Hassan Azaizeh

Safety of Traditional Arab Herbal Medicine

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.

Tradition and Perspectives of Arab Herbal Medicine: A Review

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 state of the art of traditional arab herbal medicine in the eastern region of the mediterranean: a review.

Historical and current studies indicate that the Eastern region of the Mediterranean has been distinguished from other regions by a rich inventory of complementary alternative medicine (CAM), in particular herbal medicine. Data collected from several surveys and studies indicate that there is a flourishing and well-developed trade of herbs. These surveys also reveal that 200–250 herbs are used in treating human diseases and are sold or traded in market places in the Mediterranean region or internationally. In addition, some of these herbs are rare or even endangered species. In regard to the status of the know-how of herbalists, unfortunately, herbal medicine in our region is mostly prescribed by ethnopharmacologists symptomatically—based on signs and symptoms alone, rather than as a result of a full understanding of the underlying disease. In some cases, herbs used today may not even correspond to the plants described originally in the old literature, as the former are cultivated from herbs that went through different breeding procedures throughout several centuries. This article presents a systematic review of both the state of the art of traditional Arab herbal medicine and the status of the know-how of Arab herbalists.

Maintaining a Physiological Blood Glucose Level with ‘Glucolevel’, a Combination of Four Anti-Diabetes Plants Used in the Traditional Arab Herbal Medicine

Safety and anti-diabetic effects of Glucolevel, a mixture of dry extract of leaves of the Juglans regia L, Olea europea L, Urtica dioica L and Atriplex halimus L were evaluated using in vivo and in vitro test systems. No sign of toxic effects (using LDH assay) were seen in cultured human fibroblasts treated with increasing concentrations of Glucolevel. Similar observations were seen in vivo studies using rats (LD50: 25 g/kg). Anti-diabetic effects were evidenced by the augmentation of glucose uptake by yeast cells (2-folds higher) and by inhibition of glucose intestinal absorption (∼49%) in a rat gut-segment. Furthermore, treatment with Glucolevel of Streptozotocin-induced diabetic rats for 2–3 weeks showed a significant reduction in glucose levels [above 400 ± 50 mg/dl to 210 ± 22 mg/dl (P < 0.001)] and significantly improved sugar uptake during the glucose tolerance test, compared with positive control. In addition, glucose levels were tested in sixteen human volunteers, with the recent onset of type 2 diabetes mellitus, who received Glucolevel tablets 1 × 3 daily for a period of 4 weeks. Within the first week of Glucolevel consumption, baseline glucose levels were significantly reduced from 290 ± 40 to 210 ± 20 mg/dl. At baseline, a subgroup of eleven of these subjects had glucose levels below 300 mg% and the other subgroup had levels ≥ 300 mg%. Clinically acceptable glucose levels were achieved during the 2–3 weeks of therapy in the former subgroup and during the 4th week of therapy in the latter subgroup. No side effect was reported. In addition, a significant reduction in hemoglobin A1C values (8.2 ± 1.03 to 6.9 ± 0.94) was found in six patients treated with Glucolevel. Results demonstrate safety, tolerability and efficacy of herbal combinations of four plants that seem to act differently but synergistically to regulate glucose-homeostasis.

