Polyketides with α-glucosidase inhibitory and neuroprotective activities from Aspergillus versicolor associated with Pedicularis sylvatica.

Aspergillus versicolor, an endophytic fungus associated with the herbal medicine Pedicularis sylvatica, produced four new polyketides, aspeversins A-D (1-2 and 5-6) and four known compounds, O-methylaverufin (2), aversin (3), varilactone A (7) and spirosorbicillinol A (8). Their structures were elucidated by extensive spectroscopic data analysis, and their absolute configurations were determined by calculated electronic circular dichroism (ECD) and Mo2(AcO)4-induced CD data. Compound 5 was found to exhibit α-glucosidase inhibitory activity with an IC50 value of 25.57 µM. An enzyme kinetic study indicated that 5 was a typical uncompetitive inhibitor toward α-glucosidase, which was supported by a molecular docking study. Moreover, compounds 1-3 and 5 also improved the cell viability of PC12 cells on a 1-methyl-4-phenylpyridinium (MPP+)-induced Parkinson's disease model, indicating their neuroprotective potential as antiparkinsonian agents.

Optimizing the prognostic capacity of baseline 18F-FDG PET/CT metabolic parameters in extranodal natural killer/T-cell lymphoma by using relative and absolute thresholds.

Objectives: To investigate the prognostic capacity of baseline 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) metabolic parameters in extranodal natural killer/T-cell lymphoma (ENKTCL), and the influence of relative thresholds (RT) and absolute thresholds (AT) selection on prognostic capacity. Materials and methods: Metabolic tumor volume (MTV)-based parameters were defined using RTs (41 % or 25 % of maximum standardized uptake value [SUVmax]), ATs (SUV 2.5, 3.0, 4.0, or mean liver uptake) in 133 patients. Metabolic parameters were classified into avidity-related parameters (SUVmax, mean SUV [SUVmean], standard deviation of SUV [SUVsd]), volume-related parameters (RT-MTV), and avidity- and volume-related parameters (total lesion glycolysis [TLG] and AT-MTV). The prognostic capacity of the metabolic parameters and the effects of different threshold types (RT vs. AT) were evaluated. Results: All metabolic parameters were moderately associated with prognosis. However, the area under the receiver operating characteristic curve of MTV and TLG was slightly higher than that of avidity-related parameters for predicting 5-year progression-free survival (PFS) (0.614-0.705 vs. 0.563-0.609) and overall survival (OS) (0.670-0.748 vs. 0.562-0.593). Correlations of MTV and avidity-related parameters differed between RTs (r < 0.06, P = 0.324-0.985) and ATs (r 0.56-0.84, P ≤ 0.001). AT-MTV was the optimal predictor for PFS and OS, while RT-TLG was the optimal predictor for PFS, and the combination of RT-MTV with SUVmax was the optimal predictor for OS. Conclusion: The incorporation of volume and avidity significantly improved the prognostic capacity of PET in ENKTCL. Composite parameters that encompassed both avidity and volume were recommended.

Prediction of 5-year overall survival of diffuse large B-cell lymphoma on the pola-R-CHP regimen based on 2-year event-free survival and progression-free survival.

This study aimed to predict the 5-year overall survival (OS) benefit of pola-R-CHP versus R-CHOP in the POLARIX trial based on the 2-year event-free survival (EFS) and progression-free survival (PFS) rates in diffuse large B-cell lymphoma (DLBCL). We identified randomized controlled trials (RCT) published before 31 May 2023. The correlation between the logarithmic (log) hazard ratio (HR) for EFS (HREFS ) or PFS (HRPFS ) and the HR for OS (HROS ) was estimated at the trial-level. Correlation analysis was performed between 2-year PFS or EFS and 5-year OS rates at the treatment arm-level. Linear regression models were used to calculate the 5-year OS of pola-R-CHP and R-CHOP. In the included 20 RCTs, a linear correlation between HREFS (r = 0.765) or HRPFS (r = 0.534) and HROS was observed at the trial- level. Two-year EFS (r = 0.918) or 2-year PFS (r = 0.865) correlated linearly with 5-year OS. Linear regression analysis between 2-year EFS/PFS and 5-year OS gave estimated 5-year OS rates between pola-R-CHP and R-CHOP of 6.4% and 6.3%, respectively. Two-year EFS and PFS are feasible early endpoints in patients with DLBCL treated primarily with immunochemotherapy. The pola-R-CHP regimen is expected to improve 5-year OS.

