基于肿瘤靶向的水飞蓟宾-氨基酸席夫碱的合成及性质研究

以水飞蓟宾和氨基酸为原料,通过常规方法合成了一系列具有靶向性的水飞蓟宾-氨基酸席夫碱,并对其抗肿瘤作用进行研究.采用核磁共振碳谱、质谱和红外光谱对已合成的水飞蓟宾-氨基酸席夫碱(氨基酸=甘氨酸(1)、丙氨酸(2)、赖氨酸(3)、苯丙氨酸(4)、谷氨酸(5)、半胱氨酸(6))进行结构表征.采用MTT法对化合物1-6及水飞蓟宾进行抗肝癌细胞SMMC-7721的活性研究,抑制率分别为70.2%,53.7%,47.8%,55.6%,49.2%,51.8%,33.3%.体外抗肿瘤活性实验表明,水飞蓟宾-氨基酸席夫碱系列化合物对人肝癌细胞株SMMC-7721均有抑制作用,且明显高于水飞蓟宾母核.实现了以氨基酸为载体,将具有抗肿瘤活性的天然药物靶向运输至癌细胞内,极具肝靶向药物开发潜力.     

屈昔多巴的合成

以3,4-二羟基苯甲醛为原料,经苄基保护、与甘氨酸缩合、苄氧羰基保护得到关键中间体外消旋苏赤式-3-(3,4-二苄氧基苯基)-N-苄氧羰基丝氨酸(3);3经二环己胺和S-2-氨基-1,1-二苯基-1-丙醇拆分得到屈昔多巴,总收率11.3%,其结构经1H NMR,MS和元素分析确证。     

选择性聚乙二醇化赖氨酸的合成

以单甲氧基聚乙二醇(mPEG)和Fmoc-Lys(Boc)-OH(1)为主要原料,经过羧基苄酯化、侧链Boc脱除、ε-氨基丁二酸酐修饰得到功能化的赖氨酸化合物N-α-芴甲氧羰基-N-ε-(γ-氧代丁酸)-L-赖氨酸苄酯(4);1和4分别与mPEG在偶联剂D IC/HOB t的作用下联接,最终分别实现了赖氨酸主链和侧链的mPEG定点修饰,合成了新型的N-α-芴甲氧羰基-N-ε-(γ-氧代丁酸聚乙二醇酯)-L-赖氨酸苄酯(5,总收率52.6%)和N-ε-叔丁氧羰基-N-α-芴甲氧羰基-L-赖氨酸聚乙二醇酯(6,收率93.7%),其结构经1H NMR,IR和MS表征。     

两种含氮类大豆苷元衍生物对人体红细胞的抗溶血作用（英文）

合成了2种含氮类大豆苷元衍生物,4,7-二((甘氨酸钠)羰基)甲氧基异黄酮(L1)和4′,7-二(肼羰基)甲氧基异黄酮(L2)并用元素分析、红外光谱和核磁共振氢谱对其进行了表征。研究了大豆苷元衍生物的抗氧化性能,评价了其对自由基、超氧阴离子自由基的吸附能力,以及对人体血红细胞抗氧化损伤的保护作用。实验结果表明,大豆苷元衍生物在生理pH条件下的抗氧化活性优于维生素C,特别是在清除羟自由基和抑制人血红细胞溶血方面,大豆苷元衍生物抗氧化能力表现更为突出。大豆苷元衍生物的羟自由基清除活性IC50值是维生素C的104倍。     

N-叔丁氧羰基-3-羟基-1-金刚烷基甘氨酸的合成

以金刚烷甲酸(1)为起始原料,经过酰化,取代,脱羧三步反应一锅法制得金刚烷甲基酮(2),然后氧化甲基得到1-金刚烷基乙醛酸(3),将3与盐酸羟氨反应得到1-金刚烷乙醛酸肟(4),还原4并用BOC酸酐保护氨基得到N-叔丁氧羰基-1-金刚烷基甘氨酸(5),最后经高锰酸钾氧化得到DPP-IV抑制剂沙格列汀中间体N-叔丁氧羰基-3-羟基-1-金刚烷基甘氨酸(6),总收率28%。     

手性催化剂环二肽类化合物的微波合成

以L-苯丙氨酸或L-亮氨酸为起始原料,经过氨基保护和羧基酯化得到N-苄氧羰基-L-广苯丙氨酸-对硝基苯酯(4a)或N-苄氧羰基-L-亮氨酸-对硝基苯酯(4b);4在三乙胺作用下与L-组氨酸甲酯盐酸盐缩合得到直链二肽N-苄氧羰基-L-苯丙氨酸-L-组氨酸甲酯(5a)或N-苄氧羰基-L-亮氨酸-L-组氨酸甲酯(5b);Pd/C催化5脱掉保护基后在微波辐射下,经环化反应合成了手性催化剂环二肽(6a或6b),其结构经1H NMR和IR表征.重点考察了由5合成6的反应条件.结果表明,以甲醇为溶剂,于65 W辐射120 min,6a和6b的产率分别达到90%和68%.     

