Structure and antiinflammatory activity relationships of wogonin derivatives

A number of wogonin derivatives have been synthesized as congeners of wogonin and evaluated for their inhibitory activities of PGE2 production. Wogonin derivatives modified at the B ring of wogonin were obtained from 2,4-Dihydroxy-3,6-dimethoxyacetophenone (1) via several steps. Most wogonin derivatives exhibited much reduced inhibitory activities against COX-2 catalyzed PGE2 production compared to that of wogonin. Alkylation of 5,7-phenol groups and substitution at the B ring of wogonin generally caused reduction of inhibitory activity.     

Inhibition of prostaglandin E<Subscript>2</Subscript> production by synthetic Wogonin analogs

Effects of wogonin analogs on cyclooxygenase-2 (COX-2) catalyzed prostaglandin E₂ production on lipopolysaccharide (LPS)-induced RAW 264.7 cells were investigated. Wogonin analogs were prepared via several different synthetic pathways. Among wogonin analogs tested, 8-halogeno and 8-nitro analogs showed strong inhibitory activities against COX-2 catalyzed PGE₂ production from LPS-induced RAW 264.7 cells. Effect of wogonin was largely dependent on structural alteration of the 8-methoxy group.     

In vitro and in vivo inhibitory activities of rutin,wogonin, and quercetin on lipopolysaccharide-induced nitric oxide and prostaglandin E(2) production

Flavonoids are widely distributed in plants, but their biological functions are still unclear. In the present study, in vitro and in vivo experiments were performed to demonstrate the inhibitory activities of rutin, wogonin, and quercetin on lipopolysaccharide-induced nitric oxide (NO) and prostaglandin E(2) production in RAW 264.7 macrophages, primary peritoneal macrophages, and Balb/c mice, respectively. In vitro results showed that wogonin and quercetin dose-dependently suppressed lipopolysaccharide-induced NO production in RAW 264.7 macrophages and primary peritoneal macrophages without a notable cytotoxic effect on either cell types associated with a decrease in inducible nitric oxide synthase (iNOS) protein expression in both cells. Rutin, at 80 microM only, had a slight but obvious inhibitory effect on lipopolysaccharide-induced NO production in primary peritoneal macrophages. Both wogonin and quercetin attenuated lipopolysaccharide-induced prostaglandin E(2) production in vitro. Intravenous injection of lipopolysaccharide (10 mg/kg, i.v.) resulted in a time-dependent induction of NO production in serum, and pretreatment with the L-arginine analog N-nitro-L-arginine methyl ester (L-NAME) blocked this induction. Intravenous pretreatment of Balb/c mice with rutin, wogonin or quercetin for 1 h followed by lipopolysaccharide treatment significantly inhibited lipopolysaccharide-induced NO production, but no inhibition of prostaglandin E(2) production was found. A decrease in iNOS protein, but not cyclooxygenase-2 protein, was detected in liver and lung specimens of lipopolysaccharide-treated Balb/c mice in the presence of rutin, wogonin or quercetin. In conclusion, data obtained both in vitro and in vivo suggest that wogonin and quercetin exert inhibitory activity on lipopolysaccharide-induced NO production through suppression of iNOS expression.     

Effect of wogonin, a plant flavone from Scutellaria radix, on the suppression of cyclooxygenase-2 and the induction of inducible nitric oxide synthase in lipopolysaccharide-treated RAW 264.7 cells

