Preliminary fractionation indicates that flavonoids, steroids and terpenoids are the main immunomodulatory constituents of Loranthus micranthus (Linn)

In recent times, we have established the immunomodulatory effects of the Eastern Nigerian mistletoe, Loranthus micranthus [1, 2] as well as its antimicrobial property [3,4]. In our continued efforts to isolate the active constituents, five solvents of varying polarity namely; n-hexane, chloroform, ethyl acetate, acetone and methanol were respectively and successively employed in the complete fractionation of the crude aqueous methanol extract of Loranthus micranthus Linn., harvested from Kola acuminata. The fractions were dried in vacuo using a rotary evaporator maintained at a temperature of 40±5 ^oC. The different fractions were screened for immunomodulatory activity using a well established model;- the cellular- mediated delayed type hypersensivity test in experimental mice. This was performed by administering intraperitoneally, two different dose levels: 250 and 500mg/kg of each fraction against standard positive and negative controls. Results of the study established dose dependent immunostimulatory (upregulatory) effects. The five fractions of the extract exhibited different percentage stimulations compared to controls (p<0.05). At the dose levels of 500 and 250mg/kg body weight, the percentage stimulation observed were as follows; 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 2.5mg/kg. The phytochemical evaluation of the fractions carried out showed that the most active fractions were either chiefly steroidal, terpenoidal or flavonoidal. This work suggests that the main constituents of our local mistletoe responsible for immunostimulation are the flavonoids, steroids and terpenoids. Glycosides, carbohydrates, tannins and alkaloids appear to augment the measured activities.

Acknowledgemnet: The authors acknowledge Mr. A.Ozioko of BDCP, Nsukka, Enugu State Nigeria for providing the plant material.

References. 1. Omeje, E.O. et al (2008) Asian Journal of Medicinal Plants.

2. Osadebe, P.O. et al (2008) Journal of Pharmacology and Phytochemistry- Accepted.

3. Osadebe, P.O., Ukwueze, S. (2004), Bio. Research 2(1):18–23.

4. Osadebe, P.O. et al. (2006) Journal of Pharmaceutical and Allied Sciences 3(1):263–268.