Identification of fatty acids in leaves and roots of Launaea procumbens by GC-MS and assessment of flavonoid and phenolic content and antioxidant activity
This study presents an analysis of fatty acid composition of in root and leaves of Launaea procumbens by GC-MS and hexane extract were studied for the determination of total flavonoid and phenolic content along with scavenging assays by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH).This analysis enabled the identification of 22 fatty acid in root and 18 in leaves of this plant representing 88.48 and 88.44 % of total extract respectively. The major fatty acid in root and leaves are myristic acid , palmitic acid , margaric acid , oleic acid , linoleic acid , linolenic acid , behenic acid , cerotic acid , montanic acid . Quantification data revealed that total flavonoid and phenolic was higher in leaf than root.
Keywords: Launaea procumbens ; fatty acid ; GC-MS ; soxhlet extraction ; DPPH ,antioxidant activity, flavonoid , phenol
L.procumbens, genus, Launaea Cass. belongs to the tribe Lactuceae (Cichorieae) (Tom et al.1977) family of Asteraceae consists about 40 species (El-Bassuony et al.2006) Nearly 20 species of this genus are growing in Pakistan (Krishnamurti A.1969 ; Nasir E et al.1972) growing in dry , saline and sandy habitats (Ozenda P.2004). L.procumbens is a decumbent herb with a tuft of simple or branched flowering stems having yellowish flower. It occurs as a weed throughout the plains of India (The wealth of India .1962) .
Many plants of this genus are used in the folk medicines in the treatment of various skin problems, dysentery and tumors (El-Bassuony et al.2006) , antitumor, antioxidant, insecticidal and cytotoxic activities (Rasid S et al.2000) .
Ayurvedic preparations prepared from this plant are used in wound healing , sound health and longevity, as well as used as a food supplement (Wazir et al. 2007).Traditionally , it has been used in the treatment of rheumatism (Parekh et al.2006), painful urination , liver dysfunctions , reproductive disorders (Ahmad et al. 2006) and hormonal imbalance in male (Qureshi et al. 2008) , fever, itches ,ulcer ,cuts swellings, eczema eruptions (Bhandari MM. 1988). Previous chemical analysis of L.procumbens showed salicylic acid ,vanillic acid , synergic acid , 2-methylresercinol and gallic acid (Shaukat et al. 2003).These compounds have spasmogenic,cardiovascular,anticarcinogenic,anti-inflammatory,and antioxidant properties to scavenge reactive oxygen species (Singh et al. 2007).In indigenous system of medicine the leaves of Launaea procumbens were reported to be useful in the treatment of urinary stones (Nadkarni . 2000; Sukhdev . 2006).
Naturally occurring sunstances in higher plants with their antioxidant property attention has increased on the protective effect of these natural antioxidants against chronic disorders caused by oxidative process(8,9).L.procumbens exhibited antioxidant and radical scavenging property.
Phytochemical studies of flavonoid and phenolic compounds with a broad spectrum of biological activity are important to understanding the practical uses of L.procumbens.
It is worthy to be note that there is almost no report on the chemical analysis of fatty acids of Launaea procumbens. The aim of this study is to identify fatty acids with their content in different parts of Launaea procumbens using GC-MS and determination of total flavonoid and phenolic compounds, including assessment of antioxidant property.
