Locating, tracing and sequencing multiple expanded genetic letters in complex DNA context via a bridge-base approach.

A panel of unnatural base pairs is developed to expand genetic alphabets. One or more unnatural base pairs (UBPs) can be inserted to enlarge the capacity, diversity, and functionality of canonical DNA, so monitoring the multiple-UBPs-containing DNA by simple and convenient approaches is essential. Herein, we report a bridge-base approach to repurpose the capability of determining TPT3-NaM UBPs. The success of this approach depends on the design of isoTAT that can simultaneously pair with NaM and G as a bridge base, as well as the discovering of the transformation of NaM to A in absence of its complementary base. TPT3-NaM can be transferred to C-G or A-T by simple PCR assays with high read-through ratios and low sequence-dependent properties, permitting for the first time to dually locate the multiple sites of TPT3-NaM pairs. Then we show the unprecedented capacity of this approach to trace accurate changes and retention ratios of multiple TPT3-NaM UPBs during in vivo replications. In addition, the method can also be applied to identify multiple-site DNA lesions, transferring TPT3-NaM makers to different natural bases. Taken together, our work presents the first general and convenient approach capable of locating, tracing, and sequencing site- and number-unlimited TPT3-NaM pairs.

Structural changes in the retina and serum HMGB1 levels are associated with decreased cognitive function in patients with Parkinson's disease.

BACKGROUND: Cognitive impairment is a serious nonmotor symptom in patients with Parkinson's disease (PD). Currently, there are few studies investigating the relationship of serum markers and retinal structural changes with cognitive function in PD. OBJECTIVE: To investigate the relationship between retinal structural changes, serum high mobility group box-1 (HMGB1) levels and cognitive function and motor symptoms in PD patients. METHODS: Eighty-nine participants, including 47 PD patients and 42 healthy subjects, were enrolled. PD patients were divided into Parkinson's disease with normal cognitive (PD-NC), Parkinson's disease with mild cognitive impairment (PD-MCI), and Parkinson's disease with dementia (PDD) groups. The motor and nonmotor symptoms of PD patients were evaluated with clinical scale. Serum HMGB1 levels were detected by enzyme-linked immunosorbent assay (ELISA), and ganglion cell-inner plexiform layer complex (GCIPL) thickness changes in the macula were quantitatively analyzed by swept source optical coherence tomography (SS-OCT) in all patients. RESULTS: Compared with the control group, the macular GCIPL (t = -2.308, P = 0.023) was thinner and serum HMGB1 (z = -2.285, P = 0.022) was increased in PD patients. Macular GCIPL thickness in patients with PD-MCI and PDD were significantly lower than that in PD-NC patients, but there were no significant difference between the PD-MCI and PDD groups. Serum HMGB1 levels in patients with PD-MCI and PDD were significantly higher than those in PD-NC patients, and serum HMGB1 levels in PDD patients were higher than those in PD-MCI patients. Correlation analysis showed that serum HMGB1 levels in PD patients were positively correlated with disease duration, HY stage, UPDRS-I score, UPDRS-III score, and UPDRS total score and negatively correlated with MOCA score. Macular GCIPL thickness was negatively correlated with HY stage and positively correlated with MOCA score, and macular GCIPL thickness was negatively correlated with serum HMGB1 level. Logistic regression analysis showed that elevated serum HMGB1 level, thinner macular GCIPL thickness, and higher HY stage were independent risk factors for Parkinson's disease with cognitive impairment (PD-CI). The areas under the receiver operating characteristic curve (AUC) for the serum HMGB1 level and macular GCIPL thickness-based diagnosis of PD-MCI, PDD and PD-CI based on in patients with PD were 0.786 and 0.825, 0.915 and 0.856, 0.852 and 0.841, respectively. The AUC for the diagnosis of PD-MCI, PDD and PD-CI with serum HMGB1 level and GCIPL thickness combined were 0.869, 0.967 and 0.916, respectively. CONCLUSION: The macular GCIPL thickness and serum HMGB1 level are potential markers of cognitive impairment in PD patients, and their combination can significantly improve the accuracy of the diagnosis of cognitive impairment in PD.

