Pentacyclic triterpenes as α-glucosidase and α-amylase inhibitors: Structure-activity relationships and the synergism with acarbose

In this paper, the inhibition of α-amylase and α-glucosidase by nine pentacyclic triterpenes was determined. For α-amylase inhibitory activity, the IC₅₀ values of ursolic acid, corosolic acid, and oleanolic acid were 22.6 ± 2.4 μM, 31.2 ± 3.4 μM, and 94.1 ± 6.7 μM, respectively. For α-glucosidase inhibition, the IC₅₀ values of ursolic acid, corosolic acid, betulinic acid, and oleanolic acid were 12.1 ± 1.0 μM, 17.2 ± 0.9 μM, 14.9 ± 1.9 μM, and 35.6 ± 2.6 μM, respectively. The combination of corosolic acid and oleanolic acid with acarbose showed synergistic inhibition against α-amylase. The combination of the tested triterpenes with acarbose mainly exhibited additive inhibition against α-glucosidase. Kinetic studies revealed that corosolic acid and oleanolic acid showed non-competitive inhibition and acarbose showed mixed-type inhibition against α-amylase. The results provide valuable implications for the triterpenes (ursolic acid, corosolic acid, and oleanolic acid) alone or in combination with acarbose as a therapeutic agent for the treatment of diabetes mellitus.     

泽泻中二个三萜新成分的研究Ⅱ

继前文鉴定的七个泽泻醇类成分后 ,又从泽泻中分离、鉴定出六个三萜成分 ,其中 11 乙酰 2 5 脱水泽泻醇A(2 5 anhydroalisolA 11 acetate,Ⅳ )、2 4 乙酰 2 5 脱水泽泻醇A (2 5 anhydroalisolA 2 4 ac etate ,Ⅴ )为新化合物 ,新泽泻醇 (neoalisol,Ⅵ )为新天然产物 ,其它已知成分是泽泻醇A(alisolA ,Ⅰ )、2 4 乙酰泽泻醇A(alisolA 2 4 acetate ,Ⅱ )、2 5 脱水泽泻醇A(2 5 anhydroalisolA ,Ⅲ )。     

无柄新乌檀中的三萜

采用活性跟踪的方法对无柄新乌檀(Neonauclea sessilifolia (Roxb．)Merr．)枝干的乙醇提取物进行结核杆菌活性检测。利用硅胶柱层析、Sephadex-LH20和反相硅胶RPl8柱层析,从具有活性的乙酸乙酯部分分得9个化合物,利用一维、二维核磁共振技术(HMQC,HMBC)并结合质谱与红外光谱,将它们鉴定为3β,15α,21β,23-tetrahydroxy-12-oleanen-28-oic acid(1)、3β,6α,21β,23-tetrahydroxy-12-oleanen-28-oic acid(2)、单皮酚(3)、3,4-二羟基苯甲酸(4)、东茛菪内酯(5)、葸醌大黄酚(6)、5,7-二羟基-2-甲基吡喃酮(7)、β-谷甾醇(8)和^5.22 △-豆甾醇-β-D-葡萄糖苷(9)。其中化合物1和2是两个新化合物。体外抗结核杆菌试验表明,化合物6对结核杆菌(Mycobacterium tuberculosis(Zopf)Lehmannet Neumann)具有一定的抑制效果,用量在25μg时出现抑菌圈：化合物2与4具有微弱的抑制活性。     

水分、氮肥及MeJA处理对白桦三萜积累特性的影响

以一年半生白桦幼树为试材,研究水分、氮肥和茉莉酸甲酯(MeJA)处理对白桦三萜物质积累的影响,并对白桦植株中三萜积累规律进行了探讨。结果表明:(1)白桦幼树植株中总三萜主要分布在茎皮和叶片,根皮中最低,平均含量分别为71.94、81.60和25.45mg.g-1;叶片中总三萜积累高峰出现在6、7月份,茎皮和根皮中总三萜积累高峰分别出现在8月份和7月份。(2)干旱胁迫早期(6月)中度和重度干旱胁迫显著促进了叶中总三萜积累,分别是对照的1.24和1.27倍。茎皮中,除7月水分胁迫处理显著高于对照外,其它各月份水分胁迫不利于茎皮中总三萜含量积累,干旱胁迫不利根皮中三萜积累。(3)施氮早期(6月)不利于三萜在叶片和根皮中积累,中后期(7～10月),氮肥处理对三萜积累有显著促进作用;而施氮早期(6～7月)促进茎皮中三萜积累作用。(4)MeJA喷施处理对叶片和根皮中三萜积累(7月～10月)均具有显著的促进作用,在积累高峰期分别是对照的1.42倍和1.52倍。(5)轻度干旱、氮肥均促进了白桦幼树株高的增长和生物量的积累,而MeJA处理对整株生物量的积累不利。     

