*Article* **Anti-Obesity Evaluation of** *Averrhoa carambola* **L. Leaves and Assessment of Its Polyphenols as Potential** α**-Glucosidase Inhibitors**

**Nehal S. Ramadan 1, Nabil H. El-Sayed 1, Sayed A. El-Toumy 1, Doha Abdou Mohamed 2, Zeinab Abdel Aziz 3, Mohamed Sobhy Marzouk 1, Tuba Esatbeyoglu 4,\*, Mohamed A. Farag 3,\* and Kuniyoshi Shimizu <sup>5</sup>**


**Abstract:** *Averrhoa carambola* L. is reported for its anti-obese and anti-diabetic activities. The present study aimed to investigate its aqueous methanol leaf extract (CLL) in vivo anti-obese activity along with the isolation and identification of bioactive compounds and their in vitro α-glucosidase inhibition assessment. CLL improved all obesity complications and exhibited significant activity in an obese rat model. Fourteen compounds, including four flavone glycosides (**1**–**4**) and ten dihydrochalcone glycosides (**5**–**12**), were isolated and identified using spectroscopic techniques. New compounds identified in planta included (**1**) apigenin 6-*C*-(2-deoxy-*β*-D-galactopyranoside)-7-*O*-*β*-Dquinovopyranoside, (**8**) phloretin 3 -*C*-(2-*O*-(*E*)-cinnamoyl-3-*O*-*β*-D-fucopyranosyl-4-*O*-acetyl)-*β*-Dfucopyranosyl-6 -*O*-*β*-D fucopyranosyl-(1/2)-α-L arabinofuranoside, (**11a**) phloretin3 -*C*-(2-*O*-(*E*)-pcoumaroyl-3-*O*-*β-*D-fucosyl-4-*O*-acetyl)-*β*-D-fucosyl-6 -*O*-(2-*O*-*β*-D-fucosyl)-α-L-arabinofuranoside, (**11b**) phloretin3 -*C*-(2-O-*(Z)-p*-coumaroyl-3-*O*-*β*-D-fucosyl-4-*O*-acetyl)-*β*-D-fucosyl-6 -*O*-(2-*O*-*β*-Dfucosyl)-α-L-arabinofuranoside. Carambolaside M (**5**), carambolaside Ia (**6**), carambolaside J (**7**), carambolaside I (**9**), carambolaside P (**10a**), carambolaside O (**10b**), and carambolaside Q (**12**), which are reported for the first time from *A. carambola* L. leaves, whereas luteolin 6-*C*-α-L-rhamnopyranosyl- (1-2)-*β*-D-fucopyranoside (**2**), apigenin 6-*C*-*β*-D-galactopyranoside (**3**), and apigenin 6-*C*-*α*-L-rhamnopyranosyl-(1-2)-*β*-L-fucopyranoside (**4**) are isolated for the first time from Family. Oxalidaceae. In vitro α-glucosidase inhibitory activity revealed the potential efficacy of flavone glycosides, viz., **1**, **2**, **3**, and **4** as antidiabetic agents. In contrast, dihydrochalcone glycosides (**5**–**11**) showed weak activity, except for compound **12**, which showed relatively strong activity.

**Keywords:** antidiabetic; *Averrhoa carambola* L.; dihydrochalcone; flavone glycosides; obesity; Oxalidaceae; type 2 diabetes