Clinical findings of hyperechoic substantia nigra in patients with Parkinson's disease.

This study aims to analyse hyperechoic substantia nigra (HSN) characteristics and the correlation of HSN with clinical features and blood biomarkers in patients with Parkinson's disease (PD). Transcranial sonography (TCS) evaluations of the substantia nigra (SN) were performed in 40 healthy controls and 71 patients with PD, including patients with SN hyperechogenicity (SN+) and those with normal SN echogenicity (SN-). Evaluation of motor and non-motor symptoms was assessed by a series of rating scales. The uricase method was used to determine serum uric acid (UA) levels, and enzyme-linked immunosorbent assay (ELISA) was used to measure plasma interleukin (IL)-1ß levels. TCS showed 92.50% specificity and 61.97% sensitivity in differentiating PD patients from controls. The area of SN+ contralateral to the side of initial motor symptoms (SNcontra) was larger than that ipsilateral to the side of initial motor symptoms (SNipsi). The PDSN+ group had lower Argentine Hyposmia Rating Scale (AHRS) scores and UA levels than the PDSN- group. Binary logistic regression analysis revealed that AHRS scores and UA levels could be independent predictors for HSN. The larger SN echogenic area (SNL) sizes positively correlated with plasma IL-1ß levels in PD patients with SN+. The present study provides further evidence of the potential of SN echogenicity as an imaging biomarker for PD diagnosis. PD patients with HSN have more severe non-motor symptoms of hyposmia. HSN in PD patients is related to the mechanism of abnormal iron metabolism and microglial activation.

Increased plasma lipocalin-2 levels are associated with nonmotor symptoms and neuroimaging features in patients with Parkinson's disease.

Lipocalin-2 (LCN2) is essential for the regulation of neuroinflammation and cellular uptake of iron. This study aimed to evaluate plasma LCN2 levels and explore their correlation with clinical and neuroimaging features in Parkinson's disease (PD) patients. Enzyme-linked immunosorbent assay (ELISA) was used to measure plasma LCN2 levels in 120 subjects. Evaluation of motor symptoms and nonmotor symptoms in PD patients was assessed by the associated scales. Voxel-based morphometry (VBM) was used to evaluate brain volume alterations, and quantitative susceptibility mapping (QSM) was used to quantitatively analyze brain iron deposition in 46 PD patients. Plasma LCN2 levels were significantly higher in PD patients than those in healthy controls. LCN2 levels were negatively correlated with Montreal Cognitive Assessment (MoCA) scores, total brain gray matter volume (GMV), and GMV/total intracranial volume (TIV) ratio, but positively correlated with Hamilton Anxiety Rating Scale (HAMD) scores and mean QSM values of the bilateral substantial nigra (SN). Receiver operating characteristic (ROC) curves confirmed that plasma LCN2 levels had good predictive accuracy for PD. The results suggest that plasma LCN2 levels have potential as a biomarker for the diagnosis of PD. LCN2 may be a therapeutic target for neuroinflammation and brain iron deposition.

Rapid Access to Tigliane, Ingenane, and Rhamnofolane Diterpenes from a Lathyrane Precursor via Biomimetic Skeleton Transformation Strategy.

Bioinspired skeleton transformation of a tricyclic lathyrane-type Euphorbia diterpene was conducted to efficiently construct a tetracyclic tigliane diterpene on a gram scale via a key aldol condensation. The tigliane diterpene was then respectively converted into naturally rare ingenane and rhamnofolane diterpenes through a semipinacol rearrangement and a visible-light-promoted regioselective cyclopropane ring-opening reaction. This work provides a concise strategy for high-efficiency access to diverse polycyclic Euphorbia diterpene skeletons from abundant lathyrane-type natural products and paves the way for biological activity investigation of naturally rare molecules.

Brønsted Acid-Mediated Conversion of Naturally Abundant Lathyrane Diterpenes: Are Rare 10,11-seco-Lathyrane Diterpenes Artifacts?

