Some Problems in the Assay Method of HMG-CoA Reductase Activity in Sweet Potato in the Presence of Other HMG-CoA Utilizing Enzymes

In addition to HMG-CoA reductase, another HMG-CoA utilizing enzyme is present in the Mt fraction of sweet potato root tissue and its activity interferes with the assay to HMG-CoA reductase activity.     

Effect of Conduritol A,a Polyol from Gymnema sylvestre,on the Development of Diabetic Cataracts in Streptozotocin-treated Rats and on Aldose Reductase

Streptozotocin-diabetic rats were maintained on a stock diet for 16 weeks and some were given conduritol A (10 mg/kg/day). The administration of conduritol A, having a hypoglycemic effect, markedly prevented the diabetic rats from getting cataracts. In practice, conduritol A inhibited aldose reductase (EC 1.1.1.21) that is capable of catalyzing the conversion of aldoses to sugar alcohols in the polyol pathway. In an in vitro assay, lens aldose reductase was most effectively inhibited by conduritol A when α,β-d-glucose was used as a substrate. Some enzymes from the rats were not inhibited by conduritol A. Neither an intraperitoneal injection nor oral dosage of conduritol A caused acute toxicity in the rats. These findings suggest that the inhibition of lens aldose reductase by conduritol A may be responsible for its cataract-suppressing effect.     

Evaluation of Polyethylene Glycol as a Water-soluble Marker: Absorption and Excretion of 14C-labeled Polyethylene Glycol in Rats

The absorbability of polyethylene glycol (PEG), a water-soluble nutritional marker, from the gastrointestinal tract of rat was examined using the [¹⁴C]-labeled compound ([¹⁴C]PEG) having a molecular weight of 4000. Intravenously injected [¹⁴C]PEG was readily excreted and recovered almost completely in the urine and neither hepatic nor renal uptake of the PEG was observed. Intragastrically administered [¹⁴C]PEG was eliminated in the urine with an average recovery of only 0.43 ± 0.13% (Mean ± S.D., n= 10) of the dose over 24 hr. From the gel column chromatographic profile of the radioactivity excreted in the urine after an oral dose, [¹⁴C]PEG was suggested to be absorbed in two forms, as an original form and as a low molecular weight component. The latter component might be the degraded product of PEG in the gastrointestinal tract. From these results it was confirmed that PEG with a molecular weight of 4000 is a satisfactory marker because of its low absorbability.     

Abietane diterpenoids from suspension cultured cells of Torreya nucifera var. radicans

Three abietane diterpenoids were isolated from the suspension cultured cells of Torreya nucifera var. radicans along with four known abietane diterpenoids. Based on spectroscopic evidence, the structures of the three were elucidated as (3S,5R,10S)-7-oxo-12-methoxyabieta-8,11,13-triene-3,11-diol, (3S,5R,10S)-7-oxo-12-methoxyabieta-8,11,13-triene-3,11,14-triol and (5R,10S)-3-oxo-7R,12-dimethoxyabieta-8,11,13-trien-11-ol, respectively.     

红豆杉科白豆杉属植物的分类学研究

白豆杉属Pseudotaxus现包括2种,即白豆杉P.chienii(Cheng)Cheng和李氏白豆杉P.lianaJ.Silba,二者之间的区别在于叶片宽度不同。本文对来自浙江、江西、湖南和广西等地的白豆杉属植物标本进行了观察和测量。尽管t检验分析表明来自浙江的标本与来自江西、湖南和广西的标本在叶片宽度平均数上的确存在显著差异,但是,散点图分析却显示叶片宽度变异是连续的,这与J.Silba的观察不同,因此,将P.lianaJ.Silba作为P.chienii(Cheng)Cheng的异名处理。     

In vivo anti-osteoporotic activity of isotaxiresinol, a lignan from wood of Taxus yunnanensis

Isotaxiresinol, the main lignan isolated from the water extract of wood of Taxus yunnanensis, was investigated for its effect on bone loss, on serum biochemical markers for bone remodeling and on uterine tissue, using ovariectomized (OVX) rats as the model of postmenopausal osteoporosis. After oral administration of isotaxiresinol (50 and 100mg/kg/d) for 6 weeks, bone mineral content (BMC) and bone mineral density (BMD) in total and cortical bones were increased as compared to those of OVX control rats, and decreases of three bone strength indexes induced by OVX surgery were prevented. Serum biochemical markers for bone remodeling revealed that isotaxiresinol slightly increased bone formation and significantly inhibited bone resorption without side effect on uterine tissue. These results suggest that isotaxiresinol may be useful for treatment of postmenopausal osteoporosis, especially for prevention of bone fracture induced by estrogen deficiency.     

红豆杉科、三尖杉科和罗汉松科植物叶片结构的比较观察

扫描电镜和光镜下的叶表皮特征以及叶片解剖结构的研究结果,支持在红豆杉科内建立白豆杉属的处理方式;赞同在三尖杉属内建立篦子三尖杉组,叶片解剖结构方面,三尖杉科和红豆杉科的穗花杉属的相似之处颇多。而叶表皮形态特征方面又表现为三尖杉科和罗汉松科更加接近。反映了出了红豆杉科、三尖杉科和罗汉松科之间的密切而又复杂的系统关系。     

Studies on Pollen Morphology of Taxaceae of China

The present study deals with pollen morphology of 4 genera and l0 species of Taxaceae in gymnosperms. Pollen grains of the family are spheroidal or subspheroidal, 20.8μm in diameter and with laptoma or papilla in the distal face. Exine is two-layered, with sexine equal to nexine in thickness, but sometimes the stratification is indistinct. The surface is scabrous or slightly granular under LM. Coarse verrucae and fine tuberculae on pollen surface are observed under SEM. From thin section, endexine is shown to have lamellate structure, and ectexine is made of verrucate elements. In Amentotaxus argotaenia, some pollen grains show remnant saccate. According to pollen morphology, this family may be divided into two tribes: 1, Pseudotaxeae (including Pseudotaxus only), and 2, Taxeae (including Taxus and Torreya). Owirg to the special feature of pollen grains in Amentotaxus the present author suggests that the genus be separated from Taxaceae and raised to the level of family, Amentotaxaceae.     

从幼苗形态学特征探讨红豆杉科各属间的系统演化

本文根据幼苗的形态学特征,尤其是子叶的结构、说明在红豆杉科中最原始的属是榧树属,其幼苗为留土萌发,植株粗壮;子叶肥厚,有吸收功能,叶肉不分化,其细胞中充满淀粉粒：维管束在子叶的上部或顶部为单束2条,下部合并成双束1条。其次是穗花杉属,幼苗为出土萌发,植株粗壮,下胚轴的下部肥厚;子叶稍肉质,叶肉不分化,质体淡绿,有一定的光合功能,但主要是积累淀粉,维管束双束1条,在子叶的顶端趋于分裂。最进化的是红豆杉属和白豆杉属,可能还有澳洲红豆杉属,其幼苗为出土萌发,植株纤细;子叶薄,叶状,叶肉分化成栅栏和海绵组织,维管束单束1条。本科中族的划分和属的系统排列,从原始到进化,应该是：族1．榧树族(1．榧树属);族2．穗花杉族(2．穗花杉属);族3．红豆杉族(3．澳洲红豆杉属,4．红豆杉属,5．白豆杉属)。