Bioinspired light-driven chloride pump with helical porphyrin channels.

Halorhodopsin, a light-driven chloride pump, utilizes photonic energy to drive chloride ions across biological membranes, regulating the ion balance and conveying biological information. In the light-driven chloride pump process, the chloride-binding chromophore (protonated Schiff base) is crucial, able to form the active center by absorbing light and triggering the transport cycle. Inspired by halorhodopsin, we demonstrate an artificial light-driven chloride pump using a helical porphyrin channel array with excellent photoactivity and specific chloride selectivity. The helical porphyrin channels are formed by a porphyrin-core star block copolymer, and the defects along the channels can be effectively repaired by doping a small number of porphyrins. The well-repaired porphyrin channel exhibits the light-driven Cl- migration against a 3-fold concentration gradient, showing the ion pumping behavior. The bio-inspired artificial light-driven chloride pump provides a prospect for designing bioinspired responsive ion channel systems and high-performance optogenetics.

Selection of HBV key reactivation factors based on maximum information coefficient combined with cosine similarity.

BACKGROUND: Hepatitis B Virus (HBV) reactivation is the most common complication for patients with primary liver cancer (PLC) after radiotherapy. How to reduce the reactivation of HBV has been a hot topic in the study of postoperative radiotherapy for liver cancer. OBJECTIVE: To find out the inducement of HBV reactivation, a feature selection algorithm (MIC-CS) using maximum information coefficient (MIC) combined with cosine similarity (CS) was proposed to screen the risk factors that may affect HBV reactivation. METHOD: Firstly, different factors were coded and MIC between patients was calculated to acquire the association between different factors and HBV reactivation. Secondly, a cosine similarity algorithm was constructed to calculate the similarity relationship between different factors, thus removing redundant information. Finally, combined with the weight of the two, the potential risk factors were sorted and the key factors leading to HBV reactivation were selected. RESULTS: The results indicated that HBV baseline, external boundary, TNM, KPS score, VD, AFP, and Child-Pugh could lead to HBV reactivation after radiotherapy. The classification model was constructed for the above factors, with the highest classification accuracy of 84% and the AUC value of 0.71. CONCLUSION: Comparing multiple feature selection methods, the results showed that the effect of the MIC-CS was significantly better than MIM, CMIM, and mRMR, so it has a very broad application prospect.

Amphiphilic HZSM-5 for Cyclopentene Hydration at the Liquid-Liquid Interface in Pickering Emulsion.

Zeolite is considered an ideal catalyst for olefin hydration due to its high specific surface area and abundant acid sites. However, the immiscibility of the water-oil two phases in olefin hydration limits mass transfer, and the side reaction of etherification occurs acutely, resulting in a low yield of alcohol. Thus, water-oil amphiphilic HZSM-5 was prepared by sulfonating silanized zeolite. The successful introduction of organic and sulfonic acid groups is demonstrated by FT-IR, TG, and water contact angles. Amphiphilic HZSM-5 can stabilize the Pickering emulsion and catalyze cyclopentene hydration at the phase interface. In addition, NH3-TPD and Py-IR show that the amount of strong BroÌ·nsted acid sites of zeolites increases significantly after sulfonation. This facilitates the rate-determining step of cyclopentene activation by H+ to form carbocation. Moreover, the nucleophilic side reactions are inhibited by a high concentration of H+. Finally, under the optimized reaction condition, the conversion of cyclopentene can achieve 5.066% with a selectivity of 85.37% to cyclopentanol, which almost reaches the reaction equilibrium.

Decreased lymphoma-related deaths and improved long-term relative survival with radiotherapy for early-stage diffuse large B-cell lymphoma in the rituximab era.

