Figure 4: Effects of various BG compounds on GLP-1 secretion in STC-1. After a 3 hr starvation in 10% FBS DMEM (low glucose), cells were treated with 0.2% BSA DMEM (low glucose) containing tested compounds for 1 hr. Tested compounds include (a) compound 1, cucurbita-6,22(E),24-trien-3β-ol-19,5β-olide; (b) compound 2, 5β,19-epoxycucurbita-6,22(E),24-triene-3β,19-diol; (c) compound 3, 3β-hydroxycucurbita-5(10),6,22(E),24-tetraen-19-al; (d) compound 4, 19-dimethoxycucurbita-5(10),6,22(E),24-tetraen-3β-ol; (e) compound 5, 19-nor-cucurbita-5(10),6,8,22-(E),24-pentaen-3β-ol; (f) Compound 6, 5β,19-epoxycucurbita-6,24-diene-3β,23ξ-diol (karavilagenine E,); (g) oleanolic acid; (h) conjugated linolenic acid (CLN) and other fatty acids (PA, palmitic acid; OA, oleic acid; LA, linoleic acid; LN, Linoleic acid; CLA, conjugated linoleic acids). All data were calculated as GLP-1 secretion per cell, and the secretion of vehicle-treated cells was taken as 1. Data shown are mean ± SD of 1~3 batches of experiments, with 1~3 for each treatment. *, **, and *** denote significant difference compared to vehicle-treated cells analyzed by Student’s test with RCBD to adjust for the differences between separate experiments.