小果南烛三萜类化学成分研究

羊毛甾烷三萜是南烛属植物主要活性成分之一.为进一步研究南烛属植物功效物质基础,结合民族民间对小果南烛的应用实际,该文利用硅胶、MCI、Sephadex LH-20、半制备高效液相色谱等植物化学技术手段对该植物95％乙醇提取物进行分离、纯化,综合理化性质和波谱数据对其化合物进行鉴定.结果表明:从小果南烛的茎、叶提取物中分...     

Dammarane triterpenes from the leaves of Panax ginseng enhance cellular immunity

In our search for immune stimulating materials from natural source, bioassay-guided fractionation of a methanol extract of Panax ginseng leaves led to the isolation of three dammarane triterpenes (1–3), including two previously unknown compounds 27-demethyl-(E,E)-20(22),23-dien-3β,6α,12β-trihydroxydammar-25-one (1) and 3β,20(S)-dihydroxydammar-24-en-12β,23β-epoxy-20-O-β-d-glucopyranoside (2). Their structures were elucidated on the basis of spectroscopic methods, chemical transformation, and by the comparison with those of literature data. Compounds 1–3 significantly increased interleukin-12 expression in LPS-activated mouse peritoneal macrophage at a concentration of 100 ng/mL. Furthermore, compound 1 strongly increased the Th1 response-mediated cytokine IL-2, and decreased Th2 response-mediated cytokines IL-4 and IL-6 expression at 100 ng/mL on ConA-activated splenocytes. This study indicated that compound 1 showed a better effect on cellular immunity, and provided new chemical entities as promising lead compounds for the treatment of cellular immunity-related diseases.     

Friedelin and associated triterpenoids

The literature is reviewed for the natural occurrence of the pentacyclic triterpenes, friedelin and the epimeric 3-friedelanols. A summary of the literature relating to the structure elucidation, physical properties, synthesis and biosynthesis of these friedelane derivatives is presented. Compounds possessing the same carbon skeleton (D: A-friedelooleanane) and occurring with at least one of the above friedelane derivatives are also tabulated.     

Triterpenoids

Triterpenoids isolated from various sources are reviewed. The newer techniques used in their isolation and structure elucidation are discussed. A compi     

New alkaloids from Tabernaemontana divaricata

A re-investigation of the root bark of Tabernaemontana divaricata resulted in the isolation of 18 compounds, viz. α-amyrin acetate, lupeol acetate, α-amyrin, lupeol, cycloartenol, β-sitosterol, campesterol, benzoic acid, aurantiamide acetate, coronaridine, coronaridine hydroxyindolenine (1), ibogamine, 5-hydroxy-6-oxocoronaridine (6), 5-oxocoronaridine (9), 6-oxocoronaridine (10), (±)-19-hydroxycoronaridine (11), 3-oxocoronaridine (12) and voacamine. The alkaloids 6, 9, 10 and 11 are new compounds, whereas cycloartenol, campesterol, ibogamine, benzoic acid, aurantiamide acetate and coronaridine hydroxyindolenine are reported from this plant for the first time.     

Anticancer indole alkaloids of Ervatamia heyneana

The wood and stem bark of Ervatamia heyneana (Apocynaceae) yielded 14 indole alkaloids and 3 triterpenoids. Six of these isolates, camptothecin (2), 9-methoxycamptothecin (3), coronaridine (1), pericalline (25), heyneatine (18) and 10-methoxyeglandine- N-oxide (4) displayed cytotoxic activity. Three of the indole alkaloids 18, 4 and 10-hydroxycoronaridine (8) are new members in the iboga series and their structures were determined by a combination of spectral interpretation and chemical correlation.