Conventional and Microwave Assisted Extraction of Eulophia ochreta Lindl and Zingiber cassumunar Roxb: An Comparitive Account.

 

Akshada A. Koparde*, Dr. C.S. Magdum

Department of Pharmaceutical Chemistry, Rajarambapu College of Pharmacy, Kasegaon.415404

 

ABSTRACT:

MAE is the simplest and the most economical technique for extraction of many plant derived compounds. Conventional techniques as heating, boiling, or refluxing can be used to extract the plant material, however, the disadvantages are the loss of active constituents due to ionization, hydrolysis and oxidation during extraction as well as the long extraction time. Other techniques like ultrasonic assisted extraction (UAE) and microwave assisted extraction (MAE) have also become of interest as alternatives for conventional methods. Microwave extraction can be the better alternative to conventional extraction. Microwave assisted extraction requires shorter time, less solvents, higher extraction rate and better products with lower loss. There is less risk of decomposition and oxidation of phytoconstituents.An attempt has been made to make use of microwave for extraction of two indigenous drugs Eulophia ochreta lindl and Zingiber cassumunar Roxb. The widely used plants were selected on the basis of their phytochemical profile. In the present study, the tubers of Eulophia ochreata lindl  and roots of Zingiber cassumunar Roxb were subjected to successive solvent extraction using petroleum ether, chloroform, methanol ,water etc. Similarly the powders of both the drugs were subjected to extraction using microwave. The parameters selected for comparison were time required and % yield. Trial and error methods was followed to select different intensity and to set time. It was observed that there was significant increase in the yield but the time required was much less as compared to conventional extraction. The results were found to be encouraging to conduct further studies.

 

 

INTRODUCTION:

Extraction and characterization of several active phyto-compounds from these green factories have given birth to some high activity profile drugs¹. Extraction forms the first basic step in medicinal plant research because the preparation of crude extracts from plants is the starting point for the isolation and purification of chemical constituents present in plants². Extraction is one of the crucial points in the analytical chain in the effort of achieving complete recovery of target compounds³. The traditional techniques of solvent extraction of plant materials are mostly based on the correct choice of solvents and the use of heat or/and agitation to increase the solubility of the desired compounds and improve the mass transfer. Usually the traditional technique requires longer extraction time thus running a severe risk of thermal degradation for most of the phyto-constituents⁴.

 

The fact that one single plant can contain up to several thousand secondary metabolites, makes the need for the development of high performance and rapid extraction methods an absolute necessity⁵. Keeping in pace with such requirements recent times has witnessed the use and growth of new extraction techniques with shortened extraction time, reduced solvent consumption, increased pollution prevention concern and with special care for thermolabile constituents. Novel extraction methods including microwave assisted extraction (MAE), supercritical fluid extraction (SCFE), pressurized solvent extraction (PSE) have drawn significant research attention in the last decade. If these techniques are explored scientifically, can prove out to be an efficient extraction technology for ensuring the quality of herbal medicines worldwide. Soxhlet extraction has been the most respected among all other conventional techniques⁶. It serves a dual purpose of (a): extraction step for the isolation of phyto-constituents and (b): as a well established model for the comparison of new extraction alternatives. One of the major significant shortcomings of Soxhlet extraction is the lengthy extraction time that can be 8, 16, 24 hours or more⁷, which results in consumption of considerable time and heat energy. The lengthy time requirement makes it more labor-intensive and limits the number of samples that can be processed which may not be entertained from commercial aspects. Use of large amount of organic solvents requires an additional recovery step and subsequent evaporation to concentrate the extract, resulting in more cumbersome process and also being detrimental to environment. So extraction of phyto-constituents by microwave provides a vast scope of research exploration. The potential natural anticancer drugs like vincristine, vinblastine and taxol can be the best example. Considering this short coming of conventional extrcation an attempt has been made to carry out MAS of two indigenous drugs Eulophia ochreta lindl and Zingiber cassumunar Roxb.

 

MAE is the simplest and the most economical technique for extraction of many plant derived compounds^8,9 .The reduced time is not just of economic advantage but also there is less risk of decomposition and oxidation of phytoconstituents. For heat sensitive materials microwave would be a better option³. The speed of breaking up of plant cells is much higher. The penetration of microwave into the plant tissues depends on the dielectric properties of the plant. The energy required for dense materials is higher than that for leaves.¹⁰ The energy requirement can be controlled well than with conventional extraction. Extraction of different herbal drugs like Gention roots, Calendula flowers, Neem has been successfully performed using microwave technique.^11-13 The enhancement of product recovery by microwave is generally attributed to its heating effect, which occurs due to the dipole rotation of the solvent in the microwave field. This causes the solvent temperature to rise, which then increases the solubility of the compound of interest. Specifically, solvent heating by microwave occurs when molecules of the polar solvent could not align themselves quickly enough to the high frequency electric field of microwave. This discrepancy causes the solvent molecules to dissipate the absorbed energy in the form of heat.⁹ Nevertheless, no reports on MAE of Eulophia ochreta lindl and Zingiber cassumunar Roxb  have been published.

