Fig. 4 in Insulin-mimetic activity of 23-glycosyl oleanane triterpenoids isolated from Gymnema latifolium

Fig. 4. Stimulatory effects of compounds 1⎯9 on glucose uptake in 3T3-L1 adipocytes using the fluorescent glucose derivative 2-NBDG. (A) Differentiated adipocytes were treated with isolated compounds (1–9) at a concentration of 20 μM and insulin (100 nM) as a positive control. After 1 h of incubation with or without 2-NBDG, images were captured by fluorescence microscopy. (B) The fluorescence signal in the adipocytes was measured and analyzed. After the cells were incubated for 1 h with or without 2-NBDG, the fluorescence signals were measured at Ex/Em = 450/535 nm. The results are presented as the mean ± SD (n = 3) of experiments performed in triplicate; *p <0.05, **p <0.01, and ***p <0.001, compared to the vehicle group. (C) Differentiated 3T3-L1 adipocytes were treated with compounds 2 and 4 at concentrations of 1, 5, and 20 μM or insulin at 100 nM. After 1 h of incubation, the fluorescence intensities were measured using a fluorescence microscope. (D) The concentration–response effects on glucose uptake in 3T3-L1 adipocytes. Cells were exposed to compounds at various concentrations (5, 10, and 20 μM) and incubated for 1 h. The cells were lysed, and the fluorescence signals were measured at Ex/Em =450/535 nm. Data are expressed as the mean ±SD (n =3) of experiments performed in triplicate; *p <0.05, **p <0.01, and ***p <0.001, compared to the negative control.