HPLC法测定藜豆中左旋多巴的含量

采用HPLC法建立测定藜豆中左旋多巴含量的方法。色谱柱为岛津C-18甲基硅烷柱(250 min×4.6mm,5μm),流动相为甲醇:0.1 mol／L醋酸溶液(25:75,v／v),以硫唑嘌呤为内标物,检测波长280 nm,流速1.0 mL／min,柱温为室温,供试品的前处理方法为微波辅助提取法。结果表明,该方法准确度高,线性关系好,重现性好,平均加样回收率为97.34％,RSD 1.01％(n=5),结果满意。     

Rat- and bat-pollination of Mucuna championii (Fabaceae) in Hong Kong

Mucuna (Fabaceae) species possess gullet-type flowers that open explosively and which are thought to be specifically adapted for bat- or bird-pollination. However, recent studies have shown that non-flying mammals are also important pollinators of this genus in Asia. Here we report on the pollination system of Mucuna championii (endemic in southeast China) in Hong Kong. As is typical for the genus, explosive opening is essential for fruit set, but flowers are unable to open in the absence of manipulation by an effective pollinator. Camera trap surveys of three individuals revealed both chestnut spiny rats (Niviventer fulvescens) and short-nosed fruit bats (Cynopterus sphinx) to be capable of triggering explosive opening. The number of flowers opened by each species did not differ significantly, and both removed most pollen grains from the flowers they visited, but either species visited different individuals. Sucrose-rich nectar was secreted by flowers throughout the day. Our results reveal that M. championii can be pollinated by both rats and bats, with this representing only the second report of rat-pollination in tropical Asia. The sympatric M. birdwoodiana often occurs in close proximity to M. championii and has an overlapping flowering season, suggesting that pollinator segregation may have played a role in shaping the evolutionary ecology of these two species.     

Aluminium avoidance by Mucuna pruriens

The hypothesis was tested that the avoidance of acid subsoil by the velvet bean Mucuna pruriens is based on a mechanism acting on the whole root system rather than on individual roots. In a split-root experiment with circulating nutrient solution the growth of plants with Al-containing (+/+) or Al-free (0/0) solution on both sides of the root system was compared with that of plants which had a choice (0/+). Two levels of Al (110 and 185 μ M ) were tested at two levels of Ca (50 and 1250 μ M ). In the 185 μ M Al treatment the concentration of monomeric Al varied between 53 μ M , directly after refreshing the solution, and 5 μ M at harvest time.
An external Al concentration of 110 μ M had no effect on shoot and root dry weight, while 185 μ M Al applied to both sides of the root system (+/+) increased root dry weight and reduced shoot dry weight and shoot/root ratio, compared with the 0/0 control. Application of 185 μ M Al to half of the roots, ied to a significant shift in root growth in favour of the control side; this response is described here as Al avoidance. On the basis of total root length, root dry weight and root surface area, the ratio of 0/+ roots was 3.1, 2.8 and 2.4, respectively.
Al avoidance at 185 μ M Al was confirmed in another experiment, in which root response was measured to a local P source, supplied in a third compartment containing only KH₂PO₄. A significant increase in root length and dry weight in this compartment was observed, when other roots of the same plant were growing in the presence of Al. This result indicates that Al avoidance by Mucuna roots is related to P preference.     

Alkaloidal constituents of Mucuna pruriens seeds

The seeds of Mucuna pruriens (L.) DC. after chemical analysis afforded four tetrahydroisoquinoline alkaloids which have been isolated for the first time from M. pruriens. Out of them, two are new whose structures have been elucidated by spectroscopic methods.     

Symbionts in Mucuna pruriens stimulate plant performance through nitrogen fixation and improved phosphorus acquisition

