Physicochemical characteristics and antioxidant activity of arginine-modified melanin from Lachnum YM-346

► A new water-soluble arginine-melanin (ALEM346) was prepared for the first time. ► ALEM346 had characteristic absorption peaks at 1672.346 and 1637.679 cm−1. ► ALEM346 contained three types of arginine-melanin molecules. ► ALEM346 has higher antioxidant activity than that of LEM346. ► Structural formula of LEM346 is speculated to be.