 

MATERIALS AND METHODS:

Materials:

The tubers of Eulophia ochreata Lindl.  And  roots of  Zingiber cassumunar Roxb was obtained from the bhimashankar region of Maharashatra, India. Plant material was authenticated by Dr. G.G. Potdar, Department of Botany, Y.C. College of Science, Karad; voucher specimen was deposited at the same college as number AAK1 and AAK2.

 

Apparatus and chemicals:

Microwave oven (Catalyst  scientific microwave synthesis system) LR grade solvents were used for extraction.

 

Conventional extraction:

60 gm of powder of both the drugs was subjected to successive solvent extraction. The solvents used for  Eulophia ochreata Lindl was petroleum ether, chloroform, methanol. The solvents used for Zingiber cassumunar Roxb was n-hexane, dichloromethane, chloroform, acetone, ethanol. The extract were concentrated and weighed to calculate % yield.

 

Microwave assisted extraction:

10 gm of powders of both the drugs were separately taken in 250 ml reaction flask and were subjected to microwave irradiation. The different parameters are selected such as time and intensity. Trial and Error method was followed to set time and intensity. At first the time set was 5 mins and increased by +5min till 30mins. Side by side reaction was monitored till colourless solvent was obtained in reflux flask. The intensity  was not fixed but checked for 140 W, 210W, 245W, 280W, 350W, 420W, 455W, 490W, 560W, 700W for both drugs but the extraction was stopped when vigorous boiling started. In both the cases, the extracts were concentrated and weighed to calculate % yield. The extracts obtained by conventional as well as microwave assisted extraction were subjected to preliminary phytochemical screening.¹⁴ The presence of phytoconstituents was confirmed by thin layer chromatography.¹⁵

 

RESULTS:

The yield obtained was more in some of the cases in microwave assisted extraction than conventional extraction but time required for microwave assisted extraction was much less. The color and consistency obtained in both the methods of extractions were same.  Better results were obtained in microwave assisted extraction in  Eulophia ochreata Lindl and Zingiber cassumunar Roxb  where intensity was 210W and 245W respectively. According to trial and error basis all different intensities were checked and intensity which gives constant reaction was selected and high intensity was neglected because it damage secondary plant metabolites. Thus In case of both herbal plants,  intensity was fixed and time was not fixed but it was stopped when vigorous boiling of solvent started.

 

 

Table1: Comparative account of Conventional extraction and Microwave assisted extraction of Eulophia ochreata Lindl

Sr.No	Solvent	Eulophia ochreata Lindl
		Conventional extraction			Microwave assisted extraction
		Colour and consistency	Time (Hrs)	% Yield	Colour and consistency	Watt (W)	Power (%)	Time (mins)	% Yield
1	Pet.Ether	Light yellow powder	6	13.66	Yellow semisolid mass	210	30	25	15.2
2	Chloroform	Reddish brown powder	7	7.1	Reddish brown powder	210	30	20	16.0
3	Methanol	Brown semisolid mass	4	3.66	Brown semisolid mass	210	30	20	8.2
4	Water	Brown semisolid mass	5	10.66	Brown semisolid mass	210	30	25	13.2

Table 2: Comparative account of Conventional extraction and Microwave assisted extraction of Zingiber cassumunar Roxb

Sr.No	Solvent	Zingiber cassumunar Roxb
		Conventional extraction			Microwave assisted extraction
		Colour and consistency	Time (Hrs)	% Yield	Colour and consistency	Watt (W)	Power (%)	Time (mins)	% Yield
1	n-Hexane	Light yellow semisolid mass	6	7.14	Light Yellow semisolid mass	245	35	17	12
2	Dichloromethane	Dark yellow non sticky mass	4	10.28	Dark yellow non sticky mass	245	35	15	15
3	Chloroform	Brownish semisolid mass	6	6.28	Brownish semisolid mass	245	35	18	9.2
4	Acetone	Brown semisolid mass	5	5.71	Brown semisolid mass	245	35	17	8.1
5	Ethanol	Brown semisolid mass	8	10.0	Brown semisolid mass	245	35	17	9.0
6	Water	Brown sticky mass	4	7.14	Brown sticky mass	245	35	20	7.0

 

DISCUSSION:

Microwave energy for heating has been in commercial use since 1950.¹⁶  The hallmark of microwave extraction (MAE) is accelerated dissolution kinetics as a consequence of the rapid heating processes that occur when a microwave field is applied to a sample. It has gained acceptance as a mild and controllable processing tool. The main advantages of MAE are shorter extraction times (typically 15 minutes), shorter cooling times (2 minutes) and less use of solvent (10 mL for MAE versus 250 mL for Soxhlet).The encouraging results were observed in microwave extraction as compared to conventional extraction. In case of both drugs, better results were seen  with reference to % yield at medium intensity and time. The drastic reduction in extraction time results in a higher sample throughput without significant losses in analyte recovery. MAE is a viable candidate for performing extractions due to its applicability over a wide range of sample types because the selectivity can be easily manipulated by altering solvent polarities. Hence, it is necessary to carry out further study for separation of active constituents and its pharmacological activity.

 

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Received on 16.03.2014          Modified on 21.05.2014

Accepted on 30.05.2014          © RJPT All right reserved