白桦酯醇的研究进展

白桦酯醇以及由白桦酯醇转化的次级产物白桦酯酸及其衍生物具有镇咳祛痰、清热利湿、消肿解毒、提高机体免疫力、调血脂等作用。更重要的是白桦酯醇、白桦酯酸作为天然药物在抗肿瘤和抗HIV等活性方面显示出了与以往药物不同的作用机制,靶向作用性更强,不良反应较小。因此,对于新型天然药物白桦酯醇和白桦酯醇的研究已逐步受到研究者的注视,就近年来白桦酯醇及其衍生物的制备,白桦酯醇的生物活性、合成途径及其关键酶等方面的研究追踪前人研究报道,为今后白桦酯醇相关研究的深入提供理论参考。     

白桦酯酸及其衍生物的研究概况

 目的总结白桦酯酸及其衍生物的各种药理活性及制备方面的研究概况,进一步提出对这类天然产物的研究开发方向。方法检索查阅了国内外近10年来的30多篇有关文献和专利。结果与结论白桦酯酸及其衍生物具有显著的抗肿瘤、抗HIV和抗茵等活性,目前尚处于临床前的研究阶段,具有可预见的开发前景。     

乌骨藤中白桦酯酸的提取分离及抗肿瘤活性

目的:对乌骨藤中白桦酯酸进行提取分离,并探讨其抗肿瘤活性.方法:采用硅胶柱色谱法、Sephadex LH-20凝胶柱色谱法及半制备高效液相色谱法,对白桦酯酸进行提取分离,并采用结晶紫法,以细胞死亡率为检测指标,观察白桦酯酸在不同质量浓度1-500mg·L-1情况下,对细胞密度为1×104/孔的4种肿瘤细胞分别作用12,24.36,48 h的生长抑制作用.结果:白桦酯酸对人宫颈癌细胞HeLa、人胃癌细胞MGC、人乳腺癌细胞MCF-7具有很好的增殖抑制作用,并呈剂量依赖效应,在质量浓度为500 mg·L-1作用48h时,对Hela细胞及MGC细胞的死亡率分别为77.9％,81.7％,质量浓度为100 mg·L-1作用48 h时,对MCF-7的细胞死亡率为74.1％,但对人乳腺导管癌细胞(ZR株)作用不显著.结论:白桦酯酸对HeLa,MGC,MCF-7肿瘤细胞具有抗肿瘤活性,对ZR株肿瘤细胞作用不明显.     

白桦酯醇对SKOV3肿瘤细胞调亡作用的影响

目的：通过研究白桦酯醇对卵巢SKOV3生长、细胞周期及凋亡相关基因的影响,探讨白桦酯醇抗肿瘤活性及其可能的作用机制。方法：应用MTT法检测白桦酯醇对SKOV3的生长抑制率;荧光染色法检测细胞凋亡;Western blot法检测Caspase-3表达的影响。流式细胞术检测肿瘤细胞周期。结果：MTT法检测白桦酯醇的IC50为143.5μg/mL,且细胞抑制率随白桦酯醇的浓度的增高而增高,呈明显的时间和剂量的依赖性;白桦酯醇处理后的SKOV3细胞凋亡率增加,Caspase-3表达量增加,且可使SKOV3发生G2/M期阻滞。结论：白桦酯醇在体外能抑制肿瘤细胞生长,其可能机制为阻滞细胞周期,并且激活Caspase-3,增加Caspase-3的表达量,从而引起肿瘤细胞的凋亡。     

23-羟基白桦酸在Caco-2细胞模型中的吸收特性研究

 目的研究23-羟基白桦酸在Caco-2细胞模型中的吸收特性,为设计合理的给药方式提供依据。方法利用MTT实验筛选出23-羟基白桦酸在Caco-2细胞中的安全浓度,然后用Caco-2细胞单层模型研究23-羟基白桦酸的双向转运,采用同位素示踪法检测药物浓度,计算其表观渗透系数,考察时间、药物浓度对23-羟基白桦酸吸收的影响。结果23-羟基白桦酸在Ca- co-2细胞模型中的转运中对应时间点表观渗透系数值(P_app)A→B约等于(P_app)B→A,随时间增加P_app逐渐下降,而在所测浓度范围内P_app值基本保持恒定。结论23-羟基白桦酸在Caco-2细胞模型中的吸收机制主要是被动转运。     

蒙古绣线菊化学成分的研究

从蔷薇科植物蒙古绣线菊Ｓｐｉｒａｅａ ｍｏｎｇｏｌｉｃａ Ｍａｘｉｍ．中分得６个单体化合物，经化学和光谱分析确定了其中５个成分的结构，它们分别是β－谷甾醇（Ｉ）、白桦脂醇（Ⅱ）、白桦脂酸（Ⅲ）、白桦脂酸３，５－二羟基肉桂酸酯（Ⅳ）和胡萝卜甙（Ⅵ）。这些化合物系首次从该植物中得到。     