Plant flavonoids show anti-inflammatory activity both in vitro and in vivo. Some flavonoids, such as flavone derivatives, have been reported previously to inhibit nitric oxide (NO) production by suppressing inducible nitric oxide synthase (iNOS) expression. In this investigation, the effects of wogonin, a potent inhibitor of NO production among the flavonoids tested, on cyclooxygenase-2 (COX-2) induction and activity were elucidated further in connection with iNOS, using a mouse macrophage cell line, RAW 264.7. Wogonin inhibited NO and prostaglandin E(2) (PGE(2)) production from lipopolysaccharide-induced RAW cells with IC(50) values of 31 and 0.3 microM, respectively. When added after the induction of iNOS and COX-2, wogonin inhibited the formation of PGE(2) (IC(50) = 0.8 microM), but not the production of NO. Wogonin inhibited COX-2 activity directly (IC(50) = 46 microM) from the homogenate of aspirin-pretreated RAW cells, as determined by measuring [(14)C]PGE(2) formation from [(14)C]arachidonic acid. However, it did not inhibit iNOS or phospholipase A(2) activity. Western blotting showed that wogonin suppressed the induction of both iNOS and COX-2. Prednisolone also suppressed the induction of iNOS and COX-2. Whereas RU-486 (a steroid receptor antagonist) reversed the suppressive activity of prednisolone, it did not affect the suppressive activity of wogonin, suggesting that the suppressive activity of wogonin is not mediated by binding to a steroid receptor. Results from the present study demonstrated that wogonin is a direct COX-2 inhibitor, as well as an inhibitor of iNOS and COX-2 induction. Wogonin may be a potential agent for use in the treatment of inflammatory diseases.     

Synthesis and PGE<Subscript>2</Subscript> inhibitory activity of vinylated and allylated chrysin analogues

Vinylated and allylated chrysin analogues were prepared as congeners of prenylated flavonoids and evaluated their anti-inflammatory activity. 8-Substituted chrysin analogues were prepared from 2'-hydroxy-3'-iodo-4',6'-dimethoxyacetophenone in 3 steps. 3-Allylated chrysin analogues were prepared from chrysin in 3 steps. Synthesized chrysin analogues (4, 5 and 8) showed moderate inhibitory activities of PGE2 production from LPS-induced RAW 264.7 cells.     

Novel selective PDE4 inhibitors. 3. In vivo antiinflammatory activity of a new series of N-substituted cis-tetra- and cis-hexahydrophthalazinones

The synthesis and biological activities of a series of N-substituted cis-4a,5,6,7,8,8a-hexa- and cis-4a,5,8,8a-tetrahydro-2H-phthalazin-1-ones are described. It was found that compounds bearing a cycloalkyl group at the 2-position exhibit the highest PDE4 inhibitory activities (pIC(50) = 8.6-9.4). The N-cycloheptyl- and N-adamantanyltetrahydrophthalazinones (7h, 8, 10, 11) show high in vivo antiinflammatory activities after oral application. Additionally, some phthalazinones were found to exhibit potent suppression of LPS-induced TNFalpha release and show moderate potency against fMLP-stimulated production of ROS.     

Synthetic wogonin derivatives suppress lipopolysaccharide-induced nitric oxide production and hydrogen peroxide-induced cytotoxicity

Wogonin (5,7-dihydroxy-8-methoxyflavone) has been reported to exhibit a variety of biological properties including anti-inflammatory and neuroprotective functions. In this study, biological activities of diverse synthetic wogonin derivatives have been evaluated in two experimental cell culture models. Inhibitory activities of wogonin derivatives on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV2 microglial cells and on hydrogen peroxide (H2O2)-induced neuronal cell death in SH-SY5Y human neuroblastoma were examined. Wogonin derivatives such as WS2 and WS3 showed more potent suppressive activities on LPS-induced NO production and H2O2-induced cytotoxicity than wogonin itself. In addition, thiol substitution played a minor role in enhancing the activities of the derivatives. These findings may contribute to the development of novel anti-inflammatory and neuroprotective agents derived from wogonin.     

Synthesis and antiinflammatory activity of 1,5-Diarylimidazoles

A number of 1,5-diarylimidazoles has been synthesized and evaluated for their inhibitory activities of COX-2 catalyzed PGE2 production. 1,5-Diarylimidazoles were obtained from imimes and p-toluenesulfonylmethyl cyanide (TosMIC). Imines were prepared from commercially available amines and aldehydes. Among the compounds tested, 1-(2,4-difluorophenyl)-5-(4-methylsulfonylphenyl)imidazole (2r) showed strong inhibitory activity, however, most diarylimidazoles exhibited little to low inhibitory activities against COX-2 catalyzed PGE2 production.     