The question of whether rare 10,11-seco-lathyranes are natural products or artifacts is thoughtfully considered after a Brønsted acid-mediated chemical conversion of naturally abundant 5/11/3 lathyrane type diterpenes into 10,11-seco-lathyranes was developed. Benefiting from this concise route, a series of 10,11-seco-lathyrane products (1-14) were smoothly synthesized. The conversion may involve an acid promoted cyclopropane ring opening accompanied by a double bond shift with final trapping of carbocation. The ease of this chemical conversion under mildly acidic conditions may imply that the 10,11-seco-lathyranes isolated to date are artifacts. This work not only develops a new modular synthetic strategy for efficient constructing rare 10,11-seco-lathyranes, but also provides a promising bioactive diterpene with excellent effect against the NO production on LPS-induced BV-2 cells.

Lathyrane and premyrsinane Euphorbia diterpenes against Alzheimer's disease: Bioinspired synthesis, anti-cholinesterase and neuroprotection bioactivity.

The first systematic acylated diversification of naturally scarce premyrsinane diterpenes, together with their biosynthetic precursors lathyrane diterpene were carried out. Two new series of premyrsinane derivates (1a-32a) and lathyrane derivates (1-32) were synthesized from the naturally abundant lathyrane diterpene Euphorbia factor L3 through a bioinspired approach. The cholinesterase inhibitory and neuroprotective activities of these diterpenes were investigated to explore potential anti-Alzheimer's disease (AD) bioactive lead compounds. In general, the lathyrane diterpenes showed the better acetylcholinesterase (AChE) inhibitory activity than that of premyrsinanes. The lathyrane derivative 17 bearing a 3-dimethylaminobenzoyl moiety showed the best AChE inhibition effect with the IC50 value of 7.1 µM. Molecular docking demonstrated that 17 could bond with AChE well (-8 kal/mol). On the other hand, premyrsinanes showed a better neuroprotection profile against H2O2-induced injury in SH-SY5Y cells. Among them, the premyrsinane diterpene 16a had significant neuroprotective effect with the cell viability rate of 113.5 % at 12.5 µM (the model group with 51.2 %). The immunofluorescence, western blot and reactive oxygen species (ROS) analysis were conducted to demonstrate the mechanism of 16a. Furthermore, a preliminary SAR analysis of the two categories of diterpenes was performed to provide the insights for anti-AD drug development.

Diagnostic value of plasma SIRT1 levels and whole-brain gray matter volume in Parkinson's disease patients with cognitive impairment.

OBJECTIVE: This study was designed to investigate the diagnostic value of plasma SIRT1 levels and whole-brain gray matter (GM) volume in Parkinson's disease (PD) patients with cognitive impairment. METHODS: Automated enzymatic analysis was performed to measure plasma SIRT1 levels in 80 healthy controls and 77 PD patients. Motor symptoms and nonmotor symptoms in PD patients were assessed using the corresponding scales. A Siemens MAGNETOM Prisma 3 T MRI scanner was used to acquire images in 35 of 77 PD patients. RESULTS: Plasma SIRT1 levels in PD patients were lower than those in healthy controls. Plasma SIRT1 levels were negatively correlated with the age, Unified Parkinson's Disease Rating Scale Part III (UPDRS-III) scores, anxiety, depression, excessive daytime sleepiness (EDS), quality of life, and especially cognitive impairment. Thus, it showed that plasma SIRT1 levels were relevant to visuospatial/executive function, memory, and language. Receiver-operating characteristic (ROC) analysis confirmed that plasma SIRT1 levels had good diagnostic accuracy for PD with anxiety and EDS. Furthermore, plasma SIRT1 levels had a significant positive correlation with GM volume in the whole brain, and ROC analysis confirmed that plasma SIRT1 levels and the total GM volume had good diagnostic accuracy for PD with cognitive impairment. CONCLUSIONS: This study showed that plasma SIRT1 levels were correlated with the nonmotor symptoms of anxiety, depression, EDS, and especially cognitive impairment as well as the total GM volume. Furthermore, the combination of plasma SIRT1 levels and the total GM volume had good diagnostic accuracy for PD with cognitive impairment.

Examination of learning ability development through the implementation of the "autonomy-collaboration" learning mode grounded in evidence-based medicine practice.

