular networking, bisorbicillchaetones A-C, three undescribed hybrid sorbicillinoids, were isolated from cultures of the deep-sea derived fungus Penicillium sp. SCSIO06868. The planar structures and absolute configurations of these compounds were determined by extensive spectroscopic analyses. Bisorbicillchaetones are the first examples of hybrid sorbicillinoids containing a coniochaetone unit. Bisorbicillchaetones A and B exhibited moderate inhibitory effect on NO production in LPS activated RAW264.7 cells with the IC₅₀ values of 80.3 ± 3.6 μM and 38.4 ± 3.3 μM, respectively, without cytotoxicity observed.

Output-Only Time-Varying Modal Parameter Identification Method Based on the TARMAX Model for the Milling of a Thin-Walled Workpiece

The process parameters chosen for high-performance machining in the milling of a thin-walled workpiece are determined by a stability prediction model, which needs accurate modal parameters of the machining system. However, the in-process modal parameters are different from the offline modal parameters and are difficult to precisely obtain due to material removal. To address this problem, an accurate time-dependent autoregressive moving average with an exogenous input (TARMAX) method is proposed for the identification of the modal parameters in the milling of a thin-walled workpiece. In this process, a TARMAX model considering external force excitation is constructed to characterize the actual condition in the milling of a thin-walled workpiece. Then, recursive method and sliding window recursive method are used to identify TARMAX model parameters under time-varying cutting conditions. Subsequently, a three-degree of freedom (3-DOF) time-varying structure numerical model under theoretical milling forces and white-noise excitation is established, and the computational results show that the predicted natural frequencies using the proposed method are in close agreement with the simulated values. Finally, several experiments are designed and carried out to validate the effectiveness of the proposed method. The experimental results show that the predicted accuracy of the proposed method using actual cutting forces is 95.68%. Good agreement has been drawn in the numerical simulation and machining experiments. Our further research objectives will focus on the prediction of the damping ratios, modal stiffness, and modal mass.

New diterpene and indole alkaloid analogues from the Streptomyces malaysiensis SCSIO 41397

One new cyclooctatin-type diterpenoid, 15-hydroxyl-cyclooctatin ( 1 ), and one new indole alkaloid, streptoprenylindole D ( 3 ), along with 9 known compounds, were isolated from the Streptomyces   malaysiensis  SCSIO 41397. Their structures were established on the basis of spectroscopic analysis, optical rotation, and by a comparison with data from the literature. All isolated compounds were evaluated for their antibacterial (MRSA), antitumor (22Rv1 and PC-3) and antiviral (HSV-1/2) activities. According to the analysis of biological gene clusters in the whole genome, we preliminarily locate the gene clusters related to the synthesis of 15-hydroxyl-cyclooctatin ( 1 ).

The Role of Mental Adjustment in Mediating Post-Traumatic Stress Disorder Symptoms and Social Support in Chinese Ovarian Cancer Patients: A Cross-Sectional Study

Background

Post-traumatic stress disorder (PTSD) can manifest in individuals following a traumatic event. There is a paucity of studies focusing on PTSD symptoms in ovarian cancer (OC) patients. This study aimed to investigate the association of social support, mental adjustment and PTSD symptoms in Chinese OC patients with a view to exploring whether mental adjustment could mediate the relationship.

Methods

A cross-sectional study was conducted from January 2015 to December 2016. A total of 171 OC subjects were recruited and the effective response rate was 81.3%. The PTSD Checklist-Civilian Version (PCL-C), Mini-Mental Adjustment to Cancer scale (Mini-MAC) and Duke-UNC Functional Social Support Questionnaire were disseminated to the patients. The Chinese Mini-MAC was used in this study focusing on three components, namely negative emotion, positive attitude, and cognitive avoidance. Hierarchical linear regression analyses were employed to investigate the association of social support and PTSD symptoms, and the role of mental adjustment in their mediation.

Results

The prevalence of PTSD symptoms was 17.3% in OC patients. PTSD symptoms were negatively related with both social support and positive attitude, and positively associated with negative emotion and cognitive avoidance. Social support was negatively associated with negative emotion and cognitive avoidance, and positively related with positive attitude. In addition, negative emotion and positive attitude mediated the association between social support and PTSD symptoms.

