ReviewTherapeutic effects of Aloe spp. in traditional and modern medicine: A review
Introduction
Plants belonging to the genus Aloe have a long history of popular and traditional use in the Islamic traditional medicine (ITM). It has been used as a folk remedy for the treatment of a wide range of illnesses, including skin problems and gastrointestinal disorders. Hitherto, only few species of Aloe have been considered for commercial and pharmaceutical uses, of which Aloe vera is considered as the most widely studied and commercialized species [1], [2], [3]. Aloe spp. has not only been used in traditional medicine, but exhibited various pharmacological properties according to the findings of modern pharmacological studies. Numerous in vitro and in vivo pharmacological studies as well as clinical trials have confirmed the traditional uses of Aloe including wound healing and anti-ulcer activities. These studies have also indicated new properties such as anti-diabetic, hypoglycaemic, anti-cancer, antimicrobial, antiviral, antihyperlipidemic and antiulcer activities [4].
The use of plants as medicines or food stuff dates back several millennia. Nowadays, various strategies are being used to find new and effective drugs from natural sources. To this end, investigating folk and traditional medicine systems, such as Islamic traditional medicine (ITM), is a rational strategy owing to their antiquity and long-term history of human use. In ITM, a considerable attention has been paid to the qualities of individual herbs. The general and specific properties of each herb such as its nature, natural habitat, energy pattern, effects, indications, duration of action, relationships to the body organs, toxicity and contraindications, dosage, types of preparations, and antidotes are discussed in ITM [5]. In the Islamic school, expert scientists like al-Majusi (Haly Abbas), ar-Rhazi (Rhazes) and Ibn-Sina (Avicenna) could establish notable developments. In the present study, we aimed to summarize the information about Aloe spp. described in major ITM texts. As a secondary aim, we tried to assess the conformity of ITM instructions with the findings obtained from modern pharmacological studies. The names of books that were explored for this review are listed in Table 1.
Section snippets
Nature of Aloe spp. described in ITM
Avicenna has described Aloe as follows: “It is a red-yellow dried juice obtained from different species of Aloe. It is of three varieties: (a) Scotarian, (b) Arabian, and (c) Samanjani. Its best variety is Scotarian with the smell of myrrh and the color of saffron. It is clear, brittle and free from pebbles. The Arabian variety is comparatively less yellow, lighter and not so shining. Nevertheless, it is harder and more viscous. Samanjani variety is inferior in quality, putrefactive in nature,
Botany of Aloe
Aloe is a large genus with 446 species [20] that belongs to the Xanthorrhoeaceae. A. vera (L.) Burm. f., also known as Aloe barbadensis Mill., is the most studied species in this genus (Fig. 1) [21]. Aloe spp. grows wildly in the tropical climates around the world particularly South Africa, Madagascar, Arabia and the Canary Islands. They are cultivated mainly for medicinal and decorative purposes [20].
Phytochemicals
Several constituents from various phytochemical classes such as alkaloids, anthrones, chromones, flavonoids, glyocoproteins, naphthalenes and pyrones have been isolated from different Aloe spp. (Table 2) [22]. Aloin, aloesin, aloenin, aloeresin, aloe-emodin and chrysophanol are some examples of such bioactive compounds [22]. Although many biological investigations have been performed to reveal the active constituents of Aloe spp., it is still not yet completely clear which compounds are
Medicinal uses of Aloe spp. in ITM
In the present study, the properties of Aloe spp. are categorized according to the organs or systems in the body on which they exert their effects (Fig. 3).
Toxicity and safety studies
Although natural products and plants are a good candidate to cure human diseases, it should be considered that they are not as safe as the public thinks, and may cause problems in long-term use. Aloe is not an exception in this regard. Some species of this genus such as A. ferox are potentially toxic. Generally, Aloe is considered as an almost safe remedy in ITM. Nevertheless, toxicity of Aloe on liver has been mentioned by several ITM scientists. For instance, Ibn Sina has declared that
Conclusion
Systems of traditional medicine around the world play important roles in discovering new drugs owing to the antiquity of their instructions, practices, skills and knowledge, and the use of their preparations and prescriptions over generations. ITM benefits from the instructions made by several renowned scientists, and is a pioneer and effective school in medical sciences. Hence, exploring ITM texts could be a valuable approach for detecting new medicines. In the current study, the applications
Conflict of interest
None.
Acknowledgements
The authors wish to thank Mashhad University of Medical Sciences.
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