Abstract:
Essential oils (EOs) extracted from six medicinal herbs and food plants [Cinnamomum zeylanicum
(CZ), Psiadia arguta (PA), Psiadia terebinthina (PT), Citrus grandis (CGp), Citrus hystrix
(CH), and Citrus reticulata (CR)] were studied for any inhibitory potential against key
physiological enzymes involved in diabetes (a-glucosidase), skin aging (collagenase and
elastase), and neurodegenerative disorders (acetylcholinesterase). Kinetic studies of the
active EOs on the aforementioned enzymes were determined using LineweavereBurk
plots. The intracellular and extracellular antimelanogenic potential of the EOs were evaluated
on B16F10 mouse melanocytes. CH and CR were found to significantly inhibit
(2.476 ± 0.13 mg/mL and 3.636 ± 0.10 mg/mL, respectively) acetylcholinesterase, compared
with galantamine (3.989 ± 0.16 mg/mL). CH inhibited collagenase (50% inhibitory concentration
28.71 ± 0.16 mg/mL) compared with the control (24.45 ± 0.19 mg/mL). The percentage
inhibition in the elastase assay of CH was 63.21% compared to the positive control (75.09%).
In addition, CH, CR, CGp, CZ, and PT were found to significantly inhibit a-glucosidase
(276.70 ± 0.73 mg/mL, 169.90 ± 0.58 mg/mL, 240.60 ± 6.50 mg/mL, 64.52 ± 0.69 mg/mL, and
313.0 ± 5.0 mg/mL, respectively), compared to acarbose (448.80 ± 0.81 mg/mL). Active EOs
showed both uncompetitive and competitive types of inhibition. The EOs also inhibited
intracellular (50% inhibitory concentration 15.92 ± 1.06 mg/mL, 23.75 ± 4.47 mg/mL, and
28.99 ± 5.70 mg/mL for CH, CR, and CGp, respectively) and extracellular (< 15.625 mg/mL for
CH, CR, CGp, and PT) melanin production when tested against B16F10 mouse melanocytes.
Results from the present study tend to show that EOs extracted from these medicinal plants can inhibit key enzymes and may be potential candidates for cosmetic and pharmaceutical
industries.