白桦酯醇对人宫颈癌裸鼠皮下移植瘤生长的抑制作用及其对MMP-2、MMP-9表达的影响

目的：观察白桦酯醇对人宫颈癌裸鼠皮下移植瘤生长的抑制作用,并探讨其作用机制。方法：建立人宫颈癌裸鼠皮下移植瘤模型,将35只小鼠随机分为模型组、白桦酯醇高、中、低剂量组及顺铂组（阳性对照）,观察并记录各组裸鼠移植瘤的生长情况,计算肿瘤抑制率;免疫组织化学法检测各组裸鼠皮下移植瘤中MMP-2、MMP-9表达水平。结果：白桦酯醇各组移植瘤瘤重和体积均较模型组明显减轻或缩小,高剂量组抑瘤率与顺铂组无差异（P〉0．05）;白桦酯醇组移植瘤MMP-2、MMP-9的表达较模型组均明显降低（P〈0．01）,且MMP-2、MMP-9的表达量与白桦酯醇的浓度成反比;其高剂量组作用与阳性药顺铂相当。结论：白桦酯醇对人宫颈癌移植瘤具有明显的抑制作用,其机制可能与抑制血管生成拟态的形成有关。     

白头翁药效成分的提取

目的：提取分离白头翁中的活性成分.方法：采用醇提、酸解、酰化、硅胶柱层析提取23-羟基白桦酸及衍生物,考察提取溶媒、酸解条件等因素对提取分离的影响.结果：提取分离得到23-羟基白桦酸及其酰化产物.结论：乙醇比甲醇适宜作提取剂,采用70%乙醇回流提取6 h,再在92 ℃-96 ℃下使用5%硫酸水解反应3 h,可有效提取23-羟基白桦酸;得到23-羟基白桦酸酰化产物的适宜条件是室温反应60 h.     

一氧化碳对白桦悬浮细胞生长和三萜累积的影响

目的分析外源一氧化碳(CO)对白桦悬浮细胞生长和三萜累积的影响。方法在白桦悬浮细胞培养的第8天添加5、10、20、30μmol/L的CO供体高铁血红素处理0.25～8 d,采用高效液相色谱法、比色法和实时荧光定量PCR方法分析白桦三萜含量及其合成关键酶基因的表达。结果除20和30μmol/L CO处理2 d后显著降低白桦悬浮细胞干质量外,CO处理未对白桦悬浮细胞干质量产生显著影响。除30μmol/L CO处理提高pH值和丙二醛含量外,CO处理未对pH值和丙二醛含量产生显著影响。CO处理不同程度地增加了三萜、白桦酯醇和齐墩果酸含量,其中,30μmol/L CO处理1 d时三萜积累量达最大值,为同期对照的1.3倍;10μmol/L CO处理4 d时白桦酯醇含量达最高值,为对照的1.5倍;10μmol/L CO处理2 d时齐墩果酸含量达最高值,为对照的4.2倍。三萜合成关键酶FPPS、LUS、CAS1、CAS2和β-AS基因的实时荧光定量PCR检测结果进一步证实了CO对白桦三萜累积的促进作用。结论 CO处理促进了白桦悬浮细胞中三萜的合成。     

HPLC法测定不同产地地菍中三萜类成分含量

目的 建立测定地菍中三萜类成分积雪草酸、白桦酯酸、齐墩果酸含量的HPLC方法 .方法色谱柱为Waters SunFire C18柱(4.6 mm×150 mm,5μm);流动相为乙腈-0.1%磷酸水,梯度洗脱;柱温30℃;检测波长200 nm;流速0.6 ml/min;进样量25μl.结果 积雪草酸、白桦酯酸、齐墩果酸分别在0.310~6.200μg(r=0.9999)、0.405~8.100μg(r=0.9999)、0.169~3.375μg(r=0.9998)线性关系良好,平均回收率分别为102.08%、101.81%、102.22%.结论 地菍中积雪草酸、白桦酯酸、齐墩果酸含量因产地而异,建立的分析方法简便灵敏、重复性与稳定性良好,适用于地菍药材的质量评价.     

