# Marine Bioactives and Their Application in the Food Industry: A Review
## 2 Marine Sources of Bioactive Molecules
### Marine Algae
#### 2.2.3 Other Biomolecules from Marine Algae  
Some of the other valuable components originating from algae include pigments, phenolic compounds, and vitamins. Many of the pigments found in algae are photosynthetic compounds that are crucial for autotrophic organisms to capture solar energy during photosynthesis [82]. The principal types of photosynthetic pigments in marine life consist of phycobilproteins, carotenoids, and chlorophyls. Carotenoids act as potent antioxidants, neutralizing reactive oxygen species (ROS). In green algae, lutein, violaxanthin, \(\beta\)-carotene, zeaxanthin, and neoxanthin are abundant, while red algae predominantly contain lutein, \(\alpha\)- and \(\beta\)-carotenes, and zeaxanthin. In brown algae, violaxanthin, \(\beta\)-carotene, and fucoxanthin are prevalent [84]. Fucoxanthin, which is among the most abundant carotenoids, displays antioxidant, antidiabetic, antiangiogenic, antiviral, anticancer, and antiphotoaging properties, as well as anti-obesity effects. Other carotenoid derivatives like diatoxanthin, heterochromatin, peridin, and siphonaxanthin may also be present in algae [81]. Conversely, \(\beta\)-carotene, with provitamin A potential, has demonstrated cancer prevention abilities and a reduced risk of cardiovascular and ophthalmological ailments. Its antioxidant characteristics counteract the detrimental effects of free radicals, with naturally sourced microalgal \(\beta\)-carotene being more biologically active than its synthetic counterpart [85]. Tocopherol, a potent antioxidant, is found in \(\alpha\)-, \(\beta\)-, and \(\delta\)-tocopherol forms across microalgae species (e.g., _Tetraselmis_) and can aid in preventing cardiovascular diseases [81]. Apart from this, chlorophyls, lipid-soluble pigments, are often utilized as natural colorantsin the food and beverage industries. These pigments can undergo transformations during food processing and ingestion by humans, converting them into pyropheophytin, pheophytin, and pheophorbide. In particular, pigments (e.g., tucoxanthin, zeaxanthin, lutein, and \(\beta\)-carotene), phenolic compounds (e.g., anthocyanin and phlorotannins), proteins (e.g., phycobiliproteins), and glycosides are among the colorants derived from marine algae, which also provide nutritional value to food products in addition to enhancing its acceptability, appeal, and flavor. Additionally, chlorophylls and their derivatives exhibit other bioactivities, including antigenotoxic, anticancer, antioxidant, antimutagenic, and anti-obeseogenic properties [52, 85, 86]. Marine algae are a rich source of phenolic compounds, rendering them highly potent bioactive resources in marine ecosystems. Seaweed species like _Undaria_ sp., _Laminaria_ sp., _Porphyra_ sp. (red algae), and _Fucus_ sp. (brown algae) are notable sources of phenolic compounds. Generally, phenolic acids, such as protocatechuic, caffeic, gallic, chlorogenic, p-hydroxybenzoic, vanillic, and salicylic acids, and flavonoids, such as quercetin, naringenin, apigenin, luteolin, hesperidin, kaempfer, catechin, genistein, and epicatechin, were found in different species of marine algae. Typically, brown algae contain a higher content of tannins, primarily due to elevated phlorotannin levels, than the red and green algae. Phlorotannins contribute to numerous biological activities, encompassing antioxidant, antitumor, anti-inflammatory, antidiabetic, antiallergic, and antihypertensive effects. Moreover, phenolic compounds from marine algae could be used as alternatives to synthetic antioxidants, which are useful for rendering lipid oxidation in oils as well as fish and fish-based products [49, 87, 88]. For example, [PERSON] et al. [89] identified around 100 bioactive compounds, mainly polysaccharides, flavonoids, tannins, glycosides, and steroids, from seagrass (_Cymodoca serurlata_) and red seaweed (_Kappaphycus alvarezii_), which exhibited antioxidant and antibacterial properties. Aside from this, marine algae also serve as a valuable vitamin source.