Conclusion

PTSD symptoms in OC patients should be paid attention to. Social support and mental adjustment were positive resources associated with PTSD symptoms. Moreover, mental adjustment could mediate the relation between social support and PTSD symptoms in OC patients. Therefore, intervention management that focusing on improving perceived social support as well as strengthening mental adjustment, especially negative emotion and positive attitude, may be useful for reducing PTSD symptoms in this context.

Orbital angular momentum spectrum of pin-like optical vortex beams in turbulent atmosphere

The analytical formula of the probability density of a single orbital angular momentum (OAM) mode for pin-like optical vortex beams (POVBs) in turbulent atmosphere is derived. Its OAM spectrum in the receiving plane is obtained by the numerical calculation. For comparison, the OAM spectrum of commonly Gaussian vortex beams is showed, too. Those results show that POVBs show good performance on resisting the cross talk of the OAM mode induced by the turbulence in some cases, such as smaller radius of the receiving aperture, longer propagation distance, and stronger turbulence. Our finding has application in free-space optical communication based on the OAM mode.

Topological flowers and spider webs in 3D vector fields

Topological structures currently are of special interest in the integration of singular optics and topological photonics. In this article, the topological flowers and spider webs, which got less attention comparing to the lemon-, star- structures of the same category, are investigated in 3D vector fields. We show that by strongly focusing higher-order singular beams, both the spin density (SD) vectors and the polarization states of the transverse fields on the focal plane exhibit flowers and spider webs structures in topology with 2|m - 1| folds/sectors (m is the beam order), and the topological structures of the SD vectors are demonstrated to have a 90°/|m - 1| rotation. On the other hand, the topological theory also needs to be developed according to the rapid growth of topological photonics. Here, by defining a 'relative topological charge', we have observed and analyzed the topological reactions of the loops (composed of SD singularities) rather than the 'point-type' singularities in conventional reactions. More specially, the 'radial index' and 'azimuthal index' are proposed to characterize the topological features of the flowers and spider webs, and have been verified that the 'radial index' is peculiar to 3D vector fields and proportional to 1/|m - 1| in general. Our work provides a way to describe the topological behaviors of groups of singularities and supplies new parameters for measuring the topological patterns in 3D vector fields, which will rich the topological theory and may have applications in topological photonics.

Anti-inflammatory alkaloids from the cold-seep-derived fungus Talaromyces helicus SCSIO41311

One new natural alkaloid, chaetominine B (1), together with twenty known compounds was isolated from the South China Sea cold-seep-derived fungus Talaromyces helicus SCSIO41311. Their structures were elucidated on the basis of nuclear magnetic resonance spectrum (NMR), mass spectrometry (MS) and ECD calculation, as well as comparing with previous literatures. Among them, twelve compounds showed potent NO inhibitory activities and two of them, azaspirofurans A (13) and fumiquinones B (21), exhibited NO inhibitory effects more than the positive control eicosapentaenoic acid (EPA) with IC₅₀ values of 9.65 and 15.54 μM, respectively. Moreover, compound 13 attenuated LPS-induced imbalance of cytokines release such as TNF-α, IL-1β, IL-4, and IL-10. Additionally, the NMR data and absolute configuration of compound 20 were first reported.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03237-9.

[Recent advances in the application of nanobody technology: a review]

As a malleable and novel tool for antigen recognition and modulation, nanobodies have the advantages of small size, easiness of expression, screening and modification, as well as high affinity and stability. Nanobodies are capable of recognizing more cryptic antigenic epitopes that are difficult to be recognized by traditional antibodies, making them increasingly used in the diagnosis and treatment of various diseases and assays. Nanobodies are also playing an irreplaceable role in the basic research. This review summarized the recent development of nanobodies and their derivatives in the detection of small molecules, pathogenic microorganisms and diagnosis of diseases, as well as in the fields of targeted therapies, cellular and molecular imaging. Broad prospects of nanobodies in the field of protein conformation studies were also reviewed.

Diversified Chaetoglobosins from the Marine-Derived Fungus Emericellopsis sp. SCSIO41202

Two undescribed cytochalasins, emeriglobosins A (1) and B (2), together with nine previously reported analogues (3–11) and two known tetramic acid derivatives (12, 13) were isolated from the solid culture of Emericellopsis sp. SCSIO41202. Their structures, including the absolute configurations of their stereogenic carbons, were fully elucidated based on spectroscopic analysis and the calculated ECD. Some of the isolated compounds were evaluated for their cytotoxicity and enzyme inhibitory activity against acetylcholinesterase (AChE) in vitro. Among them, 8 showed potent AChE inhibitory activity, with an IC₅₀ value of 1.31 μM, and 5 showed significant cytotoxicity against PC-3 cells, with an IC₅₀ value of 2.32 μM.

