These experiments were carried out to investigate whether accumulation of carbohydrate leads to decreased expression of genes involved in photosynthesis. Addition of glucose to autotrophic cell suspension cultures of Chenopodium led to a large and reversible decrease of the steady state transcript levels of rbcS, cab and atp8 within 5 h, but did not decrease 18s rRNA or transcript for two glycolytic enzymes. Run-on transcription in isolated nuclei showed that transcription rate had been decreased. f%]Methionine feeding showed that de novo synthesis of Rubisco was inhibited. Decreased rbcS transcript was also found after feeding glucose to detached leaves, and in transgenic plants expressing invertase in the apoplast to inhibit phloem transport, and in leaves on intact tobacco and potato plants which were cold-girdled to decrease export. The decrease of rbcS transcript level occurred within 12 h of coldgirdling. Comparison of carbohydrate content and rbcS transcript level indicated that carbohydrate content perse is not the direct signal for regulation of gene expression. Feeding of transported analogues indicates that metabolism rather than transport of the sugars is required. Over-expression of rbcS was found in low COP, again indicating metabolic control of expression. It is proposed that photosynthetic gene expression is inhibited by metabolic factors related to high carbohydrate content, and that this represents a basic mechanism for the 'sink regulation' of photosynthesis.When 50 mM glucose is added to autotrophically growing Chenopudium rubrum cell suspension cultures, it is rapidly 81 7

The structure- and chemistry-based hierarchical organization of library scaffolds in tree-like arrangements provides a valid, intuitive means to map and navigate chemical space. We demonstrate that scaffold trees built using bioactivity as the key selection criterion for structural simplification during tree construction allow efficient and intuitive mapping, visualization and navigation of the chemical space defined by a given library, which in turn allows correlation of this chemical space with the investigated bioactivity and further compound design. Brachiation along the branches of such trees from structurally complex to simple scaffolds with retained yet varying bioactivity is feasible at high frequency for the five major pharmaceutically relevant target classes and allows for the identification of new inhibitor types for a given target. We provide proof of principle by identifying new active scaffolds for 5-lipoxygenase and the estrogen receptor ERalpha.

5-Lipoxygenase (5-LO) is an important enzyme of the arachidonic acid cascade and catalyses with the help of FLAP, the 5-LO-activating protein, the formation of bioactive leukotrienes (LTs). LTs are inflammatory mediators playing a pathophysiological role in different diseases such as asthma, allergic rhinitis as well as cardiovascular diseases and certain types of cancer. Up to now, only one 5-LO inhibitor is on the market, zileuton for the treatment of asthma. With the rising number of indications for anti-LT therapy, 5-LO inhibitor drug development becomes more and more important. This MiniReview gives an update on 5-LO inhibitors currently under clinical development. Furthermore, the recent advances in the search for novel 5-lipoxygenase inhibitors with a focus on computational methods are summarized. Currently, licofelone is the compound with the highest clinical development status (completed phase III trials). 5-LO inhibitor screening programmes based on computational methods could deliver several promising drug-like new molecules. These activities can be expected to be driven by the newly resolved structure of human 5-LO in the future, enabling structure-based drug design. For the prospective drugs in late-stage clinical development, the future will show their clinical safety and efficacy in the particular diseases. The 5-LO-derived arachidonic acid metabolites have been shown to be potent mediators of inflammatory reactions. During the last decades, many investigations demonstrated that the 5-LO pathway plays a role in the development of allergic diseases such as asthma [2] Most of the 5-LO inhibitors bind to the catalytic site and show a more or less competitive inhibition of the enzyme. 5-LO inhibitors can be classified into three main groups: redoxactive compounds, iron-ligand inhibitors with weak redoxactive properties and non-redox-type inhibitors [7].Insights into the pharmacological potential of 5-LO inhibitors were obtained in studies using 5-LO-deficient mice. 5-LOdeficient mice are strongly resistant against PAF-induced shock and show reduced airway reactivity [8]. Furthermore, interference with the 5-LO pathway via blockage of FLAP was found to reduce collagen-induced arthritis [9]. Another study with 5-LO-deficient mice suggests that 5-LO plays a critical role in the development of chronic myeloid leukaemia [4].Up to now, the iron-ligand type-5-LO inhibitor zileuton is the only 5-LO inhibitor that came on the market for the treatment of asthma. So, how to come up with novel inhibitors? There are several different strategies in drug design, divided mainly in (I) the improvement of already known compounds by medicinal chemistry approaches to cope with, for example, a poor pharmacokinetic profile and (II) the identification of novel scaffolds. For the latter, high-throughput screening of large databases of synthetic compounds or natural product extracts to find active compounds can be applied. Alternatively, computational methods are quite helpful tools to speed up the drug discovery p...

Frankincense preparations, used in folk medicine to cure inflammatory diseases, showed anti-inflammatory effectiveness in animal models and clinical trials. Boswellic acids (BAs) constitute major pharmacological principles of frankincense, but their targets and the underlying molecular modes of action are still unclear. Using a BA-affinity Sepharose matrix, a 26-kDa protein was selectively precipitated from human neutrophils and identified as the lysosomal protease cathepsin G (catG) by mass spectrometry (MALDI-TOF) and by immunological analysis. In rigid automated molecular docking experiments BAs tightly bound to the active center of catG, occupying the same part of the binding site as the synthetic catG inhibitor JNJ-10311795 (2-[3-{methyl[1-(2-naphthoyl)piperidin-4-yl]amino}carbonyl)-2-naphthyl]-1-(1-naphthyl)-2-oxoethylphosphonic acid). BAs potently suppressed the proteolytic activity of catG (IC50 of ∼600 nM) in a competitive and reversible manner. Related serine proteases were significantly less sensitive against BAs (leukocyte elastase, chymotrypsin, proteinase-3) or not affected (tryptase, chymase). BAs inhibited chemoinvasion but not chemotaxis of challenged neutrophils, and they suppressed Ca2+ mobilization in human platelets induced by isolated catG or by catG released from activated neutrophils. Finally, oral administration of defined frankincense extracts significantly reduced catG activities in human blood ex vivo vs placebo. In conclusion, we show that catG is a functional and pharmacologically relevant target of BAs, and interference with catG could explain some of the anti-inflammatory properties of frankincense.

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