Discovery of diarylheptanoids that activate α7 nAchR-JAK2-STAT3 signaling in macrophages with anti-inflammatory activity in vitro and in vivo.

Acute inflammatory diseases, such as sepsis, are life-threatening illnesses. Regulating the α7 nicotinic acetylcholine receptor (α7 nAchR)-mediated signaling may be a promising strategy to treat sepsis. Diarylheptanoids have long been found to exhibit anti-inflammatory properties. However, the possible mechanism of diarylheptanoids has rarely been investigated. In this study, we isolated and synthesized 49 diarylheptanoids and analogues and evaluated their anti-inflammatory activities. Among them, compounds 28 and 40 markedly blocked lipopolysaccharide (LPS)-induced production of nitric oxide (NO), interleukin-1ß (IL-1ß) and interleukin-6 in murine RAW264.7 cells. Furthermore, compounds 28 and 40 also effectively attenuated LPS-induced sepsis, acute lung injury, and cytokines release in vivo. Mechanistically, compounds 28 and 40 significantly induced phosphorylation of janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling and suppression of nuclear factor-κB (NF-κB) pathway. Furthermore, blocking α7 nAchR could effectively abolish compounds 28 and 40-mediated activation of JAK2-STAT3 signaling as well as inhibition of NF-κB activation and NO production in LPS-exposed RAW264.7 cells. Collectively, our findings have identified a new diarylheptanoid, compound 28, as an agonist of α7 nAchR-JAK2-STAT3 signaling, which can be potentially developed as a valuable candidate for the treatment of sepsis, and provide a new lead structure for the development of anti-inflammatory agents targeting α7 nAchR-JAK2-STAT3 signaling.

Trienone analogs of curcuminoids induce fetal hemoglobin synthesis via demethylation at Gγ-globin gene promoter.

The reactivation of γ-globin chain synthesis to combine with excess free α-globin chains and form fetal hemoglobin (HbF) is an important alternative treatment for ß-thalassemia. We had reported HbF induction property of natural curcuminoids, curcumin (Cur), demethoxycurcumin (DMC) and bis-demethoxycurcumin (BDMC), in erythroid progenitors. Herein, the HbF induction property of trienone analogs of the three curcuminoids in erythroleukemic K562 cell lines and primary human erythroid progenitor cells from ß-thalassemia/HbE patients was examined. All three trienone analogs could induce HbF synthesis. The most potent HbF inducer in K562 cells was trienone analog of BDMC (T-BDMC) with 2.4 ± 0.2 fold increase. In addition, DNA methylation at CpG - 53, - 50 and + 6 of Gγ-globin gene promoter in K562 cells treated with the compounds including T-BDMC (9.3 ± 1.7%, 7.3 ± 1.7% and 5.3 ± 0.5%, respectively) was significantly lower than those obtained from the control cells (30.7 ± 3.8%, 25.0 ± 2.9% and 7.7 ± 0.9%, respectively P < 0.05). The trienone compounds also significantly induced HbF synthesis in ß-thalassemia/HbE erythroid progenitor cells with significantly reduction in DNA methylation at CpG + 6 of Gγ-globin gene promoter. These results suggested that the curcuminoids and their three trienone analogs induced HbF synthesis by decreased DNA methylation at Gγ-globin promoter region, without effect on Aγ-globin promoter region.

Curcumin analogues inhibit phosphodiesterase-5 and dilate rat pulmonary arteries.

OBJECTIVES: Phosphodiesterase (PDE)-5 inhibitors are useful as vasodilators for the treatment of pulmonary arterial hypertension. We aimed to study curcumin analogues for PDE5 inhibitory activity and vasorelaxation of rat pulmonary arteries. METHODS: Three natural curcuminoids (1-3) and six synthetic analogues (4-9) were tested for PDE5 and PDE6 inhibitory activities using enzymatic radioassay. Their vasorelaxation was measured using freshly isolated segments of rat pulmonary artery and aorta. KEY FINDINGS: Curcuminoids (1-3) mildly inhibited PDE5 (half maximal inhibitory concentration (IC50 ) = 18 µm): the metamethoxyl of curcumin was important for PDE5 inhibition. But hydroxyl rearrangements, removing both methoxyls and one ketomethylene, yielded the potent 7 and 9 (IC50 = 4 µm) (compared with sildenafil, IC50 = 0.03 µm). Only 1, 3 and 4 were PDE5 selective over PDE6. Triazole-carboxylic addition provided water-solubility while preserving potency. All analogues possessed concentration-dependent vasorelaxant activity on pulmonary arteries (40% of maximal effective concentration (EC40 ) = 29-90 µm, maximum response = 60-90% at 300 µm), while compounds (1-8) were weakly acting in aorta (maximum response <40%). Only demethoxycurcumin (2) and analogues 5, 8, 9 had endothelium-dependent actions. Sildenafil was highly potent (EC40 = 0.04 µm) and highly endothelium dependent in pulmonary artery but weak on intact aorta (EC40 = 1.8 µm). Activity profiles suggest actions through additional cell pathways for promoting vasorelaxation. CONCLUSIONS: Curcumin analogues are potential leads for developing efficacious and selective PDE5 inhibitors and other pathologies of pulmonary hypertension.

Synthesis, cytotoxicity against human oral cancer KB cells and structure-activity relationship studies of trienone analogues of curcuminoids.

A general method for the synthesis of substituted (1E,4E,6E)-1,7-diphenylhepta-1,4,6-trien-3-ones, based on the aldol condensations of substituted 4-phenylbut-3-en-2-ones and substituted 3-phenylacrylaldehydes, was achieved. The natural trienones 4 and 5 have been synthesized by this method, together with the trienone analogues 9-20. These analogues were evaluated for their cytotoxic activity against human oral cancer KB cell line. The structure-activity relationship study has indicated that the analogues with the 1,4,6-trien-3-one function are more potent than the curcuminoid-type function. Analogues with meta-oxygen function on the aromatic rings are more potent than those in the ortho- and para-positions. Free phenolic hydroxy group is more potent than the corresponding methyl ether analogues. Among the potent trienones, compounds 11, 18 and 20 were more active than the anticancer drug ellipticine. All compounds were also evaluated against the non-cancerous Vero cells and it was found that compounds 11, 12 and 17 were much less toxic than curcumin (1); they showed high selectivity indices of 35.46, 33.46 and 31.68, respectively. These analogues are regarded as the potent trienones for anti-oral cancer study.

Bioactive flavonoids of the flowers of Butea monosperma.

One new dihydrochalcone, dihydromonospermoside (7), was isolated from the flowers of Butea monosperma together with three known chalcones, butein (2), monospermoside (4) and isoliquiritigenin (8), one flavone, 7,3',4'-trihydroxyflavone (6), four flavanones, (-)-butin (1a), (-)-butrin (3a), (+)-isomonospermoside (5b) and (-)-liquiritigenin (9a), and three isoflavones, formononetin (10), afrormosin (11) and formononetin-7-O-beta-D-glucopyranoside (12). The structure of the new compound was elucidated by spectroscopic techniques whereas those of the known compounds were identified by comparisons of spectroscopic and some physical data with those of reported compounds. The absolute configurations at the 2-position of the flavanones 1a, 3a, 5b and 9a were established to be 2S, 2S, 2R and 2S, respectively, by circular dichroism spectral measurements and were confirmed by comparison of the optical rotations with those of reported values and by enzymic hydrolysis of the glucosides to the corresponding aglycones. The isolated flavonoids exhibited varying antimycobacterial activity with the chalcone 2 being the most active compound (MIC 12.5 microg/ml).