Hepatoprotective Activity of Easter Lily (Lilium longiflorum Thunb.) Bulb Extracts

The hepatoprotective activities of two different extracts, a hydroethanolic crude bulb extract (CB) and a steroidal glycoside-rich 1-butanol extract (BuOH), prepared from the bulbs of Easter lily (Lilium longiflorum Thunb.), were evaluated in a 24 week study in the female KK.Cg-A(y)/J Type 2 diabetic mouse model. Animals were divided into six groups (n = 16): control mice received Easter lily bulb extract-free drinking water together with a low- or high-fat diet (diabetic control); drinking water for the remaining groups was supplemented with CB extract (1%), BuOH extract (0.1 or 0.2%), and reference drug Metformin (0.001%), together with a high-fat diet. Both CB and BuOH extract treatment groups exhibited significantly improved liver function based on comparisons of triglycerides [diabetic 219 +/- 34 mg/dL, CB 131 +/- 27 mg/dL, BuOH(0.2%) 114 +/- 35 mg/dL], CB total cholesterol (TC) (diabetic 196 +/- 12 mg/dL, CB 159 +/- 5 mg/dL), average liver mass [diabetic 2.96 +/- 0.13 g, CB 2.58 +/- 0.08 g, BuOH(0.1%) 2.48 +/- 0.13 g], alanine transferase [diabetic 74 5 units/L, CB 25 +/- 1 units/L, BuOH(0.1%) 45 +/- 1 units/L], and histological examinations. Glucose metabolism was improved only in CB, which was confirmed by oral glucose tolerance tests (OGTT) in diet-induced obese C57BL/6J mice exposed to CB extract. These data suggest that steroidal glycosides 1-5 might play a role in the hepatoprotective activity of the BuOH extracts, while the results of the TC measurements and OGTT study indicate that other constituents present in the CB extract are responsible for its hypocholesterolemic and hypoglycemic activity.