INTRODUCTION:
Extraction, as the term is used pharmaceutically, involves the separation of medicinally active portions of plant or animal tissues from the inactive or inert components by using selective solvents in standard extraction procedures. The products obtained from plants are relatively impure liquids, semisolids, or powders intended only for oral or external use. The use of traditional medicine and medicinal plants in most developing countries has been widely observed and about 80% of the world’s population depend on herbal medicines than current modern medicine.1 extraction of herbal drugs is the process of separating the desired bioactive compounds from plant material, such as leaves, flowers, roots, seeds using various techniques and solvent.
The main purpose is to obtain concentrated form of the herb’s therapeutic properties, can be futher used for forming medicinal products. several points include in herbal drug extraction are, plant selection and processing, extraction method, solvent selection, optimization of extraction conditions, post-extraction processing, quality control. Herbal medicine can be applied as a substitute choice in the treatment plans in case of several side effects and in the resistance of various drugs.2-6 The secondary metabolites or secondary plant constituents include alkaloids, saponins, terpenoids, flavonoids, phenolic compounds, and tannins. These metabolites account for several of the biological and/or pharmacological properties.7,8
General solvents used in extraction:
In extraction processes, common general solvents used include:
1. Water:
Water is the most common solvent which is very useful to extract the substances with antimicrobial activity. However, the organic solvents have been found to be more useful to show predictable antimicrobial activity than that extracted with water. Moreover, water dissolvable flavonoids (such as anthocyanins) have no antimicrobial importance and water dissolvable phenolics is just essential as an antioxidant substance.9
2. Alcohol:
Since the alcoholic extract has a greater number of polyphenols than the aqueous extract, so it has more activity. It is more productive in the degradation of cell walls and the seeds having non-polar character and it cause polyphenols to be discharged from the cells. In water the chemical, polyphenol oxidase cause degeneration of polyphenols whereas in alcohol (methanol, ethanol) it remains inactive. Besides, water is a good medium for the growth of microbes when contrasted with ethanol.10 The higher strength of more bioactive flavonoids was distinguished with ethanol (70%) because of its higher polarity than absolute ethanol. By adding water to the unadulterated ethanol up to 30% for planning ethanol 70% the polarity of dissolvable was enhanced.11 It is also easy to enter the cell membrane by the ethanol to extricate the intracellular substances from plant material.12 Almost all the distinguished parts of plants effective against microbes are aromatic or saturated organic compounds and they are effectively extracted by ethanol or methanol.13 Methanol has more polarity than ethanol but it is cytotoxic in nature so it is unsatisfactory for extraction in certain sort of studies as it may yield false results
3. Acetone:
Acetone disintegrates various hydrophilic and lipophilic portions of plants. It shows miscibility with water and has volatile nature, also it has low poisonous nature. Because of these qualities, it is a very important extractant, especially for antimicrobial studies. According to a study aqueous acetone shows better extraction of tannins and phenolics as compared to aqueous methanol14 Both acetone and methanol can extract saponins having antimicrobial effectiveness.15
4. Choloform:
It is used mainly for the extraction of tannins and terpenoids.
5. Ether:
It is used mainly for the extraction of fatty acids and coumarins.
6. Dicholoromethanol:
Non-polar, fast-evaporating, and often used for extracting alkaloids, terpens, and another organic compound. It is another dissolvable utilized for completing the extraction methods. Sometimes, it is used for the extraction of terpenoid.16
Table No. 1: General solvent and their therapeutic active compound.
|
Solvent’s |
Active compound’s |
|
Water |
Saponins, starch, terpenoids, tannins |
|
Alcohol |
Terpenes, flavonoids |
|
Acetone |
Flavanol’s, phenol |
|
Chloroform |
Terpenoids, flavonoids |
|
Ether |
Alkaloids, fatty acid |
|
Dicholoromethanol |
Terpenes, steroids |
Different Approaches of Extraction:
(1). Duration of extraction (2). The solvent utilized (3). Temperature (4). pH of the solvent used (5). Size reduction of the plant specimen (6). Solvent: sample ratio
Extraction methodology:
1. Maceration:
In this process either entire plant or its some part or its roughly powdered specimen is kept in a solvent, which has ability of dissolving a number of active ingredients, in a closed container for a specific period of time with successive stirring. This strategy is best suitable for use if there should be an occurrence of the thermolabile medications. It's a technique for extracting solids from liquids.
