Thermal cooking changes the profile of phenolic compounds, but does not attenuate the anti-inflammatory activities of black rice
Sammanfattning
Background: Evidence on biological activities of cooked black rice is limited. This study examined the effects of
washing and cooking on the bioactive ingredients and biological activities of black rice.
Methods: Cooked rice was prepared by washing 03 times followed by cooking in a rice cooker. The acidic
methanol extracts of raw and cooked rice were used for the analyses.
Results: Raw black rice, both washed and unwashed, had higher contents of polyphenols, anthocyanins, and
cyanidin-3-glucoside (C3G), but lower protocatechuic acid (PA), than did cooked samples. Similarly, raw rice
extracts were higher in ferric-reducing antioxidant power (FRAP) activities than extracts of cooked samples.
Nonetheless, extracts of raw and cooked rice showed similar inhibitory potencies on nitric oxide, tumor
necrosis factor-a, and interleukin-6 productions in lipopolysaccharide-activated macrophages, whereas
equivalent amounts of C3G and PA did not possess such inhibitory effects.
Conclusions: Thermal cooking decreased total anthocyanin and C3G contents and the FRAP antioxidative
capacity, but did not affect anti-inflammatory activities of black rice. Neither C3G nor PA contributed to the
anti-inflammatory activity of black rice.