## 3 Results and Discussion
### Yield of Extraction of Bioactive Compounds from the Microalgae Biomass  
The extraction yields of bioactive compounds from the various microalgae species ranged from 11.64 \(\pm\) 0.28% to 52.96 \(\pm\) 3.25% (Table 4). _Dunaliella_ sp. exhibited the highest extraction yield among the microalgae studied, using hydroalcoholic ultrasound-assisted extraction, followed by _Odontella_ sp. (Table 4). The lowest yields were recorded for _Tetraselmis_ sp. and _Limnospira_ sp.  
[PERSON] et al. [42] reported a water extraction yield of 35 \(\pm\) 1% (37 \({}^{\circ}\)C, 60 min) from dried spirulina (_Limnospira_ sp.), which is higher than that observed in the present study (Table 4). However, their subsequent ethanol (96%) extraction yielded 9.6 \(\pm\) 0.2%, which is closer to the values obtained here. [PERSON] et al. [39] performed both aqueous and 80% ethanol extractions on dried spirulina powder, with the resulting extracts containing varying concentrations of carotenoids, chlorophyll \(a\), total phenols, flavonoids, phycocyanin, free amino acids, total proteins, and carbohydrates.  
[PERSON] et al. [40] carried out an ethanol extraction from dried _Dunaliella_ sp., obtaining yields of 8.8% (ethanol), 6.1% (hexane), and 17.0% (chloroform/methanol, 1:1). These values are lower than those reported in the present study, underscoring the influence of solvent polarity on extraction efficiency. Among all analyzed microalgae, _Dunaliella_ sp. consistently exhibited the highest extraction yield.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Microalgae Species** & **Yield of Extraction (\%)** \\ \hline _Limnospira_ sp. & 12.67 \(\pm\) 0.88 d \\ _Dunaliella_ sp. & 52.96 \(\pm\) 3.25 a \\ _Lobosphaera_ sp & 15.48 \(\pm\) 1.35 d \\ _Nannochloropsis_ sp. & 27.72 \(\pm\) 0.76 bc \\ _Odontella_ sp. & 31.01 \(\pm\) 0.57 b \\ _Porphyridium_ sp. & 26.12 \(\pm\) 0.86 c \\ _Tetraselmis_ sp. & 11.64 \(\pm\) 0.28 d \\ \hline \hline \end{tabular} Different letters mean significant differences (\(p<0.05\)). Three replicates.  
\end{table}
Table 4: Yield of extraction of bioactive compounds from the microalgae biomass.  
Figure 2: Composition of the microalgae biomass.  
[PERSON] et al. [43] reported an extraction yield of 23.33% using an ethanolic solution for _Nannochloropsis_ sp., which is comparable to the 27.72% obtained in the present work.  
[PERSON] et al. [44] achieved yields of 20.4% using a 70% hydroethanolic solution and 23.4% with hot water (125 \({}^{\circ}\)C, 15 min) for _Odontella_ sp., both of which are lower than the 31.01% yield found in the present study.  
[PERSON] et al. [45] conducted water extraction (25 \({}^{\circ}\)C, 60 min) on freeze-dried _Porphyridium cruentum_ powder, resulting in a yield of 36.14 \(\pm\) 0.18%, which exceeds the 26.12% yield reported here.  
[PERSON] et al. [46] obtained a yield of 21.7% from freeze-dried _Tetraselmis suecia_ using methanol and a protease enzyme, which is significantly higher than the 11.64% yield observed in the current study.  
[PERSON] et al. [47] generally reported improved extraction efficiencies with ultrasound-assisted extraction compared to conventional methods. The use of enzymes and thermal treatment also contributed to enhance yields. Similarly, [PERSON] et al. [34] observed increased extraction efficiency when using viscoenzyme and cellulase.