两种含氮类大豆苷元衍生物对人体红细胞的抗溶血作用

合成了2种含氮类大豆苷元衍生物,4,7-二（（甘氨酸钠）羰基）甲氧基异黄酮（L1）和4'',7-二（肼羰基）甲氧基异黄酮（L2）并用元素分析、红外光谱和核磁共振氢谱对其进行了表征。研究了大豆苷元衍生物的抗氧化性能,评价了其对自由基、超氧阴离子自由基的吸附能力,以及对人体血红细胞抗氧化损伤的保护作用。实验结果表明,大豆苷元衍生物在生理pH条件下的抗氧化活性优于维生素C,特别是在清除羟自由基和抑制人血红细胞溶血方面,大豆苷元衍生物抗氧化能力表现更为突出。大豆苷元衍生物的羟自由基清除活性IC₅₀值是维生素C的104倍。     

肽的研究 Ⅰ.带保护基的胰岛素A鏈氨端五肽的合成

本文报告三种带不同保护基的胰岛素A键氨端五肽的合成。它们是N-苄氧羰基甘氨酰-异亮氨酰-缬氨酰-γ-甲酯-谷氨酰-谷氨酰胺(Ⅰ)、N-苄氧羰基甘氨酰-异亮氨酰-缬氨酰-γ-甲酯-谷氨酰-谷氨酰胺酰肼基甲酸叔丁酯(Ⅱ)和N-苄氧羰基甘氨酰-异亮氨酰-纈氨酰-谷氨酰-谷氨酰胺甲酯(Ⅲ)。五肽Ⅰ是由初次合成的N-苄氧羰基甘氨酰-异亮氨酰-纈氨酸(Ⅵ)与γ-甲酯-谷氨酰-谷氨酰胺(Ⅸ)经羧酸碳酸混合酸酐法,或Ⅵ的酰肼衍生物与Ⅸ经迭氮化物法缩合而成。五肽Ⅱ是由Ⅵ与γ-甲酯-谷氢酰-谷氨酰胺酰肼基甲酸叔丁酯(Ⅺ)经混合酸酐法合成。五肽Ⅲ则系用活化酯法由谷氨酰胺甲酯的氨端开始,逐步与相应的N-保护的氨基酸对硝基苯酯缩合、延伸而得。在用混合酸酐法合成五肽Ⅰ中,从反应混合物分离得N-苄氧羰基甘氯酰-异亮氨酰-D-纈氨酸(ⅩⅫ)。由ⅩⅫ与Ⅸ合成五肽Ⅰ的立体异构体,N-苄氧羰基甘氨酰-异亮氢酰-D-纈氨酰-γ-甲酯-谷氨酰一谷氨酰胺(ⅩⅩⅢ)。由N-苄氧羰基-γ-甲酯-谷氧酰-谷氨酰胺酰肼基甲酸叔丁酯(Ⅹ)经脱去酰肼上的保护基后,用迭氮法与S-苄基-半胱氨酰-S-苄基-半胱氨酸缩合而得N-苄氧羰基-γ-甲酯-谷氨酰-谷氨酰胺酰-S-苄基-半胱氨酰-S-苄基-半胱氨酸(四肽ⅩⅩⅤ)。五肽Ⅰ、Ⅱ、Ⅲ,四肽ⅩⅩⅤ及其主要的合成中间肽的光学纯度均经亮氨酸氨肽酶、胰羧肽酶法或旋光法检定。在五肽的酶水解的条件下有部分的谷氨酰胺和谷氨酸变为四氢吡咯酮-(5)-羧酸-(2),致使该二氨基酸的测定值偏低。     

