Coumarins as Antimitotics

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.

An analysis of cytotoxic botanical formulations used in the traditional medicine of ancient Persia as abortifacients

We report here an analysis of plants used by traditional healers of ancient Persia to induce abortions. Six herbal formulations that contain 39 different species from 21 plant families with their vernacular names, English names, amounts used, and their methods of preparation are reported. Our initial objective of this ethnobotanical analysis was to evaluate the validity and the efficacy of the plants used by (1) comparing other reported uses of these plants in traditional medicine, (2) investigating the medical and pharmacological literature on the medicinal properties of the plant species used, and (3) investigating the reported cytotoxic effects of compounds prevalent in these plants. Previous phytochemical analyses have shown that a number of plant species are rich in coumarin compounds that have potential antineoplastic or cytotoxic activities. Our results indicate a correlation between the reported use of these plants as abortifacients and their cytotoxic (antineoplastic) effects. In addition, we discuss the process in which this ethnobotanical investigation led to the discovery of dicoumarol (a coumarin anticoagulant) as a potential chemotherapeutic agent.

Coumarin inhibits the growth of carrot (Daucus carota L. cv. Saint Valery) cells in suspension culture

We used a carrot (Daucus carota L. cv. Saint Valery) cell suspension culture as a simplified model system to study the effects of the allelochemical compound coumarin (1,2 benzopyrone) on cell growth and utilisation of exogenous nitrate, ammonium and carbohydrates. Exposure to micromolar levels of coumarin caused severe inhibition of cell growth starting from the second day of culture onwards. At the same time, the presence of 50 mumol/L coumarin caused accumulation of free amino acids and of ammonium in the cultured cells, and stimulated their glutamine synthetase, glutamate dehydrogenase, glucose-6-phosphate dehydrogenase and phosphoenolpyruvate carboxylase activities. Malate dehydrogenase, on the other hand, was inhibited under the same conditions. These effects were interpreted in terms of the stimulation of protein catabolism and/or interference with protein biosynthesis induced by coumarin. This could have led to a series of compensatory changes in the activities of enzymes linking nitrogen and carbon metabolism. Because coumarin seemed to abolish the exponential phase and to accelerate the onset of the stationary phase of cell growth, we hypothesise that such allelochemical compounds may act in nature as an inhibitor of the cell cycle and/or as a senescence-promoting substance.

Differences in the activity and distribution of peroxidases from three different portions of germinating Brassica oleracea seeds

Peroxidase (POD, EC 1.11.1.7) activity, cellular localization and isozyme patterns were investigated in the seed integument, cotyledon and embryo axis of Brassica oleracea cv. Cappuccio during pregermination and seedling growth. Seeds started to germinate after 24 h of imbibition. POD activity was localized in the pigmented layer of the integument and in procambial strands of the cotyledon and embryo axis in the first 24 h of imbibition. It was localized in the integumental cells of palisade, pigmented and aleurone layers and in epidermal, meristematic, procambial cells and xylem elements of the root and hypocotyl after 48 h of imbibition. POD activity increased during germination and early seedling growth: in the integument, it reached a maximum value after 72 h of imbibition, in the embryo axis and cotyledons, it increased up to 144 h of imbibition. The increase in peroxidase activity was accompanied by the appearance of new isozymes correlated with the development of seedling tissues. The isozyme profile was characterized by nine peroxidases: isoperoxidase of 50 kDa peculiar to integuments, that of 150 kDa to cotyledons and that of 82 kDa to the embryo axis. During pregerminative phase isozymes of 84 kDa were detected in the integument and cotyledons, of 48.5 kDa in the embryo axis. After germination, peroxidase activity and the complexity of the isozyme pattern increased, suggesting that they play a relevant role after rupture of the integument.

Paclitaxel in combination with coumarin as a potentially effective anticancer agent

The antimitotic and clastogenic effects induced by paclitaxel alone, and when combined with coumarin at varying concentrations and volume ratios, were investigated on meristematic cells of Allium sativum L. root tips. Paclitaxel exhibited antimitotic effects by blocking cell division in metaphase at concentrations ranging from saturated to 10 -12 ppm. Paclitaxel when used alone at high concentrations (saturated, 10 -3 ppm, 10 -6 ppm) induced cytotoxic and chromosomal aberrations after 1 and 3 h incubation and cell death after 24 h incubation. Paclitaxel demonstrated fewer cytotoxic and clastogenic effects when combined with coumarin in a 1:9 ratio at low concentrations. The combination of 10 -12 ppm of paclitaxel with 200 ppm coumarin (1:9) produced the best results as these agents worked together synergistically at the biochemical level to produce antimitotic effects with the fewest chromosomal aberrations. This mixture exhibited the potential to be used as an anticancer drug owing to its abilities to exert antimitotic activity without causing extreme clastogenic effects. Paclitaxel, when used alone or in combination with coumarin at high concentrations (greater than 10 -12 ppm), demonstrated possible carcinogenic potential when used in cancer therapy.