BACKGROUND: We aimed to investigate the incidence of lymphoma-related death (LRD) and the long-term net survival benefit of radiotherapy (RT) for early-stage diffuse large B-cell lymphoma (DLBCL) in the rituximab era. METHODS: 10,841 adults diagnosed with early-stage DLBCL between 2002-2015 were retrospectively analyzed using data from the Surveillance, Epidemiology, and End Results database. Primary therapy was categorized into combined-modality treatment (CMT, n = 3,631) and chemotherapy alone (n = 7,210). Competing risk analysis was used to evaluate the cumulative incidence of mortality. Inverse probability of treatment weighting (IPTW) was used to balance groups. The net survival benefit of RT was estimated through relative survival (RS), standardized mortality ratio (SMR), and transformed Cox regression, while controlling for background mortality. RESULTS: Patients initially treated with CMT had a lower cumulative incidence of LRD compared to those who received chemotherapy alone (HR 0.63, 95%CI: 0.57-0.69; P < 0.001). The 10-year overall survival (OS), RS, and SMR for CMT were 66.1%, 85.0%, and 1.71 respectively, which were significantly better than those for chemotherapy alone (53.0%; 69.8%; 2.62; all P < 0.001). IPTW and multivariable analysis revealed that the addition of RT led to better OS (HR 0.67, 95%CI: 0.62-0.71; P < 0.001) and RS (HR 0.69, 95%CI: 0.65-0.74; P < 0.001). Moreover, compared with chemotherapy alone, the benefit of OS and RS for CMT increased over time within 10 years of diagnosis. CONCLUSION: RT reduced LRD and improved the long-term net survival in early-stage DLBCL in the rituximab era. Further prospective studies are warranted to assess the specific patient population that would benefit the most from consolidative RT in early-stage DLBCL.

Ultra-mechanosensitive Chloride Ion Transport through Bioinspired High-Density Elastomeric Nanochannels.

Mechanosensitive ion channels play crucial roles in physiological activities, where small mechanical stimuli induce the membrane tension, trigger the ion channels' deformation, and are further transformed into significant electrochemical signals. Artificial ion channels with stiff moduli have been developed to mimic mechanosensory behaviors, exhibiting an electrochemical response by the high-pressure-induced flow. However, fabricating flexible mechanosensitive channels capable of regulating specific ion transporting upon dramatic deformation has remained a challenge. Here, we demonstrate bioinspired high-density elastomeric channels self-assembled by polyisoprene-b-poly4-vinylpyridine, which exhibit ultra-mechanosensitive chloride ion transport resulting from nanochannel deformation. The PI-formed continuous elastic matrix can transmit external forces into internal tensions, while P4VP forms transmembrane chloride channels that undergo dramatic deformation and respond to mechanical stimuli. The integrated and flexible chloride channels present a dramatic and stable electrochemical signal toward a low pressure of 0.2 mbar. This research first demonstrates the artificial mechanosensory chloride channels, which could provide a promising avenue for designing flexible and responsive channel systems.

Momentum contrast transformer for COVID-19 diagnosis with knowledge distillation.

Intelligent diagnosis has been widely studied in diagnosing novel corona virus disease (COVID-19). Existing deep models typically do not make full use of the global features such as large areas of ground glass opacities, and the local features such as local bronchiolectasis from the COVID-19 chest CT images, leading to unsatisfying recognition accuracy. To address this challenge, this paper proposes a novel method to diagnose COVID-19 using momentum contrast and knowledge distillation, termed MCT-KD. Our method takes advantage of Vision Transformer to design a momentum contrastive learning task to effectively extract global features from COVID-19 chest CT images. Moreover, in transfer and fine-tuning process, we integrate the locality of convolution into Vision Transformer via special knowledge distillation. These strategies enable the final Vision Transformer simultaneously focuses on global and local features from COVID-19 chest CT images. In addition, momentum contrastive learning is self-supervised learning, solving the problem that Vision Transformer is challenging to train on small datasets. Extensive experiments confirm the effectiveness of the proposed MCT-KD. In particular, our MCT-KD is able to achieve 87.43% and 96.94% accuracy on two publicly available datasets, respectively.

Pathogen protein modularity enables elaborate mimicry of a host phosphatase.

