Rhinacanthins‑rich Extract Enhances Glucose Uptake and Inhibits Adipogenesis in 3T3‑L1 Adipocytes and L6 Myotubes

Background: Obesity is one of the imperative dynamics in the incidence and intensification of type 2 diabetes mellitus (T2DM). Rhinacanthus nasutus leaf extracts are previously reported for their antidiabetic and antiobesity potential. Objective: The present study was performed to evaluate glucose uptake stimulatory and antiadipogenic activities of a standardized rhinacanthins‑rich extract (RRE) and its marker compounds namely rhinacanthin‑C (RC), rhinacanthin‑D (RD), and rhinacanthin‑N (RN) in 3T3‑L1 and L6 cells. Materials and Methods: RRE was prepared by a green extraction process, and the marker compounds (RC, RD, and RN) were isolated from the RRE using a silica gel column chromatography. Glucose uptake stimulation in both 3T3‑L1 and L6 cells was performed by quantification of residual glucose in the media using glucose oxidase kit. Antiadipogenic activity in 3T3‑L1 adipocytes was performed by intracellular lipids quantification using oil red O dye. Results: At the highest effective dose, RRE (20 µg/mL) exhibited satisfactory glucose uptake stimulatory effect in 3T3‑L1 adipocytes that equivalent to RN (20 µg/mL) and the positive control insulin (0.58 µg/mL) but higher than RC (20 µg/mL) and RD (20 µg/mL). In addition, treatments of L6 myotubes showed that RRE (2.5 µg/mL) exhibited potent and equivalent glucose uptake stimulation (>80%) to RC (2.5 µg/mL) and the standard drugs, insulin (2.90 µg/mL) and metformin (219.5 µg/mL), but higher than RD (2.5 µg/mL) and RN (2.5 µg/mL). Furthermore, RRE (20 µg/mL) exhibited potent antiadipogenic effect in 3T3‑L1 adipocytes, which equivalent to RC (20 µg/mL) but higher than RD (20 µg/mL) and RN (20 µg/mL). Conclusions: The undertaken study suggests that RRE could be used as an effective remedy in the treatment of obesity‑associated T2DM.