Evaluation of Several Microalgal Extracts as Bioactive Metabolites as Potential Pharmaceutical Compounds Ceren Gürlek, Çağla Yarkent, Ayşe Köse, İzel Oral, Suphi Ş. Öncel, and Murat Elibol Abstract The nature derived therapeutics is getting intense atten- tion rather than chemical synthesis and synthetic ones. Today the expansion of natural bioactive molecule market is started to be dominated and generic drug and therapeutic understanding looks like to leave its place to a new horizon. Thus, natural originated therapeutics under controlled production conditions are of importance. Besides the public attention on natural molecules are also gain advance and the demand on this bioactive molecules is also increasing dramatically. The bioactive molecules from microalgae show antioxidant, antibacterial, antiviral, anticancer, skin regenerative, sunscreen, antihypertensive, neuroprotective and immunostimulatory effects which are favorable for pharmaceutical, nutraceutical and cosmetics industry. Also a new concept known as functional nutrition also broaden the acceptability and utilization of microalgae derived bioactive metabolites in new dietary formulations. The expansion of microalgal biotechnology and the number of research gained from the role of biologically active microalgal metabolites display the emergence of the microalgae farming for new pharmaceutical formulations. In this study, we prepared solvent and water extracts of G. sulphuraria, N. texensis, S. bacillaris, E. carotinosa, C. minutissima, S. limacinum, C. cohnii, and C. vulgaris. Antioxidant activity using DPPH radical scavenging activity and total phenolic compounds were measured from the methanolic extracts and water extracts. With the bioactive extracts cytotox- icity test were performed on Hep-G2 and B16-F10 cell lines. The results display potential onset of novel therapeutic compounds derived from microalgae. Keywords Microalgae  Cyanobacteria  Bioactivity  Pharmaceutical  Extraction 1 Introduction The natural sources are becoming a sustainable and reliable resource in order to develop new pharmaceuticals with its high potential of patentability criteria and formulation [1]. Microalgae as being one of the promising source in single cell protein market is also a promising volunteer with its biologically active molecules [2]. Microalgae are the simple microscopic autotrophic photosynthetic organisms, ranging from unicellular to multi-cellular forms in aquatic environ- ments. In contrast to microalgae do not have real embryos, roots, stems and leaves. They have the competence to use utilize water, sun-light and CO 2 to synthesize biomass through photosynthesis. For a long time ago humans started to consume microalgae for dietary purposes as well as a source for tra- ditional medicine and cosmetics [3]. The benefits and health promising characteristics of microalgae derive from the essential fatty acids, proteins, peptides, free amino acids, minerals, polysaccharides, carotenoids, phenolic compounds and other microalgae specific molecules [4–6]. However the biologically active molecules of microalgae opened a new era in bioactive metabolites for pharmaceutical and cosme- ceutical purposes [7]. Microalgal compounds show antioxidant, antibacterial, antiviral, anticancer, skin regenerative, sunscreen, antihy- pertensive, skin whitening, immunomodulatoray, neuropro- tective and immunostimulatory effects which are favorable for pharmaceutical, nutraceutical and cosmetics industry [4, 5, 8]. Also a new concept known as functional nutrition also broaden the acceptability and utilization of microalgae derived bioactive metabolites in new dietary formulations [9]. The expansion of microalgal biotechnology and the C. Gürlek  Ç. Yarkent  A. Köse (&)  İ. Oral  S. Ş. Öncel  M. Elibol Department of Bioengineering, Ege University, 35100 İzmir, Turkey e-mail: ayse.kose@ege.edu.tr © Springer Nature Switzerland AG 2020 A. Badnjevic et al. (eds.), CMBEBIH 2019, IFMBE Proceedings 73, https://doi.org/10.1007/978-3-030-17971-7_41 267