In general, gamma irradiation’s enhancement of radical scavenging activity is correlated with the formation of new
compounds. To determine whether the observed increase in the
radical-scavenging activity of aloe gel extracts by gamma irradiation was due to the formation of a new compound, gamma
irradiated samples were subjected to HPLC. While only one peak
1 was found in the non-irradiated aloe gel extracts, 2 peaks were
detected in the gamma-irradiated sample. One peak was identical
to that found in the non-irradiated sample (peak1), and the other
peak was newly generated by irradiation (peak2, Fig. 4A). The
formation of the new peak was dose-dependently increased and
reached a plateau at 40kGy of gamma irradiation. However, peak
1 decreased as peak 2 in creased. The newly formed compound
was well-correlated with enhanced antioxidant activity in aloe
gel extracts. Next, liquid chromatography/mass spectrometry
(LC/MS) was used to identify peak 2. The molecular weight of
the small fragment was 132.0 (Fig. 4B). These results suggest that
the improved antioxidant activity by gamma irradiation was most
likely due to the new compound generated by gamma irradiation,
which could be a fragment of peak 2