Betulinic acid has an inhibitory effect on pancreatic lipase and induces adipocyte lipolysis

Betulinic acid is a pentacyclic triterpenic acid that exists naturally in many kinds of food and has many biological functions. The present study investigated the antiobesity properties of betulinic acid and possible mechanisms by which betulinic acid functions. To examine the antilipase function of betulinic acid, the ability of betulinic acid to inhibit pancreatic lipase activity in vitro and to prevent the elevation of plasma triacylglycerol levels was tested after oral administration of a lipid emulsion in rats. In addition, the lipolytic effects of betulinic acid were assayed in rat adipose tissues. The activity of cAMP‐dependent phosphodiesterase was also measured in vitro. Betulinic acid inhibited pancreatic lipase activity in a dose‐dependent manner at concentrations of 1.5–100 µ m (IC₅₀ value of 21.10 µ m ) and prevented the elevation of plasma triacylglycerol levels 2 h after oral administration of the lipid emulsion at a dose of 100 mg/kg. In addition, betulinic acid had a strong lipolytic effect, which was mediated by cAMP‐dependent phosphodiesterase inhibition. In conclusion, betulinic acid may exert antiobesity effects by directly inhibiting pancreatic lipase, which would prevent the absorption of lipid from the small intestine. In addition, it was found that betulinic acid may further accelerate fat mobilization by enhancing the levels of lipolysis in adipose tissues. Copyright © 2011 John Wiley & Sons, Ltd.     

A Metalloproteinase Inhibitor from Doliocarpus verruculosus

In our natural products screening programme for the discovery of competitive inhibitors of the matrix metalloproteinases, stromelysin and collagenase, we have isolated an active compound, betulinic acid (1), from the plant Doliocarpus verruculosus. Betulinic acid inhibits stromelysin and collagenase with K _i values of 2.2 and 1.3 μM , respectively. The analogous C-28 alcohol, betulin, was a less potent inhibitor of these proteases. We therefore postulate that the moiety of 1-carboxyl-3-(2-propenyl)-cyclopentane in betulinic acid may mimic the hydroxamate-containing residue of actinonin (3), a known stromelysin and collagenase inhibitor. Because a hydroxamate can serve as a bidentate ligand for the active site zinc, we synthesized the hydroxamate of 3-acetoxy-betulinic acid (2), hoping to observe an increase in potency relative to 1. However, the K _i values against stromelysin and collagenase were essentially equal to those of 1. These data suggest that the rigid cyclopentyl ring is probably restricting the tight binding as seen in the flexible peptidal hydroxamates, or the acid moiety is not interacting directly with the active site zinc of the metalloproteinases.     

基于一测多评法的大枣药材三萜酸类化学成分检测分析方法的建立

目的 建立基于一测多评法（QAMS）同时测定大枣药材中多种三萜酸类成分的分析方法,为大枣药材的品质评价和质量控制提供技术支撑。方法 采用HPLC-ELSD技术,以白桦脂酸对照品为内参物,测定其与齐墩果酸、熊果酸、桦木酮酸、齐墩果酮酸、熊果酮酸的相对校正因子,采用相对校正因子计算此5种三萜酸类化学成分的量,实现一测多评;同时比较外标法所测得的大枣药材中该6种化学成分的实际值与经QAMS所得的计算值之间的差异,以验证QAMS的适用性、可行性和重复性。结果 相对校正因子的重现性较好,15批大枣药材样品中6种三萜酸类化学成分的QAMS计算值与外标法实测值之间无显著性差异。结论 以白桦脂酸为内参物建立的同时测定齐墩果酸、熊果酸、桦木酮酸、齐墩果酮酸、熊果酮酸的一测多评方法操作简便,测定结果准确,实现了采用1种对照品同步测定大枣样品中6种化学成分的量,可为大枣药材质量标准的制定和提升提供支撑,为中药多指标成分质量评价模式的建立提供借鉴。     

Antimalarial Active Principles of Spathodea campanulata Stem Bark

Antimalarial principles of Spathodea campanulata stem bark extract were isolated and characterized. The antimalarial principles in the stem bark were 3β-hydroxyurs-12-en-28-oic acid (ursolic acid) and two of its derivatives; 3β-hydroxyurs-12,19-dien-28-oic acid (tomentosolic acid) and 3β,20β-dihydroxyurs-12-en-28 oic acid. This is the first report of the isolation of ursolic acid and its derivatives as antimalarial compounds     

白桦脂酸对质粒急性感染模型小鼠的HBV DNA抑制作用研究

桦木酸是一种天然存在的五环三萜系化合物,它具有抗逆转录病毒,抗疟疾和抗炎特性。该研究主要目的是观察白桦脂酸对Payw1.3质粒急性感染小鼠模型的HBV DNA复制的抑制作用。实验的Payw1.3质粒急性感染小鼠模型（n=15）采用水动力转染技术构建,随机分为PBS对照组（n=5）,白桦脂酸药物治疗组（n=5）及拉米夫定对照组（n=5）,建模成功后次日分别予以白桦脂酸（100 mg·kg^-1）,拉米夫定（50 mg·kg^-1）,PBS药物灌胃,每日1次,连续7 d,分别在3,5,7 d眼眶静脉后采血,ELISA法测血清中HBsAg及HBeAg表达,并在7 d后处死小鼠,southern法检测肝组织HBV DNA表达。结果发现与PBS对照组相比,5 d时白桦脂酸能明显抑制Payw1.3质粒急性感染小鼠HBsAg表达（P<0.05）,与拉米夫定效果无明显差异。与对照组相比,白桦脂酸和拉米夫定对HBeAg表达均无明显抑制作用,白桦脂酸和拉米夫定对肝组织HBV DNA表达均有抑制作用。这些结果揭示了白桦脂酸能够抑制Payw1.3质粒急性感染小鼠血清HBsAg表达及肝脏内HBV DNA的复制。     