刺毛黎豆共生体通过固氮和提高磷吸收来提高植株的生长表现南非主要以热带稀树草原和草原生态系统为主,这些生态系统具有酸性和营养缺乏的属性,特别是磷和氮素的缺乏。刺毛黎豆(Mucuna pruriens)是在大多数非洲国家广泛存在的一种本土豆科植物,该 植物可以抵御这些不利的土壤条件。豆科植物在世界上许多国家具有药用价值,也被用于土壤施肥。尽管已有文献记载了在营养胁迫生态系统中刺毛黎豆的生长和建植,但尚未对其在磷缺乏条件下的共生互作、氮源偏好和与生长相关的碳成本进行研究。在本研究中,我们确定了微生物共生体对磷缺乏条件下的刺毛黎豆氮营养和生长相关的碳成本的影响。我们从4个不同的地理位置采集微生物接种土壤,然后将种子在这些天然土壤中发芽,在根瘤发育的早期,将幼苗转移到无菌石英砂中,并提供不同磷 浓度的营养培养基。16S RNA序列结果显示,在不考虑磷浓度的情况下,Burkholderia sp., Paenibacillus sp.和Bacillus 均有分枝。尽管磷缺乏导致总生物量/生长下降,但根系生物量、根瘤数量和碳成本增加。低磷供给的幼树丛枝菌根真菌根系定殖率最高。刺毛黎豆中,大气中的氮与磷水平呈正相关关系,幼树对大气氮素和土壤氮素具有双重依赖,低磷植株对土壤氮素的依赖程度增加。因此,在磷缺乏的情况下,刺毛黎豆表现出不同的形态和微生物共生关系。     

The effects of glacial atmospheric CO2 concentrations and climate on isoprene emissions by vascular plants

Isoprene (C₅H₈) emissions by terrestrial vegetation vary with temperature and light intensity, and play an important role in biosphere–chemistry–climate interactions. Such interactions were probably substantially modified by Pleistocene climate and CO₂ cycles. Central to understanding the nature of these modifications is assessment and analysis of how emissions changed under glacial environmental conditions. Currently, even the net direction of change is difficult to predict because a CO₂‐depleted atmosphere may have stimulated emissions compensating for the negative impacts of a cooler climate. Here, we address this issue and attempt to determine the direction of change from an experimental standpoint by investigating the interaction between isoprene emissions and plant growth of two known isoprene‐emitting herbaceous species (Mucuna pruriens and Arundo donax) grown at glacial (180 ppm) to present (366 ppm) CO₂ levels. We found a significant enhancement of isoprene emissions per unit leaf area in M. pruriens under subambient CO₂ concentrations relative to ambient controls but not for A. donax. In contrast, canopy emissions remained unaltered for both plant species because enhanced leaf emissions were offset by reductions in biomass and leaf area. Separate growth experiments with M. pruriens revealed that lowering day/night temperatures by 5°C decreased canopy isoprene emissions irrespective of the CO₂ level. Incorporation of these results into a simple canopy emissions model highlights their potential to attenuate reductions in the total isoprene flux from forests under glacial conditions predicted by standard models.     

Potential of Leguminous Cover Crops in Management of a Mixed Population of Root-knot Nematodes (Meloidogyne spp.)

Root-knot nematode is an important pest in agricultural production worldwide. Crop rotation is the only management strategy in some production systems, especially for resource poor farmers in developing countries. A series of experiments was conducted in the laboratory with several leguminous cover crops to investigate their potential for managing a mixture of root-knot nematodes (Meloidogyne arenaria, M. incognita, M. javanica). The root-knot nematode mixture failed to multiply on Mucuna pruriens and Crotalaria spectabilis but on Dolichos lablab the population increased more than 2- fold when inoculated with 500 and 1,000 nematodes per plant. There was no root-galling on M. pruriens and C. spectabilis but the gall rating was noted on D. lablab. Greater mortality of juvenile root-knot nematodes occurred when exposed to eluants of roots and leaves of leguminous crops than those of tomato; 48.7% of juveniles died after 72 h exposure to root eluant of C. spectabilis. The leaf eluant of D. lablab was toxic to nematodes but the root eluant was not. Thus, different parts of a botanical contain different active ingredients or different concentrations of the same active ingredient. The numbers of root-knot nematode eggs that hatched in root exudates of M. pruriens and C. spectabilis were significantly lower (20% and 26%) than in distilled water, tomato and P. vulgaris root exudates (83%, 72% and 89%) respectively. Tomato lacks nematotoxic compounds found in M. pruriens and C. spectabilis. Three months after inoculating plants with 1,000 root-knot nematode juveniles the populations in pots with M. pruriens, C. spectabilis and C. retusa had been reduced by approximately 79%, 85% and 86% respectively; compared with an increase of 262% nematodes in pots with Phaseolus vulgaris. There was significant reduction of 90% nematodes in fallow pots with no growing plant. The results from this study demonstrate that some leguminous species contain compounds that either kill root-knot nematodes or interfere with hatching and affect their capacity to invade and develop within their roots. M. pruriens, C. spectabilis and C. retusa could be used with effect to decrease a mixed field populations of root-knot nematodes.     