OBJECTIVE: Currently, there are still some shortcomings in EBM education in China.The study aimed to investigate the effectiveness of the novel evidence-based medicine (EBM) learning model of "autonomy-collaboration." METHODS: A total of 91 undergraduate students majoring in clinical medicine at Zhongshan Clinical College of Dalian University from the 2019 batch were selected as the participants in this study. They were instructed to follow the EBM learning model of "autonomy-collaboration." Upon completion of the course, questionnaires, records of participants' sentiments and insights, and evidence-based clinical practice reports were used as indicators to evaluate the effectiveness of the training. RESULTS: This learning modality effectively enhanced independent learning ability of the students, stimulated their interest in learning, and strengthened the communication between students and teachers, thereby improving the quality of teaching. CONCLUSION: The novel EBM learning model of "autonomy-collaboration," exhibited robust effectiveness in instruction and facilitated the seamless integration of theoretical knowledge with clinical practice. Consequently, its widespread adoption is strongly recommended.

Wound infection prevention strategies in colorectal endoscopic mucosal resection: A meta-analysis of prophylactic measures.

Colorectal endoscopic mucosal resection (EMR) is associated with the risk of postoperative wound infections, prompting investigations into effective prophylactic measures. This meta-analysis aimed to evaluate the efficacy of various prophylactic interventions in reducing the incidence of wound infections following EMR. Adhering to PRISMA guidelines, we conducted a comprehensive search across multiple databases for randomized controlled trials (RCTs) and cohort studies from 2015 to 2022. We included studies that compared the efficacy of antibiotic prophylaxis and antiseptic measures, with clear data on post-procedure infection rates. Eight studies met our inclusion criteria, and data were extracted for meta-analysis. The risk of bias was assessed using the Cochrane Collaboration tool and the Newcastle-Ottawa Scale. The meta-analysis included 3765 patients from eight RCTs. Prophylactic antibiotics (cefixime and cefuroxime) showed moderate to high efficacy, with infection rates as low as 0% and 0.76%. Prophylactic endoscopic closure and clipping showed the highest efficacy, with zero reported infections. The standardized surgical site infection prevention bundle had lower effectiveness, with an infection incidence of 3.83%. The risk of bias assessment indicated potential performance bias due to lack of blinding, but overall evidence quality was upheld by proper random sequence generation and diligent outcome data monitoring. The effectiveness of specific prophylactic measures, notably prophylactic antibiotics and mechanical closure techniques, has been shown in significantly reducing the risk of wound infections following colorectal EMR.

Inhibiting NLRP3 inflammasome signaling pathway promotes neurological recovery following hypoxic-ischemic brain damage by increasing p97-mediated surface GluA1-containing AMPA receptors.

BACKGROUND: The nucleotide-binding oligomeric domain (NOD)-like receptor protein 3 (NLRP3) inflammasome is believed to be a key mediator of neuroinflammation and subsequent secondary brain injury induced by ischemic stroke. However, the role and underlying mechanism of the NLRP3 inflammasome in neonates with hypoxic-ischemic encephalopathy (HIE) are still unclear. METHODS: The protein expressions of the NLRP3 inflammasome including NLRP3, cysteinyl aspartate specific proteinase-1 (caspase-1) and interleukin-1ß (IL-1ß), the α-amino-3-hydroxy-5-methyl-4-isoxazole-propionicacid receptor (AMPAR) subunit, and the ATPase valosin-containing protein (VCP/p97), were determined by Western blotting. The interaction between p97 and AMPA glutamate receptor 1 (GluA1) was determined by co-immunoprecipitation. The histopathological level of hypoxic-ischemic brain damage (HIBD) was determined by triphenyltetrazolium chloride (TTC) staining. Polymerase chain reaction (PCR) and Western blotting were used to confirm the genotype of the knockout mice. Motor functions, including myodynamia and coordination, were evaluated by using grasping and rotarod tests. Hippocampus-dependent spatial cognitive function was measured by using the Morris-water maze (MWM). RESULTS: We reported that the NLRP3 inflammasome signaling pathway, such as NLRP3, caspase-1 and IL-1ß, was activated in rats with HIBD and oxygen-glucose deprivation (OGD)-treated cultured primary neurons. Further studies showed that the protein level of the AMPAR GluA1 subunit on the hippocampal postsynaptic membrane was significantly decreased in rats with HIBD, and it could be restored to control levels after treatment with the specific caspase-1 inhibitor AC-YVAD-CMK. Similarly, in vitro studies showed that OGD reduced GluA1 protein levels on the plasma membrane in cultured primary neurons, whereas AC-YVAD-CMK treatment restored this reduction. Importantly, we showed that OGD treatment obviously enhanced the interaction between p97 and GluA1, while AC-YVAD-CMK treatment promoted the dissociation of p97 from the GluA1 complex and consequently facilitated the localization of GluA1 on the plasma membrane of cultured primary neurons. Finally, we reported that the deficits in motor function, learning and memory in animals with HIBD, were ameliorated by pharmacological intervention or genetic ablation of caspase-1. CONCLUSION: Inhibiting the NLRP3 inflammasome signaling pathway promotes neurological recovery in animals with HIBD by increasing p97-mediated surface GluA1 expression, thereby providing new insight into HIE therapy.

