# Microalgae as Potential Sources of Bioactive Compounds for Functional Foods and Pharmaceuticals
## 3 Results and Discussion
### Evaluation of Bioactivities of Microalgal Extracts
#### 3.1.3 Anti-Tumoral Activity  
Cytotoxicity activity against HepG2 and S17 cell lines was performed only for the EA from _Phaeodactylum tricornutum_, _Porphyridium_ sp., _Skeletonema_ sp., _Nannochloropsis_ sp., _Tetraselmis striata_ CTP4 and _Tisochrysis lutea_ as it was previously found that non-polar extracts are generally richer in cytotoxic compounds [52]. Additionally, the ethanol extracts of PHA and TIL were tested (Table 6). Best results were obtained at the highest concentration tested (125 ug/mL) at which extracts from PHA, TIL, SKE and POC were able to decrease cell viability of HepG2 down to 6.44%, 4.92%, 4.88% and 14.2%, respectively. Extracts from NANNO and TCTP4 did not significantly affect HepG2 cell viability. \begin{table}
\begin{tabular}{c c c c} \hline
**Microalga** & **Extract** & **\% Ca2+ CA** & **IC50 (mg/mL) for Ca2+ CA** \\ \hline _Porphyridium_ sp. & W & 28.6 \(\pm\) 0.01 & n.d. \\ (POC) & ET & 75.8 \(\pm\) 0.08 & 0.0519 \(\pm\) 0.0019 a  \\  & EA & 67.3 \(\pm\) 1.30 & 0.150 \(\pm\) 0.004 c  \\ \hline _Nannochloropsis_ sp. (NANNO) & W & 13.2 \(\pm\) 1.48 & n.d. \\  & ET & 15.5 \(\pm\) 0.59 & n.d. \\  & EA & 7.98 \(\pm\) 0.15 & n.d. \\ \hline _Tetraselmis striata_ CTP4 & W & 58.6 \(\pm\) 1.50 & n.d. \\ (TCTP4) & ET & 54.7 \(\pm\) 1.07 & n.d. \\  & EA & 12.3 \(\pm\) 0.26 & n.d. \\ \hline _Tisochrysis lutea_ & W & 6.67 \(\pm\) 0.46 & n.d. \\  & ET & 52.8 \(\pm\) 0.63 & n.d. \\  & EA & 38.0 \(\pm\) 0.12 & n.d. \\ \hline _Phaeodactylum tricornutum_ & W & 47.4 \(\pm\) 0.49 & n.d. \\ (PHA) & ET & 35.2 \(\pm\) 0.97 & n.d. \\  & EA & 48.1 \(\pm\) 0.50 & n.d. \\ \hline _Skeletonema_ sp. & W & 24.3 \(\pm\) 0.75 & n.d. \\ (SKE) & ET & 87.8 \(\pm\) 1.66 & 0.0638 \(\pm\) 0.0038 a  \\  & EA & 86.7 \(\pm\) 1.58 & 0.0906 \(\pm\) 0.0001 b  \\ \hline _Spirulina_ & W & 7.12 \(\pm\) 0.30 & n.d. \\ (SPR) & ET & 48.8 \(\pm\) 0.37 & n.d. \\  & EA & 19.4 \(\pm\) 0.30 & n.d. \\ \hline _Tetraselmis chui_ & W & 23.1 \(\pm\) 1.98 & n.d. \\  & ET & 48.9 \(\pm\) 0.44 & n.d. \\  & EA & 57.0 \(\pm\) 1.98 & n.d. \\ \hline _Haematococcus pluvialis_ & W & 8.12 \(\pm\) 0.76 & n.d. \\  & ET & 0.70 \(\pm\) 0.12 & n.d. \\  & EA & 2.40 \(\pm\) 0.76 & n.d. \\ \hline EGTA * & - & 85.9 \(\pm\) 0.42 & n.d. \\ \hline \end{tabular}  
* Positive control, EGTA, 0.06 mg/mL. Presented values are mean with standard deviation and extracts with different superscript letters (a, b, c, d) are significantly different from each other (\(p\) < 0.05). ET = Ethanol; H = Hexane; DCM = dichloromethane; EA = ethyl acetate. \(n\) = 3.  
\end{table} 
Table 4: Calcium chelating activity (Ca2+ CA) of water (W), ethanol (ET) and ethyl acetate (EA) extracts of different microalgae species tested at 0.6 mg/mL (%) and IC50 (mg/mL) of the most active extracts. Given the low selectivity observed for the promising cytotoxic ethyl acetate extracts of PHA and TIL, the ethanol extracts were also tested (Table 6) [30]. The ethanolic extract of _Phaeodactylum tricornutum_ (PHA ET) displayed higher toxicity and selectivity than the ethyl acetate extract, however, the result was not the same for TIL. \begin{table}
\begin{tabular}{c c c c c c} \hline  & & & **Cell Line** & & **Selectivity Index** \\ \hline
**Microalgae** & **Extract** & **HepG2** & **S17** & **THP-1** & **HepG2 vs. S17** & **THP1 vs. S17** \\ \hline _Phaeodactylum_ & & & & & \\ (PHA) & & & & & \\ \hline _Porphyridium_ sp. & EA & 42.3 \(\pm\) 2.7 b  & \textgreater{}125 c  & n.d. & \textgreater{}2.7 a  & n.d. \\ (POC) & EA & 44.7 \(\pm\) 3.1 b  & 79.2 \(\pm\) 2.7 b  & n.d. & 1.77 \(\pm\) 0.09 c  & n.d. \\ (TIL) & EA & 37.2 \(\pm\) 3.6 a  & 34.8 \(\pm\) 5.4 a  & n.d. & n.s & n.d. \\ \hline _Nanochloropsis_ & & & & & \\ sp. (  
As the ethanol extract of _Phaeodactylum tricornutum_ had the highest selectivity towards HepG2 cells, which are known to be resistant to most anticancer drugs [53], this extract was used in the cytotoxicity assessment towards the THP-1 cell line. However, this extract was also neither toxic nor selective between THP-1 and S17 cells.