Pathogens produce diverse effector proteins to manipulate host cellular processes. However, how functional diversity is generated in an effector repertoire is poorly understood. Many effectors in the devastating plant pathogen Phytophthora contain tandem repeats of the "(L)WY" motif, which are structurally conserved but variable in sequences. Here, we discovered a functional module formed by a specific (L)WY-LWY combination in multiple Phytophthora effectors, which efficiently recruits the serine/threonine protein phosphatase 2A (PP2A) core enzyme in plant hosts. Crystal structure of an effector-PP2A complex shows that the (L)WY-LWY module enables hijacking of the host PP2A core enzyme to form functional holoenzymes. While sharing the PP2A-interacting module at the amino terminus, these effectors possess divergent C-terminal LWY units and regulate distinct sets of phosphoproteins in the host. Our results highlight the appropriation of an essential host phosphatase through molecular mimicry by pathogens and diversification promoted by protein modularity in an effector repertoire.

Ergostane-type sterols and sesquiterpenes with anti-neuroinflammatory activity from a Nigrograna species associated with Clematis shensiensis.

Nigrograna sp. LY66, an endophytic fungus associated with the herbal medicinal plant Clematis shensiensis, produced four undescribed steroids, nigergostanes A-D (1-4), including an unusual ketal-containing nigergostane (1), and four undescribed sesquiterpenoids decorated with cyclohexanone motifs, nigbisabolanes A-D (7-10), along with three known compounds, 23R-hydroxy-(20Z,24R)-ergosta-4,6,8(14),20(22)-tetraen-3-one (5), ergosta-5,7,22-trien-3ß-ol (6), and curculonone A (11). The structures and absolute configurations of these undescribed compounds were confirmed using spectroscopic data (NMR and HRESIMS), modified Mosher's method, and ECD experiments. Additionally, compounds 5 and 8 displayed significant inhibition of nitric oxide generation in lipopolysaccharide-induced BV-2 microglial cells with IC50 values of 2.8 and 2.7 µM, respectively, and is thus more potent than that of the positive control, quercetin (IC50 = 8.77 µM). A molecular docking study revealed that 23-OH of 5 binds to the Y347 residue of inducible nitric oxide synthase (iNOS), whereas the 2-OH and 9,10-diol moieties of 8 bind to R381 and W463 and haeme residues of iNOS, respectively, which has rarely been reported in previous studies. These findings provide a set of undescribed lead compounds that can be developed into anti-neuroinflammatory agents.

Clinical characteristics of patients with prenatal hydronephrosis in early postnatal period: a single center retrospective study.

BACKGROUND: The study aims to investigate the clinical characteristics of early postnatal period in children with prenatal hydronephrosis (HN) in our single center for 8 years. STUDY DESIGN: The clinical data of 1137 children with prenatal HN from 2012 to 2020 were retrospectively analyzed in our center. Variables of our study mainly included different malformations and urinary tract dilation (UTD) classification, and main outcomes were recurrent hospitalization, urinary tract infection (UTI), jaundice, and surgery. RESULTS: Among the 1137 children with prenatal HN in our center, 188 cases (16.5%) were followed-up in early postnatal period, and 110 cases (58.5%) were found malformations. The incidence of recurrent hospitalization (29.8%) and UTI (72.5%) were higher in malformation, but the incidence of jaundice (46.2%) was higher in non-malformation(P < 0.001). Furthermore, UTI and jaundice were higher in vesicoureteral reflux (VUR) than those in uretero-pelvic junction obstruction (UPJO) (P < 0.05). Meanwhile, Children with UTD P2 and UTD P3 were prone to recurrent UTI, but UTD P0 was prone to jaundice (P < 0.001). In addition, 30 cases (16.0%) of surgery were all with malformations, and the surgical rates of UTD P2 and UTD P3 were higher than those of UTD P0 and UTD P1 (P < 0.001). Lastly, we concluded that the first follow-up should be less than 7 days, the first assessment should be 2 months, and the follow up should be at least once every 3 months. CONCLUSION: Children with prenatal HN have been found many malformations in early postnatal period, and with high-grade UTD were more prone to recurrent UTI, even to surgery. So, prenatal HN with malformations and high-grade UTD should be followed up in early postnatal period regularly.

Effect of Age and Sex on Stroke Mortality of Young and Middle-aged Adults in China, 2002-2019, and Predictions to 2030.

