Preparation of Spice Extracts: Evaluation of Their Phytochemical, Antioxidant, Antityrosinase, and Anti-α-Glucosidase Properties Exploring Their Mechanism of Enzyme Inhibition with Antibrowning and Antidiabetic Studies In Vivo

Abstract

Tyrosinase and α-glucosidase enzymes are known as promising target candidates for inhibitors to control unwanted pigmentation and type II diabetics mellitus. Therefore, twenty extracts as enzyme inhibitors were prepared from edible spices: nutmeg, mace, star anise, fenugreek, and coriander aiming to explore their antioxidant, antibrowning, and antidiabetic potential. Results confirmed that all extracts showed potent antioxidant activity ranging from $\text{I}{\text{C}}_{50}=0.14\pm 0.03$ to $3.69\pm 0.37\mu \text{g}/\text{mL}$ . In addition, all extracts exhibited excellent antityrosinase ( $\text{I}{\text{C}}_{50}=1.16\pm 0.06$ to $71.32\pm 4.63\mu \text{g}/\text{mL}$ ) and anti-α-glucosidase (IC50 $4.76\pm 0.71$ to $42.57\pm 2.13\mu \text{g}/\text{mL}$ ) activities outperforming the corresponding standards, hydroquinone, and acarbose, respectively. Among all extracts, star anise ethyl acetate (Star anise ETAC) was found most potent inhibitor for both tyrosinase and α-glucosidase enzymes and was further studied to explore the mechanism of enzyme inhibition. Kinetic analysis revealed its irreversible but mixed-type tyrosinase inhibition with preferentially competitive mode of action. However, it binds reversibly with α-glucosidase through competitive mode of action. Further, star anise ETAC extract showed concentration dependent and posttreatment time-dependent antibrowning effect on potato slices and antidiabetic effect on diabetic rabbits in vivo proposing it promising candidate for tyrosinase-rooted antibrowning and α-glucosidase-associated diabetes management for future studies.