Objective:To evaluate Brachychiton acerifolius leaf extracts as antidiabetic potential agent and to identify the main active constituents using bioactivity guided fractionation.Methods:In vitro antioxidant activity was evaluated for B.acerifolius different extracts using DPPH assay and vitamin C as control.Antidiabetic activity was then determined using STZ-induced rats treated daily with ethyl acetate and 70% ethanol leaf extracts for4 weeks at a dose of 200 g/kg body weight against gliclazide reference drug.Blood glucose,a-amylase,lipid profile,liver function enzymes and oxidative stress markers were assessed along with histopathological study for liver and pancreatic tissues.Isolation and structural elucidation of active compounds were made using Diaion and Sephadex followed by spectral analyses.Results:The results indicated that ethyl acetate and ethanol leaf extracts exhibited the strongest antioxidant activity compared to that of vitamin C(IC500.05,0.03 and 12 mg/m L,respectively).Both extracts showed potent anti-hyperglycemic activity evidenced by a significant decrease in serum glucose levels by 82.5% and 80.9% and a-amylase by45.2% and 53.6%,as compared with gliclazide 68% and 59.4%,respectively.Fractionation of ethanol extract resulted in the isolation of 9 flavonoids including apigenin-7-O-arhamnosyl(1/2)-b-D-glucuronide,apigenin-7-O-b-D-glucuronide,apigenin-7-O-b-Dglucoside and luteolin-7-O-b-D-glucuronide.Conclusions:This study highlights the potential use of B.acerifolius leaf extract enriched in flavones for the treatment of diabetes that would warrant further clinical trials investigation. Objective: To evaluate Brachychiton acerifolius leaf extracts as antidiabetic potential agent and to identify the main active constituents using bioactivity guided fractionation. Methods: In vitro antioxidant activity was evaluated as B. acerifolius different extracts using DPPH assay and vitamin C as control. Antidiabetic activity was then determined using STZ-induced rats treated daily with ethyl acetate and 70% ethanol leaf extracts for 4 weeks at a dose of 200 g / kg body weight against gliclazide reference drug. Blood glucose, a-amylase, lipid profile, liver function enzymes and oxidative stress markers were assessed along with histopathological study for liver and pancreatic tissues. Isolation and structural elucidation of active compounds were made using Diaion and Sephadex followed by spectral analyzes. Results: The results indicated that ethyl acetate and ethanol leaf extracts showed the strongest antioxidant activity. to that of vitamin C (IC 500.05, 0.03 and 12 mg / m L, respectively ). Bothience extracts showed potent anti-hyperglycemic activity evidenced by a significant decrease in serum glucose levels by 82.5% and 80.9% and a-amylase by 45.2% and 53.6%, as compared with gliclazide 68% and 59.4% respectively. Fractionation of ethanol extract resulted in the isolation of 9 flavonoids including apigenin-7-O-arhamnosyl (1/2) -bD-glucuronide, apigenin-7- ObD-glucuronide, apigenin-7- Ob- Dglucoside and luteolin-7-ObD- glucuronide.Conclusions: This study highlights the potential use of B.acerifolius leaf extract enriched in flavones for the treatment of diabetes that would warrant further clinical trials investigation.