Stress influenced increase in phenolic content and radical scavenging capacity of Rhodotorula glutinis CCY 20-2-26

Rhodotorula glutinis CCY 20-2-26 when grown under controlled stress of either NaCl (1-5 %) or H₂O₂ (1-5 mM) on basal media exhibited a twofold increase in its total phenolic contents. The radical scavenging capacities (RSCs) as determined by ABTS test were found to be highest in 4 mM H₂O₂ (1.44 mM TEAC mg^-1) and 4 % NaCl (1.13 mM TEAC mg^-1) as compared to control samples (0.41 mM TEAC mg^-1). Similarly, the RSCs as determined by DPPH test were also highest in 4 % NaCl (1.83 mM TEAC mg^-1) and 4 mM H₂O₂ (1.78 mM TEAC mg^-1) compared to control (0.48 TEAC mg^-1). The relative RSCs from EPR spin-trapping assay for H₂O₂-stressed cultures were highest in 1 mM H₂O₂ (56.1 μM TEAC g^-1) whereas in NaCl-stressed cultures it was highest in 5 % NaCl (44.6 μM TEAC g^-1) as compared to control (30.9 μM TEAC g^-1). Five phenolic compounds (gallic acid, benzoic acid, catechin, caffeic acid and ferulic acid) were detected for the first time in R. glutinis CCY 20-2-26.