Spirulina platensis is a microalga that contains a lot of secondary metabolites and is utilized as a dietary supplement. It can inhibit fat peroxidation better compared to the chemical antioxidant. Laboratory-scale closed reactor system was designed for Spirulina cultivation. This research aims to analyze identified secondary metabolite (Phytochemical contents) and the antioxidant activity or value of Inhibition Concentration 50% (IC50) of the fresh lab-scale cultivated Spirulina platensis. The antioxidant content was evaluated using DPPH method (1,1–diphenyl-2-pikrilhidrazil) on various sample concentrations as well as using Vc (Ascorbic Acid) as a positive control. The principle of hydrogen absorption by free radicals from antioxidants was demonstrated with the absorption value using a spectrophotometer at a wavelength of 517 nm. The results show that Spirulina platensis lab-scale cultivation was resulting in 5.0±0.01 g/10.0 L wet basis on the 10th day. The results show that Spirulina platensis has positive compounds of flavonoid, steroids, triterpenoids, phenolic, and saponins. Fresh Spirulina platensis has a value of IC50 647.045 ppm and Vc as a positive control has the IC50 of 2.085 ppm. The potential as a source of natural antioxidants was categorized as a very weak capacity. Therefore this study can be concluded that Spirulina platensis cultivated in Laboratory-scale has a potential to act as antioxidant candidate.
Oktaviani et al. (Sat,) studied this question.