Human bronchopulmonary disposition and plasma pharmacokinetics of oral bemnifosbuvir (AT-527), an experimental guanosine nucleotide prodrug for COVID-19.

BACKGROUND: Bemnifosbuvir (AT-527) is a novel oral guanosine nucleotide antiviral drug for the treatment of persons with COVID-19. Direct assessment of drug disposition in the lungs, via bronchoalveolar lavage, is necessary to ensure antiviral drug levels at the primary site of SARS-CoV-2 infection are achieved. OBJECTIVES: This Phase 1 study in healthy subjects aimed to assess the bronchopulmonary pharmacokinetics, safety and tolerability of repeated doses of bemnifosbuvir. METHODS: A total of 24 subjects were assigned to receive bemnifosbuvir twice daily at doses of 275, 550 or 825 mg for up to 3.5 days. RESULTS: AT-511, the free base of bemnifosbuvir, was largely eliminated from the plasma within 6 h post dose in all dosing groups. Antiviral drug levels of bemnifosbuvir were consistently achieved in the lungs with bemnifosbuvir 550 mg twice daily. The mean level of the guanosine nucleoside metabolite AT-273, the surrogate of the active triphosphate metabolite of the drug, measured in the epithelial lining fluid of the lungs was 0.62 µM at 4-5 h post dose. This exceeded the target in vitro 90% effective concentration (EC90) of 0.5 µM for antiviral drug exposure against SARS-CoV-2 replication in human airway epithelial cells. Bemnifosbuvir was well tolerated across all doses tested, and most treatment-emergent adverse events reported were mild in severity and resolved. CONCLUSIONS: The favourable pharmacokinetics and safety profile of bemnifosbuvir demonstrates its potential as an oral antiviral treatment for COVID-19, with 550 mg bemnifosbuvir twice daily currently under further clinical evaluation in persons with COVID-19.

First-in-human trial evaluating safety and pharmacokinetics of AT-752, a novel nucleotide prodrug with pan-serotype activity against dengue virus.

AT-752 is a novel guanosine nucleotide prodrug inhibitor of the dengue virus (DENV) polymerase with sub-micromolar, pan-serotype antiviral activity. This phase 1, double-blind, placebo-controlled, first-in-human study evaluated the safety, tolerability, and pharmacokinetics of ascending single and multiple oral doses of AT-752 in healthy subjects. AT-752 was well tolerated when administered as a single dose up to 1,500 mg or when administered as multiple doses up to 750 mg three times daily (TID). No serious adverse events occurred, and the majority of treatment-emergent adverse events were mild in severity and resolved by the end of the study. In those receiving single ascending doses of AT-752, no pharmacokinetic sensitivity was observed in Asian subjects, and no food effect was observed. Plasma exposure of the guanosine nucleoside metabolite AT-273, the surrogate of the active triphosphate metabolite of the drug, increased with increasing dose levels of AT-752 and exhibited a long half-life of approximately 15-25 h. Administration of AT-752 750 mg TID led to a rapid increase in plasma levels of AT-273 exceeding the target in vitro 90% effective concentration (EC90) of 0.64 µM in inhibiting DENV replication, and maintained this level over the treatment period. The favorable safety and pharmacokinetic results support the evaluation of AT-752 as an antiviral for the treatment of dengue in future clinical studies.Registered at ClinicalTrials.gov (NCT04722627).

Bemnifosbuvir (BEM, AT-527), a novel nucleotide analogue inhibitor of the hepatitis C virus NS5B polymerase.

INTRODUCTION: Chronic hepatitis C virus (HCV) persists as a public health concern worldwide. Consequently, optimizing HCV therapy remains an important objective. While current therapies are generally highly effective, advanced antiviral agents are needed to maximize cure rates with potentially shorter treatment durations in a broader patient population, particularly those patients with advanced diseases who remain difficult to treat. AREAS COVERED: This review summarizes the in vitro anti-HCV activity, preclinical pharmacological properties of bemnifosbuvir (BEM, AT-527), a novel prodrug that is metabolically converted to AT-9010, the active guanosine triphosphate analogue that potently and selectively inhibits several viral RNA polymerases, including the HCV NS5B polymerase. Results from clinical proof-of-concept and phase 2 combination studies are also discussed. EXPERT OPINION: BEM exhibits potent pan-genotype activity against HCV, and has favorable safety, and drug interaction profiles. BEM is approximately 10-fold more potent than sofosbuvir against HCV genotypes (GT) tested in vitro. When combined with a potent NS5A inhibitor, BEM is expected to be a promising once-daily oral antiviral for chronic HCV infection of all genotypes and fibrosis stages with potentially short treatment durations.

