Isolation, structure modification, and anti-rheumatoid arthritis activity of isopimarane-type diterpenoids from Orthosiphon aristatus.

Orthosiphon aristatus is a well-known folkloric medicine and herb for Guangdong soup for the treatment of rheumatism in China. Eight isopimarane-type and migrated pimarane-type diterpenoids (1-8), including a new one with a rarely occurring α,ß-unsaturated diketone C-ring, were isolated from O. aristatus. Their structures were determined by spectroscopic methods and quantum chemical calculations. Furthermore, the most abundant compound, orthosiphol K, was structurally modified by modern synthetic techniques to give seven new derivatives (9-15). The anti-rheumatoid arthritis activity of these diterpenoids were evaluated on a TNF-α induced MH7A human rheumatoid fibroblast-like synoviocyte model. Compound 10 showed the most potent activity among these compounds. Based on their inhibitory effects on the release levels of IL-1ß, the preliminary structure-activity relationships were concluded. Furthermore, western blot analysis revealed that 10 could increase the expression of IκBα and decrease the expression of NF-κB p65, and the expression levels of COX-2 and NLRP3 proteins were consequently down-regulated.

Au-Catalyzed Asymmetric Polyene Cyclization and Its Application in the Total Synthesis of (+)-2-Ketoferruginol, (+)-Fleuryinol B, (+)-Salviol, and (-)-Erythroxylisin A.

A catalytic asymmetric 1,3-acyloxy shift/polyene cyclization cascade has been achieved with good enantioselectivities under the catalysis of the chiral Au(I) reagent. The synthetic utility of this method has been showcased by the catalytic asymmetric total syntheses of (+)-2-ketoferruginol, (+)-fleuryinol B, and (+)-salviol. Notably, the first enantioselective total synthesis of (-)-erythroxylisin A has also been realized in 15 steps.

Palladium Catalyzed Annulation of o-Iodo-Anilines with Propargyl Alcohols: Synthesis of Substituted Quinolines.

A palladium catalyzed annulation of o-iodo-anilines with propargyl alcohols for the synthesis of substituted quinolines has been developed. The reaction tolerates diverse functional groups under mild conditions, providing direct access to 2,4-disubstituted quinolines from easily available starting materials. A broad range of 2,4-disubstituted quinolines were efficiently prepared in good to excellent yields.

Bicyclic Amidine-Triggered Cyclization of o-Alkynylisocyanobenzenes: Synthesis of Lactam-Derived Quinolines.

Efficient access to the synthesis of lactam-derived quinoline through a bicyclic amidine-triggered cyclization reaction from readily prepared o-alkynylisocyanobenzenes has been developed. The reaction was initiated by nucleophilic attack of the bicyclic amidines to o-alkynylisocyanobenzenes, subsequently with intramolecular cyclization to produce a DBU-quinoline-based amidinium salt, followed by hydrolysis to afford the lactam-derived quinoline in moderate to good yields.

Rh(I)-Catalyzed [5 + 2]/[2 + 2] Cycloaddition Cascade to Access a Cyclobutane-Fused [4-5-6-7] Tetracyclic Framework.

A Rh(I)-catalyzed [5 + 2]/[2 + 2] cycloaddition cascade has been developed to afford a complex and highly strained [4-5-6-7] tetracyclic framework in good yields and excellent diastereoselectivities. During this transformation, three rings, three C-C bonds, and four contiguous stereocenters were formed efficiently. Mechanistically, the rare sterically congested multisubstituted cyclobutanes are constructed readily through Michael addition and a Mannich reaction cascade.

Catalyst-Controlled Nickel-Catalyzed Intramolecular endo-Selective C-H Cyclization of Benzimidazoles with Alkenes.

Compared with the widely explored exo-selective C-H cyclization, transition metal-catalyzed endo-selective C-H cyclization of benzimidazoles with alkenes has been a formidable challenge. Previous efforts mainly rely on substrate-controlled methods, rendering the product complexity restricted. Herein we report a catalyst-controlled method to facilitate endo-cyclization, in which a bulky N-heterocyclic carbene ligand and tBuOK base-enabled Ni-Al bimetallic catalyst prove critical to the endo selectivity.

InI3-catalyzed polyene cyclization of allenes and its application in the total synthesis of seven abietane-type diterpenoids.

