Total Synthesis and Antibacterial Evaluation of Lupinifolin and Its Natural Analogues.

In this study, lupinifolin (1) and its natural analogues, mundulin (2), minimiorin (3), khonklonginol H (4), flemichin D (5), and eriosemaone A (27), were obtained by chemical synthesis for the first time. Key steps involved an electrocyclization to build the linear pyran rings and a Claisen/Cope rearrangement to install the 8-prenyl substituents. All compounds were assessed for their in vitro antimicrobial activities against clinically relevant human pathogens, including one Gram-negative bacterial strain (E. coli ATCC 25922) and four Gram-positive bacterial strains (S. aureus ATCC 29213, E. faecalis ATCC 29212, MRSA21-5, and VRE ATCC 51299). The result indicated that eriosemaone A (27) was the most potent one against Gram-positive bacteria, with minimum inhibitory concentrations in the range of 0.25-0.5 µg/mL. Mechanistic studies indicated that 27 has good membrane-targeting ability to bacterial inner membranes and can bind to phosphatidylglycerol and cardiolipin in bacterial membranes, thereby disrupting the bacterial cell membranes and causing bacterial death.

Total Syntheses and Antibacterial Studies of Natural Isoflavones: Scandenone, Osajin, and 6,8-Diprenylgenistein.

Isoflavones are a class of natural products that exhibit a wide range of interesting biological properties, including antioxidant, hepatoprotective, antimicrobial, and anti-inflammatory activities. Scandenone (1), osajin (2), and 6,8-diprenylgenistein (3) are natural prenylated isoflavones that share the same polyphenol framework. In this research, the key intermediate 15 was used for the synthesis of the natural isoflavones 1-3, establishing a stereoselective synthetic method for both linear and angular pyran isoflavones. The antibacterial activities of 1-3 were also evaluated, and all of them displayed good antibacterial activity against Gram-positive bacteria. Among them, 2 was the most potent one against MRSA, with a MIC value of 2 µg/mL, and the SEM assay indicated that the bacterial cell membranes of both MRSA and E. faecalis could be disrupted by 2. These findings suggest that this type of isoflavone could serve as a lead for the development of novel antibacterial agents for the treatment of Gram-positive bacterial infections.

Total Synthesis of Kuwanons A and B and Discovery of Their Antibacterial Mechanism.

Kuwanons A (1) and B (2) are two natural prenylated flavones isolated from the root bark of Morus alba L. In this study, the first total syntheses of kuwanons A (1) and B (2) were achieved from a common intermediate with overall yields of 6.6% and 11.6%, respectively. Kuwanon B (2) exhibited antibacterial activity against Gram-positive bacteria and concentration-dependent bactericidal activity against Staphylococcus aureus bacteria. Preliminary mechanism of action studies suggested that this compound killed bacteria rapidly by disrupting bacterial membrane integrity.

Total syntheses and antibacterial evaluations of cudraflavones A-C and related Flavones.

The total syntheses of the natural prenylated flavones cudraflavones A-C (1-3), artoheterophyllin D (28) and artelasticin (29) are reported, along with the evaluations of their antibacterial activities. The key steps of the synthesis involved a Baker-Venkataraman rearrangement and an intramolecular cyclization for the construction of the flavone core and the regioselective formation of the pyran and isopentenyl scaffolds. The tested natural flavones 1-3 and 27-29 exhibited potent activity against S. aureus ATCC 29213, S. epidermidis ATCC 14990, E. faecalis ATCC 29212 and B. subtilis ATCC 6633 with MIC values ranging from 0.125 µg/mL to 16 µg/mL. Compound 3 displayed the strongest potency, with MIC values in the range between 0.125 and 1 µg/mL, as a potential candidate to combat G+ bacterial infections. Preliminary mechanism of action studies suggested that this compound killed bacteria by disrupting bacterial membrane integrity.

Differences in air displacement plethysmography, bioelectrical impedance analysis and dual-energy X-ray absorptiometry for estimating body composition in Chinese children and adolescents.