Oral bemnifosbuvir (AT-527) vs placebo in patients with mild-to-moderate COVID-19 in an outpatient setting (MORNINGSKY).

Aim: This phase III study assessed the efficacy/safety/antiviral activity/pharmacokinetics of bemnifosbuvir, a novel, oral nucleotide analog to treat COVID-19. Patients & methods: Outpatient adults/adolescents with mild-to-moderate COVID-19 were randomized 2:1 to bemnifosbuvir/placebo. Time to symptom alleviation/improvement (primary outcome), risk of hospitalization/death, viral load and safety were evaluated. Results: Although the study was discontinued prematurely and did not meet its primary end point, bemnifosbuvir treatment resulted in fewer hospitalizations (71% relative risk reduction), COVID-19-related medically attended hospital visits, and COVID-19-related complications compared with placebo. No reduction in viral load was observed. The proportion of patients with adverse events was similar; no deaths occurred. Conclusion: Bemnifosbuvir showed hospitalization reduction in patients with variable disease progression risk and was well tolerated. Clinical Trial Registration: NCT04889040 (ClinicalTrials.gov).

A Phase 2 Randomized Trial Evaluating the Antiviral Activity and Safety of the Direct-Acting Antiviral Bemnifosbuvir in Ambulatory Patients with Mild or Moderate COVID-19 (MOONSONG Study).

Bemnifosbuvir is an oral antiviral drug with a dual mechanism of action targeting viral RNA polymerase, with in vitro activity against SARS-CoV-2. We conducted a phase 2, double-blind study evaluating the antiviral activity, safety, efficacy, and pharmacokinetics of bemnifosbuvir in ambulatory patients with mild/moderate COVID-19. Patients were randomized 1:1 to bemnifosbuvir 550 mg or placebo (cohort A) and 3:1 to bemnifosbuvir 1,100 mg or placebo (cohort B); all doses were given twice daily for 5 days. The primary endpoint was a change from baseline in the amount of nasopharyngeal SARS-CoV-2 viral RNA by reverse transcription PCR (RT-PCR). The modified intent-to-treat infected population comprised 100 patients (bemnifosbuvir 550 mg, n = 30; bemnifosbuvir 1,100 mg, n = 30; cohort A placebo, n = 30; cohort B placebo, n = 10). The primary endpoint was not met: the difference in viral RNA adjusted means at day 7 was -0.25 log10 copies/mL between bemnifosbuvir 550 mg and cohort A placebo (80% confidence interval [CI], -0.66 to 0.16; P = 0.4260), and -0.08 log10 copies/mL between bemnifosbuvir 1,100 mg and pooled placebo (80% CI, -0.48 to 0.33; P = 0.8083). Bemnifosbuvir 550 mg was well tolerated. Incidence of nausea and vomiting was higher with bemnifosbuvir 1,100 mg (10.0% and 16.7% of patients, respectively) than pooled placebo (2.5% nausea, 2.5% vomiting). In the primary analysis, bemnifosbuvir did not show meaningful antiviral activity on nasopharyngeal viral load as measured by RT-PCR compared with placebo in patients with mild/moderate COVID-19. The trial is registered at ClinicalTrials.gov under registration number NCT04709835. IMPORTANCE COVID-19 continues to be a major global public health challenge, and there remains a need for effective and convenient direct-acting antivirals that can be administered outside health care settings. Bemnifosbuvir is an oral antiviral with a dual mechanism of action and potent in vitro activity against SARS-CoV-2. In this study, we evaluated the antiviral activity, safety, efficacy, and pharmacokinetics of bemnifosbuvir in ambulatory patients with mild/moderate COVID-19. In the primary analysis, bemnifosbuvir did not show meaningful antiviral activity compared with placebo as assessed by nasopharyngeal viral loads. The negative predictive value of nasopharyngeal viral load reduction for clinical outcomes in COVID-19 is currently unclear, and further evaluation of bemnifosbuvir for COVID-19 may be warranted despite the findings observed in this study.