Asperbenzophenone A and Versicolamide C, New Fungal Metabolites from the Soft Coral Derived Aspergillus sp. SCSIO 41036

Two new compounds, asperbenzophenone A (1) and versicolamide C (5), together with fifteen known compounds were isolated from a soft coral derived fungus Aspergillus sp. SCSIO 41036. Their structures were elucidated by spectroscopic methods, ECD analysis, and by a comparison with data from the literature. In bioassay, compound 8 showed significant inhibitory activity against lipopolysaccharide-inducted nitric oxide (NO) in RAW264.7 cells at the concentration of 10 μM. Additionally, the anti-acetylcholinesterase activity assay showed that 14 exhibited weak inhibition with an IC₅₀ value of 157.8 μM.

Natural products from mangrove sediments-derived microbes: Structural diversity, bioactivities, biosynthesis, and total synthesis

The mangrove forests are a complex ecosystem, and the microbial communities in mangrove sediments play a critical role in the biogeochemical cycles of mangrove ecosystems. Mangrove sediments-derived microbes (MSM), as a rich reservoir of natural product diversity, could be utilized in the exploration of new antibiotics or drugs. To understand the structural diversity and bioactivities of the metabolites of MSM, this review for the first time provides a comprehensive overview of 519 natural products isolated from MSM with their bioactivities, up to 2021. Most of the structural types of these compounds are alkaloids, lactones, xanthones, quinones, terpenoids, and steroids. Among them, 210 compounds are obtained from bacteria, most of which are from Streptomyces, while 309 compounds are from fungus, especially genus Aspergillus and Penicillium. The pharmacological mechanisms of some representative lead compounds are well studied, revealing that they have important medicinal potentials, such as piericidins with anti-renal cell cancer effects, azalomycins with anti-MRSA activities, and ophiobolins as antineoplastic agents. The biosynthetic pathways of representative natural products from MSM have also been summarized, especially ikarugamycin, piericidins, divergolides, and azalomycins. In addition, the total synthetic strategies of representative secondary metabolites from MSM are also reviewed, such as piericidin A and borrelidin. This review provides an important reference for the research status of natural products isolated from MSM and the lead compounds worthy of further development, and reveals that MSM have important medicinal values and are worthy of further development.

Natural Products Targeting Liver X Receptors or Farnesoid X Receptor

Nuclear receptors (NRs) are a superfamily of transcription factors induced by ligands and also function as integrators of hormonal and nutritional signals. Among NRs, the liver X receptors (LXRs) and farnesoid X receptor (FXR) have been of significance as targets for the treatment of metabolic syndrome-related diseases. In recent years, natural products targeting LXRs and FXR have received remarkable interests as a valuable source of novel ligands encompassing diverse chemical structures and bioactive properties. This review aims to survey natural products, originating from terrestrial plants and microorganisms, marine organisms, and marine-derived microorganisms, which could influence LXRs and FXR. In the recent two decades (2000-2020), 261 natural products were discovered from natural resources such as LXRs/FXR modulators, 109 agonists and 38 antagonists targeting LXRs, and 72 agonists and 55 antagonists targeting FXR. The docking evaluation of desired natural products targeted LXRs/FXR is finally discussed. This comprehensive overview will provide a reference for future study of novel LXRs and FXR agonists and antagonists to target human diseases, and attract an increasing number of professional scholars majoring in pharmacy and biology with more in-depth discussion.

