Synthesis and Biological Evaluation of Gentiopicroside Derivatives as Novel Cyclooxygenase-2 Inhibitors with Anti-Inflammatory Activity.

Purpose: Nonsteroidal anti-inflammatory drugs cause a series of adverse reactions. Thus, the search for new cyclooxygenase-2 selective inhibitors have become the main direction of research on anti-inflammatory drugs. Gentiopicroside is a novel selective inhibitor of cyclooxygenase-2 from Chinese herbal medicine. However, it is highly hydrophilic owing to the presence of the sugar fragment in its structure that reduces its oral bioavailability and limits efficacy. This study aimed to design and synthesize novel cyclooxygenase-2 inhibitors by modifying gentiopicroside structure and reducing its polarity. Materials and Methods: We introduced hydrophobic acyl chloride into the gentiopicroside structure to reduce its hydrophilicity and obtained some new derivatives. Their in vitro anti-inflammatory activities were evaluated against NO, TNF-α, PGE2, and IL-6 production in the mouse macrophage cell line RAW264.7 stimulated by lipopolysaccharide. The in vivo inhibitory activities were further tested against xylene-induced mouse ear swelling. Molecular docking predicted that whether new compounds could effectively bind to target protein cyclooxygenase-2. The inhibitory activity of new compounds to cyclooxygenase-2 enzyme were verified by the in vitro experiment. Results: A total of 21 novel derivatives were synthesized, and exhibit lower polarities than the gentiopicroside. Most compounds have good in vitro anti-inflammatory activity. The in vivo activity results demonstrated that 8 compounds were more active than gentiopicroside. The inhibition rate of some compounds was higher than celecoxib. Molecular docking predicted that 6 compounds could bind to cyclooxygenase-2 and had high docking scores in accordance with their potency of the anti-inflammatory activity. The confirmatory experiment proved that these 6 compounds had significant inhibitory effect against cyclooxygenase-2 enzyme. Structure-activity relationship analysis presumed that the para-substitution with the electron-withdrawing groups may benefit the anti-inflammatory activity. Conclusion: These gentiopicroside derivatives especially PL-2, PL-7 and PL-8 may represent a novel class of cyclooxygenase-2 inhibitors and could thus be developed as new anti-inflammatory agents.

Synthesis, and anti-inflammatory activities of gentiopicroside derivatives.

A series of 26 novel derivatives have been synthesized through structural modification of gentiopicroside, a lead COX-2 inhibitor. And their in vivo and in vitro anti-inflammatory activities have been investigated. The in vitro anti-inflammatory activities were evaluated against NO, PGE2, and IL-6 production in the mouse macrophage cell line RAW264.7 stimulated by LPS. Results showed that most compounds had good inhibitory activity. The in vivo inhibitory activities were further tested against xylene-induced mouse ear swelling. Results demonstrated that several compounds were more active than the parent compound gentiopicroside. The inhibition rate of the most active compound P23 (57.26%) was higher than positive control drug celecoxib (46.05%) at dose 0.28 mmol·kg-1. Molecular docking suggested that these compounds might bind to COX-2 and iNOS. Some of them, e.g P7, P14, P16, P21, P23, and P24, had high docking scores in accordance with their potency of the anti-inflammatory activitiy, that downregulation of the inflammatory factors, NO, PGE2, and IL-6, was possibly associated with the suppression of iNOS and COX-2. Therefore, these gentiopicroside derivatives may represent a novel class of COX-2 and iNOS inhibitors.

Nickel-Catalyzed Reductive C-Ge Coupling of Aryl/Alkenyl Electrophiles with Chlorogermanes.

Cross-electrophile coupling has emerged as a promising tool for molecular synthesis; however, current studies have focused mainly on forging C-C bonds. We report a cross-electrophile C-Ge coupling reaction and thereby demonstrate the possibility of constructing organogermanes from carbon electrophiles and chlorogermanes. The reaction proceeds under mild conditions and offers access to both aryl and alkenyl germanes. Electron-rich, electron-poor, and ortho-/meta-/para-substituted (hetero)aryl electrophiles, as well as cyclic and acyclic alkenyl electrophiles, were coupled. Gram-scale reaction, incorporation of the -GeR3 moiety into complex biologically active molecules, and derivatization of formed organogermanes are demonstrated.

Enantioselective Reductive Divinylation of Unactivated Alkenes by Nickel-Catalyzed Cyclization Coupling Reaction.

Catalytic asymmetric dicarbofunctionalization of tethered alkenes has emerged as a promising tool for producing chiral cyclic molecules; however, it typically relies on aryl-tethered alkenes to form benzene-fused compounds. Herein, we report an enantioselective cross-electrophile divinylation reaction of nonaromatic substrates, 2-bromo-1,6-dienes. The approach thus offers a route to new chiral cyclic architectures, which are key structural motifs found in various biologically active compounds. The reaction proceeds under mild conditions, and the use of chiral t-Bu-pmrox and 3,5-difluoro-pyrox ligands resulted in the formation of divinylated products with high chemo-, regio-, and enantioselectivity. The method is applicable for the incorporation of chiral hetero- and carbocycles into complex molecules.