Wogonin, baicalin, and baicalein inhibition of inducible nitric oxide synthase and cyclooxygenase-2 gene expressions induced by nitric oxide synthase inhibitors and lipopolysaccharide

We previously reported that oroxylin A, a polyphenolic compound, was a potent inhibitor of lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In the present study, three oroxylin A structurally related polyphenols isolated from the Chinese herb Huang Qui, namely baicalin, baicalein, and wogonin, were examined for their effects on LPS-induced nitric oxide (NO) production and iNOS and COX-2 gene expressions in RAW 264.7 macrophages. The results indicated that these three polyphenolic compounds inhibited LPS-induced NO production in a concentration-dependent manner without a notable cytotoxic effect on these cells. The decrease in NO production was in parallel with the inhibition by these polyphenolic compounds of LPS-induced iNOS gene expression. However, these three compounds did not directly affect iNOS enzyme activity. In addition, wogonin, but not baicalin or baicalein, inhibited LPS-induced prostaglandin E2 (PGE2) production and COX-2 gene expression without affecting COX-2 enzyme activity. Furthermore, N-nitro-L-arginine (NLA) and N-nitro-L-arginine methyl ester (L-NAME) pretreatment enhanced LPS-induced iNOS (but not COX-2) protein expression, which was inhibited by these three polyphenolic compounds. Wogonin, but not baicalin or baicalein, similarly inhibited PGE2 production and COX-2 protein expression in NLA/LPS or L-NAME/LPS-co-treated RAW 264.7 cells. These results indicated that co-treatment with NOS inhibitors and polyphenolic compounds such as wogonin effectively blocks acute production of NO and, at the same time, inhibits expression of iNOS and COX-2 genes.     

Wogonin attenuates endotoxin‐induced prostaglandin E2 and nitric oxide production via Src‐ERK1/2‐NFκB pathway in BV‐2 microglial cells

Microglia are the major component of intrinsic brain immune system in neuroinflammation. Although wogonin expresses anti‐inflammatory function in microglia, little is known about the molecular mechanisms of the protective effect of wogonin against microglia activation. The aim of this study was to evaluate how wogonin exerts its anti‐inflammatory function in BV2 microglial cells after LPS/INFγ administration. Wogonin not only inhibited LPS/ INFγ‐induced PGE2 and NO production without affecting cell viability but also exhibited parallel inhibition on LPS/INFγ‐induced expression of iNOS and COX‐2 in the same concentration range. While LPS/INFγ‐induced expression of P‐p65 and P‐IκB was inhibited by wogonin — only weak inhibition on P‐p38 and P‐JNK were observed, whereas it significantly attenuated the P‐ERK1/2 and its upstream activators P‐MEK1/2 and P‐Src in a parallel concentration‐dependent manner. These results indicated that the blockade of PGE2 and NO production by wogonin in LPS/INFγ‐stimulated BV2 cells is attributed mainly to interference in the Src‐MEK1/2‐ERK1/2‐NFκB‐signaling pathway. © 2013 Wiley Periodicals, Inc. Environ Toxicol 29: 1162–1170, 2014.     

Inhibitory effects of baicalein and wogonin on lipopolysaccharide-induced nitric oxide production in macrophages.

In order to elucidate the mechanism of the antiinflammatory action of baicalein and wogonin, flavonoids from the root of Scutellaria baicalensis, the effects of these compounds were investigated on lipopolysaccharide-induced nitric oxide production in a macrophage-derived cell line, RAW 264.7. Baicalein (5-25 microM) and wogonin (5-50 microM) inhibited lipopolysaccharide-induced nitric oxide generation in a concentration-dependent manner. The inhibitory effect of these compounds was observed only when they were added at the start of cell incubation soon after the stimulation with lipopolysaccharide. Baicalein (25 microM) and wogonin (25 microM) also inhibited protein expression of inducible nitric oxide synthase. This inhibitory effect of wogonin was stronger than that of baicalein, which agrees with the result that wogonin showed stronger inhibition of nitric oxide production than baicalein. These results suggest that baicalein and wogonin attenuate lipopolysaccharide-stimulated nitric oxide synthase induction in macrophages and thus may help to explain the antiinflammatory action of these flavonoid compounds.     

