嘉兰栽培及其秋水仙碱含量测定

嘉兰原属热带性地区的植物,但从云南南部引种到广州地区种植。表现生长发育良好,且其秋水仙碱含量高达0.40—0.45％。是一种有推广种植价植的药用植物。     

In Vitro Organogenetic Responses of Gloriosa superba

An efficient protocol was developed for regeneration of healthy plant derived from six categories of explants from both in vivo and in vitro raised plants, viz. roots, corm buds (dormant and nondormant), young leaves, stems, pedicels, and shoot tips from aerial shoots. MS medium supplemented with various concentrations and combinations of auxin, cytokinin, and organic acids was used. 98% of callus induction occurred in nondormant corm bud explants. The greatest number of multiple shoots (57) was observed in corm-derived calluses. Vigorous root formation occurred in all cases when multiple shoots were derived. Histomorphogenetic studies revealed that not only the origin of shoot and root buds in in vitro systems, but the morphology and structure of leaves resemble those of in vivo plants too.     

Bioprocess Intensification for Production of Novel Marine Bacterial Antibiotics Through Bioreactor Operation and Design

There is a lack of research into bioreactor engineering and fermentation protocol design in the field of marine bacterial antibiotic production. Most production strategies are carried out at the shake-flask level and lack a mechanistic understanding of the antibiotic production process, offering poor prospects for successful scale-up. This review shows that data need to be collated on media and physical optima differences between the trophophase and idiophase, along with investigations into the control mechanisms for biosynthesis, to allow implementation of novel fermentation protocols. Immobilization may play a part in bioprocess intensification of marine bacterial antibiotic production, through again this area is understudied. Similarly, mass transfer and shear stress data of fermentations are needed to provide the bioreactor design requirements to intensify antibiotic biosynthesis, with process scale-up in mind. The application of bioprocess intensification methods to the production of antibiotics (and other metabolites) from marine microbes will become an important strategy for improving supply of natural products, in order to assess their suitability as chemotherapeutic drugs. Received March 11, 1999; accepted May 4, 1999.     

Enzyme inhibition activities of the extracts from rhizomes of Gloriosa superba Linn (Colchicaceae)

An alcoholic extract obtained from the rhizomes of Gloriosa superba Linn (Colchicaceae) was screened for enzyme inhibition activities. The crude extract and its subsequent fractions including chloroform, ethyl acetate, n-butanol and aqueous were screened against lipoxygenase, actylcholinesterase, butyrylcholinesterase and urease. An outstanding inhibition on lipoxygenase was observed. The highest enzyme inhibition potency was expressed by the chloroform fraction (90%) among the tested fractions on lipoxygenase. Overall 67– 90% inhibition was found for lipoxygenase, 46-69% for acetylcholinesterase and 10–33% for butyrylcholinesterase, while urease was not inhibited.     

具有抗癌活性含氮天然产物的研究进展

综述了近年来分离得到的具有抗癌活性含氮天然产物的研究进展。     

Enhanced colchicine production in root cultures of Gloriosa superba by direct and indirect precursors of the biosynthetic pathway

Excised root cultures of Gloriosa superba reached 7.5 g dry wt l^–1 and accumulated 240±40 g colchicine g^–1 cell dry wt after 4 weeks growth. While all precursors (except trans-cinnamic acid) enhanced colchicine content of root cultures without adversely affecting root growth, treatment with p-coumaric acid + tyramine (each at 20 mg l^–1) increased colchicine content to 1.9 mg g^–1 cell dry wt.     

ANTINEOPLASTIC ACTIVITY OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

A large-scale screening program was initiated to evaluate laboratory-cultured blue-green algae (cyanobacteria) as a source of novel antineoplastic agents. Approximately 1000 cyanophyte strains from diverse habitats were cultured to provide extracts for testing. The screening program identified the families Scytonemataceae and Stigonemataceae as prolific producers of novel cytotoxic compounds. Rates of rediscovery of known compounds were relatively low.     

