Quality Control of Medicinal Plants Part II PDF

Quality Control of Medicinal Plants Part II List the procedures utilized for the Standardization and Quality evaluation of Herbal drugs. Mention the cases in which each procedure is used.  Plant material Plant materials fulfil diverse roles, encompassing: Ho...

Quality Control of Medicinal Plants Part II List the procedures utilized for the Standardization and Quality evaluation of Herbal drugs. Mention the cases in which each procedure is used.  Plant material Plant materials fulfil diverse roles, encompassing: Home remedies Over-the-counter drug products As essential ingredients in the pharmaceutical industry. Homeopathic remedies They constitute a significant share of the worldwide drug market.Consequently, the assessment of medicinal plants holds great significance. This process encompasses the identification of the material and the assessment of its quality and purity. To facilitate this evaluation>> a range of numerical standards is outlined in pharmacopoeias and other authoritative publications, such as the WHO manual https://iris.who.int/bitstream/handle/10665/42052/9241545178.pdf?sequence=1 Standardization & Quality Evaluation of Herbal drugs PHYSICAL QUALITY EVALUATION OF HERBAL DRUGS What does this test give information  Sampling In some pharmacopoeias and in the WHO manual. Preliminary examination In the case of whole drugs macroscopical and sensory characters are usually sufficient to enable the drug to be identified. The price of certain drugs depends largely on such factors as size and color, which are not necessarily related to therapeutic value. This applies to such important drugs as senna leaflets, senna pods, chamomile flowers, ginger, nutmegs and rhubarb Considerable care must be exercised to ensure that this sample is truly representative. Methods of sampling are fully described.  Moisture content ❑Moisture, in conjunction with temperature, activates enzymes and provides suitable conditions for the proliferation of living organisms. ❑All drugs are at risk of decaying if the humidity in the drug material exceeds 15%. ❑However, different levels of moisture are acceptable for each drug. ❑The moisture content is especially important for material which absorbs moisture easily or deteriorates quickly in the presence of water, as in cases of drugs containing glycosides (cleavage of glycosidic linkage).  Determination of moisture 1. Gravimetric method based on the loss on drying. 2. Separation and measurement of moisture. 3. Chemical methods 4. Spectroscopic methods 1. Gravimetric method based on the loss on drying. Direct drying involves heating a drug sample at 100-105 C until its weight becomes constant. [Although the loss in weight principally is due to water, small amounts of other volatile materials will also contribute to weight loss, so this method is suitable for drugs containing little or no volatile material, such as digitalis and aloes.  Determination of moisture Drying of Heat-Sensitive Food Components Certain food products contain components, such as fructose, which can undergo decomposition when exposed to temperatures as low as 100°C under standard atmospheric pressure. In such cases, it is advisable to employ a vacuum oven operating at a reduced pressure of 70C for the purpose of drying. Drying Substances with Volatile Constituents A specialized approach is utilized for substances that possess a notable concentration of volatile constituents, like balsamic materials. This approach involves applying a thin layer of the weighed substance onto glass plates, followed by placement within a desiccator. Within the desiccator, phosphorus pentoxide serves as the desiccating agent ‫ﻣﺎدة ﻣﺠﻔﻔﮫ‬. This process can be conducted under either standard atmospheric pressure or reduced pressure conditions.  Determination of moisture 2. Separation and measurement of moisture To enhance the precision of moisture determination, specialized techniques within the loss-on drying method can isolate and quantify the water content extracted from a given sample. One effective approach involves passing a dry inert gas through the heated sample and utilizing a dedicated absorption system designed specifically for water. This setup facilitates the collection of the moisture transported by the gas stream.  Determination of moisture ❑Gas chromatographic GC methods are important for moisture determination because of their specificity and efficiency. ❑The water in the weighed, powdered sample can be extracted with dry methanol and an aliquot‫ اﻟﻌﯿﻨﮫ‬submitted to chromatography on a suitable column. ❑The water separated by this means is readily determined from the resulting chromatogram. 