## 3 Results and Discussion
### Phytochemical Constituents of the Studied Seaweeds  
Carbohydrates, proteins, and lipids are the main biochemical components of algae. The proportion of each component varies from the taxonomic group (2019). The data in Figure 5 show the carbohydrates, protein, lipids, and fibers of the four studied seaweeds. The concentration of carbohydrates was higher in the species of Phaeophyceae, followed by Rhodophyceae. Carbohydrate contents of the studied seaweeds ranged from 20.17% to 38.62% DW. The greatest carbohydrate content was found in _T. ornata_ (38.62% \(\pm\) 0.11%), while the lowest was found in _L. obtusa_ (20.17% \(\pm\) 0.1%) of algal dry weight (Figure 5). Similarly, [PERSON] and [PERSON] (2019) and [PERSON] et al. (2019) recorded the highest carbohydrates content in brown seaweeds than in red seaweeds. Figure 4: DPPH radical scavenging activity, total antioxidant capacity (TAC), and total reducing capacity (TRC) of the tested seaweed species are expressed as inhibition percentages. Values are the mean of three replicates \(\pm\) standard deviations (SD). Different letters refer to significant differences between species (\(p\) < 0.05). Carbohydrates are necessary for organisms' metabolism because they supply energy, and they often contain high levels of polysaccharides such alginate and fucoidan in brown algae and carrageenanan and agar in red algae [46]. Polysaccharides are edible and described as an energy reserve and structural components of all organisms, including marine and higher plants. In seaweed, polysaccharides are the most significant macromolecule, which accounts for more than 80% of its weight. The protein content of seaweeds varies between 5% and 17% of DW (Figure 5). The largest protein content in the brown seaweeds (_P. indica_, 17.61\(\pm\) 0.14% and _T. ornata_, 10.32 \(\pm\) 0.10% of DW) and the lowest amounts in the red seaweeds (_L. obtusa_, 5.41\(\pm\) 0.11% and _S. scinaioide_, 7.52 \(\pm\) 0.13% of DW), as compared to other protein-rich meals derived from terrestrial plants, such as pulses (ex. _Phaseolus vulgaris_ and _Lens culinaris_) and moong dal (_Vigna radiate_), the obtained values were discovered to be complementary protein sources according to [PERSON] et al. [47]. These results are consistent with those of [PERSON] et al. [39], who reported that brown seaweeds species usually contain a larger protein fraction than red seaweeds. According to FAO [48], the daily protein intake should be 1 g/kg BW; hence, the selected seaweed would be a balanced protein with a high biological value of vital amino acids. According to [PERSON] et al. [49], the source of these variances might be that the protein content of seaweeds varies across species and within species according to levels of maturity, time of year, and different habitats. Seaweeds have comparatively low lipid content with wide variances among species [50]. Depending on the algal species, the lipid content of the four macroalgae investigated ranged from 1.12% to 3.04% (Figure 5). The red alga _L. obtusa_ had the highest lipid content (3.04 \(\pm\) 0.12% DW), followed by _S. scinaioides_ (2.03 \(\pm\) 0.08% DW), and the brown alga _T. ornata_ had the lowest (1.12 \(\pm\) 0.12% DW). Normally, seaweeds do not appear to be a suitable source of fat, with total lipid contents in most species being less than 4% of dry weight [51]. The results for _L. obtusa_ were similar to the total lipid percentage found in the two _Laurencia_ species previously investigated, which ranged from 1.1% to 6.4% DW ([PERSON] et al. [49] and [PERSON] et al. [37]. In contrast, [PERSON] et al. [47] observed that the highest content of lipid was detected in brown alga _Padina gympospora_ (1.4 g) and a low value found in red alga _Acanthophora spicifera_ (0.48 g). However, fat is necessary for  
Figure 5: Biochemical composition (% of DW) of the four studied seaweeds. Values are the mean of three replicates \(\pm\) standard deviations (SD). Different letters refer to significant differences between species (_p_ < 0.05).