Study on anti-diabetic activities of crude methanolic extracts of Loranthus micranthus (Linn.) sourced from five different host trees.

The hypoglycaemic and anti-hyperglycemic activities of dried leaves of Loranthus micranthus (Linn.) (Loranthaceae), parasitic on Persea americana, Baphia nitda, Kola acuminata, Pentaclethra macrophylla, Azadirchta indica, were evaluated in normoglycemic and alloxan-induced diabetic albino rats. Normoglycemic and alloxan-induced diabetic rats were treated (intraperitoneally) with 200 mg/kg of the respective methanolic extracts of Loranthus micranthus (Linn.), glibenclamide (positive control), and 20% (v/v) Tween 20 solution (negative control). The sugar levels of the withdrawn blood samples were determined by o-toluidine spectrophotometric method. The studies indicate that the crude methanolic extract of Loranthus micranthus (Linn.) exhibited statistically significant hypoglycaemic (P < 0.001) and anti-hyperglycemic (P < 0.001) activities in normoglycemic and alloxan-induced diabetic albino rats, respectively. The hypoglycaemic effect was found to be dose-dependent. The maximum effect of the mistletoe extract (400 mg/kg) from Persea americana on alloxan-induced diabetic rats was found to be statistically comparable with that of the positive control, glibenclamide, at 24 h after administration, with a percentage reduction of blood sugar levels of 82.59 and 83.34%, respectively. Acute toxicity tests of the methanolic extracts of Persea americana, Baphia nitda, Kola acuminata, Pentaclethra macrophylla, Azadirchta indica host trees in mice gave LD(50) values of 11650, 11650, 5900, 5900 and 5900 mg/kg, respectively, which are all within the practically non-toxic range. The methanolic extract of African mistletoe was found to be a good candidate for alternative and/or complimentary medicine in the management of diabetes mellitus. The leaves of the Eastern Nigerian species of the African mistletoe harvested from Kola acuminata, Azadirchta indica and Baphia nitda host trees exhibited comparatively better anti-hyperglycemic activities among the host trees studied.