Extraction, purification, antioxidant properties and stability conditions of phytomelanin pigment on the sunflower seeds

Phytomelanin pigment, a rare secondary matabolite in plants, has potential for use in the cosmetic and food sectors. This pigment has antioxidant, antimicrobial and ultraviolet (UV) light absorbing properties, so it can be used as natural food coloring and in the field of cosmetics. In this study, extraction, purification, antioxidant properties and stability conditions of phytomelanin pigment found in sunflower (Helianthus annuus L.) seed coat were investigated. NaOH, KOH and NH4OH solutions were tested at different concentrations for extraction. It has been determined that the most suitable solvent for extraction is 0.3 M NaOH. The purification process involves precipitation with HCl followed by washing with ethyl alcohol, ethyl acetate and acetone. The findings show that the proportion of phytomelanin in sunflower seeds is 1.95% and that the antioxidant capacity is 9.8% ascorbic acid equivalent. The purity degree of the purified phytomelanin pigment and that of the synthetic phytomelanin pigment were compared by thin layer chromatography (TLC). Chromatography findings have shown that the purification performance is quite high. It was determined that the pigment was slowly deteriorated in temperature and light, and was not affected by air. Consequently, sunflower seed coat can be a convenient and economical source of producing pure phytomelanin for industrial use.