Priyanka Chandra

Assay of antioxidant potential of two Aspergillus isolates by different methods under various physio-chemical conditions

The objective of this work was to screen fungi isolated from soil of different areas of Punjab, India for antioxidant activity by dot blot assay and around 45% of fungal isolates demonstrated antioxidant potential. Two selected strains of Aspergillus spp (Aspergillus PR78 and Aspergillus PR66) showing quantitatively best antioxidant activity by DPPH assay were further tested for their reducing power, ferrous ion and nitric oxide ion scavenging activity, FRAP assay and total phenolic content. Different physio-chemical parameters were optimized for enhancement of the activity. This revealed stationary culture grown for 10 days at 25 oC at pH 7 to be the best for antioxidant activity. Sucrose in the medium as carbon source resulted in highest antioxidant activity. Sodium nitrate, yeast extract, and peptone were good sources of nitrogen but sodium nitrate was the best among these. The extraction of the broth culture filtrates with different solvents revealed ethyl acetate extract to possess the best antioxidant activity. The activity as expressed by ethyl acetate extract of Aspergillus PR78 was equally effective as that of commonly used antioxidant standard, ascorbic acid.

Antioxidant Activity of Aspergillus fumigatus

The antioxidant activity of Aspergillus fumigatus was assayed by different procedures and correlated with its extracellular total phenolic contents. Different physio-chemical parameters were optimized to enhance the activity. The culture grown under stationary conditions for 10 days at 25°C at pH 7 gave the best antioxidant activity. Statistical approaches demonstrated sucrose and NaNO3 to be the most suitable carbon and nitrogen sources, respectively. Response surface analysis showed 5% sucrose, 0.05% NaNO3, and incubation temperature of 35°C to be the optimal conditions for best expression of antioxidant activity. Under these conditions, the antioxidant potential assayed through different procedures was 89.8%, 70.1%, and 70.2% scavenging effect for DPPH radical, ferrous ion and nitric oxide ion, respectively. The reducing power showed an absorbance of 1.0 and FRAP assay revealed the activity of 60.5%. Extracellular total phenolic content and antioxidant activity as assayed by different procedures positively correlated.

In Vitro Antioxidant Potential of Some Soil Fungi: Screening of Functional Compounds and their Purification from Penicillium citrinum

Fungal isolates (Aspergillus wentii 1, A. wentii 2, Penicillium citrinum, Penicillium granulatum) were selected to study their in vitro antioxidant potential by various assay procedures. Czapek–Dox’s medium was selected for the growth of fungi as it supported the best antioxidant activity based on their EC50 values, P. citrinum was the best followed by P. granulatum, A. wentii 1, and A. wentii 2. The chromatographic analyses showed several compounds possessing antioxidant activity in the fungal extracts. Two such compounds were partially purified from P. citrinum which demonstrated potent antioxidant activity, equally effective or better than some of the standard antioxidants.

Optimization of Antioxidant Potential of Penicillium granulatum Bainier by Statistical Approaches.

A three-step optimization strategy which includes one-factor-at-a-time classical method and different statistical approaches (Plackett-Burman design and response surface methodology) that were applied to optimize the antioxidant potential of Penicillium granulatum. Antioxidant activity was assayed by different procedures and compared with total phenolic content. Primarily, different carbon and nitrogen sources were screened by classical methods, which revealed sucrose and NaNO3 to be the most suitable. In second step, Plackett-Burman design also supported sucrose and NaNO3 to be the most significant. In third step, response surface analysis showed 4.5% sucrose, 0.1% NaNO3, and incubation temperature of 25°C to be the optimal conditions. Under these conditions, the antioxidant potential assayed through different procedures was 78.2%, 70.1%, and 78.9% scavenging effect for DPPH radical, ferrous ion, and nitric oxide ion, respectively. The reducing power showed an absorbance of 1.6 with 68.5% activity for FRAP assay.

Optimization of antioxidant potential of Aspergillus terreus through different statistical approaches

A three‐step optimization strategy, which includes a one‐factor‐at‐a‐time classical method and different statistical approaches [Plackett–Burman design and RSM (response surface methodology)], were applied to optimize the antioxidant potential of Aspergillus terreus. Antioxidant activity was assayed by different procedures and compared with TPC (total phenolic content). Primarily, different carbon and nitrogen sources were screened by classical methods, which revealed sucrose and NaNO3 to be the most suitable. The significance of the components of Czapek Doxs medium with respect to antioxidant activity was evaluated with the Plackett–Burman design, which supported sucrose and NaNO3 to be the most significant. In a second step, sucrose and NaNO3 along with temperature were further taken as three variables for RSM to study their interaction. Response surface analysis showed 4% sucrose, 0.1% NaNO3 and an incubation temperature of 30 °C to be the optimal conditions. Under these conditions, the antioxidant potential assayed through the different procedures was 88.1, 74.9 and 70.2% scavenging effect for DPPH (1,1‐diphenyl‐2‐picryl hydrazyl) radical, ferrous ion and nitric oxide ion respectively. The reducing power showed an absorbance of 2.0 with 71.5% activity for the FRAP (ferric reducing antioxidant power) assay. TPC under different physio‐chemical conditions and antioxidant potential under various assay procedures correlated positively.