The relationship between vitamin D levels in umbilical cord blood and infantile eczema.

A total of 179 normal full-term pregnant women and their newborns were randomly selected. Umbilical venous blood was extracted after the delivery, and the serum level of 25(OH)D3 was measured. Forty 2 days, 3 months, 6 months, and one year after the birth to be asked about the occurrence and development of infant eczema. Thirteen cases were lost to follow-up. The median concentration of 25(OH)D3 in the cord blood was 25.40 ng/mL. Thirty eight cases (22.9%) were vitamin D deficient (<20 ng/mL), 77 cases (46.4%) were vitamin D insufficient (20-30 ng/mL), and 51 cases (30.7%) were vitamin D sufficient (≥30 ng/mL). The incidence of eczema in the umbilical cord blood vitamin D sufficient group was lower than that in the deficient and insufficient groups (p < .05). Sufficient umbilical cord blood vitamin D levels are associated with a lower incidence of eczema in infants up to one year of age. IMPACT STATEMENTWhat is already known on this subject? A number of studies have suggested that vitamin D levels in early life are related to the occurrence of allergic diseases, but the conclusions are not uniform.What do the results of this study add? The rate of sufficient umbilical cord blood vitamin D was low in the Songjiang area of Shanghai. Sufficient umbilical cord blood vitamin D levels (≥30 ng/mL) are associated with a lower incidence of eczema in infants up to 1 year of age.What are the implications of these findings for clinical practice and/or further research? At present, the dose of vitamin D for pregnant women at home and abroad is not consistent, so the specific dose of vitamin D for pregnant women to maintain the foetus needs further discussion. It is expected that a reasonable recommended dose can be developed to reduce the risk of allergic diseases in future generations from a primary prevention perspective.

Organocatalyzed asymmetric dearomative 1,3-dipolar cycloaddition of 2-nitrobenzofurans and N-2,2,2-trifluoroethylisatin ketimines.

A readily available chiral cyclohexanediamine-derived bifunctional tertiary amine-squaramide catalyst is more effective for the asymmetric dearomative 1,3-dipolar cycloaddition of 2-nitrobenzofurans and N-2,2,2-trifluoroethylisatin ketimines. A range of structurally diverse spiro-fused polyheterocyclic compounds containing oxindole, pyrrolidine, and hydrobenzofuran motifs were smoothly obtained in excellent results (up to 99% yield, >20:1 dr in all cases and up to 99% ee). This method features high efficiency, mild reaction conditions, exquisite asymmetric induction, wide functional group tolerance, great potential for scale-up synthesis, and attractive product diversification.

Efficacy and safety of salmeterol/fluticasone compared with montelukast alone (or add-on therapy to fluticasone) in the treatment of bronchial asthma in children and adolescents: a systematic review and meta-analysis.

BACKGROUND: Despite the recommendation of inhaled corticosteroids (ICSs) plus long-acting beta 2-agonist (LABA) and leukotriene receptor antagonist (LTRA) or ICS/LTRA as stepwise approaches in asthmatic children, there is a lack of published systematic review comparing the efficacy and safety of the two therapies in children and adolescents aged 4 to 18 years. This study aimed to compare the safety and efficacy of salmeterol/fluticasone (SFC) vs. montelukast (MON), or combination of montelukast and fluticasone (MFC) in children and adolescents aged 4 to 18 years with bronchial asthma. METHODS: A systematic search was conducted in MEDLINE, EMBASE, the Cochrane Library, China BioMedical Literature Database, Chinese National Knowledge Infrastructure, VIP Database for Chinese Technical Periodical, and Wanfang for randomized controlled trials (RCTs) published from inception to May 24, 2021. Interventions are as follows: SFC vs. MON, or combination of MFC, with no limitation of dosage or duration. Primary and secondary outcome measures were as follows: the primary outcome of interest was the risk of asthma exacerbation. Secondary outcomes included risk of hospitalization, pulmonary function, asthma control level, quality of life, and adverse events (AEs). A random-effects (I2 ≥ 50%) or fixed-effects model (I2 < 50%) was used to calculate pooled effect estimates, comparing the outcomes between the intervention and control groups where feasible. RESULTS: Of the 1006 articles identified, 21 studies met the inclusion criteria with 2643 individuals; two were at low risk of bias. As no primary outcomes were similar after an identical treatment duration in the included studies, meta-analysis could not be performed. However, more studies favored SFC, instead of MON, owing to a lower risk of asthma exacerbation in the SFC group. As for secondary outcome, SFC showed a significant improvement of peak expiratory flow (PEF)%pred after 4 weeks compared with MFC (mean difference [MD]: 5.45; 95% confidence interval [CI]: 1.57-9.34; I2 = 95%; P = 0.006). As for asthma control level, SFC also showed a higher full-controlled level (risk ratio [RR]: 1.51; 95% CI: 1.24-1.85; I2 = 0; P < 0.001) and higher childhood asthma control test score after 4 weeks of treatment (MD: 2.30; 95% CI: 1.39-3.21; I2 = 72%; P < 0.001) compared with MFC. CONCLUSIONS: SFC may be more effective than MFC for the treatment of asthma in children and adolescents, especially in improving asthma control level. However, there is insufficient evidence to make firm conclusive statements on the use of SFC or MON in children and adolescents aged 4 to 18 years with asthma. Further research is needed, particularly a combination of good-quality long-term prospective studies and well-designed RCTs. PROSPERO REGISTRATION NUMBER: CRD42019133156.