含半胱氨酸多肽的研究——Ⅲ.牛胰岛素A链带保护基的氨端九肽的合成

本文报告带保护基的牛胰岛素A链氨端九肽酯■和相应的九肽酰肼■与九肽酸■的合成.苄氧羰基甘氨酰-异亮氨酰-缬氨酰-γ-叔丁酯谷氨酸乙酯(III)分别由已知的苄氧羰基缬氨酰-γ-叔丁酯谷氨酸乙酯经催化氢解法脱去N-保护基后与苄氧羰基甘氨酰-异亮氨酰肼(VIII)按迭氮化合物法缩合,以及由已知的苄氧羰基甘氨酰-异亮氨酰-缬氨酸(VIII)与γ-叔丁酯谷氨酸乙酯按碳二亚胺法合成.III经肼解或皂化分别得四肽酰肼■和四肽酸■.苄氧羰基谷氨酰胺酰-S-苄基半胱氨酰-S-苄基半胱氨酰-丙氨酰-O-乙酰丝氨酸甲酯(V)分别由已知的苄氧羰基-S-苄基半胱氨酰-S-苄基半胱氨酰-丙氨酰-丝氨酸甲酯XII_a或苄氧羰基-S-苄基半胱氨酰-S-苄基半胱氨酰-丙氨酰-O-乙酰基丝氨酸甲酯XII以溴化氢-乙酸脱去N-保护基后与苄氧羰基谷氨酰胺对硝基苯酯(XIII)按活化酯法缩合而得.如以溴化氢-三氟乙酸脱去XIIa的N-保护基后与XIII按活化酯法缩合则得Va,合成Va的另一方法是将已知的苄氧羰基谷氨酰胺酰-S-苄基半胱氨酰-S-苄基半胱氨酰肼XIV通过迭氮化物法与丙氨酰-丝氨酸甲酯(X)缩合而得.五肽V经溴化氢-乙酸脱去N-保护基后与四肽酰肼IV或四肽酸IV_a分别通过迭氮化物法和碳二亚胺法缩合得到同一的九肽甲酯(I).化合物I用三氟乙酸脱去叔丁酯后肼解得九肽肼(II).化合物I经皂化得相应的九肽酸IIa.     

用反相高压液相色谱法分离N-苄氧羰基-L-天门冬氨酰慢心律衍生物的β-和α-异构体及非对映异构体

 〕本工作是用反相高压液相色谱法分离N-苄氧羰基天门冬氨酰慢心律〔学名为N-苄氧羰基-L-天门冬氨酰-dl-1-（2，6一二甲基苯氧基）-2-氨基丙烷）的α-和β-异构体及非对映异构体。用化学键合的十八硅烷为固定相，用甲醇／水为移动相，分离的结果符合定性和定量的要求。本方法也可作为鉴定合成含有天门冬氨酸肽类的α-和β-异构体的方法。     

In vitro antioxidative activities of three marine oligosaccharides

The antioxidant activities of three marine oligosaccharides, alginate oligosaccharides (AOs), chitosan oligosaccharides (COs), and fucoidan oligosaccharides (FOs), were investigated in vitro by several antioxidant assays, including hydroxyl radical scavenging, superoxide radical scavenging, erythrocyte hemolysis inhibiting, metal chelating activities, and anti-lipid peroxidation. The results show that these oligosaccharides exhibited different activities in various assays. AOs had the highest scavenging hydroxyl radical activity than FOs and COs at all the tested amounts. COs had the highest scavenging superoxide radical and inhibiting erythrocyte hemolysis activity than AOs and FOs at all the tested amounts. In the assay of chelating Fe2+, COs and FOs indicated good chelation while AOs hardly had any activity. In the assay of anti-lipid peroxidation, only COs had significantly high antioxidant activity.     

Antioxidative effects of 6-methoxysorigenin and its derivatives from Rhamnus nakaharai

In the search for potential antioxidants, the naphthalenic compounds, 6-methoxysorigenin (2) and its glycosides [i.e. 6-methoxysorigenin-8-O-glucoside (3), alpha-sorinin (4), and 6-methoxysorigenin-8-rutinoside (5)] isolated from Rhamnus nakaharai together with two acylates (peracetate and perpropionate) of 2 were evaluated for antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl (DPPH), metal chelating, and electron spin resonance (ESR) assays as well as anti-lipid peroxidation assay. The results showed that 2 possesses the most potent DPPH radical scavenging, metal chelating, and anti-lipid peroxidation activities with IC50 values of 3.48, 615.90, and 5.95 microg/ml, respectively. The glycosides 3, 4, and 5 showed decreasing antioxidant activity that was related to an increased substitution at 1,8-dihydroxyl with sugar molecules. This suggests the importance of 1,8-dihydroxyl of 2 in the antioxidative effect. The iron chelation result could further explain the main cause of increasing antioxidant activity in 2. The acylates of 2 (2a peracetate and 2b perpropionate), although lacking a free hydroxyl, also exhibited significant anti-lipid peroxidation effect. ESR results further demonstrated that 2 possesses strong antioxidant activities. Taken together, this study shows that 2 is a potent antioxidant and may also be used for designing new iron chelators for clinical applications.     

