Exploring cholesterol presence in Allium cepa and Allium fistulosum L using LC-APCI-MS/MS

A limited number of studies have shown the presence of trace amounts of cholesterol in plants. However, due to the extremely low concentrations and structural similarities between cholesterol and other compounds including phytosterols and lathosterol, advanced analytical techniques are crucial for improving the detection reliability. This study investigated cholesterol presence in four species within the same Allium genus: onion (Allium cepa), spring onion (Allium fistulosum L.), garlic (Allium sativum), and chives (Allium tuberosum Rottl.) using GC-MS and LC-APCI-MS/MS. Cholesterol was quantified only in onions and spring onions at concentrations of 23.4 and 7.3 mg/100 g dry weight. The MS spectrum showed that fragmentation occurred at the A-ring steroid in the cholesterol-TMS derivatives, producing abundant ions at m/z 129 and 329. Ions at m/z 368 and 353 were also created from the fragmentation of TMSO and methyl groups. LC-APCI-MS/MS generated precursor ions [M+H–H₂O]⁺ , which fragmented at the C-ring, resulting in major ions at m/z 161 and 147, while m/z 257 was the least abundant ion produced from two fragmentations at the C-ring and side chain.