A novel polyene cyclization using the allene group as the initiator has been successfully developed. This methodology provides an efficient strategy for the construction of an abietane-type tricyclic skeleton with a functionalizable C2-C3 double bond and features a wide substrate scope and excellent stereoselectivities. Potential utility of this approach has been well demonstrated by the collective total synthesis of seven abietane-type diterpenoids. Specifically, (±)-2,3-dihydroxyferruginol and (±)-2,3-dihydroxy-15,16-dinor-ent-pimar-8,11,13-triene were synthesized for the first time.

Alteration of gut microbiota in high-fat diet-induced obese mice using carnosic acid from rosemary.

Rosmarinus officinalis (rosemary) is widely used as a food ingredient. Rosemary extract (containing 40% carnosic acid) exhibited potent antiobesity activity. However, the relationship between carnosic acid (CA) and changes in the gut microbiota of high-fat diet (HFD)-induced obese mice has not been fully investigated. C57BL/6 mice were fed a normal diet, an HFD, or an HFD containing 0.1% or 0.2% CA for 10 weeks. CA exhibited promising antiobesity effects and caused marked alterations in the gut microbiota of HFD-induced obese mice. CA caused the prevalence of probiotics and functional bacteria, including Akkermansia muciniphila, Muribaculaceae unclassified, and Clostridium innocuum group, and inhibited diabetes-sensitive bacteria, including Proteobacteria and Firmicutes. The ratio of Firmicutes to Bacteroidetes was regulated by CA in a dose-dependent manner, decreasing it from 13.22% to 2.42%. Additionally, CA reduced bile acid-metabolizing bacteria, such as Bilophila, Clostridium, Lactobacillus, and Leuconostoc. The results of the linear discriminant analysis and effect size analysis indicated that CA attenuated the microbial changes caused by HFD. The high CA (HCA) group (HFD containing 0.2% CA) exhibited a greater abundance of Verrucomicrobiae (including Akkermansia muciniphila, genus Akkermansia, family Akkermansiaceae, and order Verrucomicrobiales), Eubacterium, and Erysipelatoclostridium, and the low CA (LCA) group (HFD containing 0.1% CA) exhibited a greater abundance of Eisenbergiella, Intestinimonas, and Ruminococcaceae. Our results demonstrate that the antiobesity effects of CA might be strongly related to its prebiotic effects.

Synthesis and bioactivities evaluation of oleanolic acid oxime ester derivatives as α-glucosidase and α-amylase inhibitors.

Different oleanolic acid (OA) oxime ester derivatives (3a-3t) were designed and synthesised to develop inhibitors against α-glucosidase and α-amylase. All the synthesised OA derivatives were evaluated against α-glucosidase and α-amylase in vitro. Among them, compound 3a showed the highest α-glucosidase inhibition with an IC50 of 0.35 µM, which was ∼1900 times stronger than that of acarbose, meanwhile compound 3f exhibited the highest α-amylase inhibitory with an IC50 of 3.80 µM that was ∼26 times higher than that of acarbose. The inhibition kinetic studies showed that the inhibitory mechanism of compounds 3a and 3f were reversible and mixed types towards α-glucosidase and α-amylase, respectively. Molecular docking studies analysed the interaction between compound and two enzymes, respectively. Furthermore, cytotoxicity evaluation assay demonstrated a high level of safety profile of compounds 3a and 3f against 3T3-L1 and HepG2 cells.HighlightsOleanolic acid oxime ester derivatives (3a-3t) were synthesised and screened against α-glucosidase and α-amylase.Compound 3a showed the highest α-glucosidase inhibitory with IC50 of 0.35 µM.Compound 3f presented the highest α-amylase inhibitory with IC50 of 3.80 µM.Kinetic studies and in silico studies analysed the binding between compounds and α-glucosidase or α-amylase.

Pd(II)-Catalyzed Atroposelective C-H Allylation: Synthesis of Enantioenriched N-Aryl Peptoid Atropisomers.

A Pd-catalyzed atroposelective C-H allylation with 1,1-disubstituted alkenes was developed for the synthesis of enantioenriched N-aryl peptoid atropisomers via ß-H elimination using commercially available and inexpensive L-pGlu-OH as a chiral ligand. Exclusive allylic selectivity was achieved. Additionally, a series of enantioenriched N-aryl peptoid atropisomers were obtained in synthetically useful yields with excellent enantioselectivities (up to 90% yield and 97% ee).

