POLYETHYLENE GLYCOL-BASED ISOLATION AND CHARACTERIZATION OF PLANT-DERIVED EXOSOME-LIKE NANOPARTICLES FROM CARICA PAPAYA L. LEAVES AND THEIR POTENTIAL AS AN ANTICANCER AGENT

Abstract

Plant-derived exosome-like nanoparticles (PDENs) have attracted increasing attention as potential nanocarriers for bioactive compounds because they are biocompatible, have low immunogenicity, and can transport diverse biological cargo. The present study aimed to optimize a polyethylene glycol (PEG)-based isolation method for PDENs from Carica papaya L. leaves and evaluate their in vitro anticancer activity against SCC-131 oral squamous cell carcinoma cells. Papaya leaf extract was subjected to differential centrifugation followed by PEG-based precipitation using PEG of different molecular weights (3, 6, and 8 kDa) at concentrations of 6%, 8%, and 12% (w/v). The isolated nanoparticles were characterized through protein and lipid quantification, nanoparticle tracking analysis (NTA), and zeta potential measurements. Their cytotoxic activity against SCC-131 cells was evaluated using the MTT assay. Among the tested formulations, 8 kDa PEG at 6% (w/v) was the most favorable isolation condition, with a protein-to-lipid ratio of 2.91. The isolated nanoparticles had a median diameter of 133.4 nm and a mean diameter of 154.0 ± 84.4 nm. The mean zeta potential was −30.73 mV, indicating favorable colloidal stability. MTT assay results showed a progressive reduction in SCC-131 cell viability with increasing PDEN concentration, with a half-maximal inhibitory concentration (IC₅₀) of 34.32 µg/mL. Microscopic observations also revealed cell rounding, loss of adhesion, and increased floating cells, particularly at higher treatment concentrations. These findings demonstrate the feasibility of PEG-based isolation of C. papaya leaf-derived PDENs and indicate measurable in vitro cytotoxic activity against SCC-131 oral squamous cell carcinoma cells. Further molecular characterization, mechanistic investigations, and in vivo validation are required to establish their therapeutic potential.