In this study the content of
anacardic acids, cardanols and cardols in cashew apple, nut (raw and roasted) and cashew nut shell liquid (CNSL) were analysed. The higher amounts (353.6 g/kg) of the major alkyl
phenols,
anacardic acids were detected in CNSL followed by cashew fibre 6.1 g/kg) while the lowest (0.65 g/kg) amounts were detected in roasted cashew nut. Cashew apple and fibre contained
anacardic acids exclusively, whereas CNSL also contained an abundance of cardanols and cardols. Cashew nut (raw and roasted) also contained low amounts of hydroxy alkyl
phenols. Cashew nut shell liquid was used for a basic fractionation of the alkyl
phenol classes and the individual
anacardic acids, major cardanols and cardols were purified to homogeneity from these fractions by semi-preparative HPLC and definitively identified by nano-ESI-MS-MS, GC-MS and NMR analyses. The
hexane extracts (10 mg/ml) of all cashew products tested plus CNSL, displayed significant
antioxidant capacity. Cashew nut shell liquid was the more efficient (inhibition=100%) followed by the
hexane extract of cashew fibre (94%) and apple (53%). The
antioxidant capacity correlated significantly (P<0.05) with the concentration of alkyl
phenols in the extracts. A mixture of
anacardic acids (10.0 mg/ml) showed the higher
antioxidant capacity (IC50=0.60 mM) compared to cardols and cardanols (IC50>4.0 mM). The data shows that of these substances, anacardic-1 was by far the more potent
antioxidant (IC50=0.27 mM) compared to
cardol-1 (IC50=1.71 mM) and
cardanol-1 (IC50>4.0 mM). The
antioxidant capacity of
anacardic acid-1 is more related to inhibition of
superoxide generation (IC50=0.04 mM) and
xanthine oxidase (IC50=0.30 mM) than to scavenging of
hydroxyl radicals. At present a substantial amount of cashew fibre is mostly used in formulations of animal or poultry feeds. The data presented in this study, indicates that this
waste product along with CNSL, both of which contain high contents of
anacardic acids, could be better utilized in functional food formulations and may represent a cheap source of
cancer chemopreventive agents.