Many chemicals extracted from marine organisms have different mechanisms of antitumor and cell growth effects (Lichota and Gwozdzinski 2018). In the present study, methanol was used to maximize the potential for extracting organic components from each sample.
Cancer starts when cells begin to grow out of control. Melanoma one of the most problematic cancers starts in certain skin cells (melanocytes) and can develop anywhere on the skin.
Ning and Andl (2013) reported the significant roles of microRNAs on the pathogenesis of some skin cancers such as squamous cell carcinoma (SCC) and melanoma.
In melanoma, the over expression of miR-182 promotes survival, migration, and metastasis repressed by the tumor suppressor FOXO3 and microphthalmia-associated transcription factor-M, while its expression increases with the development from primary to metastatic melanoma (Segura et al. 2009).
The most active anticancer compounds include the psammaplin isolated from marine microalgae, cyanobacteria, and heterotrophic bacteria (Lichota and Gwozdzinski 2018). In addition, the alkaloids from marine algae produce anticancer compounds (Güven et al. 2010; Tohme et al. 2011). Polyphenols and polysaccharides are extracted from marine flora (Boopathy and Kathiresan 2010). Further, bryostatins, halichondrins, spongistatin, discodermolide, hemiasterlins, and salinosporamides derived from the marine organism metabolites exhibit cytostatic activity. Some researchers outlined the antiproliferative activity of the 3-Epi-29-hydroxystelliferin E derivative of stelliferin against melanoma cells (MALME-3M) (Meragelman et al. 2001). In fact, this compound is an isomalabaricane- type triterpenoid, which is extracted from the sponge Jaspis stellifera (McCabe et al. 1982). According to Berge et al. (2002), the sulfolipid classes (SLs) in the total lipids of Porphyridium cruentum (S.F.Gray) Nägeli show inhibitory effects on malignant melanoma (M4 Beu) cancer cells. The sulfolipids in algae were considered to be high in palmitic acid (C16:0) in Galaxaura cylindrica (J. Ellis & Solander) J.V. Lamouroux and Taonia atomaria (Woodward) J.Agardh. Furthermore, sulfoquinovosyl-di-acylglycerol and sulfoquinovosylacylglycerol (SQAG) have been recognized as the main sulfolipids in algae (El Baz et al., 2013).
The results of our GC-MS analysis demonstrated several important sources of anticancer agents. The compounds were effective in vitro due to their anti-proliferative activities against melanoma and fibroblast cell lines. In addition, 1,4-benzenedicarboxylic acid,1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester, diisooctyl ester, ethylhexyl methyl phthalate (1,2-benzenedicarboxylic acid, butyl methyl ester), and butyl octyl ester were found in the fractions from P. boergeseni and P. myrica. The compounds have been reported in many medicinal plants (Save et al. 2015; Beulah et al. 2018) and in red algae such as Jania rubens (L.) Lamouroux, Corallina mediterranea J.E. Areschoug and Pterocladia capillacea (S.G. Gmelin) Bornet (El-Din and El-Ahwany 2016).
1,2-benzenedicarboxylic acid and diisooctyl ester have found in Allium autumnale, which is associated against two human breast cancer cell lines MDA-MB-231 and MCF-7 (Isbilen et al. 2018). Furthermore, 1,2-benzenedicarboxylic acid showed effectiveness on human prostate, breast, and colon cancers with strong immunomodulatory B-cell stimulation (Save et al. 2015).
Wang and Tao (2009) suggested the antitumor activities of 1, 4-benzenedicarboxylic acid, dimethyl ester, as the volatile component of Stigmatella WXNXJ-B, on mouse melanoma cell lines. According to Kannabiran et al. (2014), 1 2-benzenedicarboxylic acid, mono 2-ethylhexyl ester from marine Streptomyces sp. VITSJK8 exhibits above 80% the cytotoxic activity on the growth of mouse embryonic fibroblast cancer cell lines and normal human keratinocytes.
The human melanoma cell lines are more resistant to the toxic effect of fatty acids. Cytotoxicity is observed in SK-Mel 23 cells after treatment with arachidonic, linoleic (LA), palmitic, and palmitoleic acids (Andrade et al. 2005). Palmitic acid or hexadecanoic acid is the most common saturated fatty acid in the fractions of G. salicornia and P. myrica, and the second most common compound in the fractions of P. boergesenii.
Octadecanoic acid, methyl ester, 9, 12-octadecadienoic acid, methyl ester, and 9-octadecenoic acid, methyl ester were identified also in the detected fractions.
Altuner et al. (2018) emphasized the antimicrobial bioactivity of 9,12-octadecadienoic acid. Additionally, 9,12-octadecadienoic acid plays an inhibitory role in the metabolites of cancer metastasis (Horrobin and Ziboh 1997, Maggiora et al. 2004). Researchers proposed different anticancer activities for 9,12-octadecadienoic acid. In low concentration it stimulates cell proliferation in the human breast cancer and lung cancer cell lines in vitro, as well as promoting colon and prostate tumorigenesis, and tumor growth in animal models (Xu and Qian 2014). Horrobin and Ziboh (1997) reported the endogenous conversion of 9, 12-octadecadienoic acid into various downstream ω-6 PUFAs. Thus, the effects of 9, 12-octadecadienoic acid on cancer growth can actually be related to a combination of the effects of its downstream products.
Lu et al. (2010) showed that the relative resistance of colorectal cancer cell lines to the cytotoxic action of 9, 12-octadecadienoic acid is related to its concentration and a reduction in caspase-3 activation which induces cancer cell apoptosis. Kachhap et al. (2000) observed a synergistic effect of linoleic acid and endogenous estrogen in a diet rich in ω-6-polyunsaturated fatty acid which may modulate BRCA1 gene expression thereby promoting breast cancer.
9-octadecenoic acid or oleic acid has the potential of antibacterial and antifungal activities (McGraw et al. 2002). Regarding the present study, it was the second most abundant component of P. boergesenii (P1) and G. salicornia (G2 and G3) although no significant effect was obtained for the fractions P1 of P. boergesenii and G3 of G. salicornia on melanoma cell lines.
Based on the 1H NMR spectra of the third fraction (P3 and G3) in the methanol extract of P. boergesenii and G. salicornia, all protons appeared at high field and low chemical shifts, which can be attributed to aliphatic protons rather than aromatic ones. Finally, the compounds detected in the two fractions possessed aliphatic protons and were devoid of any aromatic substitution.
The present research has shown that additional and continued exploration of the diverse chemicals produced by the metabolism of marine algae may continue to result in discovery and identification of new resources of potential benefit to human health and welfare.