Total Synthesis of (±)-Furanether A.

The first total synthesis of (±)-furanether A, which exhibits good antifeedant activity, has been concisely achieved in 13 linear steps. Notably, the key rigid tetracyclic skeleton containing a 1-methyl-8-oxabicyclo[3.2.1]octane moiety with two vicinal quaternary carbon centers was rapidly constructed in one step through a unique tandem C-H oxidation/oxa-[3,3] Cope rearrangement/aldol cyclization sequence.

Copper-catalyzed monoselective C-H amination of ferrocenes with alkylamines.

A copper-catalyzed mono-selective C-H amination of ferrocenes assisted by 8-aminoquinoline is presented here. A range of amines, including bioactive molecules, were successfully installed to the ortho-position of ferrocene amides with high efficiency under mild conditions. A range of functionalized ferrocenes were compatible to give the aminated products in moderate to good yields. The gram-scale reaction was smoothly conducted and the directing group could be removed easily under basic conditions.

Divergent Synthesis of Skeletally Distinct Arboridinine and Arborisidine.

A divergent synthesis of skeletally distinct arboridinine and arborisidine was achieved. The central divergent strategy was inspired by the divergent biosynthetic cyclization mode of arboridinine and arborisidine and their hidden topological connection. The branch point was reached through a Michael and Mannich cascade process. A site-selective intramolecular Mannich reaction was developed to construct the tetracyclic core of arboridinine, while a site-selective intramolecular α-amination of ketone was used to access the tetracyclic core of arborisidine. A strategic Peterson olefination through intramolecular nucleophile delivery was able to set up the exocyclic olefin of arboridinine.

Synthesis of Chiral Sulfoxides via Pd(II)-Catalyzed Enantioselective C-H Alkynylation/Kinetic Resolution of 2-(Arylsulfinyl)pyridines.

A Pd(II)-catalyzed enantioselective C-H alkynylation of 2-(arylsulfinyl)pyridines via kinetic resolution using cheap and commercially available l-pGlu-OH as a chiral ligand is reported. A wide range of 2-(arylsulfinyl)pyridines were compatible with this protocol, giving the alkynylation products and recovered sulfoxides in high yields with high enantioselectivities (up to 99% ee). Furthermore, the enantioenriched products can be easily transformed to several other types of chiral sulfoxide scaffolds with the retention of enantiopurity.

TEMPO-Enabled Electrochemical Enantioselective Oxidative Coupling of Secondary Acyclic Amines with Ketones.

An electrochemical asymmetric coupling of secondary acyclic amines with ketones via a Shono-type oxidation has been described, affording the corresponding amino acid derivatives with good to excellent diastereoselectivity and enantioselectivity. The addition of an N-oxyl radical as a redox mediator could selectively oxidize the substrate rather than the product, although their oxidation potential difference is subtle (about 13 mV). This electrochemical transformation proceeds in the absence of stoichiometric additives, including metals, oxidants, and electrolytes, which gives it good functional group compatibility. Mechanistic studies suggest that proton-mediated racemization of the product is prevented by the reduction of protons at the cathode.

In vitro and in silico studies of bis (indol-3-yl) methane derivatives as potential α-glucosidase and α-amylase inhibitors.

In this paper, bis (indol-3-yl) methanes (BIMs) were synthesised and evaluated for their inhibitory activity against α-glucosidase and α-amylase. All synthesised compounds showed potential α-glucosidase and α-amylase inhibitory activities. Compounds 5 g (IC50: 7.54 ± 1.10 µM), 5e (IC50: 9.00 ± 0.97 µM), and 5 h (IC50: 9.57 ± 0.62 µM) presented strongest inhibitory activities against α-glucosidase, that were ∼ 30 times stronger than acarbose. Compounds 5 g (IC50: 32.18 ± 1.66 µM), 5 h (IC50: 31.47 ± 1.42 µM), and 5 s (IC50: 30.91 ± 0.86 µM) showed strongest inhibitory activities towards α-amylase, ∼ 2.5 times stronger than acarbose. The mechanisms and docking simulation of the compounds were also studied. Compounds 5 g and 5 h exhibited bifunctional inhibitory activity against these two enzymes. Furthermore, compounds showed no toxicity against 3T3-L1 cells and HepG2 cells.HighlightsA series of bis (indol-3-yl) methanes (BIMs) were synthesised and evaluated inhibitory activities against α-glucosidase and α-amylase.Compound 5g exhibited promising activity (IC50 = 7.54 ± 1.10 µM) against α-glucosidase.Compound 5s exhibited promising activity (IC50 = 30.91 ± 0.86 µM) against α-amylase.In silico studies were performed to confirm the binding interactions of synthetic compounds with the enzyme active site.

