Natural products as sources of new antioxidants: Synthesis and antioxidant evaluation of Mannich bases of novel sesamol derivatives

Sesamol, a natural phenolic compound with good antioxidant activity, is a nonoil component of sesame seed oil. Two series of novel Mannich bases, 4-(aminoalkyl)-6-allyl-sesamols were synthesized from sesamol, substituted benzaldehydes and piperidine/morpholine via the one-pot reaction. An efficient way using toluene as solvent, catalyst-free and one-pot reaction for the synthesis of these sesamol derivatives was developed. The structures of all 4-(aminoalkyl)-6-allyl-sesamols were determined by spectral analysis. Compound 6f was unambiguously confirmed by X-ray diffraction further. The antioxidant assays have demonstrated that the sesamol derivative 7i displayed excellent antioxidant activity. The structure–activity relationships (SARs) of these sesamol derivatives were also observed. Further, the representative compounds 7a , 7g and 7i exhibited relative low toxicity to normal cells. Based on these characteristics, these sesamol derivatives will have great potential application in food and drugs.