Alicja M. Zobel

Seasonal changes of furanocoumarin concentrations in leaves ofHeracleum lanatum

Concentrations of three dermatitis-inducing furanocoumarins— xanthotoxin, bergapten and psoralen—were measured in whole leaves ofHeracleum lanatum and in extracts of the leaf surface over an entire vegetative season. The concentrations of surface furanocoumarins, localized by extraction involving brief dipping in almost-boiling water followed by HPLC quantitative analysis, increased until the middle of May and decreased until maturity. The concentration on autumn leaves (new growth) was 20–100 times as high as the ones in May, or those of similar size in April. Furanocoumarin concentrations in the whole leaf at different stages of leaf development varied, being the highest April 25, then decreasing sharply with rapid leaf enlargement. Again, in the small autumn leaves the coumarin concentration was two to three times that in April. Seasonal changes in surface furanocoumarins may be important in that these compounds are postulated to form the first defense barrier of the plant.

Antimitotic effect, G2/M accumulation, chromosomal and ultrastructure changes in meristematic cells of Allium cepa L. root tips treated with the extract from Rhodiola rosea roots

Abstract Rhodiola rosea is a Russian and Chinese medicinal plant used in medical practice as a stimulating, adaptogenic and antiarrhythmic agent. Many investigations have pointed to the anticancer and antimutagenic role of R. rosea. In spite of these therapeutic effects of R. rosea extract. little is known about the mechanism of its anticancer action, because few cytological investigations havebeen conducted on the mitotic activity, cellular cycle, structure, ultrastructure, and cytophysiology of both animal and plant cells treated with the extract. Our studies have shown that extract from R. rosea roots (containing rosavine and cinnamyl alcohol) cause the inhibition of a mitotic activity; however, cells resume their divisions after the postincubation period. During incubation in the extract, accumulation of G2/M cells was observed. Chromosomes inprophase and metaphase were shorter and thicker but the extract did not cause chromosomal aberrations or the formation of micronuclei. Ultrastructure changes after 24 h of incubation were connected with an increase in the electron density of ground cytoplasm, decrease in the number of mitochondria but with an increase of their surface. As early as after 6h postincubation, the number ofmitochondria doubled but their surface declined by over two times. After 24 h of incubation, the surface of plastids increased over twice in spite of their unchanged number. In postincubation (6h), their number doubled and the surface declined dramatically. The ultrastructure of the mitochondria was changed by the disappearance of cristae and a lowered electron density of the matrix, suggestingthat one of the mechanisms could be connected with changes in mitochondrial function.

Effect of coumarin and xanthotoxin on mitochondrial structure, oxygen uptake, and succinate dehydrogenase activity in onion root cells.

At concentrations in which they occur on the plant surface and retard mitosis, coumarin and xanthotoxin lowered uptake of oxygen (by 60 and 30%, respectively) by meristematic cells ofAllium cepa root tips. They caused changes in the structure of the mitochondrial matrix to become dense, and protrusions of mitochondrial membranes were visible parallelling their hypertrophy, indicating alteration in the structure and physiology of these organelles. Coumarin and, to a lesser extent, xanthotoxin increased succinate dehydrogenase production in mitochondria and also in the cytoplasm, indicating changes in membrane permeability. Changes in oxygen uptake and mitochondrial structure, in addition to the retardation of mitosis, may be the reason these compounds act as allelochemicals after they have been removed from the plant surface and reach the root meristem.

Dermatitis-inducing furanocoumarins on leaf surfaces of eight species of rutaceous and umbelliferous plants

Eight species of Rutaceae or Umbelliferae, known to cause or suspected of causing photophytodermatitis, had the linear furanocoumarins psoralen, bergapten, and xanthotoxin on their leaf surfaces, in concentrations varying from 0.014 to 1800 /gmg/g fresh weight, equivalent to 0.17–56% of the total leaf concentration. The higher percentage generally observed for spring leaves compared to autumn leaves suggests a higher rate of transfer of these furanocoumarins to the surface in the younger leaves. Among the plants studied,Ruta graveolens had the highest surface concentrations of all three furanocoumarins. The relatively high effectiveness in causing dermatitis of some species with low surface concentrations may be explained by a more effective mechanism of transfer of the furanocoumarins to the skin. A role in the defense of the plant is suggested by their accumulation on the plant surface.

Identification of eight coumarins occurring with psoralen, xanthotoxin, and bergapten on leaf surfaces

Surface extracts of the leaves of five species in the Umbelliferae,Citrus limon (Rutaceae), andPsoralea bituminosa (Leguminosae) were examined for the presence of coumarins, after a previous study had shown the presence of three psoralens. In the current investigation eight more coumarins were identified by mass spectrometric techniques: the simple coumarins scopoletin, scoparone, and osthol, the linear furanocoumarins imperatorin and phellopterin, the angular furanocoumarins angelicin and pimpinellin, and the pyranocoumarin seselin. Five of these occur inApium graveolens, and scopoletin, scoparone, and imperatorin were each found in three of the species examined. The co-occurrence of all these coumarins on the surface may be significant in communication between the plant and its environment.

