Extraction methods

Extraction methods

1. EXTRACTION METHODS BY A.JEEVARATHINAM

2. INTRODUCTION The basic knowledge about the phytoconsttuents nature and their characteristics is essential to select the method and solvent for extraction. Extraction - the separation of medicinally active compounds of plant or animal tissues from the inactive or inert components (desired and undesired) by using selective solvents in standard extraction procedures

3. SELECTION OF EXTRACTION METHOD 1. Nature of component – not lost, distorted or destroyed preparing the extract. 2. Nature of material to be used - bulk collection, pre-washing, crushing and grinding the plant material homogeneous and uniform sample of extraction and increases the contact surface with the solvent. 3. Solvent system available - polar solvents such as water, methanol, and ethanol are used in extraction of polar compound, whereas nonpolar solvents such as hexane and dichloromethane are used in extraction of nonpolar compounds

4. EXTRACTION METHODS Conventional Methods Decoction Infusion Soxhlet extraction Maceration and Hydrodistillation Non conventional methods Ultrasound assisted extraction (UAE ) Microwave assisted extraction (MAE )

5. DECOCTION

6. MACERATION Maceration is one of the conventional methods of extraction that is very simple and the cheapest because it only requires a simple container as the place for extraction, but this method requires a long time for the extraction process. The maceration method can be done anywhere and this method is most often used in extracting active compounds

7. INFUSION In this method, extraction consist in soaking the solids plants powder either cold or boiling water for a short period of time. The plant material is grinded into ­the powder, and then placed inside a clean container. The extraction solvent hot or cold is then poured on top of the material, soaked, and kept for a short period of time. This method is suitable for extraction bioactive constituents that are readily soluble Infusions are generally prepared for immediate use, as preservatives are absent.

8. SOXHLET EXTRACTION This tool consists of several parts including a heat source, round bottom flask, soxhlet extractor, and condenser. The solid material which is to be extracted is placed in thimble . and placed in an extractor. The bottom end of the extractor is connected to a round bottom flask containing a solvent, and is connected to a reflux condenser. The bottom flask is heated to boil the solvent, the vapor rises through the branch pipe of the extractor, is condensed and drops into the thimble and the solvent is contacted with the solid for extraction. When the solvent surface exceeds the highest point of the siphon, the solvent containing the extract is return back to the round bottom falsk . This cycle is repeated until the all the material extracted from the solid sample.

9. SOXHLET EXTRACTION S mall amount of solvent is reused to perform an extraction many times. This means that much less solvent is used in a Soxhlet extraction, making it more time and cost effective. Also , the Soxhlet extractor can run continuously without any further operation, making it an excellent choice for extracting compounds over hours or even days. Filtration is not required So it save lot of time, energy and financial inputs.

10. DISTILLATION Simply, distillation is the process in which a liquid is vaporized (turned to steam), recondensed (turned back into a liquid) and collected in a container. Distillation has been used widely to separate volatile components from nonvolatile compounds. 

11. TYPES OF DISTILLATION There are several methods of distillation depending on the procedure and the instrument setup. Each distillation type is used for purification of compounds having different properties. 

12. SIMPLE DISTILLATION Simple distillation is practiced for a mixture in which the boiling point of the components differ by at least 70° C. It is also followed for the mixtures contaminated with nonvolatile particles (solid or oil) and those that are nearly pure with less than 10 percent contamination. Double distillation is the process of repeating distillation on the collected liquid in order to enhance the purity of the separated compounds.

13. FRACTIONAL DISTILLATION Those mixtures, in which the volatility of the components is nearly similar or differs by 25° C (at 1 atmosphere pressure), cannot be separated by simple distillation. In such cases, fractional distillation is used whereby the constituents are separated by a fractionating column. In the fractionating column, the plates are arranged and the compound with the least boiling point are collected at the top while those with higher boiling point are present at the bottom. A series of compounds are separated simultaneously one after another. Fractional distillation is used for the alcohol purification and gasoline purification in petroleum refining industries.