An imaging-based machine learning model outperforms clinical risk scores for prognosis of cirrhotic variceal bleeding.

OBJECTIVES: To develop and validate a machine learning model based on contrast-enhanced CT to predict the risk of occurrence of the composite clinical endpoint (hospital-based intervention or death) in cirrhotic patients with acute variceal bleeding (AVB). METHODS: This retrospective study enrolled 330 cirrhotic patients with AVB between January 2017 and December 2020 from three clinical centers. Contrast-enhanced CT and clinical data were collected. Centers A and B were divided 7:3 into a training set and an internal test set, and center C served as a separate external test set. A well-trained deep learning model was applied to segment the liver and spleen. Then, we extracted 106 original features of the liver and spleen separately based on the Image Biomarker Standardization Initiative (IBSI). We constructed the Liver-Spleen (LS) model based on the selected radiomics features. The performance of LS model was evaluated by receiver operating characteristics and calibration curves. The clinical utility of models was analyzed using decision curve analyses (DCA). RESULTS: The LS model demonstrated the best diagnostic performance in predicting the composite clinical endpoint of AVB in patients with cirrhosis, with an AUC of 0.782 (95% CI 0.650-0.882) and 0.789 (95% CI 0.674-0.878) in the internal test and external test groups, respectively. Calibration curves and DCA indicated the LS model had better performance than traditional clinical scores. CONCLUSION: A novel machine learning model outperforms previously known clinical risk scores in assessing the prognosis of cirrhotic patients with AVB CLINICAL RELEVANCE STATEMENT: The Liver-Spleen model based on contrast-enhanced CT has proven to be a promising tool to predict the prognosis of cirrhotic patients with acute variceal bleeding, which can facilitate decision-making and personalized therapy in clinical practice. KEY POINTS: • The Liver-Spleen machine learning model (LS model) showed good performance in assessing the clinical composite endpoint of cirrhotic patients with AVB (AUC ≥ 0.782, sensitivity ≥ 80%). • The LS model outperformed the clinical scores (AUC ≤ 0.730, sensitivity ≤ 70%) in both internal and external test cohorts.

Photochemical Selective Oxidation of Benzyl Alcohols to Aldehydes or Ketones.

Using Eosin Y as a metal-free photocatalyst and O2 as an oxidant, the present study reports a new photochemical protocol that enables efficient aerobic oxidation of various benzyl alcohols to the corresponding aldehydes or ketones in excellent yields under mild reaction conditions. The catalyst system presents good functional-group tolerance and exquisite chemoselectivity, which also can easily be scaled-up to gram scale. Moreover, the methodological applications in practical synthesis of several organic molecules and the primary reaction mechanism were also discussed.

Discovery of myrsinane-type Euphorbia diterpene derivatives through a skeleton conversion strategy from lathyrane diterpene for the treatment of Alzheimer's disease.

