Comparative analysis of volatile composition and anticholinesterase activity of Egyptian Hedychium coronarium and Alpinia zerumbet using chemometric assessment of extraction techniques

Abstract

Hedychium coronarium and Alpinia zerumbet are rhizomatous plants belonging to the family Zingiberaceae. They are rich in essential oils. Hydrodistillation and headspace (HS) were employed for the extraction of the essential oils from the leaves and rhizomes of both plants. Essential oils were then analysed by GC/MS and the obtained results were subjected to chemometric analysis. The oil samples obtained by hydrodistillation were tested for their antioxidant and anti-cholinesterase activities using oxygen radical antioxidant capacity assay and colorimetric inhibition kit, respectively. Hydro-distilled oil from H. coronarium leaves showed the presence of forty-seven compounds (97.73%) compared to sixteen compounds (99.17%) in the HS volatiles. Meanwhile, hydro-distilled oil from H. coronarium rhizomes showed the presence of thirty-nine components (95.84%) compared to fifteen compounds (98.68%) in the HS volatiles with 1,8-cineole (41.69% and 58.41%) as the major component in both samples. A. zerumbet leaves oil showed the presence of nineteen compounds (94.54%) in the hydrodistilled oil and twenty-one compounds (99.53%) in the HS volatiles. Besides, the rhizomes hydrodistilled essential oil showed twenty-three compounds (91.85%) and sixteen compounds (100%) in the HS with 1,8-cineole (20.78% and 23.63%) representing the major component in both samples. Chemometric analysis of the results provided a clear and statistically robust discrimination between the hydrodistilled and headspace-isolated oil samples demonstrating that extraction method is a primary determinant of volatile profile. Principal component analysis score plot explained 75% of total variance and distinctly separated samples into four main clusters with key discriminating components β-pinene, and caryophyllene were the major responsible for the segregation of H. coronarium leaves by headspace and hydrodistillation extraction methods, respectively, besides, 1,8-cineole accounted for the discrimination of H. coronarium rhizomes extracted by hydrodistillation. Hierarchial cluster analysis (HCA) fully supported this classification, confirming consistent grouping patterns across both analyses. Importantly, A. zerumbet oils from both extraction methods clustered closely, indicating compositional stability, whereas H. coronarium samples showed strong method-dependent divergence. A. zerumbet rhizomes oil showed the strongest activity as anticholinesterase with IC50 of 0.54 ± 0.02 µg/mL while H. coronarium rhizomes showed the strongest antioxidant activity (10.06 ± 0.16 TE µM/L). H. coronarium leaves and A. zerumbet rhizomes showed anticholinesterase and antioxidant activities to such an extent that may make them a useful adjuvant in the treatment of cognitive diseases such as Alzheimer’s.