2. Results and Discussion
In this study the fatty acids composition in root and leaves of L.procumbens were compared by GC-MS and assessment of flavonoid and phenolics content in hexane extract . The antioxidant activity of the leaf and root extracts was evaluated by spectrophotometry of the presence of the DPPH radical which is often used to compare the activity of plant extracts.This analysis enabled the identification of 22 fatty acid in root and 18 fatty acid in leaves of total extract. Comparative study of identified fatty acids in root and leaves of L.procumbens are listed in Table 1. The composition percentage of fatty acids in root follows oleic acid (12.68 % ), linoleic acid (14.84) , behenic acid (6.38 %) , lignoceric acid (3.83%) and Montanic acid (3.69 %) whereas in leaves oleic acid (12.68 % ), linoleic acid (14.84) , behenic acid (6.38 %) , lignoceric acid (3.83%) and Montanic acid (3.69 %) . In leaves myristic acid (6.47 %) , palmitic acid (43.78 %) , margaric acid (3.22 % ) linolenic acid (4.26 %) are in higher amount than root.The main free fatty acids in root and leaves are myristic (5.52 and 6.47 %) , palmitic (30.80 and 43.78%) , margaric (1.52 and 3.22%) , oleic acid (12.68 and 8.33%) , Linoleic acid (14.84 and 11.12%) , linolenic (2.47 and 4.26 %), behenic (6.38 and 1.41%) , lignoceric (3.83) , cerotic (1.20 and 1.31%) , montanic( 3.69 and 2.14 %) respectively.The minor fatty acids are caprylic , pelargonic, capric, lauric, pentadecanoic , palmitoleic,arachidic , henicosanoic, tricosanoic , pentacosanoic acid. The proportions of saturated fatty acid (55.76 – 63.84 %) were higher than unsaturated fatty acid (32.82-24.82 %) in root and leaves by GC-MS analysis respectively. GC-MS confirmation of fatty acids by mass spectral structure elucidation represented saturated, unsaturated and branched chain fatty acid.Therefore these results revealed both root and leaves have almost similar fatty acid but in different amount.
Considerable amount of flavonoid and phenolic content were found in hexane extract and exhibited efficient scavenging of DPPH are enlisted in Table 2. The hexane extract of leaves possessed the highest total flavonoid and phenolic content than root .Result showed that leaves have highest antioxidant activity as compared to root.
Table 1. Fatty acid composition in root and leaves of Launaea procumbens
|MW||Peak area %(Root)||Peak area % (Leaf)|
|∑ Saturated Fatty acid||55.76||63.84|
|∑ Unsaturated Fatty acid||32.82||24.82|
|Total Fatty Acid||88.48||88.44|
Plant samples was collected from local area of Lucknow (India) in the month of June , 2014 and identified by Dr.Anand Prakash , Botanist , National Botanical Research Institute (NBRI) , Lucknow.A voucher specimen (No.216343) has been deposited in the herbarium of NBRI. Plant was dried out away from direct sunlight and stored in a dried area till the time of the experiment.
3.2. Soxhlet Extractionof Leaves and Root
The powdered root (20gm) and leaves (15gm) was extracted with 500 ml of petroleum ether (40-600C) in soxhlet apparatus for 8 hrs . The extracts were filtered , cooled and concentrated under reduced pressure at 400 C to afford 3.06% and 4.17% of the extract respectively until dryness. The extracts were stored in dark bottle and kept at 40C until analysis.
3.3.Formation of fatty acid methyl ester (FAME)
The crude extract (500 mg) in concentrated sulphuric acid (2 mL) and methanol (20 mL) was heated under reflux on a water bath for 3 h. It was cooled to room temperature and extracted with petroleum ether (3×20 mL) and water in a separating funnel. The petroleum ether extract was dried over Na2SO4. The extract was dried under reduced pressure at 400C. Prepared fatty acid methyl ester (FAME) was stored for further analysis.
3.4.Determination of the total phenolic content
Total phenolics contents (TPC) were estimated using the method of Singleton and Rossi. Two hundred micro liters (1-5 mg / ml; dissolved in respective solvent) of each fraction was added in ten milliliter of 1:10 folin –cicocalteu reagent and incubated for 5 min before the addition of 7 ml of 0.115 mg/ml Na2CO3.The resulting solution was incubated a further 2 h before absorbance readings were taken at 765 nm.Gallic acid was used in the calibration curve.Results were expressed as mg gallic acid (GAE)/g dried plant extract.Data for each fraction was recorded in triplate.