A Novel Updated Full-Discretization Method for Prediction of Milling Stability

This paper presents an updated full-discretization method for milling stability prediction based on cubic spline interpolation. First, the mathematical model of the time-delay milling system considering regenerative chatter is represented by a dynamic delay differential equation. Then, in a single tooth passing period, the time is divided into a finite time intervals, the state item and the time-delay item are approximated in each time interval by cubic spline interpolation and third-order Newton interpolation, respectively. Afterward, a transition matrix is constructed to represent the transfer relationship of the teeth in a period. Finally, based on Floquet theory, the milling stability lobes can be obtained. Meanwhile, in order to improve computational efficiency, an optimized method is proposed based on the traditional algorithm and the proposed method has high precision without losing high efficiency. Finally, several milling experiments are conducted to verify the accuracy of the proposed method, and the results show that the predicted results agree well with the experimental results.

p-Terphenyls as Anti-HSV-1/2 Agents from a Deep-Sea-Derived Penicillium sp

Guided by Global Natural Products Social molecular networking, two p-terphenyl derivatives and one 4,5-diphenyl-2-pyrone analogue, peniterphenyls A-C (1-3), together with five known p-terphenyl derivatives (4-8) and sulochrin (9), were obtained from a deep-sea-derived Penicillium sp. SCSIO41030. Their structures were elucidated using extensive NMR spectroscopic and HRESIMS data and by comparing the information with literature data. Peniterphenyl B (2) represented the first reported natural product possessing a 4,5-diphenyl-substituted 2-pyrone derivative. The p-terphenyl derivatives displayed inhibitory activities against HSV-1/2 with EC₅₀ values ranging from 1.4 ± 0.6 to 9.3 ± 3.7 μM in Vero cells, which showed that they possessed antiviral activities with low cytotoxicity, superior to the current clinical drug acyclovir (EC₅₀ 3.6 ± 0.7 μM). Peniterphenyl A (1) inhibited HSV-1/2 virus entry into cells and may block HSV-1/2 infection through direct interaction with virus envelope glycoprotein D to interfere with virus adsorption and membrane fusion, and thus differs from the nucleoside analogues such as acyclovir. Our study indicated peniterphenyl A (1) could be a promising lead compound against HSV-1/2.

New Tetramic Acid Derivatives From the Deep-Sea-Derived Fungus Penicillium sp. SCSIO06868 With SARS-CoV-2 Mpro Inhibitory Activity Evaluation

Three new tetramic acid derivatives (1–3) and a new polyketide (4) along with eight known compounds (5–12) were isolated from cultures of the deep-sea-derived fungus Penicillium sp. SCSIO06868. Four new structures were elucidated by analysis of one-dimensional/two-dimensional nuclear magnetic resonance (NMR) data and high-resolution electrospray ionization mass spectrometry. Their absolute configurations were established by X-ray crystallography analysis and comparison of the experimental and reported electronic circular dichroism (ECD) values or specific optical rotation. Compound 3 exhibited potent, selective inhibitory activities against Staphylococcus aureus and methicillin-resistant S. aureus with minimum inhibitory concentration values of both 2.5 μg/ml. Also, compound 3 showed weak antiviral activity against severe acute respiratory syndrome coronavirus 2 main protease, which was responsible for the coronavirus disease 2019 pandemic.

Preparation of aerogel and its application progress in coatings: a mini overview

Aerogels are predominantly mesoporous, extremely lightweight, low density (∼ 0.003 g/cm3) and thermally insulating materials. Over the years, aerogels have gained increasing attention due to their extraordinary properties (light, heat, sound, electricity and force) and application potentials in varieties of fields. Several studies have been carried out regarding aerogel preparation and its applications in coatings on different substrates. In this review, an overview of aerogels preparation and their application progress in coatings of most common substrates is presented. Attention is paid to aerogel coatings of textiles, leather, and substrates other than leather and textiles for special functionalities that could address the application progress in coatings. This review will help to inspire scientists and engineers towards novel aerogel materials and technologies to boost the industrial fabrication of flexible advanced materials.

Cytotoxic Minor Piericidin Derivatives from the Actinomycete Strain Streptomyces psammoticus SCSIO NS126

The mangrove-sediment-derived actinomycete strain Streptomyces&nbsp;psammoticus SCSIO NS126 was found to have productive piericidin metabolites featuring anti-renal cell carcinoma activities. In this study, in order to explore more diverse piericidin derivatives, and therefore to discover superior anti-tumor lead compounds, the NS126 strain was further fermented at a 300-L scale under optimized fermentation conditions. As a result, eight new minor piericidin derivatives (piericidins L-R (1-7) and 11-demethyl-glucopiericidin A (8)) were obtained, along with glucopiericidin B (9). The new structures including absolute configurations were determined by spectroscopic methods coupled with experimental and calculated electronic circular dichroism. We also proposed plausible biosynthetic pathways for these unusual post-modified piericidins. Compounds 1 and 6 showed selective cytotoxic activities against OS-RC-2 cells, and 2-5 exhibited potent cytotoxicity against HL-60 cells, with IC₅₀ values lower than 0.1 μM. The new piericidin glycoside 8 was cytotoxic against ACHN, HL-60 and K562, with IC₅₀ values of 2.3, 1.3 and 5.5 μM, respectively. The ability to arrest the cell cycle and cell apoptosis effects induced by 1 and 6 in OS-RC-2 cells, 2 in HL-60 cells, and 8 in ACHN cells were then further investigated. This study enriched the structural diversity of piericidin derivatives and confirmed that piericidins deserve further investigations as promising anti-tumor agents.

