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 .

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 IC 50 = 0.14 ± 0.03 to 3.69 ± 0.37  μ g/mL. In addition, all extracts exhibited excellent antityrosinase (IC 50 = 1.16 ± 0.06 to 71.32 ± 4.63  μ g/mL) and anti- α -glucosidase (IC 50 4.76 ± 0.71 to 42.57 ± 2.13  μ g/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.