Various types of tumors are known to overexpress enzymes belonging to the CYP1 family of cytochromes P450. The present study aimed to characterize the metabolism and further antiproliferative activity of the natural flavonoid diosmetin in the CYP1-expressing human hepatoma cell line HepG2. Diosmetin was converted to luteolin in HepG2 cells after 12 and 30 hr of incubation. In the presence of the CYP1A inhibitor alpha-naphthoflavone, the conversion of diosmetin to luteolin was attenuated. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays revealed luteolin to be more cytotoxic than diosmetin. The antiproliferative effect of diosmetin in HepG2 cells was attributed to blockage at the G2/M phase as determined by flow cytometry. Induction of G2/M arrest was accompanied by up-regulation of phospho-extracellular-signal-regulated kinase (p-ERK), phospho-c-jun N-terminal kinase, p53 and p21 proteins. More importantly, induction of G2/M arrest and p53 and p-ERK up-regulation were reversed by the application of the CYP1 inhibitor alpha-naphthoflavone. Taken together, the data provide new evidence on the tumor-suppressing role of cytochrome P450 CYP1A enzymes and extend the hypothesis that the anticancer activity of dietary flavonoids is enhanced by P450-activation.
CYP1A1 and CYP1B1 are two extrahepatic enzymes that have been implicated in carcinogenesis and cancer progression. Selective inhibition of CYP1A1 and CYP1B1 by dietary constituents, notably the class of flavonoids, is a widely accepted paradigm that supports the concept of dietary chemoprevention. In parallel, recent studies have documented the ability of CYP1 enzymes to selectively metabolize dietary flavonoids to conversion products that inhibit cancer cell proliferation. In the present study /the authors/ have examined the inhibition of CYP1A1 and CYP1B1-catalyzed EROD activity by 14 different flavonoids containing methoxy- and hydroxyl-group substitutions as well as the metabolism of the monomethoxylated CYP1-flavonoid inhibitor acacetin and the poly-methoxylated flavone eupatorin-5-methyl ether by recombinant CYP1A1 and CYP1B1. The most potent inhibitors of CYP1-EROD activity were the methoxylated flavones acacetin, diosmetin, eupatorin and the di-hydroxylated flavone chrysin, indicating that the 4'-OCH(3) group at the B ring and the 5,7-dihydroxy motif at the A ring play a prominent role in EROD inhibition. Potent inhibition of CYP1B1 EROD activity was also obtained for the poly-hydroxylated flavonols quercetin and myricetin. HPLC metabolism of acacetin by CYP1A1 and CYP1B1 revealed the formation of the structurally similar flavone apigenin by demethylation at the 4'-position of the B ring, whereas the flavone eupatorin-5-methyl ether was metabolized to an as yet unidentified metabolite assigned E(5)M1. Eupatorin-5-methyl ether demonstrated a submicromolar IC50 in the CYP1-expressing cancer cell line MDA-MB 468, while it was considerably inactive in the normal cell line MCF-10A. Homology modeling in conjunction with molecular docking calculations were employed in an effort to rationalize the activity of these flavonoids based on their CYP1-binding mode. Taken together the data suggest that dietary flavonoids exhibit three distinct modes of action with regard to cancer prevention, based on their hydroxyl and methoxy decoration: (1) inhibitors of CYP1 enzymatic activity, (2) CYP1 substrates and (3) substrates and inhibitors of CYP1 enzymes.
Flos Chrysanthemi (the flower of Chrysanthemum morifolium Ramat.) is widely used in China as a food and traditional Chinese medicine for many diseases. Luteolin and apigenin are two main bioactive components in Flos Chrysanthemi, and chrysoeriol and diosmetin are two methylated metabolites of luteolin in vivo by cathechol-O-methyltransferase (COMT). However, there was /a/ lack of pharmacokinetic information of chrysoeriol and diosmetin after oral administration of Flos Chrysanthemi extract (FCE). The present study aimed to develop an HPLC-UV method for simultaneous determination of rat plasma concentration of luteolin, apigenin, chrysoeriol and diosmetin and utilize it in pharmacokinetic study of the four compounds after orally giving FCE to rats. The method was successfully validated and applied to the pharmacokinetic study when oral administration of FCE to rats with or without co-giving a COMT inhibitor, entacapone. Chrysoeriol and diosmetin were detected in rat plasma after oral administration of FCE and their concentrations were significantly decreased after co-giving entacapone... In conclusion, a sensitive, accurate and reproducible HPLC-UV method for simultaneous determination of luteolin, apigenin, chrysoeriol and diosmetin in rat plasma were developed, pharmacokinetics of chrysoeriol and diosmetin combined with luteolin and apigenin were characterized after oral administration of FCE to rats, which gave us more information on pharmacokinetics and potential pharmacological effects of FCE in vivo.
