Influence of culture age on the phytochemical content and pharmacological activities of five Scenedesmus strains
Five axenic Scenedesmus strains (MACC-411, MACC-422, MACC-493, MACC-720, and MACC-727) were cultured and harvested after 5 and 10 days in culture. Using colorimetric methods, the concentrations of total phenolic, condensed tannin, and iridoids in 50 % methanol extracts from both 5- and 10-day-old cultures were quantified. Different solvent extracts from the strains were also tested for antioxidant, acetylcholinesterase inhibitory (AChEI), and antimicrobial activities using various in vitro test systems. Phenolic content was highest (3.6 ± 0.42 mg GAE g−1 DW) in 10-day-old MACC-727. This was approximately fourfold and significantly higher than in the 5-day-old cultures of MACC-727. Among the tested Scenedesmus strains, 5-day-old MACC-411 had the highest iridoid content (3.4 ± 0.3 mg HE g−1 DW), and this was significantly higher than the level detected in the 10-day-old MACC-411. Scenedesmus strains showed better antioxidant potential in the β-carotene–linoleic acid model compared to the DPPH free radical scavenging assay. The AChEI activity (IC50 μg mL−1) in all strains (besides MACC-422) was higher in 10-day-old cultures compared to the 5-day-old cultures. Although a broad-spectrum of antibacterial activity was observed, the tested microalgae strains demonstrated varying degrees of antimicrobial potential depending on the harvest time, strain-type, and extracting solvent. Thus, the Scenedesmus strain and time of harvest played a significant role in determining their phytochemical content and resultant pharmacological activity. The promising bioactivity in the tested Scenedesmus strains indicates their potential as possible sources of novel/alternative antioxidants and AChE inhibitors.
KeywordsAcetylcholinesterase Antimicrobial Antioxidant Chlorophyceae Microalgae Natural product
AOA is grateful for the financial support from the Claude Leon Foundation, Cape Town, South Africa. NAM was supported by the National Research Foundation, Pretoria, South Africa. The University of KwaZulu-Natal, Pietermaritzburg, South Africa is thanked for financial support. This work was also supported by the New Széchényi Plan, TÁMOP-4.2.2.A-11/1/KONV-2012-0003 Microalgal Biotechnology in Sustainable Agriculture.
- Abedin RMA, Taha HM (2008) Antibacterial and antifungal activity of cyanobacteria and green microalgae. Evaluation of medium components by Plackett–Burman design for antimicrobial activity of Spirulina platensis. Global J Biotech Biochem 3:22–31Google Scholar
- Aremu AO, Amoo SO, Ndhlala AR, Finnie JF, Van Staden J (2011) Antioxidant activity, acetylcholinesterase inhibition, iridoid content, and mutagenic evaluation of Leucosidea sericea. Food Chem Toxicol 49:1122–1128Google Scholar
- Makarevičienė V, Andrulevičiūtė V, Skorupskaitė V, Kasperovičienė J (2011) Cultivation of microalgae Chlorella sp. and Scenedesmus sp. as a potentional biofuel feedstock. Environ Res Eng Manag 3:21–27Google Scholar
- Nair BB, Krishika A (2011) Antibacterial activity of freshwater microalga (Scenedesmus sp.) against three bacterial strains. J Biosci Res 2:160–165Google Scholar
- Ördög V (1982) Apparatus for laboratory algal bioassay. Int Rev Ges Hydrobiol 67:127–136Google Scholar