AT-527, a Double Prodrug of a Guanosine Nucleotide Analog, Is a Potent Inhibitor of SARS-CoV-2 In Vitro and a Promising Oral Antiviral for Treatment of COVID-19.

The impact of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19, is global and unprecedented. Although remdesivir has recently been approved by the FDA to treat SARS-CoV-2 infection, no oral antiviral is available for outpatient treatment. AT-527, an orally administered double prodrug of a guanosine nucleotide analog, was previously shown to be highly efficacious and well tolerated in hepatitis C virus (HCV)-infected subjects. Here, we report the potent in vitro activity of AT-511, the free base of AT-527, against several coronaviruses, including SARS-CoV-2. In normal human airway epithelial cells, the concentration of AT-511 required to inhibit replication of SARS-CoV-2 by 90% (EC90) was 0.47 µM, very similar to its EC90 against human coronavirus (HCoV)-229E, HCoV-OC43, and SARS-CoV in Huh-7 cells. Little to no cytotoxicity was observed for AT-511 at concentrations up to 100 µM. Substantial levels of the active triphosphate metabolite AT-9010 were formed in normal human bronchial and nasal epithelial cells incubated with 10 µM AT-511 (698 ± 15 and 236 ± 14 µM, respectively), with a half-life of at least 38 h. Results from steady-state pharmacokinetic and tissue distribution studies of nonhuman primates administered oral doses of AT-527, as well as pharmacokinetic data from subjects given daily oral doses of AT-527, predict that twice daily oral doses of 550 mg AT-527 will produce AT-9010 trough concentrations in human lung that exceed the EC90 observed for the prodrug against SARS-CoV-2 replication. This suggests that AT-527 may be an effective treatment option for COVID-19.

Catalytic Enantioselective Dearomatization/Rearomatization of 2-Nitroindoles to Access 3-Indolyl-3'-Aryl-/Alkyloxindoles: Application in the Formal Synthesis of Cyclotryptamine Alkaloids.

The first catalytic enantioselective dearomatization/rearomatization of 2-nitroindoles triggered by the Michael addition of 3-monosubstituted oxindoles was established. A wide range of 3-indolyl-3'-alkyloxindoles (up to 99% yield, 97% ee) and 3-indolyl-3'-aryloxindoles (up to 95% yield, 99% ee) were obtained by using an organocatalyst. This method provides an unprecedented strategy to access structurally diverse 3,3'-disubstituted oxindoles bearing a sterically congested triaryl-containing all-carbon quaternary stereocenter. The utility of this approach was verified by the formal synthesis of cyclotryptamine alkaloids.

Genetic structure, gene flow pattern, and association analysis of superior germplasm resources in domesticated upland cotton (Gossypium hirsutum L.).

