Summary HERBAL DRUGS

INTRODUCTION Medicinal plants are in use for the purpose of treatment of different ailments since centuries. There has been an immense increase in sales of herbal OTC (Over the counter drugs. This is growing to a billion dollar industry. The need for safety and efficacy has also escalated since the western interest has grown. Thus the need for standardization has come into view. The process of evaluation of the quality and purity of crude drugs by means of various parameters like morphological, microscopical, physical, chemical and biological observations is called standardization.1Standardisation of the herbal drug begins from the collection of the herbal drug to its packaging/use as medicine. The impediments in standardization of herbal drugs- • Variability in the chemical composition of the soil and changes in the climate in- fluence the range of phyto constituents present in the herbal drugs.2 • Growing deforestation is leading to increase in the number of endangered species of medicinal plants. This leads to addition of adulterants or substitutes to the herbal drug. Addition of adulterants and substitutes can change the safety and efficacy of the drug. Objectives: The present article will review the WHO guidelines for standardization of Herbal Drugs as well as focus on the current and future trends of the methods used for analysis of the herbal drug. Thus to overcome these obstacles there are many standards and parameters set by different pharmacopeias, but guidelines set by the WHO remain most significant. Materials and Methods BOTANICAL PARAMATERS4- Sensory evaluation-Visual macroscopy, Colour, Odour, Taste, Fracture are the common tests conducted for identification of the crude drug. Foreign matter-It has to be determined if the foreign matter is organic (Moulds, Insects, Animal excreta etc.) or Inorganic (Stone, soil etc).Foreign matter is considered as- • material not collected from the original plant source (insects, moulds, or other animal contamination) • Parts of the organ, or organs from which the drug is derived other than the parts named in the definition and description. Methods to determine the foreign organic matter- • Manual method • Lycopodium spore method Microscopy-Identification of histological characters(under low and high power).Study individual characteristics in all respects (Qualitative and Quantitative measurements).Observe identifying characteristics in few more slides to confirm the particular organized crude drug. Compare these characteristics with characteristics of the same powdered crude drug mentioned in the reference book. PHYSICOCHEMICAL PARAMATERS- Chromatographic fingerprint5- Separation, identification, impurity detection and assay of herbal drug in the formulation or in the extract are carried out by following methods: -HPTLC, HPLC/Densitometric chromatography, GLC, TLC Importance-The herbal drug shows variability in its chemical constituents according to various locations/weather. To avoid any erroneous identification chromatographic fingerprint remains the assessment of choice. Ash values6-The types of ash determined are Total ash, Acid insoluble and water soluble. Ash value is used to determine the quality and purity of the drug and to establish its identity. Ash contains inorganic radicals lie phosphates, carbonates, and silicates of sodium, potassium, magnesium, calcium, etc. These are present in definite amount in a particular crude drug, hence quantitative determination in terms of various ash values helps in their standardization. Ash value is used to determine foreign inorganic matter present as impurity. Total Ash Value- The method of total ash is designed to determine the amount of material that remains after ignition. Ash is classified as physiological ash which is derived from the plant tissue itself and nonphysiological ash which is the residue after ignition of extraneous matter (e.g. sand and soil).It is carried out at low temperatures possibly because alkali chlorides, which are volatile at low temperatures, may be lost. The total ash consists of carbonates, phosphates, silicates and silica. Acid insoluble ash- Sometimes, inorganic variables like calcium oxalate, silica, and carbonate content of the crude drug affects ‘Total cash value’. Such variables are removed by treating with acid (as they are soluble in hydrochloric acid) and acid insoluble ash value is determined. Acid insoluble Ash, Water soluble ash and sulphated ash are also evaluated. Extractive values7- It is useful for evaluation of a crude drug. It gives an idea about the nature of the chemical constituents present in a crude drug. Useful for estimation of constituents extracted with the solvent used for extraction. Employed for material for which as yet no suitable chemical or biological assay exists. It can be done by following methods: Cold maceration, hot extraction and ethanol. Moisture content and volatile matter8The moisture content of the drug should be minimized in order to prevent decomposition of crude drug either due to chemical change or microbial contamination. The moisture content is determined by heating a drug at 105˚c in an oven to a constant weight. E.g. – Aloe should have moisture content not more than 10% w/w Moisture content can be determined by following methods- Gravimetric, Volumetric and instrumental. Gravimetric method-Loss on Drying, Volumetric-Azeotropic Toulene distillation method, Instrumental- GC, NMR etc., Volatile oil content- Volatile oils are the liquid components of the plant cells, immiscible with water, volatile at ordinary temperature and can be steam distilled at ordinary pressure. Many herbal drugs contain volatile oil which is used as flavoring agent. For the drugs containing volatile constituents, toluene distillation method/steam distillation method is used to determine the volatile oil contents. PHARMACOLOGICAL PARAMA- TERS9- Bitterness value- Medicinal plants having strong bitter taste are therapeutically used as appetizing agents .The bitterness is determined by comparing the threshold bitter concentration of an extract material with that of quinine hydrochloride .The bitterness value is expressed as unit’s equivalent to the bitterness of a solution containing 1gm of quinine hydrochloride in 2000ml. Method for determination-0.1gm of quinine hydrochloride is dissolved in 100ml drinking water and the stock solution is prepared. Then it is diluted and tested and compared with drug. Bitterness value in unit per gm = 2000×C÷ A×B Where, A = concentration of stock solution B = volume of test solution in tube with threshold bitter concentration C = quantity of quinine hydrochloride in the tube with threshold bitter concentration Haemolytic property- Many medicinal plant materials, of the families Caryophyllaceae, Araliaceae, Sapindaceae, Primulaceae, and Dioscoreaceae contain saponins. The most characteristic property of saponins is their ability to cause haemolysis; when added to a suspension of blood, saponins produce changes in erythrocyte membranes, causing haemoglobin to diffuse into the surrounding medium. The haemolytic activity of plant materials, or a preparation containing saponins, is determined by comparison with that of a reference material, saponin R, which has a haemolytic activity of 1000 units per g. Determination- Calculate the haemolytic activity of the medicinal plant material using the following formula: 1000 ×a/b Where, 1000 = the defined haemolytic activity of saponin R in relation to ox blood, a = quantity of saponin R that produces total haemolysis (g) b = quantity of plant material that produces total haemolysis (g) Astringent property- It is determined by amount of tannins present in the drug .Tannins (or tanning substances) are substances capable of turning animal hides into leather by binding proteins to form waterinsoluble 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. Chemically, tannins are complex substances; usually occur as mixtures of polyphenols that are difficult to separate and crystallize. Determination of Tannins10 -Calculate the quantity of tannins as a percentage using the following formula: where w = the weight of the plant material in grams T1=Weight of material extracted in water T2=Weight of material not bound to hide powder T0=Weight of hide powder material soluble in water that bind to standard frieberg Hide powder. [T1-(T2-T0)]×500/w Swelling Index- The swelling index is the volume in ml taken up by the swelling of 1 g of plant material under specified conditions. Its determination is based on the addition of water or a swelling agent as specified in the test procedure for each individual plant