Novel ethyl p-methoxy cinnamate rich (L.) essential oil and its pharmacological applications: special emphasis on anticholinesterase, anti-tyrosinase, α-amylase inhibitory, and genotoxic efficiencies.

Background: (L.) is one of the prospective therapeutic plants with an aromatic rhizome, and belongs to the Zingiberaceae family. This herb is commonly used by local practitioners in traditional Asian medicine.

Methods: In the present investigation, the novel rhizome essential oil rich in ethyl p-methoxy cinnamate (EMCKG) was evaluated using GC/MS for chemical composition analysis. EMCKG was analyzed for its possible antimicrobial, neurodegenerative inhibitory, acetylcholinesterase, anti-inflammatory, and antioxidant activities as well as for the genotoxic effects using the standard methodologies. ANOVA and was performed to test the statistical significance of the study.

Results: GC/MS analysis identified ethyl p-methoxy cinnamate as the major component of EMCKG essential oil with an area percentage of 66.39%. The EMCKG exhibited moderate (DPPH assay IC = 15.64 ± 0.263 µg/mL; ABTS assay IC = 16.93 ± 0.228 µg/mL) antioxidant activity than standard ascorbic acid (DPPH assay IC = 21.24 ± 0.413 µg/mL; ABTS assay IC = 21.156 ± 0.345 µg/mL). Similarly, EMCKG showed comparable activity in albumin denaturation (IC = 2.93 ± 0.59 µg/mL) and protease inhibitor assay (IC = 17.143 ± 0.506 µg/mL) to that of standard sodium diclofenac (IC = 23.87 ± 0.729 µg/mL and IC = 19.18 ± 0.271 µg/mL, respectively). The EMCKG exhibited a dose-dependent antimicrobial activity pattern with the highest inhibitory activity at 500 µg/mL against and considerable anticholinesterase activities (IC = 21.94 ± 0.109 µg/mL) compared to the standard galanthamine (IC = 27.18 ± 0.511 µg/mL). EMCKG also showed strong anti-diabetic activity (IC = 18.503 ± 0.480 µg/mL) and anti-tyrosinase activity (IC = 14.756 ± 0.325 µg/mL) as compared to the standards used (acarbose IC = 20.39 ± 0.231 µg/mL and kojic acid IC = 17.73 ± 0.192 µg/mL) in the study. Genotoxicity analysis of EMCKG revealed that at 1 µg/mL concentration has no toxic effects in mitosis of roots (Mitotic Index MI = 13.56% and chromosomal aberration CA = 07.60%). The ANOVA confirmed that except for the anticholinesterase activity, there is insignificant difference for essential oil and standards used for all the other bioactivities thus confirming their interchangeable applicability.

Conclusions: Current research provides the basis for the fact that besides being a rich source of ethyl p-methoxycinnamate, EMCKG has the potential for future formulation and development of an inexpensive skin-care agent and for the preparation of anti-diabetic drugs.