Novel cinnamic acid magnolol derivatives as potent α-glucosidase and α-amylase inhibitors: Synthesis, in vitro and in silico studies.

In this study, twenty novel cinnamic acid magnolol derivatives were synthesized, and screened for their anti-hyperglycemic potential. All synthesized compounds exhibited good to moderate α-glucosidase and α-amylase inhibitory activities with IC50 values: 5.11 ± 1.46-90.26 ± 1.85 µM and 4.27 ± 1.51-49.28 ± 2.54 µM as compared to the standard acarbose (IC50: 255.44 ± 1.89 µM and 80.33 ± 2.95 µM, respectively). Compound 6j showed the strongest inhibitory activity against α-glucosidase (IC50 = 5.11 ± 1.46 µM) and α-amylase (IC50 = 4.27 ± 1.51 µM). Kinetic study indicated that compound 6j was reversible and a mixed type inhibitor against α-glucosidase and α-amylase. In silico studies revealed the binding interaction between 6j and two enzymes, respectively. Finally, cells cytotoxicity assay revealed that compound 6j showed low toxicity against 3 T3-L1 cells and HepG2 cells.

Pd(II)-Catalyzed enantioselective arylation of unbiased methylene C(sp3)-H bonds enabled by a 3,3'-F2-BINOL ligand.

Palladium-catalyzed asymmetric functionalization of unbiased methylene C(sp3)-H bonds is a long-standing challenge. Here, we report a Pd(ii)-catalyzed highly enantioselective arylation of unbiased methylene C(sp3)-H bonds enabled by a strongly coordinating bidentate 2-pyridinylisopropyl (PIP) directing group and an easily accessible 3,3'-F2-BINOL chiral ligand. The use of aryl iodides with the combination of 3,3'-F2-BINOL was beneficial for high enantiocontrol. A range of aliphatic amides and aryl iodides were tolerated, providing the desired arylated products in high enantioselectivities (up to 96% ee). The PIP directing group could be removed under mild conditions without erosion of enantiopurity.

Brønsted Acid-Catalyzed Formal (3+3)-Annulation of Propargylic (Aza)-para-Quinone Methides with 4-Hydroxycoumarins and 1,3-Dicarbonyl Compounds.

Herein, we describe a highly effective 1,8-conjugate-addition-mediated formal (3+3)-annulation of (aza)-para-quinone methides in situ generated from propargylic alcohols with 4-hydroxycoumarins and 1,3-dicarbonyl compounds under the catalysis of a Brønsted acid. This methodology affords efficient and practical access to synthetically important and highly functionalized pyranocoumarins and pyrans in excellent yields under mild conditions. Importantly, these products exhibit impressive inhibitory activity toward α-glucosidase.

Effects of atorvastatin in combination with celecoxib and tipifarnib on proliferation and apoptosis in pancreatic cancer sphere-forming cells.

Cancer stem cell (CSC) plays an important role in pancreatic cancer pathogenesis and treatment failure. CSCs are characterized by their ability to form tumor spheres in serum-free medium and expression of CSC related markers. In the present study, we investigated the effect atorvastatin, celecoxib and tipifarnib in combination on proliferation and apoptosis in Panc-1 sphere-forming cells. The sphere-forming cells were isolated from Panc-1 cells by sphere-forming method. These sphere-forming cells showed CSC properties. The levels of CD44, CD133 and ALDH1A1 in the sphere-forming cells were increased. Moreover, Panc-1 sphere-forming cells were resistant to chemotherapeutic drug gemcitabine. Combined atorvastatin with celecoxib and tipifarnib synergistically decreased the sphere forming ability of Panc-1 cells and the drug combination also strongly inhibited cell proliferation and promoted apoptosis in the sphere-forming cells. The effects of the drug combination on the Panc-1 sphere-forming cells were associated with decreases in the levels of CD44, CD133 and ALDH1A1, and suppression of Akt and NF-κB activation. Results of the present study indicate that the combination of atorvastatin, celecoxib and tipifarnib may represent an effective approach for inhibiting pancreatic CSCs.