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Herbal remedies are widely used for the treatment and prevention of various diseases and often contain highly active pharmacological compounds. Many medicinal herbs and pharmaceutical drugs are therapeutic at one dose and toxic at another. Toxicity related to traditional medicines is becoming more widely recognized as these remedies become popular in the Mediterranean region as well as worldwide. Most reports concerning the toxic effects of herbal medicines are associated with hepatotoxicity although reports of other toxic effects including kidney, nervous system, blood, cardiovascular and dermatologic effects, mutagenicity and carcinogenicity have also been published in the medical literature. This article presents a systematic review on safety of traditional Arab medicine and the contribution of Arab scholars to toxicology. Use of modern cell biological, biochemical, in vitro and in vivo techniques for the evaluation of medicinal plants safety is also discussed.

Complementary and Alternative Medicine (CAM), including herbal medicine, are popular in the general population worldwide. Parallel to the increasing interest in ‘modern’ CAM therapies and the historical importance of Arab medicine, there is also a similar trend in research activities dealing with the efficacy and safety of medicinal plants in our region. Historical and current studies and surveys indicate that the Eastern region of the Mediterranean has been distinguished throughout the generations with a rich inventory of natural medicinal herbs. It is well documented that indigenous Arab medicine has contributed greatly to the development of modern medicine in Europe and remains one of the closest forms of original European medicine. The rapid increase in consumption of herbal remedies worldwide has been stimulated by several factors, including the notion that all herbal products are safe and effective. This article presents a systematic review on traditional Arab medicine including historical background, medical innovations introduced by Arab physicians in the field of safety and efficacy of herbal medicine and a state-of-the-art description of traditional Arab herbal medicine in the Mediterranean region.

The effect of salinity and calcium levels on water flows and on hydraulic parameters of individual cortical cells of excised roots of young maize (Zea mays L. cv Halamish) plants have been measured using the cell pressure probe. Maize seedlings were grown in onethird strength Hoagland solution modified by additions of NaCI and/or extra calcium so that the seedlings received one of four treatments: control; +100 millimolar NaCI; +10 millimolar CaC12; +100 millimolar NaCI + 10 millimolar CaC12. From the hydrostatic and osmotic relaxations of turgor, the hydraulic conductivity (Lp) and the reflection coefficient (a.) of cortical cells of different root layers were determined. Mean Lp values in the different layers (first to third, fourth to sixth, seventh to ninth) of the four different treatments ranged from 11.8 to 14.5 (Control), 2.5 to 3.8 (+NaCI), 6.9 to 8.7 (+CaCI2), and 6.6 to 7.2. 10-7 meter per second per megapascal (+NaCI + CaC12). These results indicate that salinization of the growth media at regular calcium levels (0.5 millimolar) decreased Lp significantly (three to six times). The addition of extra calcium (10 millimolar) to the salinized media produced compensating effects. Mean cell as values of NaCI ranged from 1.08 to 1.16, 1.15 to 1.22, 0.94 to 1.00, and 1.32 to 1.46 in different root cell layers of the four different treatments, respectively. Some of these a, values were probably overestimated due to an underestimation of the elastic modulus of cells. os values of close to unity were in line with the fact that root cell membranes were practically not permeable to NaCI. However, the root cylinder exhibited some permeability to NaCI as was demonstrated by the root pressure probe measurements that resulted in as,r of less than unity. Compared with the controls, salinity and calcium increased the root cell diameter. Salinized seedlings grown at regular calcium levels resulted in shorter cell length compared with control (by a factor of 2). The results demonstrate that NaCI has adverse effects on water transport parameters of root cells. Extra calcium could, in part, compensate for these effects. The data suggest a considerable apoplasmic water flow in the root cortex. However, the cell-to-cell path also contributed to the overall water transport in maize roots and appeared to be responsible for the decrease in root hydraulic conductivity reported earlier (Azaizeh H, Steudle E [1991] Plant Physiol 97: 1136-1145. Accordingly, the effect of high salinity on the cell Lp was much larger than that on root Lpr.

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