Cyclopentenone-Containing Tetrahydroquinoline and Geldanamycin Alkaloids from Streptomyces malaysiensis as Potential Anti-Androgens against Prostate Cancer Cells

Malaymycin (1), a new cyclopentenone-containing tetrahydroquinoline alkaloid, and mccrearamycin E (2), a geldanamycin analogue bearing a rare ring-contracted cyclopentenone moiety, and a C₂-symmetric macrodiolide (7) were isolated from Streptomyces malaysiensis SCSIO41397. Their structures including absolute configurations were determined by detailed analyses of NMR and HRMS data and ECD calculations. The occurrence of mccrearamycin E (2) bearing a ring-contracted cyclopentenone is rare in the geldanamycin class. All isolated compounds were evaluated for their cytotoxicities against five cancer cell lines. As a result, compounds 1, 4, 5, and 7 showed cytotoxicity against some or all of the five cancer cell lines with IC₅₀ values ranging from 0.067 to 7.2 μM. In particular, compound 1 inhibited the growth of C42B and H446 cell lines with IC₅₀ values of 67 and 70 nM, respectively. Malaymycin (1) significantly induced cell cycle arrest at the G0/G1 phase in C42B cell lines and caused cell shrinkage and inhibited the expression of the androgen receptor (AR) at both the mRNA and protein levels in a dose-dependent manner. Further examination by qRT-PCR analysis showed that 1 strongly suppressed the expression of AR target genes KLK2 and KLK3 in the C42B and 22RV1 cell lines, which suggested that 1 might be a promising potential lead compound for the development of a treatment for the castration-resistant prostate cancer (CRPC).

Metabolic activation of retrorsine may disrupt bile acid homeostasis in mice through the Nrf2 pathway

BACKGROUND

The hepatotoxic pyrrolizidine alkaloids (PAs) were reported to increase bile acid (BA) levels in rat. However, it is still unclear whether the production of highly reactive dehydropyrrolizidine through CYP450s is directly relevant to BA changes.

OBJECTIVE

To further explore the mechanism by which metabolic activation of PAs induced BA changes, the effect of impaired or enhanced metabolic activation on the BA profiling and BA-related synthesis and transport genes were investigated and the involvement of Nrf2 pathway were explored.

METHODS

Blood and liver samples were collected after intragastrical administration of 35 mg/kg retrorsine or saline for seven days in wild-type (WT) and Nrf2 KO mice. CYP450 inhibitor, 1-aminobenzotriazole (ABT), or gamma-glutamylcysteine synthetase inhibitor, L-buthionine-sulfoximine (BSO) were employed in WT mice. Retrorsine-induced hepatotoxicity was evaluated by a biochemical method and H&E staining method. Serum BAs were quantified by high-performance liquid chromatography/triple quadrupole mass spectrometry. Blood pyrrole-protein adducts were semiquantified by high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. The gene and protein expression of BA-related transporters and enzymes in the liver were measured by a quantitative real-time PCR method and western blotting method.

RESULTS

The BA concentrations in serum were increased in the retrorsine-treated WT mice, along with the up-regulation of BA transporters, Ostβ, Mrp3, Mrp4, and Mrp2. When ABT was co-administered, the altered BA levels and Mrp4 mRNA and protein levels were reversed, accompanied by a 50% reduction of 6,7-dihydro-7-hydroxy-1- hydroxymethyl-5H-pyrrolizine (DHP) formation. When BSO was co-administered, serum BAs were not further increased but Ostβ, Mrp3, Mrp4 mRNA, and Mrp4 protein level continuously increased. The induction of Mrp4 by retrorsine among the tested BA transporters was the only one that was abolished or enhanced in the presence of ABT or BSO. The Nrf2 protein levels in the nucleus increased in the retrorsine-treated WT mice, which were remarkably repressed by co-administration of ABT and enhanced by co-administration of BSO. In Nrf2 KO mice receiving retrorsine, the bile acids and the mRNA and protein levels of Mrp2, Mrp3, Mrp4, and Ostβ were hardly changed, indicating the direct role of Nrf2 in retrorsine-induced BA changes in WT mice.

