In vitro the extract induced a dose response increase in glucose uptake (5 x [10 sub.-5] to 5 [micro]g/ml) on C2C12 myotubules. Aspalathin was effective at 1, 10 and 100[micro]M, while rutin was effective at 100 [micro]M.
For the glucose uptake assay C2C12 myotubules and Chang cells were starved for 30 min using serum free media containing 0.1% BSA, 3.7 g/l [NaHCO sub.3] and no glucose prior to exposure to the SB1 extract and compounds.
Glucose uptake activity in C2C12 myotubules treated with SBI extract at different doses yielded significant (p < 0.05) increased glucose uptake expressed on a scale relative to the vehicle (water; 0%) and positive control (insulin; 100%) at all concentrations tested (5 x [10.sup.-5] to 50 [micro]g/m1) (Fig.