Synthesis and iNOS inhibitory activities of thioflavones

A number of thioflavones has been synthesized and evaluated for their iNOS inhibitory activities. Thiowogonin (6) was obtained from naturally occurring chrysin in 5 steps. Other thioflavones were prepared from the corresponding flavones in a single step by the reaction with Lawesson's reagent. The biological activities of thioflavones were not enhanced by the functional group conversion from carbonyl to thiocarbonyl. Compounds 11 and 13 showed potent NO inhibitory activity at high concentration (40 uM), leading to the possible development of novel neuroprotective agents based on wogonin.     

Inhibitory Effects of Baicalein and Wogonin on Lipopolysaccharide-Induced Nitric Oxide Production in Macrophages

Abstract: In order to elucidate the mechanism of the antiinflammatory action of baicalein and wogonin, flavonoids from the root of Scutellaria baicalensis, the effects of these compounds were investigated on lipopolysaccharide-induced nitric oxide production in a macrophage-derived cell line, RAW 264.7. Baicalein (5–25 μM) and wogonin (5–50 μM) inhibited lipopolysaccharide-induced nitric oxide generation in a concentration-dependent manner. The inhibitory effect of these compounds was observed only when they were added at the start of cell incubation soon after the stimulation with lipopolysaccharide. Baicalein (25 μM) and wogonin (25 μM) also inhibited protein expression of inducible nitric oxide synthase. This inhibitory effect of wogonin was stronger than that of baicalein, which agrees with the result that wogonin showed stronger inhibition of nitric oxide production than baicalein. These results suggest that baicalein and wogonin attenuate lipopolysaccharide-stimulated nitric oxide synthase induction in macrophages and thus may help to explain the antiinflammatory action of these flavonoid compounds.     

2-Alkynyl-8-aryl-9-methyladenines as novel adenosine receptor antagonists: their synthesis and structure-activity relationships toward hepatic glucose production induced via agonism of the A(2B) receptor

Novel adenosine antagonists, 2-alkynyl-8-aryl-9-methyladenine derivatives, were synthesized as candidate hypoglycemic agents. These analogues were evaluated for inhibitory activity on N-ethylcarboxamidoadenosine (NECA)-induced glucose production in primary cultured rat hepatocytes. In general, aromatic moieties at the 8-position and alkynyl groups at the 2-position had significantly increased activity compared to unsubstituted compounds. The preferred substituents at the 8-position of adenine were the 2-furyl and 3-fluorophenyl groups. In modifying the alkynyl side chain, change of the ring size, cleavage of the ring, and removal of the hydroxyl group were well tolerated. The order of the stimulatory effects of adenosine agonists on rat hepatocytes was NECA > CPA > CGS21680, which is consistent with involvement of the A(2B) receptor. In Chinese hamster ovary cells stably transfected with human A(2B) receptor cDNA, one of the compounds potent in hepatocytes, 15o (IC(50) = 0.42 microM), antagonized NECA-induced stimulation of cyclic AMP production (IC(50) = 0.063 microM). This inhibitory effect was much more potent than those of FK453, KF17837, and L249313 which have been reported to be respectively A(1), A(2A), and A(3) selective antagonists. These findings agree very well with the result that, compared to 15o, these selective antagonists for each receptor subtype showed only marginal effects in rat hepatocytes. These results suggest that adenosine agonist-induced glucose production in rat hepatocytes is mediated through the A(2B) receptor. Furthermore, 15o showed hypoglycemic activity in an animal model of noninsulin-dependent diabetes mellitus, the KK-A(y) mice. It is possible that inhibition of hepatic glucose production via the A(2B) receptor could be at least one of the mechanisms by which 15o exerts its in vivo effects. Further elaboration of this group of compounds may afford novel antidiabetic agents.     

