二种石斛属植物和小叶石仙桃生物碱的组织化学定位

Histochemical Localization of Alkaloid in Dendrobium and Pholidota chinnesis Lindl.

目的对不同年龄的铁皮石斛、铜皮石斛及其石斛伪品———小叶石仙桃的不同器官进行生物碱组织化学定位,选择具有较高药用价值的石斛类药用植物和药用部位,确定铁皮石斛的最佳采收期。方法采用冰冻切片法,根据生物碱的理化性质,用碘化铋钾染色法对3种植物的生物碱进行组织化学定位。结果生物碱主要存在于3种植物茎的薄壁细胞、根的皮层细胞、叶的叶肉细胞中;其总生物碱含量顺序为:二生年的铁皮石斛≈铜皮石斛>小叶石仙桃。此外,在3种植物不同的器官中,其总生物碱的含量都呈现“叶>茎≈根”的规律。结论在种间及同种植物的不同年龄或不同器官中,其生物碱的含量存在差异。其中,以二年生铁皮石斛和铜皮石斛茎叶的生物碱含量较高,表明其药用价值也较高。

OBJECTIVE To locate the alkaloid in different organs of Dendrobium candidum Wall. ex Lindl.,D. moniliforme （L.） Sw. and Pholidota chinensis Lindl., and to choose the best Dendrobium species and organs having high alkaloid content and high medicinal value, METHODS The improved dragendorff reagent （bismuth potassium iodide reagent） was used to locate the alkaloid in root, stem and leaf of the three species. RESULTS The color reaction and special crystal depositian sites indicated that the alkaloid was located in the parenchyma of stem, cortex of root and mesophyll of leaf. Furthermore, the alkaloid cantent of D. candidum of two-year old was equal to that of D. moniliforme, but they were higher than that of P. chinensis. And in different organs of the three species, the alkaloid content in stem was almost equal to that in root, which was general lower than that in leaf. CONCLUSION The alkaloid contents are obviously different among the three species, different organs of the same species or different age of D. candidum,respectively. Based on these results, we conclude that the highest alkaloid content is in the stem and leaf of two year-old D. candidum and D. moniliforme that own higher medicinal value.