Gene flow patterns and the genetic structure of domesticated crops like cotton are not well understood. Furthermore, marker-assisted breeding of cotton has lagged far behind that of other major crops because the loci associated with cotton traits such as fiber yield and quality have scarcely been identified. In this study, we used 19 microsatellites to first determine the population genetic structure and patterns of gene flow of superior germplasm resources in upland cotton. We then used association analysis to identify which markers were associated with 15 agronomic traits (including ten yield and five fiber quality traits). The results showed that the upland cotton accessions have low levels of genetic diversity (polymorphism information content = 0.427), although extensive gene flow occurred among different ecological and geographic regions. Bayesian clustering analysis indicated that the cotton resources used in this study did not belong to obvious geographic populations, which may be the consequence of a single source of domestication followed by frequent genetic introgression mediated by human transference. A total of 82 maker-trait associations were examined in association analysis and the related ratios for phenotypic variations ranged from 3.04% to 47.14%. Interestingly, nine SSR markers were detected in more than one environmental condition. In addition, 14 SSR markers were co-associated with two or more different traits. It was noteworthy that NAU4860 and NAU5077 markers detected at least in two environments were simultaneously associated with three fiber quality traits (uniformity index, specific breaking strength and micronaire value). In conclusion, these findings provide new insights into the population structure and genetic exchange pattern of cultivated cotton accessions. The quantitative trait loci of domesticated cotton identified will also be very useful for improvement of yield and fiber quality of cotton in molecular breeding programs.

Best practice for infection prevention in pediatric respiratory clinics during the COVID-19 epidemic.

During the COVID-19 epidemic, it is important for ensuring infection prevention and control in the pediatric respiratory clinics. Herein, we introduced the practice of infection prevention and control in pediatric respiratory clinics in China. Triage measures for patients who visit respiratory clinics, quality control for pediatric respiratory clinics and other preventive measures for related examinations and treatment have been introduced in this review article.

Preclinical evaluation of AT-527, a novel guanosine nucleotide prodrug with potent, pan-genotypic activity against hepatitis C virus.

Despite the availability of highly effective direct-acting antiviral (DAA) regimens for the treatment of hepatitis C virus (HCV) infections, sustained viral response (SVR) rates remain suboptimal for difficult-to-treat patient populations such as those with HCV genotype 3, cirrhosis or prior treatment experience, warranting development of more potent HCV replication antivirals. AT-527 is the hemi-sulfate salt of AT-511, a novel phosphoramidate prodrug of 2'-fluoro-2'-C-methylguanosine-5'-monophosphate that has potent in vitro activity against HCV. The EC50 of AT-511, determined using HCV laboratory strains and clinical isolates with genotypes 1-5, ranged from 5-28 nM. The active 5'-triphosphate metabolite, AT-9010, specifically inhibited the HCV RNA-dependent RNA polymerase. AT-511 did not inhibit the replication of other selected RNA or DNA viruses in vitro. AT-511 was approximately 10-fold more active than sofosbuvir (SOF) against a panel of laboratory strains and clinical isolates of HCV genotypes 1-5 and remained fully active against S282T resistance-associated variants, with up to 58-fold more potency than SOF. In vitro, AT-511 did not inhibit human DNA polymerases or elicit cytotoxicity or mitochondrial toxicity at concentrations up to 100 µM. Unlike the other potent guanosine analogs PSI-938 and PSI-661, no mutagenic O6-alkylguanine bases were formed when incubated with cytochrome P450 (CYP) 3A4, and AT-511 had IC50 values ≥25 µM against a panel of CYP enzymes. In hepatocytes from multiple species, the active triphosphate was the predominant metabolite produced from the prodrug, with a half-life of 10 h in human hepatocytes. When given orally to rats and monkeys, AT-527 preferentially delivered high levels of AT-9010 in the liver in vivo. These favorable preclinical attributes support the ongoing clinical development of AT-527 and suggest that, when used in combination with an HCV DAA from a different class, AT-527 may increase SVR rates, especially for difficult-to-treat patient populations, and could potentially shorten treatment duration for all patients.

Safety, pharmacokinetics and antiviral activity of AT-527, a novel purine nucleotide prodrug, in HCV-infected subjects with and without cirrhosis.

