Modification of Marine Natural Product Ningalin B and SAR Study Lead to Potent P-Glycoprotein Inhibitors

In this study, new marine ningalin B analogues containing a piperazine or a benzoloxy group at ring C have been synthesized and evaluated on their P-gp modulating activity in human breast cancer and leukemia cell lines. Their structure-activity relationship was preliminarily studied. Compounds 19 and 20 are potent P-gp inhibitors. These two synthetic analogues of permethyl ningalin B may be potentially used as effective modulators of P-gp-mediated drug resistance in cancer cells.     

Inhibition of P-glycoprotein ATPase and its transport function of Helicoverpa armigera by morin, quercetin and phloroglucinol

Flavonoids (morin, quercetin and phloroglucinol) were tested for their ability to modulate the function of P-glycoprotein ATPase of the insecticide resistant pest Helicoverpa armigera (Ha-Pgp). Flavonoids in the presence of ethylparaoxon or cypermethrin significantly reduced both larval weight as well as survival rate 40-50%. Morin and quercetin inhibited the activity of Ha-Pgp ATPase by 80-90%, whereas phloroglucinol inhibited ATPase activity by 40% at 100 μM concentration. These flavonoids inhibited the verapamil, ethylparaoxon and cypermethrin-stimulated Ha-Pgp ATPase activity. Morin, quercetin and phloroglucinol binding were quantitated by quenching of the intrinsic Trp fluorescence of purified Ha-Pgp ATPase. Drug transport was monitored in proteoliposomes containing Ha-Pgp ATPase using the high affinity fluorescent substrate tetramethylrosamine (TMR) in real time. Addition of the morin and quercetin mediated the collapse of the TMR concentration gradient generated by Ha-Pgp ATPase. The inhibition studies on Ha-Pgp ATPase activity may contribute towards understanding new strategies of the pest to overcome insecticide resistance.     

穴位埋药线对难治性癫痫大鼠癫痫样波的发放及大脑海马和颞叶皮质多药耐药相关蛋白MRP1、P-gp表达的影响

目的 探讨穴位埋药线对难治性癫痫大鼠癫痫样波的发放及大脑海马和皮质中多药耐药相关蛋白MRP₁、P-gp表达的影响。方法 （1）造模：大鼠海马区注射红藻氨酸（KA）,经过点燃和再次亚惊厥剂量点燃造模,且脑电图检测有癫痫样波发放者筛选为造模成功耐药难治性癫痫模型鼠。（2）分组与处理：普通线组（PTX组）与药线组（YX组）,先埋一侧穴位,间隔15 d后埋对侧穴位。拉莫三嗪组（LTG组）按照人用拉莫三嗪剂量换算灌胃大鼠,每日2次;空白对照组（Normal组）和模型组（Model组）给予灌胃同等体积的蒸馏水,均灌胃30 d。（3）采用VEEG-1518K型数字化视频脑电监测分析系统检测脑波基本节律的波幅与频率变化。（4）标本处理与检测：采用免疫组织化学技术,检测多药耐药相关蛋白MRP₁、P-gp在海马与颞叶皮层不同部位的表达。结果 各组治疗前比较差异无统计学意义（P>0.05）;各组治疗后,YX组、LTG组分别与Model组、PTX组比较差异有统计学意义（P<0.05）,YX组与LTG组比较差异无统计学意义（P>0.05）;与Model组相比,LTG组和YX组干预后能降低致痫鼠EEG痫波放电持续时间与发放频率以及海马区和颞叶皮质区多药耐药蛋白MRP₁、P-gp的表达水平（P<0.05或P<0.01）;YX组与PTG组比较差异无统计学意义（P<0.05）。结论 （1）埋药线使KA致痫鼠EEG痫波放电持续时间缩短,发放频率减少。（2）KA点燃难治性癫痫模型大鼠大脑海马区存在多药耐药蛋白MRP₁、P-gp的表达较皮质区明显升高。（3）埋药线逆转与降低致痫鼠海马区多药耐药蛋白MRP₁、P-gp的表达水平,可能是其抗癫痫生物学作用机制之一。     

Expression of cyclooxygenase-2, P-glycoprotein and multi-drug resistance-associated protein in canine transitional cell carcinoma

Cyclooxygenase-2 (COX-2), P-glycoprotein (P-gp) and multi-drug resistance-associated protein (MRP) are considered important tumor-associated proteins in humans and dogs. In the present study, we immunohistochemically evaluated the expression of these proteins in canine patients with transitional cell carcinoma (TCC). Of 52 cases, 30 (57.7%) were positive for COX-2, 40 (76.9%) for P-gp, and only 10 (19.2%) for MRP. In addition, 27 samples (27/52, 51.9%) were positive for two markers, while 3 (5.7%) and 5 (9.6%) cases were positive and negative, respectively, for all three markers. No significant correlations were seen for COX-2 and P-gp on Fisher's exact test and Mann-Whitney's test, but a significance was seen on Spearman's rank correlation analysis using the IHC scoring system (P=0.043). These results suggest that P-gp expression is induced by overexpression of COX-2 in canine patients with TCC.     

Esters of the Marine-Derived Triterpene Sipholenol A Reverse P-GP-Mediated Drug Resistance

Our previous studies showed that several sipholane triterpenes, sipholenol A, sipholenone E, sipholenol L and siphonellinol D, have potent reversal effect for multidrug resistance (MDR) in cancer cells that overexpressed P-glycoprotein (P-gp/ABCB1). Through comparison of cytotoxicity towards sensitive and multi-drug resistant cell lines, we identified that the semisynthetic esters sipholenol A-4-O-acetate and sipholenol A-4-O-isonicotinate potently reversed P-gp-mediated MDR but had no effect on MRP1/ABCC1 and BCRP/ABCG2-mediated MDR. The results from [³H]-paclitaxel accumulation and efflux studies suggested that these two triterpenoids were able to increase the intracellular accumulation of paclitaxel by inhibiting its active efflux. In addition, western blot analysis revealed that these two compounds did not alter the expression levels of P-gp when treated up to 72 h. These sipholenol derivatives also stimulated the ATPase activity of P-gp membranes, which suggested that they might be substrates of P-gp. Moreover, in silico molecular docking studies revealed the virtual binding modes of these two compounds into human homology model of P-gp. In conclusion, sipholenol A-4-O-acetate and sipholenol A-4-O-isonicotinate efficiently inhibit the P-gp and may represent potential reversal agents for the treatment of multidrug resistant cancers.     

川续断皂苷乙对氟苯尼考在大鼠体内的药动学影响

研究川续断皂苷乙对氟苯尼考在大鼠体内药动学影响.将24只大鼠(200±10)g随机分成两组,每组12只.试验组连续7 d灌胃川续断皂苷乙(60 mg/kg,1次/d),对照组给予相同体积的生理盐水,第8天两组各6只大鼠灌服氟苯尼考(30 mg/kg)后按时间点连续采血,采用高效液相色谱法检测氟苯尼考血药浓度,数据采用D...