Production kinetics and bioactivity study of Aspulvinone pigment from Aspergillus terreus STCP01 for natural colourant applications

Abstract

This study details the isolation, optimisation and characterisation of the yellow pigment produced by Aspergillus terreus strain from mangrove soil. Process parameters including fermentation time (24–288 h), pH (4–9), and temperature (25–35 °C), were optimised using response surface modeling coupled with the Box-Behnken experimental design to predict extracellular pigment yield and biomass production. The predicted conditions of an incubation period of 278 h, a pH of 6.4 and a temperature of 30 °C resulted in optimal pigment production (7.59 AU₃₂₀) and biomass (11.119 g/L). The yellow-coloured pigment was extracted using ethyl acetate, and purified chromatographically and identified as Aspulvinone E by UV–Visible spectroscopy, FT-IR, UPLC-Q-ToF-MS, elemental analysis, and NMR data. Stable under varying temperature and pH, aspulvinone E showed notable antioxidant activity and was non-toxic to both brine shrimp nauplii and L929 cell lines. The results suggest aspulvinone E as a stable and safe natural colouring compound with antioxidant potential.