AT-527 is a novel modified guanosine nucleotide prodrug inhibitor of the hepatitis C virus (HCV) NS5B polymerase, with increased in vitro antiviral activity as compared to sofosbuvir and a highly differentiated favorable preclinical profile compared to other anti-HCV nucleoside/nucleotide analogs. This was a multiple part clinical study where multiple ascending doses of AT-527 up to 600 mg (expressed as AT-527 salt form; equivalent to 553 mg free base) once daily for seven days were evaluated in a randomized, double-blind, placebo-controlled study of treatment-naïve, non-cirrhotic, genotype 1b, HCV-infected subjects. The highest dose of AT-527 for the same duration was then evaluated in two open label cohorts of a) non-cirrhotic, genotype 3, HCV-infected subjects and b) HCV-infected subjects of any genotype with compensated (Child-Pugh A) cirrhosis. AT-527 was well tolerated for seven days in all cohorts. At the highest dose tested, mean HCV RNA reductions of up to 2.4 log10 IU/mL occurred within the first 24 hours of dosing. Mean maximum reductions observed with seven days of dosing were 4.4, 4.5 and 4.6 log10 IU/mL in non-cirrhotic subjects with HCV genotype 1b, non-cirrhotic subjects with HCV genotype 3, and subjects with compensated cirrhosis, respectively. The systemic half-life of AT-273, the nucleoside metabolite considered a surrogate of intracellular phosphates including the active triphosphate, exceeded 20 hours, supporting once daily dosing. In summary, AT-527 demonstrated rapid, potent, dose/exposure-related and pan-genotypic antiviral activity with similar responses between subjects with and without cirrhosis. Exposure-antiviral response analysis identified 550 mg (free base equivalent) as the optimal dose of AT-527. Safety and antiviral activity data from this study warrant continued clinical development of AT-527 dosed once daily.

New Naphtho-γ-Pyrones Isolated from Marine-Derived Fungus Penicillium sp. HK1-22 and Their Antimicrobial Activities.

Three novel monomeric naphtho-γ-pyrones, peninaphones A-C (compounds 1-3), along with two known bis-naphtho-γ-pyrones (compounds 4 and 5) were isolated from mangrove rhizosphere soil-derived fungus Penicillium sp. HK1-22. The absolute configurations of compounds 1 and 2 were determined by electronic circular dichroism (ECD) spectra, and the structure of compound 3 was confirmed by single-crystal X-ray diffraction analysis. Compounds 4 and 5 are a pair of hindered rotation isomers. A hypothetical biosynthetic pathway for the isolated monomeric and dimeric naphtho-γ-pyrones is also discussed in this study. Compounds 1-3 showed antibacterial activity against Staphylococcus aureus (ATCC 43300, 33591, 29213, and 25923) with minimum inhibitory concentration (MIC) values in the range of 12.5-50 µg/mL. Compound 3 exhibited significant activity against the rice sheath blight pathogen Rhizoctonia solani.

Organocatalyzed Asymmetric Dearomative Aza-Michael/Michael Addition Cascade of 2-Nitrobenzofurans and 2-Nitrobenzothiophenes with 2-Aminochalcones.

An organocatalyzed dearomative aza-Michael/Michael addition cascade of 2-nitrobenzofurans and 2-nitrobenzothiophenes with 2-aminochalcones has been developed, opening a new channel to access a series of optically active tetrahydrobenzofuro[3,2- b]quinolines and tetrahydrobenzo[4,5]thieno[3,2- b]quinolines bearing three contiguous stereocenters with excellent diastereo- and enantioselectivities (all cases >20:1 dr, up to 99% ee). This study features the first asymmetric dearomative cascade reaction of 2-nitrobenzofurans and 2-nitrobenzothiophenes beginning with aza-Michael addition. The potential applications of the methodology were demonstrated by the preparative-scale experiment and the versatile transformations of the products.

NaBr-Induced Production of Brominated Azaphilones and Related Tricyclic Polyketides by the Marine-Derived Fungus Penicillium janthinellum HK1-6.

Cultivation of the mangrove rhizosphere soil-derived fungus Penicillium janthinellum HK1-6 with NaBr led to the isolation of two new brominated azaphilones, penicilones G and H (5, 6), two new tricyclic polyketides, penijanthinones A and B (7, 8), and two known azaphilones, penicilones A and B (1, 2). The planar structures and relative configurations of the new compounds were elucidated using comprehensive spectroscopic methods including 1D and 2D NOE spectra. Their absolute configurations were determined by chemical conversions, TDDFT ECD calculations, and comparisons of their ECD spectra. Interestingly, the NaBr-induced brominated azaphilones (5, 6) had the opposite configuration at C-7 compared to the chloro analogues (3, 4) produced by this fungus cultivated with sea salt. Ester hydrolysis of penicilone B (2) afforded the carboxylic acid side chain 2,4-dimethyldec-2-enoic acid (9), with a 4 S configuration assigned by its specific rotation. Penicilone H (6) showed antibacterial activity with MIC values ranging from 3.13 to 12.5 µg/mL.