Advantages:
1. Maceration is a simple process that uses straightforward equipment.
2. An expert operator is not necessary.
3. Energy-saving techniques.
Disadvantages:
1. The extraction process takes a long time it can even take weeks to complete.
2. It takes a long time and is a very slow process.
3. More solvent is needed.
2. Percolation:
This method is mostly utilized for the preparation of tinctures and liquid concentrates. In this technique, ingredients in the solid form are kept in contact with the specific solvent and permitted to remain for around 4 hours in a properly closed container, then the mass is stuffed and the highest point of the percolator is shut. Extra menstruum is added to shape a shallow layer over the mass, and the blend is permitted to macerate in the shut percolator for 24 h. Outlet of percolator is then disclosed and the fluid contained in that is permitted to dribble gradually. Extra menstruum is included as desired, until the percolate measures around three quarters of the required volume of the final product. Now marc is squeezed and obtained fluid is then added to the percolate. Adequate menstruum is mixed to deliver the exact volume, and the blended fluid is filtered or decanted for the purpose of clarification.17
Advantages:
1. It takes less time than maceration, which is an advantage.
2. Appropriate technique for powerful and expensive medications.
3. Rapid and more successful extraction.
Disadvantages:
1. Takes longer than soxhlation.
2. Additional solvent is needed.
3. A skilled individual is needed.
3. Decoction:
Decoction is a traditional method of extraction that involves boiling or steaming plant material in water to release their active ingredient. This technique is utilized for the extraction of those substances (obtained from crude drug) that are soluble in water and are thermostable. The crude drug is boiled in water for about 15 minutes then cooled, filtered and adequate quantity of water is added to it to make the required volume.18
Advantages:
1. Suitable for extracting chemicals that are heat stable.
2. This technique doesn't need more sophisticated or expensive equipment.
3. It is simple to carry out.
4. Operators need not be trained.
Disadvantages:
1. It is time consuming.
2. Decoction can lead to over-extraction.
3. Decoction can be difficult to control.
4. Decoction may not be suitable for all materials that are sensitive to heat or water.
4. Infusion:
In it the readily soluble parts of the crude drug are dissolved in a solvent and then diluted. The preparation of fresh infusions is by maceration of the crude drug for a brief timeframe with either boiled or cold water. Steeping plant material in hot water or solvent. Infusion extraction methodology is a process used to extract flavors, oils, or other compound from plants, herbs, or other material.
Advantages:
1. Simple and cost-effective.
2. Low risk of contamination.
3. High quality extracts.
Disadvantages:
1. Time consuming process.
2. Dependent on material quality.
3. May not be suitable for all materials.
4. Can results in low yields.
5. Soxhlet extraction:
The Soxhlet extraction technique, developed by German agricultural scientist Franz Ritter von Soxhlet, is a highly effective method for continuously extracting compounds from a solid using a heated solvent. This process involves a specialized glass apparatus known as the Soxhlet extractor, which is primarily used for organic solvent extractions.
Here's a simplified explanation of how it works:
1. Preparation: The solid material to be extracted is ground into a fine powder and placed inside a filter paper thimble.
2. Setup: The thimble is then inserted into the main chamber of the Soxhlet extractor, which is connected to a round-bottomed flask containing the solvent.
3. Reflux: The flask is gently heated, causing the solvent to evaporate and travel up through the side tube to a condenser.
4. Condensation: The vapor condenses back into liquid form and drips into the chamber containing the thimble.
5. Extraction: As the solvent collects in the Soxhlet chamber, it surrounds the solid material and gradually extracts the desired compounds.
6. Siphoning: Once the solvent reaches a certain level, it automatically siphons back into the round-bottomed flask, carrying the extracted compounds with it.
This cycle repeats, allowing for continuous extraction until the process is complete.
