Optimized extraction, composition, antioxidant and antimicrobial activities of exo and intracellular polysaccharides from submerged culture of Cordyceps cicadae

Abstract

Background

Cordyceps cicadae is known as Jin Chan Hua in Traditional Chinese Medicine and known to possess different pharmacological activities. Presently, it was collected from the wild and isolated. Mycelial culture was optimized for extraction of polysaccharides under submerged culture conditions. Besides antioxidant, antibacterial activities of extracted polysaccharides were tested for first time.

Methods

Exo-polysaccharides (EPS) and intracellular polysaccharides (IPS) production was tested under different factors (medium capacity, rotation speed, pH, incubation time, temperature, carbon, nitrogen, minerals sources and carbon to nitrogen ratio) by orthogonal experiments using one-factor-at-a-time method. Monosaccharides composition of polysaccharides produced by C. cicadae was determined using high performance liquid chromatography. Antioxidant and antimicrobial activities on eight bacterial strains were checked by different standard procedures.

Results

Factors viz., medium capacity, rotation speed, incubation time, pH and temperature affected the EPS and IPS production under submerged culture conditions. EPS and IPS production was observed to vary with different carbon and nitrogen sources as well as C/N ratio. Glucose was the major component of polysaccharides (63.10 ± 4.15 %). Extracted EPS and IPS showed higher antioxidant potential with significant DPPH radical scavenging activity, ABTS radical scavenging activity, reducing power and iron chelating activity. Antimicrobial activities of EPS and IPS varied among the tested bacterial strains. IPS showed slightly higher inhibition rate to all the tested bacterial strains as compared to EPS. Maximum inhibition zones of IPS (12.9 ± 0.2 mm) and EPS (12.5 ± 0.3 mm) was observed against Pseudomonas aeruginosa at 10 % con. However, both EPS and IPS fractions showed broad spectrum for all the pathogenic microbial strains tested. The MIC of both the extracts ranged from 60–100 mg/mL.

Conclusions

EPS and IPS production from submerged culture of C. cicadae with significant antioxidant and antibacterial potential can be enhanced with the combination of several factors which can be used for large scale industrial fermentation of C. cicadae.