# Microalgae as Potential Sources of Bioactive Compounds for Functional Foods and Pharmaceuticals
## 3 Results and Discussion
### Chemical Characterization of Promising Microalgal Extracts' Fractions
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & \multicolumn{3}{c}{**Relative Abundance (\%)**} \\ \hline \multirow{3}{*}{**Compounds**} & _Porphyridium_ sp. (POC ET) & _Skeletonema_ & _triromutum_ & _Tetraselmis striata_ \\  & **(POC ET)** & **sp. (SKE ET)** & **(PHA ET)** & **CTP4 (TCTP4)** \\  & **-Hexane Fraction** & **-Hexane Fraction** & **-Dichloromethane** & **-Hexane Fraction** \\  & & & **Fraction** & \\ \hline Chloresterol & & 6.66 & & \\ \hline
24-methylcholesta-5,22- & & & & \\ dien-3ß-ol (Brassicated) & & 1.21 & & \\ \hline Ergosta-5,22-dien-3-ol, & & & & \\ acetate (Brassicated) & & & 0.76 & \\ acetate () & & & & \\ \hline Cholestera-5,22-dien-3- & & & & \\ ol, & 2.56 & & & \\ (3ß) & & & & \\ \hline Tetrapentacontane, & & & 3.04 & \\
1,54-dibromo- & & & & \\ \hline dl-\(\alpha\)-Tocopherol & & 1.16 & 0.34 & \\ \hline Pregna-5,9(11)-dien-20- & & & & \\ ol-3-one ethylene & & & & \\ ketal & & & & \\ \hline Tetrahydro-2H-pyran & & 0.98 & & \\ \hline
3-Hexadecyme & & 0.53 & & \\ trans-octadecidenoic & & 6.12 & & \\ acid & & & & \\ \hline
3,6,6-trimethyl-2- & & & & \\ Norpinanol & & & & \\ \hline
2-methyl-5-pentyl- & & & & \\ tetrahydrofuran & & & & \\ \hline Tetrahydropyran & & & & \\
12-tetradoyn-1-ol ether & & & & \\ \hline
3,28-bis([tetrahydro) & & & & \\ Lup-20(29)-en-21-ol & & & & \\ \hline (1-Methoxy-pentyl)- & & & & \\ cyclopropane & & & & \\ \hline
17-chloro7- & & & & \\ Heptadecene & & & & \\ \hline
5.alpha.-Androstan-3- & & & & \\ one, & & & & \\
17.beta.-hydroxy- & & & & \\
4.alpha.-methyl-, & & & & \\ \hline Cholesteran-3-one, & & & & \\
4,4-dimethyl-, cyclic 3 & & & & \\ \hline Total identified area & 51.51 & 78.00 & 86.96 & 83.46 \\ \hline Unknown compound & 0.19 & 1.00 & 1.05 & 0.74 \\ \hline Unresolved mixture of & & & & \\ compounds & 17.20 & 1.00 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: _Cont._Eight main chemical compound classes were identified, most of them of fatty acids, namely polyunsaturated fatty acids, saturated fatty acids, monounsaturated fatty acids, long-chain aliphatic hydrocarbons (alkanes and alkenes), long-chain alcohols, esters, ethers and sterols (Figure 3). Fatty acid composition varied greatly in the analyzed fractions and species. Whereas saturated fatty acids were the main compounds in hexane fractions of both _Porphyridium_ sp. and _Skeletonema_ sp., PUFAs were always the most abundant compounds in the analyzed fractions of _Phaodactylum tricornutum_ and _Tetraselmis striata_ CTP4, which is in accordance with previous studies [71; 72; 73; 74]. Microalgae are reportedly good sources of long-chain fatty acids, specially of PUFA. These compounds are probably responsible for a significant portion of the antioxidant, metal-chelating, anti-tumoral and anti-inflammatory activities exhibited by the fractions, considering that PUFA are reported to possess these bioactive properties and are well extracted with hexane and DCM [68; 69]. Furthermore, PUFAs have antiapoptotic activity and may be useful in delaying or preventing inflammatory, metabolic, neurodegenerative (by reducing neuroinflammation and preserving dopaminergic neurons), and neoplastic diseases, by modulating the production of inflammatory cytokines and pro-resolving or protective lipid mediators [75; 76]. Alcohols were the second most abundant compounds across all species, with special focus on 3, 7, 11, 15-tetramethyl-2-hexadecen-1-ol (Phyd), which have reported antimicrobial and anti-inflammatory action [77]. Some of the algal extracts examined contained significant amounts of long-chain aliphatic hydrocarbons, mostly in the form of n-alkanes (Table 8). It is reported that these types of compounds are produced naturally as a defense mechanism to protect the organism (mainly plants, insects, and cyanobacteria) from environmental threats [78], and despite some reports about their antioxidant, antibacterial and anti-cancer activity existing, overall evidence regarding their biological properties is still scarce [79; 80].