AIM: This study aimed to compare body composition (BC) measurements obtained by three widely used BC measuring methods, air displacement plethysmography (ADP), bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA), in Chinese children and adolescents by sex and different BMI categories. METHODS: We used three BC measuring methods to evaluate healthy Chinese children and adolescents aged 5-17 years with BMI categories ranging from underweight to obese. Fat mass (FM, kg), fat mass percentage (FMP, %), fat-free mass (FFM, kg) and appendicular skeletal muscle mass (ASM, kg) were measured by DXA, BIA and ADP on the same day within 1 h. RESULTS: A total of 172 Chinese children and adolescents were included in this study. The agreements for FM, FFM and ASM estimated by the three methods were excellent or good at the population level (intraclass correlation coefficient > 0.850, P < 0.05). However, ADP or BIA estimated lower body fat content and higher FFM than DXA (P < 0.001 for all). Moreover, the precise estimates significantly varied across BMI categories. In addition, the limit of agreements was wide, and the differences might not be clinically acceptable at the individual level. CONCLUSIONS: Body fat and FFM obtained by the three commonly used methods were highly correlated, but systematically different and influenced by BMI. This study provided a basis for mutual reference of measurements between three widely used methods.

Total syntheses of pongaflavone and its natural analogues.

The efficient total synthesis of anti-tumor natural product pongaflavone (1) was described starting from commercially available 2,4-dihydroxyacetophenone (9) via seven steps and in 16% overall yield. Its two natural analogues pongachromene (2) and 7,8-(2",2"-dimethylpyrano)-5,3',4'-trihydroxy-3-methoxyflavone (3) were also synthesized following the similar procedure with the yields of 11% and 18%, respectively. Their preliminary anti-tumor activities were evaluated by the inhibition effect on A549 cells. The result showed that this kind of natural products exhibited different levels of anti-tumor activity. Among them, pongachromene (2) displayed the best anti-tumor activity.

Total Syntheses and Antibacterial Evaluations of Neocyclomorusin and Related Flavones.

Neocyclomorusin (1), a natural bioactive pyranoflavone mainly isolated from plants of the Moraceae family, was synthesized for the first time using a Friedel-Crafts reaction, a Baker-Venkataraman (BK-VK) rearrangement, a selective epoxidation, and a novel SN2-type cyclization as the key steps. The present protocol was also successfully applied for the total synthesis of oxyisocyclointegrin (2). Structurally related natural products morusin (23) and cudraflavone B (24) were also prepared. We investigated the antibacterial activities of these natural compounds against both Gram-negative and Gram-positive strains. The prenylated flavones, morusin (23) and cudraflavone B (24), showed comparable activity to ampicillin and kanacycin A against Staphylococcus aureus. Both morusin (23) and cudraflavone B (24) showed better antibacterial activities than ampicillin against the Gram-positive bacteria Staphylococcus epidermidis and Bacillus subtilis. Both neocyclomorusin (1) and oxyisocyclointegrin (2) displayed disappointing antimicrobial activities against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis strains.

Total Syntheses and Anti-inflammatory Evaluations of Pongamosides A-C, Natural Furanoflavonoid Glucosides from Fruit of Pongamia pinnata (L.) Pierre.

The syntheses of three natural furanoflavonoid glucosides, including two flavone glucosides, pongamosides A (1) and B (2), and a flavonol glucoside, pongamoside C (3), were achieved for the first time in 9-15 steps from commercially available materials in overall yields ranging from 2.9% to 29%. The synthetic sequence featured a NaH-promoted BK-VK rearrangement and acid-catalyzed intramolecular cyclization to furnish the furanoflavonoid aglycone. Meanwhile, phase-transfer-catalyzed glycosylation and Schmidt's trichloroacetimidate procedure were employed to establish the pivotal O-glycosidic linkage. The anti-inflammatory activities of compounds 1-3, as well as their aglycones 5a, 5b, and 23, were determined against NO production in the LPS-stimulated RAW264.7 cells. The results indicated that the O-glycosylation may reduce the anti-inflammatory activity of furanoflavonoid in vitro.

First total syntheses of kanjone and its natural analogues.

Kanjone (1), a bioactive furanoflavone and a potent biomolecule, was first isolated from Pongamia pinnata (L.). Herein, we have developed two approaches to synthesize kanjone as well as its natural analogues 6-methoxyisopongaglabol (2) and 6,3'-dimethoxy-[2″,3″:7,8]furanoflavone (3) starting from khellin and 3-hydroxy-4-methoxy-benzaldehyde, respectively.

Total Syntheses and Anti-inflammatory Activities of Syringin and Its Natural Analogues.

Syringin (1), a natural bioactive glucoside isolated from the root of Acanthopanax senticosus (Rupr. Maxim.) Harms, possesses significant anti-inflammatory activity. In this study, we have accomplished the total syntheses of syringin (1), along with its natural analogues 2-12, from a common starting material, syringaldehyde (13), in 4-8 steps with an overall yields of 11.8-61.3%. The anti-inflammatory activities of these compounds were determined against NO production in the LPS-stimulated RAW264.7 cells. Among them, compounds 1-5, 7, and 9 exhibited different levels of anti-inflammatory activity.

