Salts and solvent effect on recovery and quality of Lemongrass (cymbopogon flexuosus stapf) oil and its nematicidal activity
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Date
2009
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CCSHAU
Abstract
Laboratory studies were conducted to study the effect of salts and solvent on quantity and quality of
essential oil of lemongrass (Cymbopogon flexuosus Stapf.). Nematicidal activity of aqueous extracts of essential
oil of lemongrass (Cymbopogon flexuosus) recovered by adding salts viz., NaCl, Na2CO3, CaCl2 and CaCO3 and
solvent (acetone) was also studied against the root-knot nematode Meloidogyne javanica. The essential oils were
analyzed by Gas Liquid Chromatography (GLC) techniques employing Flame Ionization Detector (FID)
equipped with capillary column Thermo TR–Wax (Polyethylene glycol). To study the effect of addition of salts
during hydro-distillation, four varieties/genotype viz., CKP-25, OD-19, OD-58 and HL-2 were taken and the
essential oils of the freshly harvested grasses were extracted by hydro-distillation using Clevenger apparatus.
During hydro-distillation additives viz., NaCl, Na2CO3, CaCl2 and CaCO3 were added in 1500 ml of water in
two amounts i.e. 50 and 100 g for each variety/genotype thereby maintaining the salt concentration of 33.6 g/L
and 66.7 g/L, respectively. The experiment was performed in three replications for each variety/genotype. The
distillation unit was boiled for 5 h and all the essential oils that distil out from the lemongrass leaves in 5 h were
collected in glass vials and subjected to GLC for qualitative analysis. Small quantity of sodium sulphate was
added in oil to remove the traces of water. The oil content increased when chlorine containing salts i.e. CaCl2
(0.56%) and NaCl (0.54%) were added in water during hydro-distillation, whereas it decreased when carbonate
containing salts i.e. CaCO3 (0.50%) and Na2CO3 (0.45%) were added in water during hydro-distillation in
comparison to control (0.53%) i.e. where no salt was added in water during hydro-distillation. Citral–a, citral–b
and total citral content in essential oil of four varieties/genotype increased when calcium containing salts viz.,
CaCl2 and CaCO3 were added in water during hydro-distillation whereas these values decreased on addition of
sodium containing salts viz., NaCl and Na2CO3 in comparison to control i.e. where no salt was added in water
during hydro-distillation. The value of citral–a content was 48.6%, 48.5%, 46.5%, 41.7% and 47.7%; citral-b
content was 30.1%, 30.0%, 28.8%, 25.5% and 29.6%; total citral content was 78.7%, 78.5%, 75.3%, 67.2% and
77.3% on addition of CaCl2, CaCO3, NaCl, Na2CO3 and in control samples, respectively. The varying amounts
of citral content in essential oils recovered by adding salts may be probably due to the conversion of citral-a
(geranial) which is aldehyde form into geraniol i.e. alcoholic form or vice-versa. On addition of solvent
(acetone) @ 0.2 to 0.8% concentrations, the oil content (FWB) increased from 0.57% to 0.60% in comparison to
control (0.53%) where no solvent was added in water during hydro-distillation. Qualitative analysis of oils
recovered by adding solvent (acetone) at various concentrations showed that desirable constituents i.e. citral–a,
citral–b and total citral content decreased approximately by 2% in comparison to control where no solvent was
added in water during hydro-distillation. Since increase in oil content may be due to increase of some undesired
chemical constituents hence, the amount of citral-a, citral-b, total citral, geraniol and citronellal content
decreased slightly in the recovered oil. Aqueous extracts of essential oils of lemongrass recovered by adding
salts and solvent (acetone) in water during hydro-distillation showed toxicity to varying extents against
Meloidogyne javanica which may be probably due to different percentage of citral content in these oils. On the
basis of these studies, it is observed that calcium chloride was found to enhance the oil yield and citral-a
(geranial), citral-b (neral) and total citral content in the essential oil. Hence, it can be inferred that the salts may
play significant role in enhancing the lemongrass oil yield and quality.
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Keywords
Cymbopogon flexuosus, Essential oil, Gas liquid chromatography, Hydro-distillation, Meloidogyne javanica, Nematicidal activity, Qualitative parameters, Salt effect, Solvent effect