Green synthesized β-caryophyllene oxide enriched fraction-derived carbon quantum dots trigger ROS production and p53...

Carbon Quantum Dots (CQDs) are highly valued in the biomedical field for their intrinsic fluorescence, excellent biocompatibility, and broad range of precursor availability. This study is the first to report the preparation of CQDs using a β-caryophyllene oxide enriched fraction (BCPO-EF) isolated from Blumea eriantha DC via microwave-assisted green synthesis approach. GC-MS profiling of the isolated fraction identified the major component eluted at 25.113 min, exhibited molecular ion peak at m/z 220. In the ¹³C NMR spectrum, 15 carbon signals were observed within the δ 17.02-151.85 ppm range, while the ¹H NMR spectrum displayed peaks between δ 0.97 and 4.98 ppm. C-O stretching bands of the epoxide ring at 1258.94 and 959.97 cm^-1 in the FTIR spectrum confirm the isolate as BCPO-EF. The structural formation of BCPO-EF-CQDs was confirmed through spectroscopic characterization. Absorption at 257 nm reflects C=C conjugation of CQDs core. BCPO-EF-CQDs cytotoxic effects on HepG2 cells were measured using the MTT cytotoxicity assay, lactate dehydrogenase (LDH) assay, apoptosis assessment, p53-MDM2 expression, and intracellular reactive oxygen species (ROS) assessment. BCPO-EF-CQDs exhibited 27.15% photoluminescence quantum yield (PLQY) and spherical particles of 3.56-8.44 nm. The IC₅₀ value of BCPO-EF-CQDs was calculated to be 47.80 μg mL^-1 on HepG2 cells. Flow cytometry detected 56.70% apoptosis, ROS levels increased by 5.057-fold and Western blot showed p53 and MDM2 upregulated 11.12- and 3.68-fold, respectively in HepG2 cells following BCPO-EF-CQDs treatment. The present results confirm ROS-mediated p53 activation by BCPO-EF-CQDs in HepG2 hepatocellular carcinoma cells, warranting further investigation.