3-Chemical methods for the determination of moisture The Karl Fischer titration is a widely used method for the accurate determination of moisture content in various substances. It's especially valuable for samples with low moisture content and is commonly employed in chemistry, pharmaceuticals, and the food industry. Here's an overview of the Karl Fischer procedure for moisture determination: Principle: Karl Fischer titration is based on the reaction between water (moisture) and a Karl Fischer reagent, which is a specialized chemical solution designed to react quantitatively with water. The reaction is usually iodometric and involves the following reaction: H2O + I2 + SO2 + RNH2 → RNH3+ + HSO4- + I- 4-Spectroscopic methods Water will absorb energy at various wavelengths throughout the electromagnetic spectrum, and this fact can be made a basis for its quantitative determination. Measurements can be made in both infrared and ultraviolet regions; interfering substances must be absent. The method is particularly suitable for very small quantities of water (trace quantities in gases). Nuclear magnetic resonance (NMR) spectroscopy has been employed for the determination of moisture in starch, cotton and other plant products. Ultraviolet-visible (UV-Vis) spectroscopy  Extractive values The determination of water-soluble or ethanol-soluble extractives is used as a means of evaluating drugs, the constituents of which are not readily estimated by other means. In certain cases, extraction of the drug is by maceration, in others by a continuous extraction process (Soxhlet extractor). The extract of a certain amount of the drug is then evaporated, dried and weighed. Please watch the following video SOXHLET EXTRACTION with Dr. Mark Niemczyk, Ph.D. (youtube.com) Soxhlet extractor  Ash values When vegetable drugs are incinerated, the organic matter is burnt away, and an inorganic residue is left, which is known as ash. The ash figure for each drug is considered as a general measure of quality and it is usually given for each drug in the pharmacopeia. The ash determinations are useful for detecting law-grade products, exhausted drugs and excess of sandy or earthy matter especially in powdered drugs. The pharmacopeias use different types of ash figure as total ash, acid-insoluble ash and water-soluble ash.  Total ash The total ash method is designed to measure the total amount of material remaining after ignition‫اﺷﺘﻌﺎل‬. This includes both ‘physiologic ash’, which is derived from the plant tissue itself, and ‘non-physiologic ash’, which is the residue of the extraneous matter (e.g. sand and soil) adhering to the plant surface. The total ash usually consists mainly of carbonates, phosphates, silicates and silica. To determine the total ash, a certain amount of the drug is incinerated to a constant weight. The ash is weighed, and the percentage is calculated.  Acid-insoluble ash Acid-insoluble ash is the residue obtained after boiling the total ash with dilute HCl and igniting the remaining insoluble matter. This measures the amount of silica present, especially as sand and siliceous earth. A high acid-insoluble ash in drugs such as senna, cloves, and licorice indicates contamination with earthy material. The ash dissolved in acid consists mainly of oxides and carbonates and is termed acid-soluble ash which is calculated by difference.  Water-soluble ash Water-soluble ash consists mainly of the water-soluble oxides and carbonates of sodium and potassium. It is the difference in weight between the total ash and the residue after treatment of the total ash with water. It is used to detect drugs exhausted by water, e.g. spent ginger, exhausted tea and liquorice.  Crude fiber The preparation of crude fibre is a means of concentrating the more resistant cellular material of drugs for microscopical examination. It is particularly useful for rhizomes as ginger which contain relatively large amounts of oleoresin and starch ( which interfere with microscopic examination). The technique involves defating the powder and boiling in turn with standard acid and alkali with suitable washing of the insoluble residue obtained at the different stages. The crude fiber so obtained can also be employed quantitatively to assay the fiber content of foods and to detect excess of certain materials in powdered drugs, e.g. clove stalk in clove.  Determination of volatile oil Minimum standards for the percentage of volatile oil present in a number of drugs are prescribed by many pharmacopeias. A distillation method is usually employed using a suitable apparatus. The recovered distillate is collected in the graduated tube, which already contains a known amount of xylene (European Pharmacopoeia, WHO manual). Vol. of volatile oil = total vol.