Abstract
This study was designed to evaluate the potential use of algal extracts in cosmeceuticals, including factors related to biosecurity. The aqueous crude extracts of Hydropuntia cornea and Gracilariopsis longissima showed a good photoprotective capacity (Sun Protection Factor, SPF) due to, among other reasons, the presence of five types of mycosporine-like amino acids (MAAs) detected by high pressure liquid chromatography-photodiode array detector (HPLC-PDA) and electrospray ionization mass spectrometry (ESI-MS) (Palythine, Asterina-330, Shinorine, Porphyra-334, and Palythinol). The toxicity of the extracts was evaluated by the MTT assay, which is based on the metabolic reduction of MTT [3-(4,5-dimethylthiazol-2yl)-diphenyl tetrazolium bromide] by the action of the mitochondrial enzyme succinate dehydrogenase. This assay was carried out in vitro in three cell lines: one related to the immune system (murine macrophages of the immune system: RAW264.7) and two human cell lines related to the skin (gingival fibroblasts: HGF, and immortalized human keratinocytes: HaCaT). Both extracts showed no cytotoxic activity in both types of human cells, whereas they showed cytotoxicity in murine tumor cells of the immune system (macrophages: RAW264.7). On the other hand, the immunological activity in the murine macrophage RAW264.7 was studied at a concentration lower than 100 μg mL−1 and lower than the EC50, and evaluated by the production of pro-inflammatory compounds through an immunosorbent assay linked to enzymes such as tumor necrosis factor-α (TNF-α) or anti-inflammatory/proinflammatory enzymes such as interleukin-6 (IL-6). Both algae extracts induced the biosynthesis of TNF-α and IL-6. The production of TNF-α was much higher than that observed in the control (at a concentration of the aqueous extract higher than 5 μg mL−1). These results support the theory that the extracts of H. cornea and G. longissima actively induce the production of cytokines. In summary, the extracts of these species did not show cytotoxicity in human cells, and they present with immunomodulatory and photoprotection capacity.
Highlights
The cytotoxic effects of algal extracts on different cell lines are currently being studied largely due to the safety requirements of the cosmetic industry [1,2]
Based on their on-line UV-visible absorption spectra and mass spectrometry, mycosporine-like amino acids (MAAs) were identified in both algae as Palythine (UV λmax 320 nm, m/z 245.11290 in H. cornea and 245.11290 in G. longissima), Asterina-330 (UV λmax 331 nm, m/z 289.13889 and 289.13895), Shinorine
This study shows that aqueous extracts of G. longissima and H. cornea stimulate the production of cytokines of both tumor necrosis factor-α (TNF-α) and IL-6 in macrophages of the cell line RAW264.7
Summary
The cytotoxic effects of algal extracts on different cell lines are currently being studied largely due to the safety requirements of the cosmetic industry [1,2]. Within these studies, cytotoxic activity in cancer and tumor cell lines has become one of the most important specificities of algae; many species have shown such bioactive effects [3,4]. The main role of TNF-α is the regulation of immune cells, and in addition it can act to reduce viral replication [12] This cytokine is involved in systemic inflammation and stimulates the acute phase reaction. Its production is induced by several factors, including TNF-α, IL-1β, and bacterial endotoxin lipopolysaccharides [14]
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