Total synthesis of three natural phenethyl glycosides.

Phenethyl glycosides having phenolic or methoxy functions at benzene rings are substances widely occurring in nature. This kind of compounds has been shown to have anti-oxidant, anti-inflammatory, and anticancer activities. However, some of them are not naturally abundant, thus the synthesis of such molecules is desirable. In this paper, natural phenethyl glycosides 3 and 4 were first totally synthesized from easily available materials with overall yields of 50.5% and 40.1%, respectively. And a new synthetic route to obtain natural phenethyl glycoside 2 in 46.2% yield was also described.

Oleanolic acid inhibits the migration and invasion of hepatocellular carcinoma cells by promoting microRNA-122 expression.

MicroRNAs are emerging as important endogenous regulators of gene function and they are playing an important role in the occurrence and development of cancer. They are also regarded as robust biomarkers of cancer diagnosis and prognosis. Hepatocellular carcinoma (HCC) is a common and complex human malignancy with high mortality and morbidity in the world. MicroRNA-122 (miR-122) is a liver-specific microRNA and is closely associated with HCC metastasis, which makes miR-122 a promising target for drug design and development. In this study, we performed a cell-based screening method for discovering miR-122 activators and found that oleanolic acid (OA), a natural pentacyclic triterpene, specifically increased miR-122 expression in a concentration-dependent manner. Two HCC cell lines (HepG2 and Sk-hep-1 cells) were used to evaluate the effect of OA on cell migration and invasion abilities. The results indicated that OA attenuated the migration and invasion abilities of HCC cells by upregulating miR-122 expression. In addition, OA increased the expression of E-cadherin and decreased the expression of ß-catenin, N-cadherin and vimentin. After knocking down miR-122 with miR-122 inhibitor, we found that the effect of OA on these epithelial-to-mesenchymal transition (EMT) related molecules was significantly weakened, indicating OA exhibited anti-EMT effect by increasing the expression of miR-122. These finding may help to better understand the molecular mechanism of OA's anti-metastasis activity.

TEMPO-Mediated C-H Amination of Benzoxazoles with N-Heterocycles.

The direct amination of benzoxazoles at C2 using N-heterocycles as nitrogen sources has been developed for the first time. Several kinds of inexpensive oxidants and also electricity were effective for this transformation in the presence of 2,2,6,6-tetramethylpiperidine-N-oxyl. This metal-free and operationally simple reaction can afford a variety of important C,N'-linked bis-heteocycles in moderate to good yields under very mild reaction conditions. The in situ generated oxoammonium salt was proved to be important for this transformation.

The prevalence of smoking, second-hand smoke exposure, and knowledge of the health hazards of smoking among internal migrants in 12 provinces in China: a cross-sectional analysis.

BACKGROUND: Previous studies have provided inconsistent findings on smoking among migrants, and very limited data exist on their second-hand smoke exposure. This study aims to investigate internal migrants' smoking prevalence, second-hand smoke exposure among non-smokers, and knowledge of the health hazards of smoking in 12 major migrant provinces in China in 2013. METHODS: Data from the 2013 Migrant Dynamics Monitoring Survey in China published by the National Commission of Health and Family Planning was used in this study. Descriptive analysis, Chi-square analysis, and sex-stratified multivariate logistic regression analysis were used to explore the determinants of current smoking and second-hand smoke exposure. RESULTS: Among 7200 migrants, 34.1% (55% male, 4% female) were current smokers. For males, factors associated with current smoking were education year (aOR = 0.95, 95% CI: 0.93-0.98), duration of stay (aOR = 1.01, 95% CI: 1.00-1.03) and occupation (aOR = 1.25, 95% CI: 1.03-1.53). For females, household registration status (aOR = 1.70, 95% CI: 1.04-2.80) was the most important factor associated with current smoking. Sixty five percent of non-smokers were exposed to second-hand smoke. Factors associated with exposure to second-hand smoke were duration of stay (aOR = 1.01, 95% CI: 1.00-1.02), divorced/widowed marital status (aOR = 0.48, 95% CI: 0.25-0.91), occupation (aOR = 1.29, 95% CI: 1.05-1.58) and the nature of employer (aOR = 0.77, 95% CI: 0.60-0.97). About 95% of participants were aware that lung cancer is one of the hazards of smoking. Non-current smokers had a better knowledge of fertility reduction and accelerated aging as hazards of smoking than current smokers (p < 0.01). Knowledge of the impact of smoking on cardiovascular diseases was relatively low compared with knowledge of other smoking-related hazards (26.1-44.3%). CONCLUSIONS: Current smoking and exposure to second-hand smoke among internal migrants in China is high. Socio-demographic characteristics and migration status were strongly associated with current smoking and second-hand smoke exposure. We recommend specifically targeted tobacco control interventions to help to address these risk factors, such as focusing on divorced/widowed women.

