Novel purification of 1'S-1'-Acetoxychavicol acetate from Alpinia galanga and its cytotoxic plus antiproliferative activity in colorectal adenocarcinoma cell line SW480.

Alpinia galanga (L.) Willd. is a valuable medicinal crop found in specific tropical regions of southeast Asia. Its crude extracts are well known for their wide medicinal properties and many compounds identified from these extracts are of great interest currently. 1'S-1'-Acetoxychavicol acetate (ACA) obtained from rhizomes of A.galanga is one such well-illustrated compound. This study strives to progress and simplifies the purification protocol for ACA from A.galanga rhizomes. It also studies the cytotoxicity and antiproliferative activity of ACA against Dukes' type B, colorectal adenocarcinoma (SW480). HPLC standardisation was carried out for purification of ACA from rhizomes of Alpinia galanga. MTT assay was executed to estimate the IC50 value of ACA against SW480 cell line. This value was used to study the apoptosis, nuclear morphological changes and mitochondrial membrane permeability using Acridine orange/ethidium bromide, DAPI, and JC-1 staining. The DNA fragmentation assay was used to substantiate the nuclear fragmentation of DNA observed in the DAPI staining. Further, cell cycle analysis was performed using flow cytometry to study the exact stage of the cell cycle where SW480 cells are arrested due to ACA, western blot analysis of relevant genes were done to further understand at molecular level. A comprehensive 1.89g of 1'S-1'-Acetoxychavicol acetate (ACA) was recovered from 500g of A.galanga rhizomes. ACA significantly suppressed the proliferation of SW480 cells at an IC50 of 80μM (48h). The mode of SW480 cell death due to ACA was initially identified as apoptosis and cell cycle halted at G0/G1 checkpoint with considerable DNA damage and mitochondrial depolarization. The expression of p21 was increased and concomitantly Cyclin D was downregulated in ACA treated in comparison to control. This study suggests that 1'S-1'-Acetoxychavicol acetate has potent anti-colorectal adenocarcinoma activity.