- vol. of xylene  Tannin content Tannins are substances capable of turning animal hides into leather by binding proteins to form water-insoluble substances that are resistant to proteolytic enzymes. This process, when applied to living tissue, is known as an “astringent” action and is the reason for the therapeutic application of tannins. Tannins (polyphenols) are easily oxidized and polymerized in solutions; if this happen they lose much of their astringent effect. A few drugs are assayed for their tannin content. The method refers to those polyphenols adsorbed by hide powder and giving a color reaction with sodium phosphomolybdotungstate reagent.  Bitterness value Medicinal plant materials that have a strong bitter taste (bitters) are employed therapeutically, mostly as appetizing agents. Their bitterness stimulates secretions in the gastrointestinal tract, especially of gastric juice. Bitter substances can be determined chemically. However, science they are mostly composed of two or more constituents with various degrees of bitterness, it is first necessary to measure total bitterness by taste. The bitterness value is determined organoleptically by comparison with a quinine hydrochloride solution which acts as the standard. One of the most intensely bitter natural compounds is amarogentin, which has a bitterness value of 58,000,000. This means that you would need to dissolve one part of amelogenin in 58,000,000 parts of water to make its bitter taste no longer perceptible.  Swelling index This is defined in the BP as the volume in millilitres occupied by 1 g of a drug, including any adhering mucilage after it has swollen in an aqueous liquid for 4 h. The drug is treated with 1 ml of ethanol (96%) and 25 ml water in a graduated cylinder, shaken every 10 min for 1h and allowed to stand as specified. The standard can be determined on the whole drug (linseed and psyllium) or on the powder (marshmallow root).  Rf values Pharmacopoeias are increasingly employing thin-layer chromatography as a means for assessing quality and purity. The Rf value ( rate of flow, distance moved by solute divided by distance moved by solvent front) of a compound, determined under specific conditions, is characteristic and can be used as an aid to identity. Quantitative extracts of crude drugs are prepared and compared chromatographically with standard reference solutions of the known constituents. In an analogous manner, GC retention times and peak areas can be employed for the examination of volatile oils and other mixtures.  Toxic residues Pesticides may arise in crude drugs as a result of pesticide application during cultivation and at a late stage from fumigation of the stored product. Appendix XI L of the BP 2000 gives the requirements relating to pesticide residues for herbal drugs; specific directions for the sampling of bulk materials are given and the various pesticides and their assays listed. Aflatoxins' presence in plant material can be hazardous to health if absorbed even in very small amounts. Therefore, they should be determined. Radioactive impurities at a certain amount can not be avoided as a result of exposure to naturally occurring radionuclitides. Dangerous contamination may be the consequence of a nuclear accident.  Standards applicable to volatile and fixed oils Certain standards are particularly appropriate for volatile and fixed oils: (assess the identity and purity of oils). 1. Refractive index 2. Optical rotation 3. Quantitative chemical tests  Refractive index The refractive index of a substance is determined by comparing the speed of light in air to its speed in the substance being examined. Therefore, the refractive index is influenced by temperature, and standard measurements in pharmacopoeias are typically conducted at 20°C. = Automatic refractometers such as Leica Auto Abbe’ refractometer  Refractive index ❑Measurements of refractive index are particularly valuable for purity assessments of volatile and fixed oils. ❑Many values can be found in EP, BP, BPC and other pharmacopoeias. ❑Oils of cassia, cinnamon and cinnamon leaf have refractive indices of about 1.61, 1.573-1.6 and about 1.53, respectively, making possible differentiation of the oils.  Optical rotation ❑The optical rotation of a liquid refers to the extent by which the plane of polarized light turns when it passes through the liquid sample. This rotation can occur in two directions: ❑Clockwise, known as dextrorotatory. ❑Anticlockwise, known as levorotatory. ❑The magnitude and direction of the observed rotation depend on various factors, including: The characteristics of the light source used for the experiment. Temperature. The thickness of the sample layer being analyzed. Thank you