Traditional Arabic and Islamic Medicine, a Re-emerging Health Aid

Complementary medicine is a formal method of health care in most countries of the ancient world. It is expected to become more widely integrated into the modern medical system, including the medical curriculum. Despite the perception of modern medicine as more efficacious, traditional medicine continues to be practiced. More than 70% of the developing worlds population still depends primarily on the complementary and alternative systems of medicine (CAM). In rural areas, cultural beliefs and practices often lead to self-care, home remedies or consultation with traditional healers. Herbal medicine can be broadly classified into four basic systems as follows: Traditional Chinese Herbalism, Ayurvedic Herbalism, Western Herbalism—which originally came from Greece and Rome to Europe and then spread to North and South America and Traditional Arabic and Islamic Medicine (TAIM). There is no doubt that today the concept of Arabic traditional herbal medicine is a part of modern life in the Middle East, and it is acquiring worldwide respect, with growing interest among traditional herbalists and the scientific community. TAIM therapies have shown remarkable success in healing acute as well as chronic diseases and have been utilized by people in most countries of the Mediterranean who have faith in spiritual healers. TAIM is the first choice for many in dealing with ailments such as infertility, epilepsy, psychosomatic troubles and depression. In parallel, issues of efficacy and safety of complementary medicine have become increasingly important and supervision of the techniques and procedures used is required for commercial as well as traditional uses. More research is therefore needed to understand this type of medicine and ensure its safe usage. The present review will discuss the status of traditional Arab medicine (particularly herbal medicine), including the efficacy and toxicity of specific medicinal preparations, with an emphasis on the modern in vitro and in vivo techniques.

Ethnobotanical knowledge of local Arab practitioners in the Middle Eastern region

An ethnobotanical survey was conducted among 31 local Arab practitioners living in Galilee, Negev, Golan Heights and West Bank. Seeing that the Arabic traditional medicine is in danger of disappearing, a multilevel program is required, involving the training of local practitioners, an establishment of a regional medicinal plant botanical garden and a field gene bank for plant preservation.

Aqueous Extracts of Teucrium polium Possess Remarkable Antioxidant Activity In Vitro

Teucrium polium L. (Lamiaceae) (RDC 1117) is a medicinal plant whose species have been used for over 2000 years in traditional medicine due to its diuretic, diaphoretic, tonic, antipyretic, antispasmodic and cholagogic properties. The therapeutic benefit of medicinal plants is often attributed to their antioxidant properties. We previously reported that an aqueous extract of the leaves and stems of this plant could inhibit iron-induced lipid peroxidation in rat liver homogenate at concentrations that were not toxic to cultured hepatic cells. Others have reported that organic extracts of the aerial components of this plant could inhibit oxidative processes. Against this background, we felt further investigation on the antioxidant action of the extract of T. polium prepared according to traditional Arab medicine was warranted. Accordingly, we assessed (i) its ability to inhibit (a) oxidation of β-carotene, (b) 2,2′-azobis(2-amidinopropan) dihydrochloride (AAPH)-induced plasma oxidation and (c) iron-induced lipid peroxidation in rat liver homogenates; (ii) to scavenge the superoxide (O2•−) radical and the hydroxyl radical (OH•); (iii) its effects on the enzyme xanthine oxidase activity; (iv) its capacity to bind iron; and (v) its effect on cell glutathione (GSH) homeostasis in cultured Hep G2 cells. We found that the extract (i) inhibited (a) oxidation of β-carotene, (b) AAPH-induced plasma oxidation (c) Fe2+-induced lipid peroxidation in rat liver homogenates (IC50 = 7 ± 2 μg ml−1); (ii) scavenged O2•−(IC50 = 12 ± 3 μg ml−1) and OH• (IC50 = 66 ± 20 μg ml−1); (iii) binds iron (IC50 = 79 ± 17 μg ml−1); and (iv) tended to increase intracellular GSH levels resulting in a decrease in the GSSG/GSH ratio. These results demonstrate that the extract prepared from the T. polium possesses antioxidant activity in vitro. Further investigations are needed to verify whether this antioxidant effect occurs in vivo.