Biological activities and metabolites from Trevoa trinervis Miers

Chilean folklore medicine uses Trevoa trinervis Miers. (Rhamnaceae), ‘trevo’, for the treatment of inflammation caused by wounds and burns. The antiinflammatory and antipyretic activities of crude methanol, aqueous and successive hexane, dichloromethane, methanol extracts of the aerial part were studied. The fractionation of the most potent extract (dichloromethane), led to the isolation of the pentacyclic triterpenoids betulinic (the major metabolite), oleanolic and ursolic acids, along with β-sitosterol. Evaluation of the acute oral toxicity of the crude methanol extract showed it to be nontoxic. The crude methanol and the aqueous extracts were assayed for their antineoplastic activity against P-388 murine leukaemia, A-549 human lung carcinoma and HT-29 colon carcinoma showing no activity. Betulinic acid was also assayed showing some activity against the neoplastic cell lines, but only residual activity against Mel-28 melanona cells. © 1997 John Wiley & Sons, Ltd.     

桦木酸和2,3-羟基桦木酸抗肿瘤作用机制的研究进展

桦木酸和2,3-羟基桦木酸均是羽扇豆烷型五环三萜类化合物,具有多方面的药理活性,其抗肿瘤作用近年来受到了极大的关注。目前,国内外关于桦木酸和2,3-羟基桦木酸抗肿瘤作用的研究表明,桦木酸和2,3-羟基桦木酸可通过抑制肿瘤细胞增殖、转移,诱导肿瘤细胞分化和凋亡,从而起到抗肿瘤的作用。     

Betulinic acid protects against ischemia/reperfusion‐induced renal damage and inhibits leukocyte apoptosis

The possible protective effect of betulinic acid on renal ischemia/reperfusion (I/R) injury was studied. Wistar Albino rats were unilaterally nephrectomized and subjected to 45 min of renal pedicle occlusion followed by 6 h of reperfusion. Betulinic acid (250 mg/kg, i.p.) or saline was administered at 30 min prior to ischemia and immediately before the reperfusion. Creatinine, blood urea nitrogen (BUN), lactate dehydrogenase (LDH) and TNF‐α as well as the oxidative burst of neutrophil and leukocyte apoptosis were assayed in blood samples. Malondialdehyde (MDA), glutathione (GSH) levels, Na⁺, K⁺‐ATPase and myeloperoxidase (MPO) activities were determined in kidney tissue which was also analysed microscopically. I/R caused significant increases in blood creatinine, BUN, LDH and TNF‐α. In the kidney samples of the I/R group, MDA levels and MPO activity were increased significantly, however, GSH levels and Na⁺, K⁺‐ATPase activity were decreased. Betulinic acid ameliorated the oxidative burst response to both formyl‐methionyl‐leucyl‐phenylalanine (fMLP) and phorbol 12‐myristate 13‐acetate (PMA) stimuli, normalized the apoptotic response and most of the biochemical indices as well as histopathological alterations induced by I/R. In conclusion, these data suggest that betulinic acid attenuates I/R‐induced oxidant responses, improved microscopic damage and renal function by regulating the apoptotic function of leukocytes and inhibiting neutrophil infiltration. Copyright © 2009 John Wiley & Sons, Ltd.     

In vivo inhibitory effects of arjunolic acid derivatives on two-stage carcinogenesis in mouse skin

In a previous study, arjunolic acid (1) isolated from Cochlospermum tinctorium and its hemisynthetic derivatives 2, 3 and 4 were shown to exhibit in vitro inhibitory effects on Epstein—Barr virus (EBV) activation. Compounds 3 and 4, which showed the strongest inhibitory activities, were further prepared from arjunolic acid isolated from Mitragyna ciliata; they were tested in vivo on a two-stage carcinogenesis assay in mouse skin, using dimethyl-benz[a]anthracene (DMBA) as initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as promoter. The activities were evaluated by both rate (%) of papilloma-bearing mice and average number of papillomas per mouse and compared with the control. In the group of mice treated with 3 and 4, the occurrence of papillomas was delayed, compared with the results of the control; with derivative 4, papillomas occurred in 100% animals only at week 15. These results suggest that arjunolic acid derivatives could be valuable compounds as antitumour-promoters.