Total antioxidant capacity and content of flavonoids and other phenolic compounds in canihua (Chenopodium pallidicaule): an Andean pseudocereal.

Total antioxidant capacity (TAC), total phenolic compounds (TPH), total flavonoids (TF) and individual phenolic compounds were determined in canihua collected at approx. 3850 m altitude. The TAC values varied among samples from 2.7 to 44.7 by the ferric reducing antioxidant power (FRAP) method and from 1.8 to 41 by the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) method expressed as micromol of Trolox equivalents/g dw. The content of TPH was 12.4-71.2 micromol gallic acid equivalents/g dw and that of the TF ranged between 2.2 and 11.4 micromol of catechin equivalents/g dw. The data obtained by the four methods showed several significant correlations. Prior to analysis by HPLC, the samples were subjected to acid hydrolysis and in the water-soluble extracts this led to an up to 20-fold increase in the TAC values in comparison with the values of the nonhydrolysed samples. HPLC analysis showed the presence of eight major compounds identified as catechin gallate, catechin, vanillic acid, kaempferol, ferulic acid, quercetin, resorcinol and 4-methylresorcinol. Their estimated contribution to the TAC value (FRAP method) indicated that resorcinols contributed most of the antioxidant capacity of the water-soluble extract. The results show that canihua is a potential source of natural antioxidant compounds and other bioactive compounds which can be important for human health.