CONCLUSION

The activation of Nrf2 translocation by the formation of the reactive metabolite of PAs induced the expressions of BA transporters and changed serum BA levels. Mrp4 was a sensitive biomarker for the perturbation of redox status caused by the formation of dehydropyrrolizidine.

Discovery of a Dimeric Zinc Complex and Five Cyclopentenone Derivatives from the Sponge-Associated Fungus Aspergillus ochraceopetaliformis

In devotion to investigating structurally novel and biologically active marine natural products, a dimer of a zinc complex, dizinchydroxyneoaspergillin (1), aspernones A-E (2-6), five cyclopentenone derivatives together with known polyketides (7-10), and neoaspergillic acid analogues (11-14) were isolated from the sponge-associated fungus Aspergillus ochraceopetaliformis SCSIO 41018. Their structures were elucidated on the basis of spectroscopic analysis, electronic circular dichroism (ECD) analysis, and X-ray diffraction. Dizinchydroxyneoaspergillin (1) displayed significant bactericide effects toward methicillin-resistant Staphyloccocus aureus, Staphyloccocus aureus, Enterococcus faecalis, Acinetobacter baumannii, and Klebsiella pneumonia with MIC values of 0.45-7.8 μg/mL and moderate in vitro cytotoxic activities against the K562, BEL-7402, and SGC-7901 cell lines with IC₅₀ values of 12.88 ± 0.14, 15.83 ± 0.23, and 15.08 ± 0.62 μM, respectively. This is the first time to report the dimer of the zinc complex of hydroxyneoaspergillic acid conjunction at Zn-N-4 by a coordination bond. Additionally, compound 1 displayed significant antibacterial and cytotoxic activities, which would be a promising drug lead and could attract much attention from both chemists and pharmacists.

Dual Action of Acidic Microenvironment on the Enrichment of the Active Metabolite of Disulfiram in Tumor Tissues

Disulfiram, an antialcoholism drug, could potentially be repurposed as an anticancer drug because of the formation of copper(II) diethyldithiocarbamate (CuET) from dithiocarb (DTC, a reduced metabolite of disulfiram) and Cu²⁺ CuET exhibited preferential distribution to tumor tissues. This study investigated the mechanism of CuET accumulation in tumor tissues by employing MDA-MB-231 human breast cancer cells. The concentration of CuET in cells treated with DTC and Cu²⁺ in acidic culture medium (pH 6.8) was significantly higher than that of the control group (pH 7.4). Subsequently, the effects of pH on the uptake of DTC, Cu²⁺, and CuET were investigated separately. The acidic environment significantly increased the uptake rate of DTC and Cu²⁺ but had no effect on CuET. MDA-MB-231 cells overexpressing copper transporter hCTR1 were constructed to evaluate its intermediate role in CuET accumulation. After treatment with CuCl₂ followed by DTC for 15 minutes, the levels of CuET and Cu²⁺ in hCTR1-overexpressed cells were 2.5 times as much as those of vector group. In the tumors of cancer xenograft models constructed by hCTR1-MDA-MB-231 cells, the concentrations of CuET and Cu were also significantly higher than those of control group. In conclusion, the acidic microenvironment of tumors can promote the enrichment of CuET in tumors through dual action. On the one hand, it can promote transmembrane transport of DTC by converting ionic DTC into molecular state. On the other hand, it enhances Cu²⁺ uptake by activating hCTR1, which ultimately leads to the enrichment of CuET. SIGNIFICANCE STATEMENT: Increasing evidence suggests that the antitumor activity of disulfiram is related to the formation of a copper(II) diethyldithiocarbamate (CuET) of its reducing metabolite dithiocarb with copper(II) ion, which is preferentially distributed in tumor tissues. We showed that the acidic microenvironment, a common feature of many solid tumor tissues, could promote intracellular CuET accumulation through dual action without changing CuET uptake. This result is helpful for the formulation of clinical dosage regimens of disulfiram in cancer treatment.