Inhibition of prostaglandin production by a structurally-optimized flavonoid derivative, 2',4',7-trimethoxyflavone and cellular action mechanism

Flavonoids possess anti-inflammatory activity in vitro and in vivo. In order to find the anti-inflammatory flavone derivatives having optimum chemical structures, various flavones were previously synthesized and evaluated for their inhibitory activity of prostaglandin E(2) (PGE(2)) production from lipopolysaccharide (LPS)-treated mouse macrophage cell line, RAW 264.7 cells. Through this screening procedure, 2',4',7-trimethoxyflavone (TMF) was selected for further pharmacological study. From the present investigation, it was found that TMF potently inhibited PGE(2) production from LPS-treated RAW cells with an IC(50) of 0.48 microM, compared to the IC(50) values of 0.07 and 1.09 microM for NS-398 and wogonin. TMF, however, did not inhibit cyclooxygenase-2 (COX-2) activity or COX-2 expression level. Instead, TMF was proved to be a phospholipase A(2) (PLA(2)) inhibitor. The IC(50) values of TMF against secretory PLA(2)-IIA (sPLA(2)-IIA) and cytosolic PLA(2) (cPLA(2)) were 70.5 and 70.4 microM, respectively. At doses of 10-250 microg/ear, TMF also showed in vivo anti-inflammatory activity by topical application against mouse croton oil-induced ear edema assay, suggesting a potential for new anti-inflammatory agent.     

汉黄芩素对人卵巢癌细胞株SKOV3裸鼠移植瘤生长及端粒酶活性的抑制作用

目的端粒酶在多种肿瘤细胞中高表达,可能是肿瘤分子靶向治疗的一个理想靶点。已有的研究表明,汉黄芩素体外具有抑制肿瘤细胞端粒酶活性和肿瘤细胞增殖的作用。该研究旨在评价汉黄芩素对人卵巢癌SKOV3细胞裸鼠移植瘤生长及端粒酶活性是否具有抑制作用。方法将移植人卵巢癌SKOV3细胞的裸鼠随机分为5组:汉黄芩素高剂量组(600mg·kg-1)、汉黄芩素低剂量组(300mg·kg-1)、空白对照组、顺铂治疗组(3mg·kg-1)和联合用药(顺铂+汉黄芩素)组,定期检测裸鼠的体重及肿瘤体积,裸鼠移植瘤组织分别提取DNA、RNA和蛋白质,用Southern印迹杂交法测定端粒长度、RT-PCR扩增观察端粒酶基因hTERT的表达、TRAP-PCR-银染法测定端粒酶活性。结果动物实验表明,汉黄芩素对SKOV3移植瘤有明显的抑瘤作用,高剂量组抑瘤率达56.67%(与对照组比较,P=0.002);低剂量组抑瘤率达38.10%(P=0.019),化疗组抑瘤率达50.83%(P=0.004),联合用药(顺铂+汉黄芩素)组的抑瘤率为66.9%,优于单独使用组(P=0.002);不同浓度汉黄芩素组肿瘤组织的端粒长度与空白对照组比较差异无显著性,汉黄芩素对瘤体端粒酶基因hTERT表达、端粒酶活性均有抑制作用,而且作用强度与剂量有关。结论汉黄芩素在体内具有抗肿瘤和抑制端粒酶活性的作用,抑制强度与剂量成正比,抑瘤率与顺铂合用有相加的作用。     

新型2-苯基苯并呋喃-3-酰胺衍生物的设计、合成及对Sortase A的抑制活性

以金黄色葡萄球菌转肽酶Sortase A与底物LPXTG的结合构象为模板,设计合成了12个具有L-shape构象的2-苯基苯并呋喃-3-酰胺衍生物作为Sortase A抑制剂,并经核磁共振和高分辨质谱确认结构,其中10个目标化合物未见文献报道。体外抑制活性结果显示,9个目标化合物对Sortase A具有较好的抑制活性[IC50=(22.2~62.3)μmol/L]。构效关系分析结果表明,苯并呋喃3-位上的取代基为-CONHCH2CH(CH3)2时抑制活性较好,而为-COOH时则抑制活性丧失;2-位苄基上带有吸电子基如氰基时抑制活性较好,而为供电子基如羟基时抑制活性较差;苯并呋喃其他位置上的取代基对抑制活性未见明显影响。     