Diosmetin has known human metabolites that include (2S,3S,4S,5R)-3,4,5-Trihydroxy-6-[5-hydroxy-2-(3-hydroxy-4-methoxyphenyl)-4-oxochromen-7-yl]oxyoxane-2-carboxylic acid.
/SRP:/ Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Poisons A and B/
/SRP:/ Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poisons A and B/
来源:Hazardous Substances Data Bank (HSDB)
毒理性
解毒与急救
/SRP:/ 高级治疗:对于无意识、严重肺水肿或严重呼吸困难的病人,考虑进行口咽或鼻咽气管插管以控制气道。使用气囊面罩装置的正压通气技术可能有益。考虑使用药物治疗肺水肿……。对于严重的支气管痉挛,考虑给予β激动剂,如沙丁胺醇……。监测心率和必要时治疗心律失常……。开始静脉输注D5W /SRP: "保持开放",最低流量/。如果出现低血容量的迹象,使用0.9%生理盐水(NS)或乳酸林格氏液。对于伴有低血容量迹象的低血压,谨慎给予液体。注意液体过载的迹象……。使用地西泮或劳拉西泮治疗癫痫……。使用丙美卡因氢氯化物协助眼部冲洗……。 /Poisons A and B/
/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poisons A and B/
/ALTERNATIVE and IN VITRO TESTS/ The aim of this study was to assess the effects of diosmetin and hesperetin, two flavonoids present in various medicinal products, on CYP2C8 activity of human liver microsomes using paclitaxel oxidation to 6alpha-hydroxy-paclitaxel as a probe reaction. Diosmetin and hesperetin inhibited 6alpha-hydroxy-paclitaxel production in a concentration-dependent manner, diosmetin being about 16-fold more potent than hesperetin (mean IC50) values 4.25 +/- 0.02 and 68.5 +/- 3.3 uM for diosmetin and hesperetin, respectively). Due to the low inhibitory potency of hesperetin, we characterized the mechanism of diosmetin-induced inhibition only. This flavonoid proved to be a reversible, dead-end, full inhibitor of CYP2C8, its mean inhibition constant (Ki) being 3.13 +/- 0.11 uM. Kinetic analysis showed that diosmetin caused mixed-type inhibition, since it significantly decreased the Vmax (maximum velocity) and increased the Km value (substrate concentration yielding 50% of Vmax) of the reaction. The results of kinetic analyses were consistent with those of molecular docking simulation, which showed that the putative binding site of diosmetin coincided with the CYP2C8 substrate binding site. The demonstration that diosmetin inhibits CYP2C8 at concentrations similar to those observed after in vivo administration (in the low micromolar range) is of potential clinical relevance, since it may cause pharmacokinetic interactions with co-administered drugs metabolized by this CYP.
/ALTERNATIVE and IN VITRO TESTS/ The survival of osteoblasts is one of the determinants of the development of osteoporosis. This study /investigates/ the osteoblastic differentiation induced by diosmetin, a flavonoid derivative, in osteoblastic cell lines MG-63, hFOB, and MC3T3-E1 and bone marrow stroma cell line M2-10B4. Osteoblastic differentiation was determined by assaying alkaline phosphatase (ALP) activity and mineralization degree and measuring various osteoblast-related markers using ELISA. Expression and phosphorylation of Runt-related transcription factor 2 (Runx2), protein kinase Cdelta (PKCdelta), extracellular signal-regulated kinase (ERK), p38, and c-jun-N-terminal kinase (JNK) was assessed by immunoblot. Rac1 activity was determined by immunoprecipitation, and Runx2 activity was assessed by EMSA. Genetic inhibition was performed by small hairpin RNA plasmids or small interfering RNA (siRNA) transfection. Diosmetin exhibited an effect on osteoblastic maturation and differentiation by means of ALP activity, osteocalcin, osteopontin, and type I collagen production, as well as Runx2 upregulation. Induction of differentiation by diosmetin was associated with increased PKCdelta phosphorylation and the activations of Rac1 and p38 and ERK1/2 kinases. Blocking PKCdelta by siRNA inhibition significantly decreased osteoblastic differentiation by inhibiting Rac1 activation and subsequently attenuating the phosphorylation of p38 and ERK1/2. In addition, blocking p38 and ERK1/2 by siRNA transfection also suppressed diosmetin-induced cell differentiation. /This shows/ that diosmetin induced osteoblastic differentiation through the PKCdelta-Rac1-MEK3/6-p38 and PKCdelta-Rac1-MEK1/2- ERK1/2-Runx2 pathways and that it is a promising agent for treating osteoporosis.
