Optimization Extraction of Cladonia foliacea (Huds.) Willd: Antioxidant Activity and Inhibition of the Key Enzymes Linked to Type II Diabetes

Abstract

Cladonia foliacea (CF) is a type of lichen belonging to the Cladoniaceae family, used as traditional medicine for various diseases. It is known that CF has strong antioxidant and antidiabetic effects originating from various secondary components. However, the bioactivity of CF is significantly affected by extraction conditions such as temperature, liquid/solid ratio, and solvent type/concentration. Herein, the extraction parameters (temperature, liquid/solid ratio, and methanol concentration) of CF were optimized by response surface methodology (RSM) based on maximum total phenolic content (TPC), antioxidant capacity, and α-glucosidase/α-amylase inhibitor activity. In the methanolic extraction of CF, 48.8 °C, 12.3 mL g-1 liquid/solid ratio, and 86.4% methanol concentration were determined as the optimum point. TPC, antioxidant capacity, α-glucosidase, and α-amylase inhibition activities of CF extracted under optimum conditions were determined as 5.55 mg GAE g-1, 33.10 g sample/g DPPH, 68.78%, and 50.03%, respectively. These results suggest that extraction conditions may be a limiting factor in terms of bioactive properties and optimized extraction parameters may improve the potential antioxidant and inhibitory activity of key enzymes associated with type II diabetes of CF.