TQ improves insulin sensitivity in HepG2 cells via a SIRT-1 dependent mechanism.

<p>HepG2 cells were cultured in high (20 mM) glucose or in growth media containing 5.5 mM glucose for 18 hours, starved with serum-free media for 2 hours, then pre-incubated with vehicle control (0.5% DMSO), nicotinamide (0.5 mM), compound C (20 μM), or with nicotinamide and compound C together for 30 mins, followed by incubation with TQ (10 μM) in the presence or absence of nicotinamide and compound C; or with TQ, resveratrol (50 μM), or AICAR (2 mM) alone for 24 hours in 20mM glucose media. Vehicle-treated cells in 5.5 mM glucose served as control. Insulin (100 nM) was added during the last 30 min. (A) Western blot images of p-Akt, Akt, and β-actin. (B) Protein band quantification using densitometry from three independent experiments. p≤ 0.05 where (*) is significantly different from 5.5G, (#) is significantly different from 20G, and (Δ) is significantly different from 20G + TQ using independent t-tests. 5.5 G: 5.5 mM glucose, 20G: 20 mM glucose, TQ: thymoquinone, R: resveratrol, AIC: AICAR, NIC: nicotinamide, C: compound C.