Wogonin inhibits inducible prostaglandin E(2) production in macrophages

Effects of 5,7-dihydroxy-8-methoxyflavone (wogonin) on cyclooxygenase-2 (COX-2)-mediated prostaglandin E(2) production in macrophages were investigated. Stimulation with lipopolysaccharide (LPS; 1 microg/ml) greatly increased prostaglandin E(2) production in RAW 264.7 murine macrophages. The stimulated prostaglandin E(2) production was abolished in the presence of indomethacin (1 microM) or cycloheximide (2 microM), suggesting that the increased production of prostaglandin E(2) by LPS reflects the inducible synthesis of prostaglandin E(2) by COX-2. Wogonin (0.1-50 microM) concentration-dependently inhibited inducible prostaglandin E(2) production. Wogonin at concentrations as low as 0.5 microM directly attenuated enzymatic activity of COX-2. The protein expression of COX-2 was depressed by wogonin at concentrations of 10 microM and more. These results suggest that wogonin decreases inducible prostaglandin E(2) production in macrophages by inhibiting both COX-2 activity and COX-2 expression. The former action requires much lower doses of wogonin. These wogonin actions may explain, in part, its anti-inflammatory action.     

Effects of naturally occurring flavonoids on nitric oxide production in the macrophage cell line RAW 264.7 and their structure-activity relationships.

Flavonoids affect the inflammatory process of the mammalian system and possess anti-inflammatory as well as immunomodulatory activities in vitro and in vivo. Since nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) is one of the inflammatory mediators, the effects of various naturally occurring flavonoids on NO production in LPS-activated RAW 264.7 cells were evaluated in vitro. Flavonoids such as apigenin, wogonin, luteolin, tectorigenin, and quercetin inhibited NO production, as measured by nitrite formation at 10-100 microM. The most active among 26 flavonoid derivatives tested were apigenin, wogonin, and luteolin, having IC50 values of 23, 17, and 27 microM, respectively, while AMT, a synthetic selective iNOS inhibitor, had an IC50 value of 0.09 microM. In contrast, flavanones, such as naringenin, and flavonoid glycosides, such as apiin, did not demonstrate significant inhibition up to 100 microM. These results clearly indicated that a C-2,3 double bond might be important, and that the potency of inhibition depended upon the substitution patterns of the flavonoid molecules. The inhibitory activity of flavonoids was not due to direct inhibition of iNOS enzyme activity because they did not reasonably inhibit iNOS activity, as measured by [3H]citrulline formation from [3H]arginine, up to 100 microM. In contrast, wogonin and luteolin concentration-dependently reduced iNOS enzyme expression, when measured by western blotting, at 10-100 microM. All these results clearly demonstrated that certain flavonoids inhibit NO production in lipopolysaccharide-activated RAW 264.7 cells, and their inhibitory activity might be due to reduction of iNOS enzyme expression.     

Inhibition of TPA-induced cyclooxygenase-2 expression and skin inflammation in mice by wogonin, a plant flavone from Scutellaria radix

Wogonin (5,7-dihydroxy-8-methoxyflavone), isolated from Scutellaria radix, was previously reported to inhibit the expression and activity of the enzyme cyclooxygenase-2 in lipopolysaccharide (LPS)-stimulated cells of a mouse macrophage cell line, RAW 264.7. Here, in order to find in vivo effects, inhibition by wogonin of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cyclooxygenase-2 expression and anti-inflammatory activity in vivo were investigated. When applied topically to the dorsal skin of mice, wogonin at doses of 50-200 microg/site/treatment (total of five treatments in 3 days) inhibited cyclooxygenase-2 expression and prostaglandin E2 production induced by multiple treatments with TPA. At 200 microg/site/treatment, wogonin caused a 55.3% reduction of prostaglandin E2 production on the dorsal skin compared with an increased production in the TPA-treated control group. The same compound significantly inhibited mouse ear edema induced by TPA in both preventive (58.1% inhibition) as well as curative treatment (31.3% inhibition) schedules at 200 microg/ear/treatment. Inhibition of neutrophil infiltration was also observed. Therefore, wogonin may be beneficial for cyclooxygenase-2-related skin disorders.