# Laminar _Ulva_ Species: A Multi-Tool for Humankind?
## 4 _Ulva_ Compounds of Interest
### Phenolic Compounds  
Phenolic compounds are secondary metabolites found in plants and algae [128] and are defined as molecules with hydroxylated aromatic rings [140; 141]. These phytochemicals show a wide variety of chemical structures, from simple moieties to high molecular poly mers. The biogenetically primary synthetic pathways that produce these phytochemicals are the shikimate or the acetate pathways [140; 141].  
Phlorotannins, bromophenols, flavonoids, phenolic terpenoids, and mycosporine-like amino acids (MAAs) are the polyphenic compounds found in seaweeds [140; 141]. Phlorotannins are oligomers of phloroglucinol and serve as primary and secondary metabolites according to [PERSON] et al., 2019 [142]. Bromophenols are characterized by the presence of phenolic groups with varying degrees of bromination with ecological functions, such as chemical defence and deterrence, with studies according to [PERSON] et al., 2011 [143] and [PERSON] et al., 2011 [144] revealing a wide variety of beneficial ecological activities. Flavonoids, as evidenced by [PERSON] et al., 2019 [145] and [PERSON] 2019 [146], are characterized as having heterocyclic oxygen attached to two aromatic rings, which might vary depending on the degree of hydrogenation. The different types are rutin, quercetin, hesperidin, kaempferol, catechchin, daidzein, or genistein [140; 141]. The origin of phenolic terpenids (also known as terpen or isoprenoids) form the largest group of natural products with more than 30,000 different structures and are products of the isoprenoid biosynthetic pathway [147]. Lastly, MAAs are a group of UV-absorbing compounds [141] whose molecular structure is based on a cyclohexanone or cyclohexanine ring with amino acid substituents [140].  
Bromophenols and flavonoids of green seaweeds have antioxidant activities. They have already been tested and proven in different species; for example, [PERSON] et al., 2004 [148] and [PERSON] et al., 2012 [149] referred to the phenolic fraction of _Ulva clathrata_ and _Ulva flexuosa_, which has an antitumoral and antibacterial effect; also, research on _Ulva prolifera_ showed antidiabetic properties in [PERSON] et al., 2019 [150] and [PERSON] et al., 2018 [151]. Other examples were proved in other species like _Ulva compressa_ (as _Enteromorpha compressa_), _Ulva intestinalis_, _Ulva litza_, _Ulva australis_ (as _Ulva perusa_), _Capsosipton fulvescens_, and _Chaetompha moniligera_[141].  
[PERSON] and [PERSON] (2012) [152], who worked with water and ethanolic extracts of 16 species of seaweeds collected along the Danish coasts, observed that _U. lactuca_ had the following acids: gallic, protocatechuic, and gentisic (only by ethanol), hydroxybenzoic, chlorogenic, vanillic, syringic, caffeic, salicylic, and comamic (by water as well). Another study developed by [PERSON] et al. (2019) [153], which collected four macroalgae from the European and Asian shores of Istanbul Strait to find the most suitable solvent system to extract polyphenic compounds, noted that ascorbic, gallic, comamic, caffeic, and ferulic acids, catechin, rutin, and quercetin were found at the highest concentration on _U. lactuca_.  
_U. lactuca_ has additional flavonoids, kaempferol, and quercetin. They are known for their antioxidant and anti-inflammatory effects. Kaempferol has been extensively investigated for its possible health advantages, especially its involvement in lowering the likelihood of chronic illnesses such as cancer, cardiovascular problems, and neurological ailments [141].