Objective: This study aimed to examine the trends in stroke mortality among young and middle-aged adults in China. Methods: Data were obtained from the China national vital registration system. Significant changes in mortality were assessed by Joinpoint regression. Age-period-cohort analysis was used to explain the reasons for the changes. Future mortality and counts were predicted by the Bayesian age-period-cohort model. Results: Between 2002 and 2019, a total of 6,253,951 stroke mortality in young and middle-aged adults were recorded. The age-adjusted mortality rates (AAMRs) of women showed a downward trend. The annual percent changes (APC) were -3.5% (-5.2%, -1.7%) for urban women and -2.8% (-3.7%, -1.9%) for rural women. By contrast, the AAMRs per 100,000 for rural men aged 25-44 years continued to rise from 9.40 to 15.46. The AAMRS for urban men aged 25-44 years and urban and rural men aged 45-64 years did not change significantly. Between 2020 and 2030, the projected stroke deaths are 1,423,584 in men and 401,712 in women. Conclusion: Significant sex and age disparities in the trends of stroke mortality among young and middle-aged adults were identified in China. Targeted health policy measures are needed to address the burden of stroke in the young generation, especially for rural men, with a focus on the prevention and management of high risk factors.

Ethylidene-Tethered Chromene-Pyrone Hybrids as Potential Plant-Growth Regulators from an Endolichenic Phaeosphaeria Species.

Phaeosphaeria sp., a lichen-associated fungus, produced six skeletally new dimeric spiciferones (1-6) and four known metabolites (7-10). The new structures were elucidated by spectroscopic analysis, and their absolute configurations were determined by electronic circular dichroism calculations. Compounds 1 and 3-6 represent the first examples of ethylidene-bridged dimers from the building blocks 4H-chromene-4,7(8H)-dione and α-pyrone, and 2 is a unique homodimer of spiciferone. Compounds 1, 2, and 5-9 significantly inhibited the growth of weed-like dicot Arabidopsis thaliana at 100.0 µM. Notably, 8 showed the strongest inhibitory activity against the fresh weight and root elongation of A. thaliana with the IC50 values of 32.04 and 26.78 µM, respectively, whereas 1, 8, and 9 stimulated the growth of A. thaliana at lower concentrations. Meanwhile, compounds 2 and 6 exhibited weak inhibitory effects on the root elongation of monocot rice, while 1 and 8 exhibited growth-promoting effects on the shoot and root elongation of rice in a roughly dose-dependent manner.

Effect of short-term mindfulness-based stress reduction on sleep quality in male patients with alcohol use disorder.

Background: Sleep disturbance is one of the most prominent complaints of patients with alcohol use disorder (AUD), with more than 70% of patients with AUD reporting an inability to resolve sleep problems during abstinence. Mindfulness-based stress reduction (MBSR) has been shown to improve sleep quality and as an alternative therapy to hypnotics for sleep disorders. Objective: The aim of the present study was to evaluate the effect of short-term MBSR on sleep quality in male patients with AUD after withdrawal. Methods: A total of 91 male patients with AUD after 2 weeks of routine withdrawal therapy were randomly divided into two groups using a coin toss: the treatment group (n = 50) and the control group (n = 41). The control group was received supportive therapy, and the intervention group added with MBSR for 2 weeks on the basis of supportive therapy. Objective sleep quality was measured at baseline and 2 weeks after treatment using the cardiopulmonary coupling (CPC). Indicators related to sleep quality include total sleep time, stable sleep time, unstable sleep time, rapid eye movement (REM) sleep time, wake-up time, stable sleep latency, sleep efficiency, and apnea index. These indicators were compared by an analysis of covariance (ANCOVA) between the two groups, controlling for individual differences in the respective measures at baseline. Results: The results showed that there were no significant differences in the age [t (89) = -0.541, P = 0.590), BMI [t (89) = -0.925, P = 0.357], educational status [t (89) = 1.802, P = 0.076], years of drinking [t (89) = -0.472, P = 0.638), daily intake [t (89) = 0.892, P = 0.376], types of alcohol [χ2 (1) = 0.071, P = 0.789], scores of CIWA-AR [t (89) = 0.595, P = 0.554], scores of SDS [t (89) = -1.151, P = 0.253), or scores of SAS [t (89) = -1.209, P = 0.230] between the two groups. Moreover, compared with the control group, the total sleep time [F (1.88) = 4.788, P = 0.031) and stable sleep time [F (1.88) = 6.975, P = 0.010] were significantly increased in the treatment group. Furthermore, the average apnea index in the patients who received MBSR was significantly decreased than in the control group [F (1.88) = 5.284, P = 0.024]. Conclusion: These results suggest that short-term MBSR could improve sleep quality and may serve as an alternative treatment to hypnotics for sleep disturbance in patients with AUD after withdrawal.