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
吸收
Diosmin is hydrolyzed to its aglycone diosmetin by intestinal microflora enzymes before its absorption into the body.
地奥司明在被身体吸收之前,通过肠道微生物酶的作用被水解为其苷元 diosmetin。
Diosmin is hydrolyzed to its aglycone diosmetin by intestinal microflora enzymes before its absorption into the body.
Synthesis and antiproliferative activities of thioxoflavonoids on three human cancer cells
摘要:
Two series of fifteen novel thioxoflavonoids 2a-2h and 4a-4g were synthesized from corresponding flavonoids 1a-1h and 3a-3g by reacting with Lawesson's reagent, respectively. Their in vitro antiproliferative activities were evaluated on a panel of three human cancer cell lines (Hela, HCC1954 and SK-OV-3) using cell counting kit-8 (CCK-8) assay. The results showed that most of the target compounds exhibited moderate to good antiproliferative activities against the three human cancer cell lines. In particular, thioxoflavonoids 2f and 2g showed the strongest antiproliferative activity on all three human cancer cell lines with IC50 values ranging from 3.34 to 4.67 mu M, 4f showed the best antiproliferative activity on Hela cells (IC50 2.30 mu M), 2e showed the best antiproliferative activity on HCC1954 cells (IC50 2.13 mu M) and SK-OV-3 cells (IC50 2.33 mu M). The antiproliferative activities may be involved in their antioxidant activity, which can be speculated by their ability to scavenge free radicals and by their capacity of affecting key redox enzymes.[GRAPHICS].
Accurate Prediction of Glucuronidation of Structurally Diverse Phenolics by Human UGT1A9 Using Combined Experimental and In Silico Approaches
作者:Baojian Wu、Xiaoqiang Wang、Shuxing Zhang、Ming Hu
DOI:10.1007/s11095-012-0666-z
日期:2012.6
Catalytic selectivity of human UGT1A9, an important membrane-bound enzyme catalyzing glucuronidation of xenobiotics, was determined experimentally using 145 phenolics and analyzed by 3D-QSAR methods. Catalytic efficiency of UGT1A9 was determined by kinetic profiling. Quantitative structure activity relationships were analyzed using CoMFA and CoMSIA techniques. Molecular alignment of substrate structures was made by superimposing the glucuronidation site and its adjacent aromatic ring to achieve maximal steric overlap. For a substrate with multiple active glucuronidation sites, each site was considered a separate substrate. 3D-QSAR analyses produced statistically reliable models with good predictive power (CoMFA: q2 = 0.548, r2 = 0.949, r pred 2 = 0.775; CoMSIA: q2 = 0.579, r2 = 0.876, r pred 2 = 0.700). Contour coefficient maps were applied to elucidate structural features among substrates that are responsible for selectivity differences. Contour coefficient maps were overlaid in the catalytic pocket of a homology model of UGT1A9, enabling identification of the UGT1A9 catalytic pocket with a high degree of confidence. CoMFA/CoMSIA models can predict substrate selectivity and in vitro clearance of UGT1A9. Our findings also provide a possible molecular basis for understanding UGT1A9 functions and substrate selectivity.
通过实验使用145种酚类化合物,并通过3D-QSAR方法分析,确定了人UGT1A9的催化选择性。UGT1A9是一种重要的膜结合酶,催化外源性物质的葡糖醛酸化反应。通过动力学分析确定了UGT1A9的催化效率。使用CoMFA和CoMSIA技术分析了定量结构活性关系。通过将葡糖醛酸化位点及其相邻的芳香环重叠,实现了底物结构的最大立体重叠。对于具有多个活性葡糖醛酸化位点的底物,每个位点被视为单独的底物。3D-QSAR分析产生了统计上可靠的模型,具有良好的预测能力(CoMFA:q2=0.548,r2=0.949,r pred 2=0.775;CoMSIA:q2=0.579,r2=0.876,r pred 2=0.700)。通过轮廓系数图阐明了底物中负责选择性差异的结构特征。将轮廓系数图叠加在UGT1A9的同源模型的催化口袋中,能够高度自信地识别UGT1A9的催化口袋。CoMFA/CoMSIA模型可以预测底物的选择性和UGT1A9的体外清除率。我们的发现还提供了理解UGT1A9功能和底物选择性的可能分子基础。
Structural Requirements of Flavonoids and Related Compounds for Aldose Reductase Inhibitory Activity.
