Fungal Antioxidant Compounds Profiling

The fungal culture having the ability to exhibit antioxidant activity, were further evaluated by LC MS/MS (LTQ XL, Thermo Electron Corporation, U.S.A.) for the presence of bioactive compounds [35 (link)]. The detection was performed through direct injection mode with Electron Spray Ionization (ESI) probe, at a positive-mode. The capillary temperature was kept at 280°C, while the sample flow rate was set at 8 μl/min. The mass range was selected from 50 to 1000 m/z. The collision-induced dissociation energy (CID) during MS/MS was kept in the range of 10–45, depending upon the nature of the parent molecular ion. As a mobile phase, the ratio of methanol and acetonitrile was 80:20 (v/v) for the HPLC fractionation. The MS parameters for each compound were optimized to ensure the most favorable ionization, ion transfer conditions. The optimum signal of both the precursor and fragment ions was attained by infusing the analytes and manually tuning the parameters. The source parameters were identical for all of the analytes.