# Pharmacological and Cosmeceutical Potential of Seaweed Beach-Casts of Macaronesia
## 3 Results and Discussion
### Anticancer Activity  
All beach-cast seaweeds extracts and fractions were evaluated for their cytotoxic activity against four cell lines representing the most frequent cancer types in our population, i.e., lung (NCI-H1299), prostate (DU145), breast (T47D), and colon (HT29) [40]. The samples were assayed against the NCI-H1299 cell line, a non-small-cell lung cancer, one of the most aggressive forms of cancers with few effective therapeutic drugs available. Twenty-one samples (fourteen extracts and seven fractions) showed interesting results (Figure 1), namely some samples which displayed cell survival values of 27-31%. For the 16 samples displaying the lowest cell survival (Figure 1), the IC\({}_{50}\) values (concentration that causes a 50% growth inhibition of the cell population) were calculated (Table 2) to learn more about their cytotoxic potential. The results showed very promising samples, since six of the IC\({}_{50}\) values are near or below 20 ug/mL, an established threshold to consider an extract active, used in this study as a selective value to discard samples with low or no activity [18], four of them exhibiting IC\({}_{50}\) values between 11.38 ug/mL to 13.13 ug/mL, which means high cytotoxic activity. A report with Pylaiella litterorialis_ (Ochrophyta, Phaeophyceaeae) seaweed extracts showed anticancer activity against various cancer cell lines, including NCI-H1299, reporting large cell survival values of ca. 80% for this cell line, but higher antiproliferative activity (ca. 20% cell survival) for the HT-29 colon cancer cell line. However, unlike the present study, this investigation assayed high extract concentrations of 100 ug/mL [41]. Phycocyanin, a pigment extracted from _ArthInospira platensis_ (formerly _Spirulina platensis_) (Cyanobacteria) but which also exists in red macroalgae, was reported to inhibit NCI-H1299 cell growth by inducing cell morphological changes, apoptosis, inhibition on cell migration and cell cycle arrest [42],  
Most cancer drugs display low selectivity for the target cancerous cells generating cytotoxicity to healthy ones, with many unwanted and often severe side effects to patients [43]. Thus, finding compounds or samples with attractive selectivity indexes (SI) would assist in developing more selective cancer drugs. Selectivity index was calculated for the most active samples to determine the prevalence of the samples to inhibit more specifically cancer cells instead of normal cells. The SI values were calculated \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**IC\({}_{50}\) (\(\mu\)g/mL)**} \\ \hline
**Sample** & **Lung NCIH1299** & **Prostate DU145** & **Breast T47D** & **Colon HT29** & **Vero** \\ \hline  
30 & 20.04 & 47.90 & 53.10 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: IC\({}_{50}\) values of samples showing anticancer activity against different cancer cell lines studied. Figure 1: Cell survival against NCI-H1299 lung cancer cell line of samples (beach-cast extracts and fractions) tested at two concentrations (20 ug/mL and 50 ug/mL). Adriamycin at 5.43 ug/mL was used as reference. applying the formula SI = IC\({}_{50}\) Vero cell line/IC\({}_{50}\) cancer cell line for all strongest cancer inhibiting samples of this study. An SI value lower than 2 is considered to induce general toxicity to normal cells, while those with larger SI values present selectivity for the indicated cancer cells [44]. As shown in Table 3, 13 samples showed SI larger than 2, with some of them as high as 7. The most interesting were the four samples 1.M.1, 1.E.2, 11.E and 12.E, which exhibit the lowest IC\({}_{50}\) values (11.38 \(\upmu\)g/mL to 13.13 \(\upmu\)g/mL) and the highest SI values (from 4.7 to higher than 7.0), indicating a very promising cytotoxic action allied with an attractive selectivity of these samples to attack and inhibit growth of lung cancer cells compared with control Vero cells.