Free‐radical scavenging activities of silybin and its analogues: A pulse radiolysis study

The flavonolignans (silybin and analogues) are important natural compounds with multiple biological activities operating at various cell levels. Many of these effects are connected with their radical scavenging activities. In the present study, free‐radical scavenging and antioxidant activities of four natural flavonoids, namely silybin, naringenin, naringin, and hesperetin, have been studied using nanosecond pulse radiolysis techniques. The kinetics and mechanisms of the reactions of silybin and analogues with various oxidizing radicals (such as ^?OH,N₃^?, CCl₃OO^?, SO₄^??) have been investigated. Furthermore, the transient species has been assigned and radical scavenging rate constants have also been measured. Moreover, the structure–activity relationships between chemical structures of the flavonoids and their radical scavenging activities are further analayzed by theoretical calculation. Combined our previous observation of the fast reparation of DNA damage and efficient DNA protection against radiation damage in vitro, it can be confirmed that test flavonoids are promising molecules to be used for their potential antioxidant properties. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 590–597, 2011     

Identifying Chemical Composition,Safety and Bioactivity of Thai Rice Grass Extract Drink in Cells and Animals

Rice grass has been reported to contain bioactive compounds that possess antioxidant and free-radical scavenging activities. We aimed to assess rice grass extract (RGE) drink by determining catechin content, free-radical scavenging and iron-binding properties, as well as toxicity in cells and animals. Young rice grass (Sukhothai-1 strain) was dried, extracted with hot water and lyophilized in a vacuum chamber. The resulting extract was reconstituted with deionized water (260 mg/40 mL) and served as Sukhothai-1 rice grass extract drink (ST1-RGE). HPLC results revealed at least eight phenolic compounds, for which the major catechins were catechin, epicatechin and epigallocatechin-3-gallate (EGCG) (2.71–3.57, 0.98–1.85 and 25.47–27.55 mg/40 mL serving, respectively). Elements (As, Cu, Pb, Sn and Zn) and aflatoxin (B1, B2, G1 and G2) contents did not exceed the relevant limits when compared with WHO guideline values. Importantly, ST1-RGE drink exerted radical-scavenging, iron-chelating and anti-lipid peroxidation properties in aqueous and biological environments in a concentration-dependent manner. The drink was not toxic to cells and animals. Thus, Sukhothai-1 rice grass product is an edible drink that is rich in catechins, particularly EGCG, and exhibited antioxidant, free radical scavenging and iron-binding/chelating properties. The product represents a functional drink that is capable of alleviating conditions of oxidative stress and iron overload.     

Mechanism of antioxidant action of pueraria glycoside (PG)-1 (an isoflavonoid) and mangiferin (a xanthonoid).

The antioxidant activities of pueraria glycoside (PG)-1 (isoflavonoid) and mangiferin (xanthonoid) were studied and compared with PG-3 and daidzein (isoflavonoids) and with wogonin (flavonoid). PG-1 and mangiferin rapidly scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and inhibited lipid peroxidation which was initiated enzymatically by reduced nicotinamide adenine dinucleotide phosphate (NADPH) or non-enzymatically by ascorbic acid or Fenton's reagent (H2O2 + Fe2+) in rat liver microsomes. Wogonin inhibited the enzymatically induced lipid peroxidation but had no scavenging effect on DPPH radical or on the non-enzymatic peroxidation. PG-3 and daidzein did not show any of these effects. Formation of Fe2+ by NADPH-dependent cytochrome P-450 reductase was inhibited by wogonin, but not by PG-1 or mangiferin. PG-1 and mangiferin had no effect on terminating radical chain reaction during the lipid peroxidation in the enzymatic system of microsomes or in the linoleic acid hydroperoxide-induced peroxidation system. These results suggest that PG-1 and mangiferin have an antioxidant activity, probably due to their ability to scavenge free radicals involved in initiation of lipid peroxidation. In contrast, wogonin may affect NADPH-dependent cytochrome P-450 reductase action, since it inhibited only the enzymatically induced lipid peroxidation.     

Isolation and characterization of 1,3-dicapryloyl-2-linoleoylglycerol: a novel triglyceride from berries of Hippophae rhamnoides

1,3-Dicapryloyl-2-linoleoylglycerol (1), a novel triglyceride, was isolated from berries of Hippophae rhamnoides. The structure was elucidated on the basis of MS, 1D and 2D NMR experiments including HMQC and HMBC. The metal chelating, free radical scavenging, and lipid peroxidation inhibiting properties of the compound were also estimated with particular reference to radiation protection. In case of metal chelation and superoxide ion scavenging, 1 showed maximum inhibition at 50 microg/ml (11%) and 100 microg/ml (55%), respectively, whereas in lipid peroxidation, 1 showed maximum inhibition (57%) at 2 mg/ml as compared to quercetin as a control.     