Optimal reference genes for real-time quantitative PCR and the expression of sigma factors in Acidithiobacillus caldus under various conditions

AIMS

Acidithiobacillus caldus is an important sulphur-oxidizing bacterium that plays crucial roles in the bioleaching industry. This study aims to analyse the optimal reference gene for real-time quantitative PCR (RT-qPCR) under different conditions and investigate the transcription levels of the sigma factor genes in the stress response.

METHODS AND RESULTS

We selected six housekeeping genes and analysed them via RT-qPCR using two energy resources, under four stress conditions. Three statistical approaches BestKeeper, geNorm, and NormFinder were utilized to determine transcription stability of these reference genes. The gapdH gene was the best internal control gene using elemental sulphur as an energy resource and under heat stress, map was the best internal control gene under pH and osmotic stress, era was the best internal control gene for the K₂ S₄ O₆ energy resource, and rpoC was the best internal control gene under Cu²⁺ stress. Furthermore, the expressional levels of 11 sigma factors were analysed by RT-qPCR in the stress response.

CONCLUSIONS

Stable internal control genes for RT-qPCR analysis of A. caldus were determined, and the expression patterns of sigma factor genes of A. caldus were investigated.

SIGNIFICANCE AND IMPACT OF THE STUDY

The identification of the optimal reference gene and analysis of transcription levels of sigma factors in A. caldus can provide clues for reference gene selection and the study of sigma factor function.

Investigations on the general properties of biomass-based aldehyde tanned sheep fur for its selective post-tanning processing

Abstract

Dialdehyde sodium alginate (DSA) is an alternative chrome-free tanning material for fur production. To obtain satisfactory resultant fur and provide suggestions for the usage of DSA in fur making, the general properties of DSA tanned sheep fur were systematically investigated. The tanning mechanism of DSA was analyzed and it was verified that DSA was mainly combined with collagen fiber by forming Schiff base covalent bonds while supplemented by a small number of hydrogen bonds and ionic bonds. Due to the acid sensitivity of Schiff base structure, DSA tanned fur had poor resistance to acid rinsing but had excellent resistance to washing and good fatliquoring performance. Also, it had good resistances to yellowing and reductant. After being retanned by chrome tanning agent, the fur was capable of enduring a high-temperature dyeing process (68 °C for 8 h). Overall, DSA tanned sheep fur had favorable properties under appropriate post-tanning processing conditions to manufacture light-colored or dark-colored fur products with desirable physical properties.

Graphical abstract

Structurally various sorbicillinoids from the deep-sea sediment derived fungus Penicillium sp. SCSIO06871

Two new hybrid sorbicillinoids (1 and 5), three new bisorbicillinoids (2-4), and three monomeric sorbicillinoids (6-8), along with eighteen known sorbicillinoids (9-26) were isolated from cultures of the deep-sea sediment derived fungus Penicillium sp. SCSIO06871. Their structures and absolute configurations were elucidated based upon the extensive spectroscopic analysis, X-ray crystallography analysis and the comparison of the experimental and calculated ECD data. Bisorbicillpyrone A (4) is the first example of bisorbicillinoid containing an α-pyrone derivative unit. All of the isolated compounds were evaluated for their antibacterial, antifungal and enzyme inhibitory activities against α-glycosidase and acetylcholinesterase (AChE) in vitro. Compound 6 displayed more potent inhibitory activity against α-glycosidase than acarbose with IC₅₀ value of 36.0 μM and compounds 4, 12, 18, 22, 23 exhibited moderate inhibitory activity with IC₅₀ values ranging from 115.8 to 208.5 μM. Compounds 10 and 22 showed weak enzyme inhibitory activities against AChE with 55.1% and 51.1% inhibitions at concentration of 50 μg/mL, respectively. Besides, compounds 11 and 12 exhibited significant antibacterial activities against Staphylococcus aureus with MIC values of 10.0 and 5.0 μg/mL, respectively. The hypothetical biosynthetic pathway of the isolated sorbicillinoids with three different structural types was discussed.

CYP2C and CYP2B Mediated Metabolic Activation of Retrorsine in Cyp3a Knockout Mice

Background:

Retrorsine is one of the hepatotoxic pyrrolizidine alkaloids, which could be converted into a highly reactive metabolite, dehydroretrorsine, by CYP3A, and to a lesser extent by CYP2C and CYP2B.

