Objective:In our continued efforts to isolate the active immunomodulatory and antiviral constituents of Loranthus micranthus Linn parasitic on Kola acuminata,we set out to fractionate the crude aqueous methanol extrac...Objective:In our continued efforts to isolate the active immunomodulatory and antiviral constituents of Loranthus micranthus Linn parasitic on Kola acuminata,we set out to fractionate the crude aqueous methanol extract of the plant.The establishment of the most potent fraction(s) as well as the isolation of the pure active secondary metabolite responsible for the immune stimulatory and antiviral activities in Eastern Nigeria mistletoe has become very needful.This will enable us prove our assumption that this particular specie is different from the European version,Viscum album.Methods:Five solvents of varying polarity namely n-hexane,chloroform, ethylacetate,acetone and methanol were successively employed in the complete fractionation of the crude aqueous -methanol extract of Eastern Nigerian mistletoe,Loranthus micranthus Linn.,harvested from Kola acuminata in that order.The fractions were dried in-vacuo using a rotary evaporator maintained at a temperature of(40±5)℃.The different fractions were screened for immunomodulatory activity using a universal model:the cellular - mediated delayed type hypersensivity test in experimental mice.This was performed by administering two different dose levels:250 mg/kg and 500 mg/kg of each fraction against standard positive and negative control. Results:Results of the study established dose-dependent immunostimulatory(upregulatory) effects of the five fractions of the extract as the model used in the study with different percentage stimulations compared to controls.At the dose levels of 500 mg/kg and 250 mg/kg body weight,the percentage stimulation observed were as following:chloroform fraction 311.11%and 122.22%,ethyl acetate fraction 193.38%and 95. 56%,n-hexane 155.56%and 3.50%,acetone fraction 95.56%and 51.11%and methanol fraction 68. 89%and 24.44%respectively.Levamisole,a known potent immunostimulant,afforded a stimulation of 68. 89%at a dose of 2.5 mg/kg.Conclusion:The study showed that the order of immunomodulatory potency is chloroform fraction > ethylacetate fraction > hexane fraction > acetone fraction > methanol fraction.Bioassayguided fractionation and purification of the active extracts led to the isolation of pure compounds phytochemically characterized as sterols and flavonoids.This work indicates that the main constituents of our local mistletoe responsible for immunostimulation are the flavonoids,terpenoids and or steroids.Glycosides,carbohydrates, tannins and alkaoids appear to augment the measured activities.展开更多
文摘Objective:In our continued efforts to isolate the active immunomodulatory and antiviral constituents of Loranthus micranthus Linn parasitic on Kola acuminata,we set out to fractionate the crude aqueous methanol extract of the plant.The establishment of the most potent fraction(s) as well as the isolation of the pure active secondary metabolite responsible for the immune stimulatory and antiviral activities in Eastern Nigeria mistletoe has become very needful.This will enable us prove our assumption that this particular specie is different from the European version,Viscum album.Methods:Five solvents of varying polarity namely n-hexane,chloroform, ethylacetate,acetone and methanol were successively employed in the complete fractionation of the crude aqueous -methanol extract of Eastern Nigerian mistletoe,Loranthus micranthus Linn.,harvested from Kola acuminata in that order.The fractions were dried in-vacuo using a rotary evaporator maintained at a temperature of(40±5)℃.The different fractions were screened for immunomodulatory activity using a universal model:the cellular - mediated delayed type hypersensivity test in experimental mice.This was performed by administering two different dose levels:250 mg/kg and 500 mg/kg of each fraction against standard positive and negative control. Results:Results of the study established dose-dependent immunostimulatory(upregulatory) effects of the five fractions of the extract as the model used in the study with different percentage stimulations compared to controls.At the dose levels of 500 mg/kg and 250 mg/kg body weight,the percentage stimulation observed were as following:chloroform fraction 311.11%and 122.22%,ethyl acetate fraction 193.38%and 95. 56%,n-hexane 155.56%and 3.50%,acetone fraction 95.56%and 51.11%and methanol fraction 68. 89%and 24.44%respectively.Levamisole,a known potent immunostimulant,afforded a stimulation of 68. 89%at a dose of 2.5 mg/kg.Conclusion:The study showed that the order of immunomodulatory potency is chloroform fraction > ethylacetate fraction > hexane fraction > acetone fraction > methanol fraction.Bioassayguided fractionation and purification of the active extracts led to the isolation of pure compounds phytochemically characterized as sterols and flavonoids.This work indicates that the main constituents of our local mistletoe responsible for immunostimulation are the flavonoids,terpenoids and or steroids.Glycosides,carbohydrates, tannins and alkaoids appear to augment the measured activities.
