Chemo diversity of ginger-a potent crop in Manipur and its acetylcholinesterase (AChE) inhibitory potential

The rate of neurodegenerative diseases such as Alzheimer's disease (AD) is rising, particularly in older people. Several medicines are available to temporarily ameliorate the signs of AD but due to adverse effects and inadequate efficacy, there is a need to search for new compounds. Zingiber officinale Roscoe (ginger) is well known for its abundant valuable medicinal properties which might be suitable for the treatment and management of AD. The extracted essential ginger oils from eight samples of Z. officinale from different locations of Senapati district, Manipur were aimed to identify the oil constituents and evaluate the acetylcholinesterase (AChE) inhibitory activity. All the ginger oils were standardized and the major compound (α-citral) was quantified in each oil. Six major volatile compounds (common in all the oils) were further studied through molecular docking analysis to evaluate the possible binding interaction profile with the acetylcholinesterase (AChE) enzyme. Gas chromatography-mass spectrometry (GC-MS) analysis of oils revealed that α-citral is the most abundant chemical constituent in all ginger oils ranging from 13.92 to 30.46%. α-citral, camphene, geraniol, α-pinene, linalool, and α-citronellol were commonly present in all eight ginger oils. Sample M1 showed the highest activity (IC50 = 51.12 ± 0.37 μg/ml; ***P < 0.001) while the lowest activity was observed in Sample M7 (IC50 = 84.47 ± 0.29 μg/ml; ***P < 0.001) against AChE activity. The AChE inhibition activity of chemical constituents was decreased in the following order: linalool > camphene > α-citronellol > α-citral > geraniol > α-pinene. The percentage of marker compound (α-citral) in ginger oil was found maximum in sample M1 (243.9 ± 3.1 μg/mg) and minimum in sample M5 (111.33 ± 1.5 μg/mg). It was observed that all six chemical compounds perfectly occupied the biologically relevant several subsites region, such as the oxyanion hole, anionic subsite binding pocket, or peripheral anionic site (PAS) of the AChE protein. Our results highlight the chemo diversity of ginger available in Manipur and its importance as a potential AChE inhibitor.