Antimicrobial activities of Gloriosa superba Linn (Colchicaceae) extracts

The methanol extract of the rhizomes of Gloriosa superba Linn (Colchicaceae) and its subsequent fractions in different solvent systems were screened for antibacterial and antifungal activities. Excellent antifungal sensitivity was expressed by the n-butanol fraction against Candida albicans and Candida glaberata (up to 90%) and against Trichophyton longifusus (78%) followed by the chloroform fraction against Microsporum canis (80%). In the antibacterial bioassay, the crude extract and subsequent fractions showed mild to moderate antibacterial activities. Chloroform fraction displayed highest antibacterial sensitivity against Staphylococcus aureous (88%) followed by the crude extract (59%). The total phenol content of the crude extract and fractions of the plant expressed no significant correlation with the antimicrobial activities.     

Natural products – modifying metabolite pathways in plants

The diversity of plant natural product (PNP) molecular structures is reflected in the variety of biochemical and genetic pathways that lead to their formation and accumulation. Plant secondary metabolites are important commodities, and include fragrances, colorants, and medicines. Increasing the extractable amount of PNP through plant breeding, or more recently by means of metabolic engineering, is a priority. The prerequisite for any attempt at metabolic engineering is a detailed knowledge of the underlying biosynthetic and regulatory pathways in plants. Over the past few decades, an enormous body of information about the biochemistry and genetics of biosynthetic pathways involved in PNPs production has been generated. In this review, we focus on the three large classes of plant secondary metabolites: terpenoids (or isoprenoids), phenylpropanoids, and alkaloids. All three provide excellent examples of the tremendous efforts undertaken to boost our understanding of biosynthetic pathways, resulting in the first successes in plant metabolic engineering. We further consider what essential information is still missing, and how future research directions could help achieve the rational design of plants as chemical factories for high-value products.     

Replacement of immobilised cell bioreactors by smaller immobilised enzyme bioreactors: unique-outcome predictability for cytochromes P450 isoforms?

Both immobilized enzymes (IME) and immobilized cells (IMC) are acceptable as the biocatalysts essential for the attainment of rapid rates of bioconversion in bioreactors. IMC can display higher than expected cellular permeability whilst IME can exhibit high catalytic constant (k_cat/K_m) despite limitations on substrate utilisation due to an unstired diffusion layer of solvent. Scale-down switching from IMC to IME involves the replacement of high-volume biotechnology by low-volume biotechnology, sometimes using IME mimics in partially non-aqueous solvent systems. Highly purified IME systems covalently immobilised to particles of, for instance, microcrystalline cellulose or porous glass, can retain both the hydrophilic and hydrophobic intermediate products in situ of the chosen sequence of enzyme reactions. These bioconversions, therefore, are as efficient as those with IMC where enzymes are often particle- or membrane-bound so that even hydrophilic intermediates are not released rapidly into solution. This mimicry of in vivo biosynthetic pathways that are compartmentalised in vivo (e.g. of lysosomes, mitochondria and endoplasmic reticulum) can replace larger IMC by IME especially in application of up to 2700 cytochromes P450 isoforms in bioprocessing. In silico investigation of appropriate model IME systems, in comparison with IMC systems, will be needed to define the optimal bioreactor configuration and parameters of operation, such as pH, T and oxygen mass transfer rate (OTR). The application solely of hazop (applied hazard and operability concepts) may, nevertheless, not be recommended to replace fully the in silico and real-lab pilot-scale and scale studies. Here, food-safe bioprocessing has to be achieved without incorporation of recognised biohazards; especially in the form of unacceptable levels of toxic metals that promote a risk-analysis uncertainty.     

Marine pharmacology

Marine organisms have provided a large proportion of the bioactive natural products reported over the last 20 years, but none of these compounds have reached the pharmaceutical marketplace. This review describes current progress in the development of a selection of new antiinflammatory and anticancer agents, discusses some difficulties encountered during the development process and suggests how these difficulties may be overcome in the near future through applications of recent advances in biotechnology.     