Advantages:
1. Large amount of plants materials can be extracted at a time.
2. This technique does not call for filtration following extraction.
3. It is a pretty easy method.
Disadvantages:
1. The extraction procedure requires a lot of labor and takes a while.
2. Not suitable for all compounds.
3. Risk of contamination.
Phytochemical screening:
Plant extracts can be utilized to detect bioactive chemicals through a process called phytochemical screening. An outline of the procedure for identifying alkaloids, one of the primary classes of phytochemicals, is provided below:
A. Alkaloid test:
1. Mayer’s test:
Combine 1-2ml of plant extract with 1-2ml of potassium mercuric iodide, or Mayer's reagent; the appearance of a creamy precipitate suggests the presence of alkaloids.
2. Dragendorff’s Test:
When 1-2ml of plant extract and 1-2ml of potassium bismuth iodide (Dragendroff's reagent) are combined, the presence of alkaloids is indicated by the production of an orange-red precipitate.
3. Wagner’s Test:
When 1-2ml of plant extract and 1-2ml of Wagner's reagent (iodine in potassium iodide) are combined, the presence of alkaloids is indicated by the production of a brownish-red precipitate.
4. Hager’s Test:
When 1-2 ml of plant extract and 1-2 ml of Hager's reagent (saturated picric acid) are combined, the presence of alkaloids is indicated by the production of a yellow precipitate.
5. Thin Layer Chromatography (TLC):
Utilizing TLC plates, separate the alkaloids, and then use iodine vapor or UV light to see the results.
These assays assist in identifying alkaloids in plant extracts by identifying different color changes and precipitate forms.
B. Flavonoids test:
1. Alkaline Reagent Test:
NaOH or KOH is added to the extract, flavonoids turn into yellow or orange color.
2. Shinoda Test:
Mg powder and HCL are added to extract, flavonoids turn into pink or red color.
3. Ferric Chloride Test:
FeCl3 is added to the extract, flavonoids turn into green or blue color.
4. Thin-Layer Chromatography (TLC):
Separates flavonoids based on polarity.
C. Glycosides Test:
1. Molisch’s Test:
Molisch’s reagent (sulfuric acid) is added to the extract, formation of purple ring indicates glycoside.
2. Borntrager’s Test:
Bontrager’s reagent (ferric chloride, hydrochloric acid) is added to the extract, formation of red precipitate indicates anthraquinone glycosides.
3. Keller-Kiliani Test:
Keller-Kiliani reagent (potassium hydroxide, ferric chloride) is added to the extract, formation of brown or black color indicates cardiac glycosides.
4. Legal’s Test:
Legal’s reagent (sodium nitrite, acetic acid) is added to the extract, formation of red color indicates cardiac glycosides.
D. Tannins Test:
1. Ferric chloride Test:
Ferric chloride is added to the extract, formation of a greenish- black color indicates tannins.
2. Gallagher’s Test:
Gallagher’s reagent (ferric chloride, potassium ferricyanide) is added to the extract, formation of a blue color indicates tannins.
3. Lead Acetate Test:
Lead acetate is added to the extract, formation of a white precipitate indicates tannins.
4. Tannic Acid Test:
Tannic acid is added to the extract, formation of a precipitate indicates tannins.
E. Saponins Test:
1. Froth Test:
5-10ml of distilled water is added to the extract, formation of a stable froth indicates saponins.
2. Saponin Test:
Saponin reagent (ethanol, water) is added to the extract, formation of a precipitate or cloudiness indicates saponins.
3. Foam Test:
5-10ml of distilled water is added to the extract, formation of a persistent foam indicates saponins.
4. Liebermann-Burchard Test:
Liebermann-Burchard reagent (acetic anhydride, sulfuric acid) is added to the extract, formation of a blue or green color indicates saponins.
CONCLUSION:
Pharmaceutical extraction is a vital process in developing medicinal products, essential for isolating bioactive compounds from plant or animal tissues. This process supports the widespread use of traditional medicine, which remains crucial in many parts of the world. The extraction of herbal drugs involves meticulous steps, including plant selection and processing, choosing appropriate extraction methods and solvents, optimizing conditions, and ensuring rigorous quality control. These steps ensure that the therapeutic properties of plants are effectively harnessed, providing valuable alternatives to conventional treatments. The bioactive compounds extracted from plants, such as alkaloids, saponins, terpenoids, flavonoids, phenolic compounds, and tannins, play significant roles in the pharmacological efficacy of herbal medicines. By adhering to stringent extraction and quality control procedures, herbal medicines can be developed into safe and effective treatments, underscoring the enduring relevance of traditional medicine in modern healthcare and contributing to the overall well-being of global populations.