A series of novel myrsinane-type Euphorbia diterpene derivatives (1-37) were synthesized from the abundant natural lathyrane-type Euphorbia factor L3, using a multi-step chemical process guided by a bioinspired skeleton conversion strategy, with the aim of discovering potential anti-Alzheimer's disease (AD) bioactive lead compounds. The synthesis process involved a concise reductive olefin coupling reaction through an intramolecular Michael addition with a free radical, followed by a visible-light-triggered regioselective cyclopropane ring-opening. The cholinesterase inhibitory and neuroprotective activities of the synthesized myrsinane derivatives were evaluated. Most of the compounds showed moderate to strong potency, highlighting the importance of ester groups in Euphorbia diterpene. In particular, derivative 37 displayed the most potent acetylcholinesterase (AChE) inhibition, with an IC50 value of 8.3 µM, surpassing that of the positive control, tacrine. Additionally, 37 also showed excellent neuroprotective effect against H2O2-induced injury in SH-SY5Y cells, with a cell viability rate of 124.2% at 50 µM, which was significantly higher than that of the model group (viability rate 52.1%). Molecular docking, reactive oxygen species (ROS) analysis, immunofluorescence, and immunoblotting were performed to investigate the mechanism of action of myrsinane derivative 37. The results indicated that derivative 37 may be a promising myrsinane-type multi-functional lead compound for the treatment of Alzheimer's disease. Furthermore, a preliminary SAR analysis was performed to study the acetylcholinesterase inhibitory and neuroprotective activities of these diterpenes.

Synthesis, antiproliferative and anti-MDR activities of lathyrane diterpene derivatives based on configuration inversion strategy.

A series of lathyrane-type Euphorbia diterpene derivatives featured 3R configuration (H-3ß) were synthesized from natural rich Euphorbia factor L3via modified Mitsunobu reaction based on configuration inversion strategy. The antiproliferation activity and MDR reversal ability of the lathyrane derivatives were evaluated, and the most synthesized compounds showed moderate or strong potencies. Among them, diterpenes 21 (IC50 values of 2.6, 5.2 and 13.1 µM, respectively) and 25 (IC50 values of 5.5, 8.6 and 1.3 µM, respectively) presented the strong cytotoxicity against MCF-7, 4 T1 and HepG2 cells. Meanwhile, derivative 25 exhibited excellent MDR reversal ability with the reversal fold of 16.1 higher than that of verapamil. The cellular thermal shift assay and molecular docking proved direct engagement of diterpene 25 to ABCB1, suggesting 25 could be a promising MDR modulator. Furthermore, the preliminary SARs of these diterpenes were also discussed.

Predictors of dopamine dysregulation syndrome in patients with early Parkinson's disease.

BACKGROUND: Dopamine dysregulation syndrome (DDS) is a complication of Parkinson's disease (PD) that seriously affects the quality of life of PD patients. Currently, the risk factors for DDS are poorly known, and it is critical to identify them in the early stages of PD. OBJECTIVE: To explore the incidence of and risk factors for DDS in patients with early PD. METHODS: A retrospective cohort study was conducted on the general data, clinical features, and imaging data of patients with early PD in the PPMI database. Multivariate Cox regression analysis was performed to analyze the risk factors for the development of DDS in patients with early PD, and Kaplan‒Meier curves examined the frequency and predictors of incident DDS symptoms. RESULTS: At baseline, 2.2% (n = 6) of patients with early PD developed DDS, and the cumulative incidence rates of DDS during the 5-year follow-up period were 2.8%, 6.4%, 10.8%, 15.5%, and 18.7%, respectively. In the multivariate Cox regression model controlling for age, sex, and drug use, hypersexuality (HR = 3.088; 95% CI: 1.416~6.732; P = 0.005), compulsive eating (HR = 3.299; 95% CI: 1.665~6.534; P = 0.001), compulsive shopping (HR = 3.899; 95% CI: 1.769~8.593; P = 0.001), anxiety (HR = 4.018; 95% CI: 2.136~7.599; P < 0.01), and lower Hoehn-Yahr (H-Y) stage (HR = 0.278; 95% CI: 0.152~0.509; P < 0.01) were independent risk factors for DDS in patients with early PD. PD patients with DDS had lower DAT uptake values than those patients without DDS. CONCLUSION: Early PD patients with hypersexuality, compulsive eating, compulsive shopping, anxiety, and lower H-Y stage were at increased risk for DDS. The occurrence of DDS may be related to the decrease in the average DAT uptake of the caudate and putamen.

