An evaluation of the phytochemical composition, antioxidant and cytotoxicity of the leaves of Litsea elliptica Blume – An ethnomedicinal plant from Brunei Darussalam

Abstract

Litsea elliptica is traditionally believed to prevent and treat stomach ulcers, cancer, fever and headaches. This study investigates the phytochemical composition, antioxidant and cytotoxic effects of L. elliptica leaf extracts. The phytochemical content was determined via GCMS analysis and total phenolic content (TPC) and total flavonoid content (TFC) were analysed using the Folin-Ciocalteu and aluminium-chloride assays. Antioxidant activities were determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) scavenging and ferric-ion reducing antioxidant power (FRAP) assays, whereas cytotoxicity was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and calcein/ethidium viability assays. The mechanism of cytotoxicity was investigated using Annexin V/propidium iodide. Modifications in the mitochondria were investigated using MitoTracker Red CMXRos. Ten and twenty-six compounds were characterized in the young-leaf and mixed-leaves extracts, respectively. The young-leaf methanolic extract demonstrated the highest antioxidant capacity of at least four-folds greater than the mixed-leaves and ethanolic extracts. The methanolic extract also had higher TPC and TFC values compared to the ethanolic extract. Although the mixed L. elliptica leaves had lower antioxidant capacities compared to the young leaves, the mixed leaves extract has demonstrated greater cytotoxicity against the A549 cancer cell line. Further investigation revealed that the L. elliptica leaves-induced cytotoxicity on A549 cells was possibly via the non-inflammatory mitochondria-mediated apoptotic pathway. Overall, our results showed the potential of the L. elliptica leaves possessing cytotoxic activities against carcinoma cells where the compounds present can be further investigated for its therapeutic application.