Objective:

We employed Cyp3a knockout (3AKO) mice to investigate whether the absence of CYP3A could attenuate dehydroretrorsine formation and the role of CYP2C and CYP2B in the formation.

Methods:

Blood and liver samples were collected after intragastrical administration of 35 mg/kg retrorsine or saline for seven days in wild-type (WT) and 3AKO mice. Blood pyrrole-protein adducts were semi quantified by high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. The formations of glutathionyl-6,7-dihydro-1-hydroxymethyl-5H-pyrrolizine (GSH-DHP) and the activities of CYP3A, CYP2B and CYP2C were evaluated in the liver microsomes of WT and 3AKO mice before and after treatment. The metabolic phenotype of retrorsine was determined in human liver microsomes. The gene and protein expression of retrorsine metabolism-related CYP450s in the liver was measured by quantitative real-time PCR method and western blotting method. The serum cytokine level was detected by the ELISA method to reveal the potential mechanism of Cyp3a, Cyp2b and Cyp2c downregulation.

Results:

After an oral administration of 35 mg/kg retrorsine for seven days, the blood exposures of DHP adducts between WT and 3AKO mice were similar, consistent with the comparable formation of GSH-DHP in their liver microsomes. The chemical inhibitor experiment in liver microsomes indicated the predominant role of CYP3A and CYP2C in GSH-DHP formation in WT and 3AKO mice, respectively. Real-time qPCR analysis showed that the expressions of Cyp2b10 and Cyp2cs increased 2.3-161-fold in 3AKO mice, which was consistent with protein changes. The increased CYP2B activity in 3AKO mice supported the potential role of CYP2B in GSH-DHP formation. After a seven-day treatment of retrorsine, the yields of GSH-DHP were lower than the untreated ones in both alleles, accompanied by the decreased mRNA of Cyp3a, Cyp2b and Cyp2c. The increased serum IL6 might mediate the retrorsine-induced downregulation of Cyp450s.

Conclusion:

These data demonstrated the increased transcription of Cyp2c and Cyp2b caused by Cyp3a ablation, which played a vital role in the metabolic activation of retrorsine, and long-term exposure of retrorsine can reduce the CYP450 activities.

Constructing a robust chrome-free leather tanned by biomass-derived polyaldehyde via crosslinking with chitosan derivatives

Tanning leather using green biomass-derived polyaldehyde (BPA) is a promising approach to eliminate the widespread Cr pollution in leather industry, but unsatisfactory thermal stability and mechanical strength of the correlated resultant leather limited its industrial application. Herein, we report a green methodology to strengthen BPA tanned leather via introducing chitosan derivatives to crosslink with free aldehyde groups on dialdehyde carboxymethylcellulose (DCMC) tanned leather. H₂O₂ was employed for purposely modifying chitosan to prepare low-molecular chitosan (LMC) with lower positive charge. The interactions between chitosan/LMC and DCMC were investigated to elucidate the strengthening mechanism. Owing to the weakened hydrogen bonding network and higher accessibility of amino groups on LMC, LMC could react much easier with aldehyde groups on DCMC. Moreover, LMC could efficiently penetrate into the internal fiber networks of leather for further interlocking, which enhanced the thermal stability and the lubricating degree of crust leather and, as a result, the tensile and tear strengths were significantly improved by 79.3% and 25.3%, respectively. Therefore, the use of LMC can promote the widespread application of BPA tanned leather, benefiting to the complete elimination of hazardous Cr pollution.

Optical rogue waves in coupled fiber Raman lasers

For coupled linear cavity-random fiber Raman lasers, for the first time, to the best of our knowledge, we demonstrate a new mechanism of emergence of the random pulses, with the anomalous statistics satisfying optical rogue waves' criteria experimentally. The rogue waves appear as a result of the coupling of two Raman cascades, namely, a linear cavity laser with a wavelength of 1.55 µm and a random laser with a wavelength nearly 1.67 µm, along with coupling of the orthogonal states of polarization (SOPs). The coherent coupling of SOPs causes localization of the trajectories in the vicinity of these states, whereas polarization instability drives escape taking the form of chaotic oscillations. Antiphase dynamics in two cascades result in the suppression of low amplitude chaotic oscillations and enable the anomalous spikes, satisfying rogue waves criteria.