Milieu-dependent pro- and antioxidant activity of juglone may explain linear and nonlinear effects on seedling development.

Juglone, 5-hydroxy-1,4-naphthoquinone, is known for its wide range of biological activities. It has been suggested that juglone's excellent redox cycling properties contribute to this reputation. Many biological activities are nonlinear with low concentrations exerting stimulating effects, whereas only higher concentrations cause inhibition. Here, we corroborate studies on the nematode Caenorhabditis elegans that point out hormetic effects by showing that juglone may cause a nonlinear effect on postgerminative shoot and root growth of Sinapis alba. This effect was only significantly visible, however, when seedlings were stressed with methanol. Classic and modified versions of the deoxyribose assay were applied successfully to characterize antioxidative (purposeful generation of hydroxyl radicals) and prooxidative (no purposeful generation of hydroxyl radicals) activities. Variants of the assay with and without the addition of the iron chelator EDTA showed that the antioxidant activity is independent on chelation of iron ions by juglone; by contrast, the strength of the prooxidative activity depended on the chelation of iron ions by juglone. The hormetic effects of lower concentrations on germination of Sinapis alba, thus, may be caused by the antioxidant activities of this compound, which are especially effective when the test organism is subjected to higher oxidative challenge. The present study suggests that pronounced prooxidative activities, which are considerably accelerated by chelation of iron ions, may contribute to the toxic effects of juglone at higher concentrations.

Phototoxic activity and the possibilities of its testing.

The photodynamically active compounds have been attracting an attention of specialists for relatively long time. The most fruitful period of their research has been probably the last decade. The structures of the photosensitizers are very different. The biological activity is based on a formation of free reactive radicals after an excitation of the molecules of the phototoxins by e.g. UV radiation. Some photosensitizers are used for treatment of various diseases in dermatology and oncology. Since the substances can occur in plants, food or cosmetics, the photodynamic activity of these compounds is necessary to be studied under various conditions. Now e.g. some photochemical reactions, cell cultures, cultures of microorganisms, suspensions of erythrocytes, and different species of animals are used to the research of the photodynamic activity of the substances.

Antiradical activity of petals of Philadelphus coronarius L.

2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay and nitroprusside assay were used for in vitro study of antiradical/scavenger activity of Philadelphus coronarius petal substances. The results obtained can be used as the basis for further studies of this type of the biological effects in the plant.

Tubifex tubifex Müll.--photosensitive organism.

The worm Tubifex tubifex Müll. (Tubificideae, Oligochaeta) is a suitable organism for the research of the biological effect of various pollutants. This pilot study deals with the responds of the organism to the treatments of two photosensitizers (bengal rose B, quinidine) and UVA radiation. The activity of the photosensitizers was evaluated by the comparison of the surfaces of tested worms and dark controls. The results showed that T. tubifex Müll. could be a suitable organism for the studies of phototoxicity. This species demonstrated relatively strong sensitivity to the effect of the selected photodynamically active substances.

Antifungal activity of a thiophene polyine from Leuzea carthamoides.

The thiophene polyine (E)-2-[5-(hept-5-en-1,3-diynyl)-thien-2-yl]-ethan-1,2-diol was isolated from an ethanolic extract of underground parts of Leuzea carthamoides. The thiophene polyine demonstrated significant antifungal activity against all tested species.

Evidence for the anti-hyperlipidaemic activity of the edible fungus Pleurotus ostreatus.

The effects are described of adding either the dried fruiting bodies of the oyster fungus Pleurotus ostreatus, or an ethanolic extract of it, to the diet of normal Wistar male rats and a strain with hereditary hypercholesterolaemia. Addition of the dry oyster fungus to the diet significantly increased, by more than two-fold, the triacylglycerol (TAG) level in the plasma of both groups of rats compared with their respective controls. In contrast, the ethanolic extract did not significantly change TAG levels. Values for total cholesterol and its high- and low-density lipoprotein fractions in the plasma, as well as the calculated atherogenic index, did not show any significant change. Levels of liver cholesterol were significantly lowered by the dried oyster fungus in both hypercholesterolaemic and normal groups of rats, and by the ethanolic extract in normal rats. A significantly increased phospholipid-to-cholesterol ratio in the aortas of both groups of rats, after the administration of either dried oyster fungus or the ethanolic extract of it, suggests a favourable anti-atherogenic effect for both.

[Phytotherapeutic aspects of diseases of the circulatory system. 4. Chitin and chitosan]. / Fytoterapeutické aspekty onemocnení obehového systému 4. Chitin a chitosan.

Chitin and chitosan are nitrogenous polysaccharides. The structure of the chitin molecule is similar to that of cellulose but it is composed of the units of 2-acetylamino-2-deoxy-D-glucopyranose bound (1 --> 4) by a glycosidic bond. In contrast to chitin, chitosan amino groups are not mostly acetylated. These polysaccharides occur particularly in the fungal kingdom, in invertebrate animals, in some brown algae, and very negligibly in higher plants. Great attention has been paid to chitin and chitosan in recent years. Of great interest are their antihypercholesterolemic and antihyperlipidemic activities which have been experimentally demonstrated. In practice there already exist some medicinal preparations and food products with medicinal and preventive properties against some risk factors of atherosclerosis. Also the anticoagulative and anti-aggregative effects of sulfated derivatives of chitosan are not negligible. The research in this field is, however, at the initial stage. Both polysaccharides have been introduced into pharmaceutical technology where they can be employed as very good drug vehicles. Promising results have been achieved in experiments with antineoplastics (5-fluorouracil and methotrexate), with nonsteroidal antiphlogistics (ibuprofen) and others. It is considered very advantageous that chitin and chitosan possess low toxicity, allergize only a little, and exert moderate immunostimulating effects. Both polysaccharides are metabolized by lysosome. Chitin is obtained from the cuticles of sea animals which are waste products from food industry. The technologies of obtaining chitin from lower fungi (e.g. the genus Aspergillus) have been worked out. Chitosan is obtained by deacetylation of chitin. Chitin and chitosan are polysaccharides with ever-extending use. Increasing attention is paid to them also due to the fact that they are contained in a large extent in food fungi, e.g. Pleurotus ostreatus.

Prenatal detection of restrictive foramen ovale.

The foramen ovale is an important communication between the two sides of the heart prenatally, allowing the left ventricle to carry its share of the prenatal circulation and providing flow for growth of left ventricular structures. Restriction of the foramen ovale appears to be a serious disorder of the fetus and can be associated with fetal hydrops, arrhythmias, and other signs of major fetal compromise. This article reviews our experience with restriction of the foramen ovale and provides a summary of the pathologic and echocardiographic literature related to the etiology and effects of restrictive foramen ovale in the fetus.