Determination of in vitro antioxidant and radical scavenging activities of propofol

Propofol (2,6-diisopropylphenol) is a hypnotic intravenous agent with in vivo antioxidant properties. This study was undertaken to examine the in vitro antioxidant activity of propofol using different antioxidant tests including by 1,1-diphenyl-2-picryl-hydrazil (DPPH.) radical scavenging, metal chelating, hydrogen peroxide scavenging, superoxide anion radical scavenging, reducing power and total antioxidant activities. At the concentrations of 25, 50, and 75 microg/ml, propofol exhibited 97.7, 98.6 and 100% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, at the 75 microg/ml concentration of standard antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and alpha-tocopherol exhibited 88.7, 94.5, and 70.4% inhibition on peroxidation of linoleic acid emulsion, respectively. In addition, at same concentrations, propofol was shown that it had effective reducing power, DPPH. free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities. These various antioxidant activities were compared to standard antioxidants such as BHA, BHT and alpha-tocopherol. These results indicate that propofol prevents lipid peroxidation and radicalic chain reactions. At the same time, propofol revealed more effective antioxidant capacity than BHA, BHT and alpha-tocopherol.     

Antioxidant xanthones from Cratoxylum cochinchinense

A new xanthone named cratoxylumxanthone A (1), together with five known compounds: dulcisxanthone B (2), alpha-mangostin (3), beta-mangostin (4), 2-geranyl-1,3,7-trihydroxy-4-(3-methylbut-2-enyl)xanthone (5) and tectochrystin (6), was isolated from Cratoxylum cochinchinense stems. The structure of new compound was characterized by 1D and 2D NMR techniques. The isolated compounds showed free radical scavenging against DPPH and lipid peroxidation inhibition.     

Radical scavenging activity and antioxidant capacity of bay leaf extracts

Bay leaves (BL) (Laurus nobilis L., Family: Lauraceae) are traditionally used orally to treat the symptoms of gastrointestinal problems, such as epigastric bloating, impaired digestion, eructation, and flatulence. In this study, lyophilized extracts (both water and ethanol) of BL were studied for their antioxidant properties. The antioxidant activity, reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities were evaluated to determine the total antioxidant capacity of both BL extracts. Both extracts exhibited strong total antioxidant activity in linoleic acid emulsion. Concentrations of 20, 40, and 60 μg ml^?1 showed 84.9, 95.7, 96.8, and 94.2, 97.7, and 98.6% inhibition of lipid peroxidation of linoleic acid emulsion, for water and ethanol extracts, respectively. On the other hand, 60 μg ml^?1 of the standard antioxidants butylated hydroxyianisole (BHA), butylated hydroxytoluene (BHT), and α-tocopherol exhibited 96.6, 99.1, and 76.9% inhibition of lipid peroxidation in linoleic acid emulsion, respectively. In addition, the both BL extracts had effective reducing power, DPPH? free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities at 20, 40, and 60 μg ml^?1. The total amount of phenolic compounds in each BL extract was determined as gallic acid equivalents.     

Evaluation of antioxidant activity and DNA cleavage protection effect of naphthyl hydroxamic acid derivatives through conventional and fluorescence microscopic methods

Antioxidant capacity of N-(1-naphthyl)valerohydroxamic acid (NVHA) and N-(1-naphthyl)phenylacetohydroxamic acid (NPAHA) has been evaluated by a novel approach employing the fluorescence microscopic single molecule observation method. This method allows direct observation of the changes in single DNA molecules. The DNA cleavage protection activity of the compounds was also assessed by the gel electrophoresis method. The applied methods confirmed that both compounds are capable of inhibiting the free radical mediated DNA damage. Free radical scavenging activity was assessed via the 2,2′-diphenyl-1-picrylhydrazyl free radical (DPPH) and lipid peroxidation inhibition methods. The effective concentration causing a 50 % inhibition of the DPPH concentration, EC50, was found to be 371.54 mM for NVHA and 365.95 mM for NPAHA. Its lipid peroxidation inhibition ability was calculated to be 40.91 % at 371.54 mM for NVHA and 41.14 % at 365.95 mM for NPAHA. These results show the antioxidant potential of the naphthyl hydroxamic acids.