Synthesis and Cytotoxicity Evaluation of Dehydroepiandrosterone Derivatives by Iron-Catalyzed Stereoselective Hydroamination.

The direct modification of structurally complex natural product dehydroepiandrosterone (DHEA) through iron-catalyzed direct hydroamination of DHEA with various nitro(hetero)arenes was carried out to afford 5α-arylamino-DHEAs (1-25) in good yields (53-72%). Though as a radical reaction, it features high stereoselectivity, and only the 5α-substituted derivatives were produced. The in vitro antiproliferative activity of these synthesized compounds against the human breast cancer MCF-7 cell was evaluated, showing that most of DHEA analogues possessed the moderate cytotoxic activity. The preliminary structure-activity relationship analysis revealed that the electron-withdrawing groups installed at the para-position of arylamine ring had a great contribution to the improvement of the DHEA's cytotoxic potency. Among them, (4-trifluoromethylaniline)-DHEA (4) displayed the most potent cytotoxicity, with an IC50 value of 19.3 µM, which was 2.3-fold more active than DHEA.

Adenophorone, An Unprecedented Sesquiterpene from Eupatorium adenophorum: Structural Elucidation, Bioinspired Total Synthesis and Neuroprotective Activity Evaluation.

(-)-Adenophorone (1), a caged polycyclic sesquiterpene featuring an unprecedented tricyclo[4.3.1.05,9 ]decane skeleton, was isolated from Eupatorium adenopharum Spreng. The structure of 1 was unambiguously established by a combination of spectroscopic analysis, X-ray crystallography, and bioinspired total synthesis. Key synthetic features include a sequential Reformatsky/oxidation/regio- and stereoselective hydrogenation, and subsequent merged MBH-Tsuji-Trost cyclization. The concise synthetic sequence efficiently constructs the bicyclic skeleton of cadinene sesquiterpene (+)-euptox A (2) in 8 steps from commercially available monoterpene (-)-carvone (6), with outstanding performance on diastereocontrol. The bioinspired synthesis of 1 was achieved from 2, a plausible biogenetic precursor, via transannular Michael addition. This work provides experimental evidence of our proposed biosynthetic hypothesis of 1. Additionally, compound 1 showed potent neuroprotective activity in H2 O2 -treated SH-SY5Y and PC12 cells.

Amplification, Enrichment, and Sequencing of Mutagenic Methylated DNA Adduct through Specifically Pairing with Unnatural Nucleobases.

3-Methylthymine (m3T) is a long-known chemically stable but strongly mutagenic DNA base adduct; however, the sequencing method to determine m3T is lacking so far. Two of the main obstacles include the capacity of m3T to stall DNA elongation and its low abundance. To address the challenges, we report an unnatural base pairing strategy in this paper. A new m3T-TPT3 base pair was developed with a Vmax/Km value 82-fold higher than that of the m3T-A pair. The TPT3 nucleobase can be specifically incorporated opposite the m3T base, and the resulting m3T-TPT3 base pair can be effectively extended to give full-length products in the presence of commercial DNA polymerases. Importantly, the feature of the m3T-TPT3 pair enables a replacement PCR amplification to transfer m3T lesions at the exact positions into unnatural base pairs, which permits Sanger sequencings as well as biotin-streptavidin-based enrichments of m3T lesions. Taken together, this work offers a simple, convenient, and practical method for amplification, enrichment, and sequencing of m3T for the first time.

Palladium-catalyzed stereoselective ring-opening reaction of aryl cyclopropyl ketones.

Herein, we report that α,ß-unsaturated ketones could be obtained by palladium-catalyzed ring-opening of mono-substituted cyclopropyl ketones efficiently and systematically. (E)-1-Arylbut-2-en-1-ones were generated from aryl cyclopropyl ketones stereoselectively in yields of 23-89% by the Pd(OAc)2/PCy3 catalytic system. The reaction exhibited stereoselectivity (only E products were found) and was suitable for both phenyl and heteroaryl cyclopropyl ketones.