3.5.Determination of the total flavonoid content
Total flavonoids content was determined by using a method described by Sakanaka et al .Briefly , 0.25 ml of each fraction (1-5 mg/ml, dissolved in respective solvent) and rutin standard solution (15-250 µg/ml) was mixed with 1.25 ml of distilled water in a test tube, followed by addition of 75 µl of a 5%(w/v) sodium nitrite solution .After 6 min, 150 µl of 10%(w/v ) aluminum chloride solution was added ,and the mixture was allowed to stand for a further 5 min before 0.5 ml of 1 M NaOH was added. The mixture was made up to 2.5 ml with distilled water and mixed well. The absorbance was measured immediately at 510 nm.The results of samples were expressed as mg of rutin equivalents of total dreid fractions.All fractions were run in triplicate.
3.6.DPPH radical scavenging assays
The free –radical scavenging activity was measured by using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay.DPPH assay was performed according to the procedure as reported by Gyamfi et al.DPPH solution was prepared by dissolving 3.2 mg in 100 ml of 82% methanol. 2.8 ml of DPPH solution was added to glass vial followed by the addition of 0.2 ml of test sample solution ,in methanol,leading to the final concentration of 1 µg/ml, 5 µg/ml,10 µg/ml, 25 µg/ml,50 µg/ml and 100 µg/ml. Mixture of DPPH, and each fraction was shaken ewell and kept in the dark al controlled room temperature (25-28 C ) for 1 hr.After incubation change in color was measured at 517 nm.Mixture of 2.8 ml of 82% methanol and 2.8 ml of DPPH solution were taken as control.The test of each fraction was performed in triplicate.Percentage inhibition was measured according to following formula and IC50 value was calculated by graph pad prism software.
% scavenging = Abs.of control- Abs.of fraction x 100 / Abs.of control
Table 2 : Extraction yield , TPC ,TFC and % Inhibition of hexane extract of Launaea procumbens
|Extraction yield ( % )||3.06||4.17|
|Total phenolic content||125 mg / g||120 mg / g|
|Total flavonoids content||14.3 mg/ g||9.6 mg / g|
|% Inhibition at 200 mg / ml||75 %||68 %|
3.7.Gas Chromatography (GC)
Gas Chromatography was accomplished with a Thermo Fisher TRACE GC ULTRA using a TR 50MS column (30m x 0.25mm ID x 0.25 µm, film thickness); carrier gas, helium; temperature programming, 2 min. delay for solvent, at 500C temperature rising at 20C/min to 1200C and at 30C/min. to 2500C and finally held isothermally for 15 min. The injector temperature was 2300C and carrier flow was constant flow 1 ml/min, in split mode (1:50) with injector volume 1µl. The relative proportion of the sample constituents were percentages obtained (% area) by FID peak–area normalization, without the use of response factor.
3.8.Gas Chromatography-Mass Spectrometry (GC-MS)
GC-MS analysis was performed with a Thermo Fisher TRACE GC ULTRA coupled with DSQ II Mass Spectrometer instrument using a TR 50MS column (30m x 0.25mm ID x 0.25 µm, film thickness); carrier gas, helium; temperature programming, 5 min. delay for solvent, at 500C temperature, hold time 5.0 min, rising at 40C/min to 2500C and finally held isothermally for 5 min. The injector temperature was 2300C and carrier flow was constant flow 1 ml/min, in split mode (1:50) with injector volume 1µl.The ion source temperature was set at 2200C, transfer line temperature was 3000C, and the ionization of the sample components was performed in EI mode at an ionization voltage of 70eV. Mass range was used from m/z 50 to 650 amu. The chemical composition of fatty acids was identified by comparing their spectra with those of a NIST library and confirmed by comparing their retention indices with data published in various literatures.
As a result of this study plant indicated the types of fatty acids in the extract contribute little to its adverse clinic effect and fatty acid present are beneficial for health.Any one or more compounds present in the plant may be valuable for the many diseses.
The authors are thankful to the Director, CSIR-National Botanical Research Institute, Lucknow, India for facilities and encouragements. The financial support received from University Grant Commission, New Delhi (India) to carry out the research work is duly acknowledged.
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