Organocatalyzed Dearomative Cycloaddition of 2-Nitrobenzofurans and Isatin-Derived Morita-Baylis-Hillman Carbonates: Highly Stereoselective Construction of Cyclopenta[ b]benzofuran Scaffolds.

The first organocatalyzed asymmetric dearomative cycloaddition between 2-nitrobenzofurans and isatin-derived Morita-Baylis-Hillman carbonates has been developed. Using a modified cinchona alkaloid as the catalyst, a series of structurally diverse cyclopenta[ b]benzofuran derivatives with three contiguous stereocenters, including a spiro-quaternary chiral center, could be smoothly obtained in excellent results (all cases >20:1 dr, up to 99% yield and 98% ee). The utility of this method was showcased by the versatile transformations of the product.

Comparative Chloroplast Genomics of Gossypium Species: Insights Into Repeat Sequence Variations and Phylogeny.

Cotton is one of the most economically important fiber crop plants worldwide. The genus Gossypium contains a single allotetraploid group (AD) and eight diploid genome groups (A-G and K). However, the evolution of repeat sequences in the chloroplast genomes and the phylogenetic relationships of Gossypium species are unclear. Thus, we determined the variations in the repeat sequences and the evolutionary relationships of 40 cotton chloroplast genomes, which represented the most diverse in the genus, including five newly sequenced diploid species, i.e., G. nandewarense (C1-n), G. armourianum (D2-1), G. lobatum (D7), G. trilobum (D8), and G. schwendimanii (D11), and an important semi-wild race of upland cotton, G. hirsutum race latifolium (AD1). The genome structure, gene order, and GC content of cotton species were similar to those of other higher plant plastid genomes. In total, 2860 long sequence repeats (>10 bp in length) were identified, where the F-genome species had the largest number of repeats (G. longicalyx F1: 108) and E-genome species had the lowest (G. stocksii E1: 53). Large-scale repeat sequences possibly enrich the genetic information and maintain genome stability in cotton species. We also identified 10 divergence hotspot regions, i.e., rpl33-rps18, psbZ-trnG (GCC), rps4-trnT (UGU), trnL (UAG)-rpl32, trnE (UUC)-trnT (GGU), atpE, ndhI, rps2, ycf1, and ndhF, which could be useful molecular genetic markers for future population genetics and phylogenetic studies. Site-specific selection analysis showed that some of the coding sites of 10 chloroplast genes (atpB, atpE, rps2, rps3, petB, petD, ccsA, cemA, ycf1, and rbcL) were under protein sequence evolution. Phylogenetic analysis based on the whole plastomes suggested that the Gossypium species grouped into six previously identified genetic clades. Interestingly, all 13 D-genome species clustered into a strong monophyletic clade. Unexpectedly, the cotton species with C, G, and K-genomes were admixed and nested in a large clade, which could have been due to their recent radiation, incomplete lineage sorting, and introgression hybridization among different cotton lineages. In conclusion, the results of this study provide new insights into the evolution of repeat sequences in chloroplast genomes and interspecific relationships in the genus Gossypium.

Diastereo- and Enantioselective Dearomative [3 + 2] Cycloaddition Reaction of 2-Nitrobenzofurans with 3-Isothiocyanato Oxindoles.

Enantioselective dearomative [3 + 2] cycloaddition reaction of 2-nitrobenzofurans with 3-isothiocyanato oxindoles was developed. The reaction employs a chiral bis(oxazoline)/Zn(OTf)2 catalyst, allowing a practical, straightforward access to structurally diverse spirooxindoles containing a 2,3-dihydrobenzofuran motif and three contiguous stereocenters with excellent diastereo- and enantioselectivities. The synthetic potentials of the method have been demonstrated by the scale-up experiment and transformations of the products. The preliminary mechanism was investigated with experimental observations, nonlinear effects studies, and MS experiments.