Dose-Volume Predictors for Radiation Esophagitis in Patients With Breast Cancer Undergoing Hypofractionated Regional Nodal Radiation Therapy.

PURPOSE: Our objective was to assess the incidence and dose-volume predictors of radiation esophagitis (RE) in patients with breast cancer undergoing hypofractionated regional nodal irradiation. METHODS AND MATERIALS: Eligible patients who received intensity modulated radiation therapy (RT) at the chest wall, the supraclavicular/infraclavicular fossa, level II axilla, and/or the internal mammary chain after mastectomy were included. The prescribed dose was 43.5 Gy in 15 fractions. RE was evaluated weekly during RT and at 1 and 2 weeks, followed by 3 and 6 months after RT, and was graded according to National Cancer Institute Common Toxicity Criteria for Adverse Events, version 3.0. The esophagus was contoured from the lower border level of the cricoid cartilage to the lower margin of the aortic arch. Esophageal total volume, mean dose, maximum dose, and the relative volumes (RV) and absolute volumes (AV) receiving at least 5 to 45 Gy by 5-Gy increments (RV5-RV45 and AV5-AV45) were evaluated. Univariable and multivariable logistic regression analyses were performed to determine risk factors for RE, and receiver operating characteristic curves were obtained to identify the thresholds of esophageal dosimetric parameters. RESULTS: In total, 298 patients were included between May 8, 2020, and January 5, 2022 (minimum post-RT follow-up: 6 months). Grade 2 and 3 RE incidence was 40.9% (122/298) and 0.3% (1/298), respectively. No grade 4 or 5 RE was observed. Esophageal RV20-RV40 and AV35-AV40 were significantly associated with the risk of grade ≥2 RE after adjusting for tumor laterality and internal mammary nodal irradiation. RV25 and AV35 were optimum dose-volume predictors for grade ≥2 RE at thresholds 20% for RV25 (35.9% vs 60.9%; P = .04) and 0.27 mL for AV35 (31.0% vs 54.6%; P = .04). CONCLUSIONS: RE is common in patients with breast cancer undergoing hypofractionated regional nodal irradiation. Maintaining the upper esophageal V25 at <20% and V35 at <0.27 mL may decrease the risk of RE.

Gut bacterium promotes host fitness in special ecological niche by affecting sugar metabolism in Drosophila suzukii.

As an important fruit pest of global significance, Drosophila suzukii occupies a special ecological niche, with the characteristics of high sugar and low protein contents. This niche differs from those occupied by other fruit-damaging Drosophila species. Gut bacteria substantially impact the physiology and ecology of insects. However, the contribution of gut microbes to the fitness of D. suzukii in their special ecological niche remains unclear. In this study, the effect of Klebsiella oxytoca on the development of D. suzukii was examined at physiological and molecular levels. The results showed that, after the removal of gut microbiota, the survival rate and longevity of axenic D. suzukii decreased significantly. Reintroduction of K. oxytoca to the midgut of D. suzukii advanced the development level of D. suzukii. The differentially expressed genes and metabolites between axenic and K. oxytoca-reintroduced D. suzukii were enriched in the pathways of carbohydrate metabolism. This advancement was achieved through an increased glycolysis rate and the regulation of the transcript level of key genes in the glycolysis/gluconeogenesis pathway. Klebsiella oxytoca is likely to play an important role in increasing host fitness in their high-sugar ecological niche by stimulating the glycolysis/gluconeogenesis pathway. As a protein source, bacteria can also provide direct nutrition for D. suzukii, which depends on the quantity or biomass of K. oxytoca. This result may provide a new target for controlling D. suzukii by inhibiting sugar metabolism through eliminating the effect of K. oxytoca and thus disrupting the balance of gut microbial communities.