Influence of low-intensity ultraviolet radiation on extrusion of furanocoumarins to the leaf surface

Exposure ofRuta graveolens leaves to low intensity 366-nm radiation led to a ca. 20% increase in concentrations of the furanocoumarins psoralen, xanthotoxin and bergapten, as compared to leaves kept in darkness. Both direct and, even more, scattered UV radiation produced increases in total concentrations. Changes in the concentrations of individual coumarins were generally parallel. Extrusion to the surface was increased, especially in lower, older leaves exposed to the scattered radiation, where it exceeded the control by factors of eight or nine. It is suggested that this response could enhance shielding of leaves against penetration of UV into the cells and that irradiation, by exciting the furanocoumarins, could augment protection against potential microbial invaders.

Influence of long-term administration of rutin on spatial memory as well as the concentration of brain neurotransmitters in aged rats.

BACKGROUND The present study was designed to investigate the behavioral and neurochemical effects of long-term oral rutin administration to old male WAG rats (100 and 200 mg/kg b.w./day). Rutin is a well-known dietary flavonol glycoside with antioxidant and anti-inflammatory properties. METHODS First, spatial memory was assessed in the water maze and then the levels of neurotransmitters in selected brain regions were estimated. RESULTS There was enhanced spatial memory in aged rats pretreated with the smaller dose of rutin in the probe trial of the water maze, nevertheless, augmented levels of noradrenaline in the hippocampi of these animals were not correlated with improved spatial memory. The increased dopamine levels in the hypothalami of the same group of animals may suggest effects other than behavioral. CONCLUSION Long-term rutin pre-treatment may cause behavioral and neurochemical changes in aged WAG male rats.

Psoralens in senescing leaves ofRuta graveolens.

Concentrations of three furanocoumarins, psoralen, xanthotoxin, and bergapten, were measured on the surface and within mature whole leaves of two groups ofRuta graveolens L. late autumn plants, 2 and 6 years old, which contained green, yellow, and dry yellow leaves. Upper green leaves contained higher concentrations of these coumarins than lower green leaves, green leaves contained several times as much as yellow leaves, and dry leaves contained even smaller amounts than yellow ones. The dry yellow leaves contained only a very small percentage of furanocoumarins on the surface, suggesting that extrusion to the surface of yellow leaves was slower or had stopped, while loss from the surface continued. The loss of psoralen was the most dramatic in and on the dry leaves. Bergaptens ratio to the other cournarins increased during senescence. Xanthotoxin was always the predominant furanocoumarin in this species.

Furanocoumarin concentrations in fruits and seeds of Angelica archangelica

Abstract Fruits and seeds of Angelica archangelica harvested in 1988 and 1989 were analyzed for three linear furanocoumarins: psoralen, xanthotoxin and bergapten. Bergapten predominated on the surface and within the fruits and seeds, but all three were present only in low concentrations on the fruit surface. Differences in the bergapten concentrations largely accounted for the differences in total concentrations of furanocoumarins. Total concentrations were lower in 1989, when the fruits were larger and showed a greater range of seed weight. Flat seeds contained 35 times the concentrations found in turgid seeds, suggesting that the size of the embryo, and thus its maturity, are inversely correlated with concentrations of these furanocoumarins. Fruits lacking embryos had very low concentrations. Fruit tissues always had smaller amounts than the seeds within, and smaller even than deposits on the seed surface.

Effect of Alkaloid-Free and Alkaloid-Rich preparations from Uncaria tomentosa bark on mitotic activity and chromosome morphology evaluated by Allium Test

ETHNOPHARMACOLOGICAL RELEVANCE Uncaria tomentosa (Willd.) DC. is the most popular Peruvian plant, used in folk medicine for different purposes. It contains thousands of active compounds with great content of alkaloids. AIM OF STUDY Two different fractions of Alkaloid-Rich and Alkaloid-Free were researched on chromosome morphology, mitotic activity and phases indexes. MATERIALS AND METHODS Cells of Allium Test (meristematic cells of root tips) were incubated up to 24h in different concentrations of Alkaloid-Free and Alkaloid-Rich fraction obtained from Uncaria tomentosa bark followed by 48 h of postincubation in water. The chromosome morphology was analyzed and the content of mitotic and phase indexes were done. Individual compounds, oxindole alkaloids, phenolic compounds and sugars were determined. RESULTS In Alkaloid-Rich and Alkaloid-Free fractions (different in chemical composition) we observed condensation and contraction of chromosomes (more in Alkaloid-Rich) with retardation and/or inhibition of mitoses and changed mitotic phases. Postincubation reversed results in the highest concentration which was lethal (in mostly Alkaloid-Rich fraction). CONCLUSIONS Our studies indicate that different action can depend on different groups of active compounds in a preparation either containing alkaloids or not. Other fraction analysis may be useful in the future.