Synergistic Antibacterial Effects of Polyphenolic Compounds from Olive Mill Wastewater

Polyphenols or phenolic compounds are groups of secondary metabolites widely distributed in plants and found in olive mill wastewater (OMW). Phenolic compounds as well as OMW extracts were evaluated in vitro for their antimicrobial activity against Gram-positive (Streptococcus pyogenes and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae). Most of the tested phenols were not effective against the four bacterial strains when tested as single compounds at concentrations of up to 1000 μg mL−1. Hydroxytyrosol at 400 μg mL−1 caused complete growth inhibition of the four strains. Gallic acid was effective at 200, and 400 μg mL−1 against S. aureus, and S. pyogenes, respectively, but not against the gram negative bacteria. An OMW fraction called AntiSolvent was obtained after the addition of ethanol to the crude OMW. HPLC analysis of AntiSolvent fraction revealed that this fraction contains mainly hydroxytyrosol (10.3%), verbascoside (7.4%), and tyrosol (2.6%). The combinations of AntiSolvent/gallic acid were tested using the low minimal inhibitory concentrations which revealed that 50/100–100/100 μg mL−1 caused complete growth inhibition of the four strains. These results suggest that OMW specific fractions augmented with natural phenolic ingredients may be utilized as a source of bioactive compounds to control pathogenic bacteria.

Anthelmintic activity of Pistacia lentiscus foliage in two Middle Eastern breeds of goats differing in their propensity to consume tannin-rich browse.

The Damascus and Mamber breeds of goats thrive in Middle Eastern Mediterranean regions where the tannin-rich (20% of polyethylene glycol-binding tannins) brush species Pistacia lentiscus L. (lentisk) is ubiquitous. In light of the increasing recognition of the anthelmintic activity of plant tannins, we examined the effect of offering lentisk foliage for 24 days on fecal egg excretion in 5.5-month-old Damascus and Mamber kid goats (n=28) following infection with 10,000 L3 larvae of mixed gastro-intestinal nematodes (GIN). Lentisk foliage was consumed with or without a daily supplement of 20 g polyethylene glycol (PEG; MW 4000). Lentisk tannins showed a strong protein-depletive effect that was totally reversed by the addition of PEG. At the peak of infection, kids of the two breeds lost weight unless they were fed with lentisk without PEG. Fecal egg counts (FEC) were lowest - and did not differ from 0 - in kids fed lentisk without PEG, highest in the controls fed hay as roughage, and intermediate in kids fed lentisk and PEG (241, 1293, and 705 eggs per gram, respectively, SEM 180; P<0.001); therefore, the anthelmintic activity of lentisk was only partly attributable to tannins. The suppressive effect of lentisk on FEC ceased when feeding was discontinued, suggesting that female parasites were not killed but their fertility was reversibly impaired. Damascus kids showed lower FEC than their Mamber counterparts, inferring that the effect of foraging on tannin-rich species is only additive to genetic differences between goat breeds in their sensitivity to GIN infection. On the basis of our results we would expect yearlong lentisk grazing to result in no or very low GIN infection, and Damascus goats to have some advantage over Mamber goats where chemical control of GIN is unfeasible. There appears to be a trade-off between the benefits of lentisk tannin as drug and its side-effects (protein depletion) when given at high level; how goats balance this trade-off requires further elucidation.

Safety of food crops on land contaminated with trace elements

Contamination of agricultural soils with trace elements (TEs) through municipal and industrial wastes, atmospheric deposition and fertilisers is a matter of great global concern. Since TE accumulation in edible plant parts depends on soil characteristics, plant genotype and agricultural practices, those soil- and plant-specific options that restrict the entry of harmful TEs into the food chain to protect human and animal health are reviewed. Soil options such as in situ stabilisation of TEs in soils, changes in physicochemical parameters, fertiliser management, element interactions and agronomic practices reduce TE uptake by food crops. Furthermore, phytoremediation and solubilisation as alternative techniques to reduce TE concentrations in soils are also discussed. Among plant options, selection of species and cultivars, metabolic processes and microbial transformations in the rhizosphere can potentially affect TE uptake and distribution in plants. For this purpose, genetic variations are exploited to select cultivars with low uptake potential, especially low-cadmium accumulator wheat and rice cultivars. The microbial reduction of elements and transformations in the rhizosphere are other key players in the cycling of TEs that may offer the basis for a wide range of innovative biotechnological processes. It is thus concluded that appropriate combination of soil- and plant-specific options can minimise TE transfer to the food chain.