Tricrilactones A-H, Potent Antiosteoporosis Macrolides with Distinctive Ring Skeletons from Trichocladium crispatum, an Alpine Moss-Associated Fungus.

Tricrilactones A-H (1-8), a new family of oligomeric 10-membered macrolides featuring collectively five unique ring skeletons, were isolated from a hitherto unexplored fungus, Trichocladium crispatum. Compounds 1 and 7 contain two unconventional bridged (aza)tricyclic core skeletons, 2, 3, 5, and 6 share an undescribed tetracyclic 9/5/6/6 ring system, 4 bears an uncommon 9/5/6/10/3-fused pentacyclic architecture, and 8 is a dimer bridged by an unexpected C-C linkage. Their structures, including absolute configurations, were elucidated by spectroscopic analysis, quantum chemical calculations, and X-ray diffraction analysis. Importantly, the absolute configuration of the highly flexible side chain of 1 was resolved by the asymmetric synthesis of its four stereoisomers. The intermediate-trapping and isotope labeling experiments facilitated the proposal of the biosynthetic pathway for these macrolides. In addition, their antiosteoporosis effects were evaluated in vivo (zebrafish).

Genomic and Metabolite Profiling Reveal a Novel Streptomyces Strain, QHH-9511, from the Qinghai-Tibet Plateau.

The prevalence of superbugs, represented by methicillin-resistant Staphylococcus aureus (MRSA), has become a serious clinical and public safety concern with rising incidence in hospitals. Polyketides with diverse chemical structures harbor many antimicrobial activities, including those of rifampin and rapamycin against MRSA. Streptomyces sp. QHH-9511 was isolated from a niche habitat in the Qinghai-Tibet Plateau and used to produce antibacterial metabolites. Herein, an integrated approach combining genome mining and metabolic analysis were employed to decipher the chemical origin of the antibacterial components with pigmented properties in strain QHH-9511, a novel Streptomyces species from a lichen symbiont on the Qinghai-Tibet Plateau. Genomic phylogeny assembled at the chromosome level revealed its unique evolutionary state. Further genome mining uncovered 36 candidate gene clusters, most of which were uncharacterized. Meanwhile, based on liquid chromatography coupled to diode array detection mass spectrometry, a series of granaticins, BSMs, chromones, phaeochromycins, and related molecules were discovered by using the Global Natural Product Social molecular networking platform. Subsequently, several pigment compounds were isolated and identified by high-resolution mass spectrometry and/or nuclear magnetic resonance, among which the structure-activity relationships of seven aromatic polyketides showed that the fused lactone ring of the C-2 carboxyl group could increase antibacterial activity. Genetic experiments indicated that all seven aromatic polyketides are a series of metabolic shunts produced by a single type II polyketide synthase (PKS) cluster. Comparative genomic analysis of granaticin producers showed that the granaticin gene cluster is widely distributed. This study provides an efficient method to combine genome mining and metabolic profiling techniques to uncover bioactive metabolites derived from specific habitats, while deepening our understanding of aromatic polyketide biosynthesis. IMPORTANCE Undescribed microorganisms from special habitats are being screened for anti-superbug drug molecules. In a project to screen actinomycetes for anti-MRSA activity, we isolated a Streptomyces strain from Qinghai Lake lichens. The phylogeny based on the genome assembled at the chromosome level revealed this strain's unique evolutionary state. The chemical origins of the antibacterial components with pigment properties in strain QHH-9511 were determined using an integrated approach combining genome mining and metabolic analysis. Further genome mining uncovered 36 secondary metabolite gene clusters, the majority of which were previously unknown. A series of aromatic compounds were discovered using molecular network analysis, separation, and extraction. Genetic experiments revealed that all seven aromatic polyketides are a series of metabolic shunts produced by a single cluster of type II PKSs. This study describes a method for identifying novel Streptomyces from specific habitats by combining genome mining with metabolic profiling techniques.