This research aims to examine the biological activities of fresh onion extract (F),
fructooligosaccharide syrup extract (H), and absorbent fructooligosaccharide syrup extract (HC).
We found that the F extract could inhibit and kill Bacillus cereus. The MIC/MBC values of the F
extract in 10% DMSO, F extract in 80% methanol, and fresh onion juice were 4 .1 8 / 3 .1 5 ,
5.22/3.15, and 7.03/12.50 mg/mL, respectively. The highest total phenolic content was found in
the H extract followed by the F and the HC extracts with GAE values of 0.73?0.11, 0.89?0.12,
and 0.19?0.07 mg/g FW, respectively. The antioxidant activity was investigated using FRAP,
DPPH, and ABTS assays. It was found that H extract had the highest antioxidant activity
followed by F and HC extracts with EC1 values of 2.28?0.06, 1.53?0.05, and 0.56?0.02 mM/g
FW, respectively. The IC50 values were 0.13?0.00, 0.18?0.00, and 0.31?0.01 mg/g FW; and the
TEAC values were 448.18?0.57, 520.56?25.37, and 555.60?2.47 mg/g FW, respectively. In an
assay for the anti-inflammatory effects, we found that 1,000 ?g/mL of the H extract (IC50 = 15.7
?g/mL) and the HC extract (IC50 = 25.5 ?g/mL) inhibited the cytokine IL-6 secretion comparably
to 250 ?g/mL of the Dexamethasone standard (IC50 = 79.4 ?g/mL). Inhibition of TNF-? by the
HC extract (IC50 = 48.6 ?g/mL) was also not different from 250 ?g/mL Dexamethasone (IC50 =
43.3 ?g/mL). The cytotoxicity of the onion extract on human skin cells type fibroblasts (WS1)
and colon cancer cells (Caco2 ) were evaluated using MTT assay with the following six
concentrations: 31.25, 62.50, 125, 500, and 1,000 mg/mL for 24 hours. While the HC extract had
the lowest toxicity on both WS1 and Caco2 cells, the F extract had the highest toxicity on WS1
(IC50 = 250.00 ? 0.00 mg/mL). Lastly, the H extract on Caco2 possessed the IC50 value of 214.93
? 0.39 mg/mL. The onion juice heated in the process of making fructooligosaccharide syrup had
higher amount of total phenolic content and antioxidant activity at the concentration of 1 ,0 0 0
?g/mL. The heated juice could inhibit the cytokine IL-6 and cytokine TNF-? secretion and
exhibited low toxicity to WS1 and Caco2 cells. The result indicated that the onion can be cooked
or subject to heat during food processing without a loss of bioactive compounds.