Abstract:

Antioxidant activities and mechanism of extracts from six spice materials including clove, rosemary, cassia bark, liquorice, nutmeg and round cardamom were investigated by different assays. Spice materials were extracted using 95% ethanol and the antioxidant activities of these extracts were evaluated by the determinations of inhibitory rate against thiobarbituric acidreactive substances (TBARS) in a liposome model system, scavenging rate against 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, ferric reducing-antioxidant power (FRAP), chelating capacity to Cu2+ or Fe2+, and total phenol content by Folin-Ciocalteau method when commercial butylated hydroxyanisole (BHA) was served as the positive control. Results indicated that the extracts from clove, rosemary, cassia bark, liquorice, nutmeg and round cardamom all exhibited a stronger inhibitory effect against TBARS and higher total phenol content. Meanwhile, total phenol content was significantly negatively correlated with TBARS (r =－0.69, P＜0.05) and scavenging capacity against DPPH free radicals (r = 0.84, P＜0.05). Moreover, scavenging capacity against DPPH free radicals was also significantly correlated with FRAP value (r = 0.84, P ＜ 0.05). However, there was no correlation found between TBARS and FRAP value or scavenging capacity against DPPH free radicals (P＞0.05). Furthermore, Fe2+ chelating capacity also did not exhibit correlation with TBARS, scavenging capacity against DPPH free radicals or FRAP value (P＞0.05). Therefore, it can be concluded that the antioxidant activities of extracts from these spice materials mainly result from polyphenolic components through scavenging free radicals, chelating metal ions and donating hydrogen.

Key words: extract from spice materials, antioxidant, TBARS, FRAP, DPPH radicals, chelating capacity