First total synthesis of a new phenylpropanoid glycoside: natural cytotoxic compound from Cirsium japonicum.

Phenylpropanoid glycoside compound 1, the natural anti-tumor compound isolated from the erial parts of Cirsium japonicum, was first totally synthesized using easily available materials in short, convenient route with overall yield of 13.9%.

The first total synthesis of anemarchalconyn and anemarcoumarin A.

Anemarchalconyn (1) and anemarcoumarin A (2), the natural bioactive compounds isolated from the rhizomes of Anemarrhena asphodeloides Bunge (Liliaceae), were first totally synthesized using easily available materials in short, convenient routes with overall yields of 32 and 48%.

Synthesis and Fungicidal Activities of (Z/E)-3,7-Dimethyl-2,6-octadienamide and Its 6,7-Epoxy Analogues.

In order to find new lead compounds with high fungicidal activity, (Z/E)-3,7-dimethyl-2,6-octadienoic acids were synthesized via selective two-step oxidation using the commercially available geraniol/nerol as raw materials. Twenty-eight different (Z/E)-3,7-dimethyl-2,6-octadienamide derivatives were prepared by reactions of (Z/E)-carboxylic acid with various aromatic and aliphatic amines, followed by oxidation of peroxyacetic acid to afford their 6,7-epoxy analogues. All of the compounds were characterized by HR-ESI-MS and ¹H-NMR spectral data. The preliminary bioassays showed that some of these compounds exhibited good fungicidal activities against Rhizoctonia solani (R. solani) at a concentration of 50 µg/mL. For example, 5C, 5I and 6b had 94.0%, 93.4% and 91.5% inhibition rates against R. solani, respectively. Compound 5f displayed EC50 values of 4.3 and 9.7 µM against Fusahum graminearum and R. Solani, respectively.

Concise stereoselective total synthesis of (+)-muricatacin and (+)-epi-muricatacin.

Efficient stereoselective total synthesis of (+)-muricatacin (1) and (+)-epi-muricatacin (8) was accomplished from commercially available chemical pent-4-ynoic acid via Shi's asymmetric epoxidation and Mitsunobu reaction as the key steps in 17.8% and 26.9% overall yields, respectively.

Synthesis and antifungal activity of 7-methyl-7-hydroxy-2,3-benzo[c]octa-1,6-olide.

The racemic 7-methyl-7-hydroxy-2,3-benzo[c]octa-1,6-olide, the analog of natural product (6R)-3,7-dimethyl-7-hydroxy-2-octen-1,6-olide, was totally synthesized using easily available (E)-2-(2-carboxyvinyl)benzoic acid as a raw material in nine-step reactions including three key steps of Wittig reaction, epoxidation, and cyclization, with an overall yield of 10.3%. The bioassay results showed that ( ± )-2 exhibited stronger antifungal activity than the natural product ( ± )-1 and (R)-1 against Alternaria solani with an EC50 value of 27.36 µg/ml.

Development of amphipathic derivatives of thymol and carvacrol as potent broad-spectrum antibacterial agents.

In the current study, to discover novel antibacterial agents, we designed and synthesized 72 carvacrol and thymol derivatives by biomimicking the structure and function of cationic antimicrobial peptides (AMPs). Many of the derivatives showed good antibacterial activity, and compound thy2I exhibited the most potent antibacterial activity with minimum inhibitory concentration (MIC) values ranging from 0.5 µg/mL to 8 µg/mL. Compound thy2I could kill both gram-positive and gram-negative bacteria via a membrane-targeting mechanism of action with a low frequency of resistance. In addition, thy2I had the advantages of good membrane selectivity, low toxicity in vitro and in vivo, and good plasma stability. The in vivo activity results revealed that thy2I exhibited a positive therapeutic effect in a mouse skin abscess model induced by Staphylococcus aureus ATCC29213. After thy2I treatment (10 mg/kg), the bacterial load of the S. aureus-infected abscesses was reduced by approximately 99.65 %. Our study suggests that thy2I may serve as an antibacterial lead for further clinical evaluation.