2nd lec 5 .pdf

Adulteration and evaluation Dr. Thukaa Z. Abdul-Jalil Lec 5 Adulteration of crude drugs: *Adulterant: herb (drug) which does not confirm to official standards. Usually practiced when the herb (drug) is expensive. Types or methods of adulteration: 1-Inferiority: this type of adulteration results natu...

Adulteration and evaluation Dr. Thukaa Z. Abdul-Jalil Lec 5 Adulteration of crude drugs: *Adulterant: herb (drug) which does not confirm to official standards. Usually practiced when the herb (drug) is expensive. Types or methods of adulteration: 1-Inferiority: this type of adulteration results naturally or by ignorance or carelessness of workers leading to destruction quality of herbs then produced substandard herbs. Ex: Fruits of opium poppy ( Papaver somniferum), when the fruits containing less than 10% of anhydrous morphine , in this case this drug is consider inferior drug. 2-Spoilage: In this type of adulteration normally results from incorrect storage (effects of water and temperature). Where, this type of storage will lead to impaired or destroyed the medicinal value of herbs by the action of bacterial, fungal, insects, and rodents. 3-Admixture: In this type of adulteration, the drugs (herb) contain another species of herbs or another plant parts which are not medicinally valuable or contain foreign materials (stones and dirt). This type of adulteration may be results of collection due to unskilled workers. 4-Sophistication: In this type of adulteration, required drug can be instead or substituted by using different materials that haven't any medicinal activities. Example: Ginger drug has yellow color, pungent or potency taste and thick form. By this type of adulteration, this drug can be substituted by using the following materials: curcuma, chilies, and powdered flour. Curcuma: to give this mixture, the yellow color, Chilies: to give this mixture potency taste, Powdered flour: to give this mixture thick form. 5-Deterioration: In this type, the crude drugs exposed to some methods like extraction and distillation. 6-Substitution: In this type of adulteration, the original drug is substituted using inferior drug that may be similar in morphological characters, active constituents, or therapeutic activity. Ex: Digitalis thaspi substitute for Digitalis purpura, with note: Digitalis purpura is better than Digitalis thaspi for treatment some heart diseases Evaluation of drugs: Evaluation of a drug ensures the identity of a drug and purity of drugs. The main reasons behind the need for evaluation of crude drugs are biochemical variation in the drug, adulteration and substitutions, stability of active compounds, and product purity. All of these gains have resulted in tremendous improvements in the quality of herbal-preparations. Methods of evaluation: 1. Organoleptic evaluation: this method is simple and means the study of drugs using organs of senses. It refers to the methods of analysis like: color, odor, taste, size, shape, touch, texture…etc.). 2. Microscopic evaluation: in this method, using many microsocial techniques in the identification of plant, herbs as well as identifying small fragments of crude or powdered herb and in detection of adulterants by studying: A. Characteristic of tissue structures ( xylem, phloem, fibers, trichomes) B. Cell wall C. Cell content (starch grains, stomata, calcium oxalate crystals, oil crystals, oil drops…etc.). 3-Chemical evaluation: the chemical evaluation includes qualitative chemical tests, quantitative chemical tests( chemical assays and instrumental evaluation). Qualitative chemical tests: Include identification tests (using chemical treatments) for various phytoconstituents like: alkaloids, glycosides, tannins…etc. Examples: 1. Alkaloids with Dragendroff reagent give orange color. 2. Alkaloids with Mayer reagent give white color. 3. Tannins with FeCl3 give either green or blue color depending on the positions and presence of OH group in the aromatic ring.  Quantitative chemical tests (Chemical assays): Includes assays for alkaloids, glycosides, volatile oils, vitamins or other constituents. Ex: the assay of total alkaloids in belladonna herb, strychnine alkaloid in Nux vomica. The results obtained refers are these drugs inferior or not. Instrumental analysis are used to analyze the chemical groups of phytoconstituents using chromatographic and spectroscopic methods. A. Chromatographic methods include: Thin layer chromatography, Paper chromatography, High performance liquid chromatography B. Spectroscopic methods include: ultraviolet and visible spectroscopy, infrared spectroscopy, and mass spectroscopy. 4-Physical evaluation: In crude drug evaluation physical methods are often used to determine the solubility, melting point, water content, degree of fiber, specific gravity, optical rotation, viscosity, refractive index, and other physical characteristics of the herb material. 5-Biological evaluation: The plant or extract can then be evaluated by various biological methods to determine pharmacological activity, potency, and toxicity. These methods are considered to be less precise, more time consuming and more expensive. Ex: Mydriatic effects of certain drugs are tested in rat’s eye. As for microbiological assays are carried out to determine the effects of drug In various methods and this is employed in the identification on antimicrobial drugs. The methods used in this type of assays are agar well diffusion method and disk diffusion method.