3种天然二萜的化感作用及机制的研究

以黑麦草(Lolium perenne L.)和莴苣(Lacutuca sativa L.)为受试植物,研究了3种对映—贝壳杉烷二萜wangzaozin A、leukamenin E和weisiensin B对受试植物种子萌发、幼苗生长、叶绿素和膜损伤的影响,旨在评估3种二萜的化感作用潜能。结果显示:不同浓度的3种二萜对黑麦草和莴苣种子的萌发稍有降低,但明显延迟种子萌发时间;较高浓度下,3种二萜对黑麦草和莴苣幼苗的根长、苗长、鲜质量和干质量均有显著的抑制作用,并显示了浓度依赖性;同时,3种二萜显著降低黑麦草和莴苣幼苗叶片叶绿素a和叶绿素b含量,显著升高丙二醛(MDA)含量和相对电导率,而相对含水量呈下降趋势。上述结果表明,3种二萜通过影响受试植物的光合作用能力,引起细胞膜氧化损伤,导致叶片保水性降低,抑制受试植物幼苗的生长。

Two New ent-Kauranoids from Isodon tenuifolia

Two new ent-kauranoids, tenuifolin A (3beta,6alpha, 15beta-trihydroxy-1alpha, 7beta-diacetoxy-11beta, 16beta-epoxy-ent-kaurane) (1) and tenuifolin B (1alpha,6alpha, 11beta-trihydroxy-3beta,7beta-diacetoxy-ent-kaur-16-en-15-one) (2), together with four known compounds were isolated from the aerial parts of Isodon tenuifolia (W. W. Smith) Kudo collected from Zhongdian County, Yunnan Province, China. Their structures were determined by the spectral methods (including 2D NMR techniques).