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Antihyperglycemic effect of Morus nigra fractions in mice

Isolation of components responsible for antidiabetic activity of extract of Morus nigra leaves was carried out using the activity-directed isolation method. Leaves were collected, dried, and powdered. The dry powder was extracted with methanol and phytochemical tests showed the presence of alkaloids, saponins and flavonoids. The blood glucose lowering activity of different extracts were tested in groups of 6 or 7 diabetic male mice at 0,1,2,4,6 and 8 hours after i p. Injection of the extracts, decoction extract, flavonoid fraction before and after extraction with ethylacetate, and n-butanolic extract of ethylacetate extracted flavonoid fraction showed 19, 31, 26 and 17 percent decrease in glucose blood levels in aloxane-induced diabetic mice, respectively. While n-butanolic extract showed maximum activity after 4h of injection, maximum blood glucose lowering activity of other extracts was observed after 8h injection. Due to higher activity of n-butanolic extract, it was subjected to further purification using column choromatography on silica gel with acetic acid: n-butanol: water (1:5:4) as eluting solvent followed by preparative TLC. Six flavonoids were detected on TLC plates from which two were scraped off and extracted with methanol. With respect to ultra-violet spectra of these two compounds in methanol containing different shift reagents and mass spectra structures 13 and D were suggested for these two flavonoids. Due to unavailability of sufficient amounts of purified flavonoids, their blood glucose lowering activity was not studied.