The methanolic extracts of several natural medicines and medicinal foodstuffs were found to show an inhibitory effect on rat lens aldose reductase. In most cases, flavonoids were isolated as the active constituents by bioassay-guided separation, and among them, quercitrin (IC50=0.15 μM), guaijaverin (0.18 μM), and desmanthin-1 (0.082 μM) exhibited potent inhibitory activity. Desmanthin-1 showed the most potent activity, which was equivalent to that of a commercial synthetic aldose reductase inhibitor, epalrestat (0.072 μM). In order to clarify the structural requirements of flavonoids for aldose reductase inhibitory activity, various flavonoids and related compounds were examined. The results suggested the following structural requirements of flavonoid: 1) the flavones and flavonols having the 7-hydroxyl and/or catechol moiety at the B ring (the 3′,4′-dihydroxyl moiety) exhibit the strong activity; 2) the 5-hydroxyl moiety does not affect the activity; 3) the 3-hydroxyl and 7-O-glucosyl moieties reduce the activity; 4) the 2–3 double bond enhances the activity; 5) the flavones and flavonols having the catechol moiety at the B ring exhibit stronger activity than those having the pyrogallol moiety (the 3′,4′,5′-trihydroxyl moiety).
Enzymatic Synthesis of Bioactive <i>O</i>-Glucuronides Using Plant Glucuronosyltransferases
作者:Tian Yue、Ridao Chen、Dawei Chen、Jimei Liu、Kebo Xie、Jungui Dai
DOI:10.1021/acs.jafc.9b01769
日期:2019.6.5
glucuronidation of bioactive natural products or drugs to generate glucuronides with better activity and druggability is important in drug discovery and research. In this study, by using two uridine diphosphate (UDP)-dependent glucuronosyltransferases (GATs, UGT88D4 and UGT88D7) from plants, we developed two glucuronidation approaches, pure enzyme catalysis in vitro and recombinant whole-cell catalysis in
在自然界和药物代谢中已发现许多表现出多种药理活性的O-葡萄糖醛酸。生物活性天然产物或药物的葡糖醛酸苷化以产生具有更好活性和可药用性的葡糖醛酸苷在药物发现和研究中很重要。在这项研究中,通过使用来自植物的两种尿苷二磷酸(UDP)依赖性葡萄糖醛酸糖基转移酶(GAT,UGT88D4和UGT88D7),我们开发了两种葡萄糖醛酸化方法,即体外纯酶催化和体内重组全细胞催化,以有效合成生物活性O。 -glucuronides通过天然产物的葡萄糖醛酸化作用。总共14 O获得了具有不同结构的β-葡糖醛酸,包括类黄酮,蒽醌,香豆素和木脂素,其中7种是新化合物。此外,生物合成的O-葡萄糖醛酸中的一种,kaempferol-7- O - β - d-葡萄糖醛酸(3a)可以有效抑制蛋白酪氨酸磷酸酶(PTP)1B,IC 50值为8.02×10 –6M。生物合成的O-葡萄糖醛酸苷也表现出显着的抗氧化活性。
O-methylation of flavonoids by cell-free extracts of calamondin orange
作者:Gunter Brunet、Ragai K. Ibrahim
DOI:10.1016/0031-9422(80)85102-8
日期:——
hydroxyls of a number of flavonoids, indicating the existence in citrus tissues of ortho, meta, para and 3-O-methyltransferases. The latter, hitherto unreported enzyme, catalysed the formation of 3-O-methylethers of galangin and quercetin. The stepwise O-methylation of a number of compounds, especially quercetin and quercetagetin, tends to suggest a coordinated sequence of O-methylations on the surface
METHOD OF IMPROVING STABILITY OF SWEET ENHANCER AND COMPOSITION CONTAINING STABILIZED SWEET ENHANCER
申请人:TACHDJIAN Catherine
公开号:US20120041078A1
公开(公告)日:2012-02-16
The present invention includes methods of stabilizing one or more sweet enhancers when they are exposed to a light source as well as liquid compositions containing one or more sweet enhancers and one or more photostabilizers.