14. HYDRODISTILLATION Hydro-distillation is a common traditional extraction method . It is used to isolate aromatic compounds and volatile compounds from the plant via boiling water and plants or using steam. Hydrodiffusion - Diffusion of essential oils and hot water through plant membranes is known as hydrodiffusion . Membranes of plant cells are almost impermeable to volatile oils. Therefore, at the temperature of boiling water, a part of volatile oil dissolves in the water present within the glands, and this oil-water solution permeates , by osmosis, the swollen membranes and finally reaches the outer surface , where the oil is vaporized by passing steam. Hydrolysis - Hydrolysis in the present context is defined as a chemical reaction between water and certain constituents of essential oils. Decomposition by heat - Almost all constituents of essential oils are unstable at high temperature. To obtain the best quality oil, distillation must be done at low temperatures.

15. The plant material is soaked in the water that is placed over a container over heat. Due to the effect of hot water or steam, the essential oils are separated from the oil glands, which are present in the plant tissue. Separated water and oil (vapor mixture) go to the condenser for conversion to liquid and then is transferred to the separator for separating essential oil from water . The final product hence obtained in the receiving flask contains only the distillate.

16. MICROWAVE ASSISTED EXTRACTION (MAE) Electromagnetic waves are absorbed by the material and converted to heat energy. This is a microwave Energy. Microwaves penetrate into biomaterials and generate heat by interacting with polar molecules such as water inside the materials. This leads to production of heat and cell structure disruption. This action, created the diffusion of bioactive compound from the plant matrix . 2450 MHz (2.45 GHz) is the most commonly used frequency for commercial microwave instruments, which has an energy output of 600-700 W.

17. ULTRASOUND-ASSISTED EXTRACTION (UAE) OR SONICATION EXTRACTION Ultrasonic is a kind of elastic mechanical vibration wave, essentially different from the electromagnetic wave . Ultrasonic extraction is the use of ultrasonic radiation pressure produced the penetration of solvent into the plant materials and increasing the target component into the solvent promote extraction. UAE uses ultrasound with frequencies ranging from 20 kHz to2000 kHz.

18. ULTRASOUND-ASSISTED EXTRACTION UAE uses acoustic waves in the kilohertz range that travel through the solvent producing cavitation bubbles . When the cavitation bubbles burst at the surface of the plant sample matrix, a shockwave-induced damage to plant cell wall enhances the mass transfer of compounds across cellular membranes into solution .

19. Compounds Plant Activity Essential Oil Based Terpene Compounds ( Diallyldisulfide , Diallyltrisulfide , Eugenol , Methyl Eugenol , Carvone , Limonene, Eucalyptol, Eudesmol , α- pinene ) Mentha piperita , Ocimum sanctum, Eucalyptus maculata , Allium sativum and Callistemon linearis Larvicidal and Adulticidal Agent against Aedes aegypti Phytochemicals(Alkaloids , glycosides, tannin, etc ) Stem Bark Extracts of Euphorbia Balsamifera Mosquito Repellent Activity Azadirachtin ( limnoid group) Neem (seeds, leaves, and other parts of the tree) anti- feedant , ovipositional deterrence, repellency , growthdisruption , sterility and larvicidal action against insect arbazole alkaloids, mahanimbine , murrayanol , and mahanine Murraya koengii   Larvicidal activity Limonenenanoemulsions ( Monoterephene ) Citrus sinensis essential oil Larvicidal activity PHYTOCHEMICALS IN MOSQUITO CONTROL

20. CONCLUSION Extraction is not a universal one it vary depend on the plant material which is depend on the factors such as compound, temperature, concentration. So the method of selection should be selected very carefully and then only can extract the target compound easily.

21. STEAM DISTILLATION Steam distillation is used for the purification of mixtures, in which the components are temperature or heat sensitive; for example, organic compounds. In the instrument setup, steam is introduced by heating water, which allows the compounds to boil at a lower temperature. This way, the temperature sensitive compounds are separated before decomposition. The vapors are collected and condensed in the same way as other distillation types. The resultant liquid consists of two phases, water and compound, which is then purified by using simple distillation. Steam distillation is practiced for the large-scale separation of essential oils and perfumes.

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