Searching for process information in the aroma of cell cultures

Aroma emissions from living cells can provide valuable information about the metabolic and physiological condition of those cells. Electronic noses are chemical gas-sensor arrays that use artificial neural network models to evaluate aromas. They can interpret the complex aroma information emitted from cultures of bacteria, yeast cells and animal cells. Potential applications for electronic noses range from medical diagnosis to industrial bioprocessing.     

Biosynthesis of marine natural products: isolation and characterization of a myrcene synthase from cultured tissues of the marine red alga Ochtodes secundiramea

The acyclic monoterpene myrcene is the likely progenitor of the unusual cytotoxic halogenated monoterpenes that are found in marine algae and that function as feeding deterrents to herbivores. Myrcene synthase was isolated from suspension cultures of the marine red alga Ochtodes secundiramea, representing the first enzyme of this type from a marine organism. The algal myrcene synthase produces exclusively myrcene from the natural substrate geranyl diphosphate (GDP), utilizes Mg(+2) as the required divalent metal ion cofactor, has a molecular mass of about 69 kDa, and exhibits a pH optimum near 7.2. These features are similar to those of monoterpene synthases from terrestrial organisms. When incubated with neryl diphosphate (the cis-isomer of GDP), the O. secundiramea myrcene synthase produces the cyclic monoterpene limonene, whereas incubation with (+/-)linalyl diphosphate (the tertiary allylic isomer of geranyl diphosphate) yields both acyclic and cyclic monoterpenes. These results suggest that the enzyme is incapable of isomerizing geranyl diphosphate to linalyl diphosphate, a feature common to all monoterpene cyclases from terrestrial sources. The limited catalytic capability of the myrcene synthase may reflect the ancient evolutionary origin of the producing organism. The ability to assay this enzyme in cultured algae, grown under strictly defined conditions, provides an unparalleled opportunity to delineate factors eliciting the biosynthesis of this class of secondary metabolites, to investigate the metabolic pathway leading to the halogenated monoterpenes, and to determine their role in the chemical ecology of marine algae.     

天然产物Combretastatins的研究进展

Combretum caffrum是南非的一种具有很强抗肿瘤活性的植物,80年代开始,一系列化合物（combretastatins）从这种植物中被分离、鉴定出来,它们大多具有较强的抑制微管聚合和有丝分裂的活性。本文综述了对这类天然产物combretastatins的全合成、药理作用机理及结构修饰等方面的研究进展。     

Plant cell bioreactor for the production of protoberberine alkaloids from immobilized Thalictrum rugosum cultures

Cultured Thalictrum rugosum cells were immobilized using a glass fiber substratum previously shown to provide optimum immobilization efficiency based on spontaneous adhesion mechanisms. When cultivated in shake flasks, immobilized cells exhibited decreased growth and protoberberine alkaloid production rates in comparison to freely suspended cells. Since alkaloid production is growth associated in T. rugosum, the decreased specific production rate was a function of the slower growth rate. Cells immobilized on glass fiber mats appear to be amenable for extended culture periods. Maximum biomass and protoberberine alkaloid levels were maintained for at least 14 days in immobilized cultures. In contrast, fresh weight, dry weight, and total alkaloid content decreased in suspension cultures following the linear growth phase.Glass fiber mats were incorporated in to a 4.5-L plant cell bioreactor as horizontal disks supported on a central rod. Mixing in the reactor was provided by the combined actions of a magnetic impeller and a cylindrical sparging colum. fThe magnetic impeller and a cylindrical sparging column. The entire inoculum biomass of T. rougosum, introduced as suspension, was spontaneously immobilized with in 8h. During liner phase, the growth rate of bioreactor cultivated immobilized cells (mu = 0.06 day(-1)) was 50% that immobilized cell viability in both systems was determined to be similar. The increase in specific production of protoberberine alklodis was initially similar in bioreactor-and culture period. The increase in specific production of protoberberine alkaloids was initially similar in bioreactor-and shake-flask-cultivated immobilized cells. However, the maximum specific production of bioreactor grown cultures was lower. The scale up potential of an immobilization strategy based on the spontaneous adhesion of immobilization strategy based on the spontaneous adhesion of cultured plant cells to glass fiber is demonstrated.