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Visual identification of alkaloids in some medicinal plants: common alkaloid reagents versus  romocresol green
R.a Gamooshi , F Shamsa , H.r Monsef Esfahani ,
Volume 66, Issue 4 (7-2008)
Abstract
Background: Alkaloids are a group of nitrogenous compounds with potential effects on the physiological behavior of human and animals. Some of these compounds are considered important drugs in modern medicine, such as atropine and morphine. Plants are considered the most important source of alkaloids. Therefore, investigating the presence of alkaloids in different plants is very important. Usually, alkaloids in plants are identified by methods such as those of Dragendorf, Wagner and Meyer, among others, which require milligrams of alkaloids for identification. In the present study, a fast and sensitive procedure for detecting of alkaloids in plants is presented.
Methods: Twelve dried plants samples were investigated for the presence alkaloids. After extracting the total alkaloid into methanol using a Soxhlet extractor, a few milligrams of the extract was transferred to a separatory funnel, buffered to pH 4.7, the bromocresol green (BCG) solution (10-4 M) was added, mixed and extracted with CHCl3 until a yellow color was observed in the CHCl3 layer, indicating the presence of the alkaloid. The crude extracts were also investigated by the standard methods of Dragendorf, Wagner and Meyer for the presence of alkaloids.
Results: Investigation of the 12 plant samples for the presence of alkaloids by the standard reagents of Dragendorf, Wagner, and Meyer showed that only Camelia sinensis (flowers), Echium amoenum Fisch & Mey (flowers), and Stachys (aerial parts) are devoid of alkaloids, with all other samples positive for alkaloids. By the BCG procedure, similar results were obtained, except for the E. amoenum flower, which was positive. The minimum detectable limit for alkaloids by the BCG method is the equivalent of approximately 40μg atropine.
Conclusions: According to previous reports, only one of these plants does not contain alkaloids. All studied plants positive for alkaloids by standard reagents were positive by the BCG procedure. Stachys was negative for alkaloids by both the standard reagents and the BCG method, in agreement with previous reports. However, black tea, reported to contain xanthine alkaloids, was negative for alkaloids by both the standard reagents and the BCG method. Therefore, the BCG method is not suitable for the detection of xanthine alkaloids. Nevertheless, the microgram detectable limit for alkaloids indicates that the BCG method is very sensitive.
Essential oils as natural medicinal substances: review article
Ehsan Aali , Razzagh Mahmoudi , Masoud Kazeminia , Reza Hazrati , Farzin Azarpey ,
Volume 75, Issue 7 (10-2017)
Abstract
Herbal essential oils are volatile, natural, complex compounds formed by medicinal plants as secondary metabolites. As reported by international organization for standardization (ISO), the term "essential oils" (EOs) is defined for a product obtained from vegetable raw materials or fruit using distillation with water or steam. The EOs are generally complex mixtures of volatile organic compounds include hydrocarbons (terpenes and sesquiterpenes) and oxygenated compounds (alcohols, esters, ethers, aldehydes, ketones, lactones, phenols, and phenol ethers) compounds. In medicinal plants, the EOs chemical profile usually very varies because of both intrinsic (sexual, seasonal, ontogenetic, and genetic variations) and extrinsic (ecological and environmental aspects) factors, also the EOs composition differs not only in the number and type of molecules but also in their stereochemical structures, and can be very different according to the extraction method. EOs represents a “green” alternative in the nutritional and pharmaceutical fields due to reported antimicrobial, antioxidant, anti-inflammatory and anticancer properties thus, in recent times; EOs has gained great popularity as consumers have developed a particular ever-growing awareness toward the use of natural ingredients, especially in food and household. Therefore, the present review provides a comprehensive summary on the method of preparation of EOs from medicinal plants, chemical composition analysis, their biological and pharmacological effects and their potential benefits on health level. Present information was compiled using keywords “Essential oil, Medicinal Plants and Natural additive in scientific database as Science Direct, Elsevier, PubMed, Google scholar and SID, until 2005 to 2015. EOs have great antimicrobial activity and mostly destroy bacteria, fungi and viruses without harmful effects on consumer’s health. Finding of this study showed that the Thymol, α-Pinene, β-Pinene, Cumin Aldehyde, Carvacrol, Germacrene, Linalool were the main components. Also, EOs have antioxidant, anti-inflammatory and many other pharmacological properties which enhance their potential application. EOs have potential biological and pharmacological activities and so have many applications in pharmaceutical and food industries.

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