Isoprene emission by plants is affected by transmissible wound signals

Isoprene (2-methyl 1,3-butadiene) is emitted from many plants, but the signals regulating isoprene emission are unknown. Mounting leaves in a gas exchange chamber or taking small leaf punches for biochemical analysis was found to reduce the rate of isoprene emission (Loreto & Sharkey 1993). This phenomenon was investigated by putting terminal leaflets of velvet bean (Mucuna deeringeniana L.) and kudzu [Pueraria lobaia (Willd) Ohwi.] into a gas exchange chamber and monitoring isoprene emission and photosynthesis. Lateral leaflets or remote leaves were then wounded or mechanically stimulated. The rate of isoprene emission was reduced after 1 min by up to 75% by burning a lateral leaflet with a match. Even a 7 ms^?1 (25km h^?1) wind imposed on a lateral leaflet reduced isoprene emission from the terminal leaflet by 18%. Photosynthesis rates were either unaffected by these treatments or reduced more slowly than isoprene emission rates, indicating that the effect of isoprene emission rates was not a consequence of changes in photosynthetic activity. Isoprene emission from a terminal leaflet was reduced by burning leaves above and below the monitored leaflet when on the same stem. The effect was much reduced if the burned leaf (all three leaflets) was on a different stem from the monitored leaflet. Reduction of the rate of isoprene emission was observed even when the burned leaf was 52 cm distant from the measured leaflet. Increasing the distance between the stressed leaf and the monitored leaf caused the effect to be slower and smaller. It is speculated that a signal is generated by wounding which propagates through the plant at 1.3 mm s^?1. This velocity was consistent throughout the measurements and is similar to the rate of propagation of electrical signals such as action potentials and variation potentials. The effect of the environmental stress, and particularly the wind effect, can be frequent in nature and should be considered when estimating local and regional emission of isoprene for modelling atmospheric chemistry. If leaf samples used for isoprene determination are exposed to the type of stress we investigated, isoprene emission inventories based on leaf level measurements will be underestimated.     

Mucuna pruriens seed extract reduces oxidative stress in nigrostriatal tissue and improves neurobehavioral activity in paraquat-induced Parkinsonian mouse model

Parkinson’s disease (PD) is a neurodegenerative disease which causes rigidity, resting tremor and postural instability. Treatment for this disease is still under investigation. Mucuna pruriens (L.), is a traditional herbal medicine, used in India since 1500 B.C., as a neuroprotective agent. In this present study, we evaluated the therapeutic effects of aqueous extract of M. pruriens (Mp) seed in Parkinsonian mouse model developed by chronic exposure to paraquat (PQ). Results of our study revealed that the nigrostriatal portion of Parkinsonian mouse brain showed significantly increased levels of nitrite, malondialdehyde (MDA) and reduced levels of catalase compared to the control. In the Parkinsonian mice hanging time was decreased, whereas narrow beam walk time and foot printing errors were increased.     

油麻藤种子中凝集素的纯化及性质的研究

中药常春油麻藤种子中含有Ａ型血专一性的凝集素（ＭＳＬ）．该凝集素可经盐析、离子交换及凝胶过滤进行纯化,当其浓度为０．４９μｇ／ｍｌ时就能凝集人Ａ型血细胞,对人类Ｂ、Ｏ型及兔红细胞无作用．Ｇａｌ,ＧａｌＮＡｃ和胃粘蛋白对ＭＳＬ的凝血活性有强抑制作用．ＭＳＬ含中性糖５．７％,凝胶过滤测得分子量为１３１８００,ＳＤＳ－ＰＡＧＥ测得分子量为６６０００和３３０００,表明ＭＳＬ可能由两个不同亚基组成．ＭＳＬ还是一种促有丝分裂原,对人外周血中淋巴细胞的转化率可达７６．２％．