REFERENCE:
1. K. Dua, R. Sheshala, H.A. Al-Waeli, D.K. Chellappan, G. Gupta. Antimicrobial Efficacy of Extemporaneously Prepared Herbal Mouthwashes. Recent Patents on Drug Delivery and Formulation. 2015; 9(3): 201-205.
2. Doughari JH. Phytochemicals: Extraction methods, basic structures, and mode of action as potential chemotherapeutic agents, phytochemicals- A global perspective of their role in nutrition and health. Publisher InTech, 2012. In: Venketeshwer R, editor. A Global Perspective of their Role in Nutrition and Health. InTech; 2012. Available from: http://www. intechopen.com. [Last accessed 2020 Sep 10]
3. Ingle KP, Deshmukh AG, Padole DA, Dudhare MS, Moharil MP, Khelurkar VC. Phytochemicals: Extraction methods, identification, and detection of bioactive compounds from plant extracts. J Pharmacogn Phytochem. 2017; 6: 32‑6.
4. Azwanida NN. A review on the extraction methods use in medicinal plants, principle, strength, and limitation. Med Aromat Plants. 2015; 4: 196.
5. Pandey A, Tripathi S. Concept of standardization, extraction, and pre‑phytochemical screening strategies for herbal drug. J Pharmacogn Phytochem. 2014; 2: 115‑9.
6. Sasidharan S, Chen Y, Saravanan D, Sundram KM, Yoga Latha L. Extraction, isolation and characterization of bioactive compounds from plants’ extracts. Afr J Tradit Complement Altern Med. 2011; 8: 1‑10.
7. Rungsung W, Ratha KK, Dutta S, Dixit AK, Hazra J. Secondary metabolites of plants in drugs discovery. World J Pharm Res. 2015; 4: 604‑13.
8. Sofowora A. The present status of knowledge of the plants used in traditional medicine in Western Africa: A medical approach and a chemical evaluation. J Ethnopharmacol. 1980; 2: 109‑18.
9. Das K, Tiwari RKS, Shrivastava DK. Techniques for evaluation of medicinal plant products as antimicrobial agent: Current methods and future trends. J Med Plants Res. 2010; 4(2): 104-111.
10. Lapornik B, Prosek M, Wondra, A. G. Comparison of extracts prepared from plant by-products using different solvents and extraction time. Journal of Food Engineering, 2005; 71: 214–222.
11. Bimakr M. Comparison of different extraction methods for the extraction of major bioactive flavonoid compounds from spearmint (Menthaspicata L.) leaves. Food Bioprod Process. 2010; 1-6.
12. Wang GX. In vivo anthelmintic activity of five alkaloids from Macleayamicrocarpa (Maxim) Fedde against Dactylogyrus intermedius in Carassiusauratus. Veterinary Parasitology. 2010; 171: 305–313.
13. Cowan MM. Plant products as antimicrobial agents. Clinical Microbiology Reviews. 1999; 12(4): 564-582
14. Eloff JN. Which extractant should be used for the screening and isolation of antimicrobial components from plants. Journal of Ethnopharmacology. 1998; 60: 1–8.
15. Ncube NS, Afolayan AJ, Okoh AI. Assessment techniques of antimicrobial properties of natural compounds of plant origin: current methods and future trends. Afri J Biotech. 2008; 7(12): 1797-1806.
16. Cowan MM. Plant products as antimicrobial agents. Clinical microbiology reviews. 1999; 12(4): 564-582.
17. Handa SS, Khanuja SPS, Longo G, Rakesh DD. Extraction Technologies for Medicinal and Aromatic Plants. Intl Centre Sci High Tech. Trieste. 2008, 21-25.
18. Remington JP. Remington: The Science and Practice of Pharmacy, 21st Edition, Lippincott Williams and Wilkins. 773-774
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Received on 10.08.2024 Revised on 05.09.2024 Accepted on 19.09.2024 Published on 20.12.2024 Available online from November 25, 2024 Res. J. Pharmacognosy and Phytochem. 2024; 16(4):249-253. DOI: 10.52711/0975-4385.2024.00046 ©A&V Publications All right reserved
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