Gentiopicroside prevents interleukin-1 beta induced inflammation response in rat articular chondrocyte.

ETHNOPHARMACOLOGICAL RELEVANCE: In traditional Chinese medicine, Gentiana macrophylla Pall have been prescribed for the treatment of pain and inflammatory conditions. In addition, it is a common Tibetan medicinal herb used for the treatment of tonsillitis, urticaria, and rheumatoid arthritis (RA), while the flowers of G. macrophylla Pall have been traditionally treated as an anti-inflammatory agent to clear heat in Mongolian medicine. The secoiridoid glycosides and their derivatives are the primary active components of G. macrophylla and have been demonstrated to be effective as anti-inflammatory agents. MATERIALS AND METHODS: Solvent extraction and D101 macroporous resin columns were employed to concentratethe gentiopicroside. Gentiopicroside cytotoxicity was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; the toxicity of gentiopicroside in chondrocytes was reconfirmed using Hoechst staining. Western blotting, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry were utilized to explore the protective effects and mechanisms of gentiopicroside prevents interleukin-1 beta induced inflammation response in rat articular chondrocyte. RESULTS: The MTT assay demonstrated that 50, 500, and 1,500 µg/mL of gentiopicroside exhibited no significant toxicity to chondrocytes (P>0.05) after 24h. Using immunohistochemistry, ELISA, RT-PCR, Western blot method to explore the protective effect and mechanism of gentiopicroside on chondrocytes induced by IL-1ß. The results showed some pathways of IL-1ß signal transduction were inhibited by gentiopicroside in rat chondrocytes: p38, ERK and JNK. Meanwhile, gentiopicroside showed inhibition in the IL-1ß-induced release of MMPs while increasing Collagen type II expression. CONCLUSIONS: The current study demonstrated that gentiopicroside exhibited a potent protective effect on IL-1ß induced inflammation response in rat articular chondrocyte. Thus, gentiopicroside could be a potential therapeutic strategy for treatment of OA.

[Chemical constituents of Tamarix chinensis].

OBJECTIVE: To study the chemical consistuents of Tamarix chinensis. METHODS: The compounds were isolated and purified by column chromatography and their structures were elucidated through spectroscopic analysis. RESULTS: Nine compounds were isolated and identified as isotamarixen(1), matairesinol(2), tetepathine(3), kaempferol(4), 4'-methylkaempferol(5),4',7-dimethylkaempferol (6), hexacosyl-3-caffeate(7), ferulic acid(8) and 3-methoxyl methyl gallate(9). CONCLUSION: Compounds 1-3,7 and 8 are isolated from this plant for the first time, compounds 1-3,7 are isolated from Tamarix genus for the first time.

[Chemical constituents from Gentiana striata].

OBJECTIVE: To study the chemical constituents of Gentiana striata. METHODS: The constituents were isolated from the whole herb of Gentiana striata by recrystalization, silica gel column chromatography, polyamide column chromatography and Sephadex LH-20,etc. Their structures were elucidated through MS, 1H-NMR, 13C-NMR. RESULTS: -8 compounds were isolated and identified as: Desoxyloganin (1), Gmephiloside (2), 5,7,4'-trihydroxy-3'-methoxyflavone (3), (+)-8-hydroxypinoresinol (4) 3S,5R, 6R, 9S-tetra-hydroxymegastigmane (5), Quercetin-3-O-beta-D-glucoside (6), Ferulic acid (7) and Ursolic acid (8). CONCLUSION: All the compounds are isolated for the first time from Gentiana striata.

[Study on the chemical constituents of Buddleja davidii].

OBJECTIVE: To study the chemical constituents of Buddleja davidii. METHODS: The constituents were isolated and purified by silica gel column chromatography, polyamide column chromatography and macroporous adsorption resin and their structures were identified by spectroscopic analysis. RESULTS: Eight compounds were elucidated as : Cranioside A (1), Eutigoside A (2), 1-O-4-Dimethoxyphenylethyl-4-O-3,4-dimethoxyphenylethy-beta-D-glucopyranoside (3), Isomartynoside (4'), 4"-O-Acetylmartynoside (5), Stigmasterol glueoside (6), beta-Sitosterol (7), Daucosterol (8). CONCLUSION: All these compounds are obtained from this plant for the first time.

[Study on the flavanone constitutes of Buddleja davidii].

OBJECTIVE: To study the chemical constitutes of Buddleja davidii. METHODS: The constitutes were isolated and purified by silica gel column chromatography, polyamide column chromatography and macroporous absorption resin and their structures were elucidated by spectroscopic analysis. RESULTS: Seven compounds including Apigenin (1), Apigenin-7-O-beta-D-glucoside (2), Acacetin (3), Acacetin-7-O-beta-D-glucoside(4), Acacetin-7-O-alpha-L-rhamnopyranosyl-(1-6)-beta-D-glucopyranoside (5), Luteolin (6), Luteolin-7-O-beta-D-glueoside (7). CONCLUSION: All these compounds are obtained from this plant for the first time.