## 3 Bioactivity of Pigments and Lipids from Plastids of Marine Phytoplankton
### Pigments  
#### 3.1.1 Tetrapyrroles  
Human populations regularly have been consuming green vegetables since the discovery of agriculture practices regularly some 15,000 years ago. This traditional and long practice made in the collective unconscious green pigments as save compounds. Indeed, Chl derivatives such as pheophytin have been found in some plants known in traditional medicine to be active against diseases such as _Clinacanthus mutans_-herpes simplex virus [41] and _Lonicar hypogaluca_-hepatitis C virus [42]. Until recently, almost nothing was known about the assimilation of closed tetrapyrroles: it was simply thought that Chl absorption was limited (1%-3%). Actually, the phytol chain of the native Chl molecules would be cleaved whereas the Mg ion is leached upon ingestion, the resulting pheophorbide and pheophytine being excreted in the feces [43]. Major progress in studying tetrapyrrole assimilation was possible when intestinal cell could be grown _in vitro_. Using such a model, _i.e._, Caco-2 human cells, [44] demonstrated that pheophytin can be absorbed as well. The anti-genotoxicity of natural Chls was revealed by [PERSON] _et al._[45] whereas others studies reported the anti-oxidant activity, the modulation of xenobiotic enzyme activity, and the induction of apoptotic event in cancer cells of Chl [46, 47]. This anti-cytotoxicity seems specific to natural Chl and could not be demonstrated with non-natural Chl molecules (see below) [48]. Chl precursors, Chl derivatives, or Chl analogs are also used in medicine for photodynamic treatments of cancers, e.g., [49]. The harmlessness of tetrapyrroles, especially Chl does not mean that the ingestion of tetrapyroles is without danger. For instance, Chl intolerance can occur due to the liberation of the Chl phytol moityin patients suffering from [PERSON]'s disease. In this pathology, phytanic acid accumulates in serum and other tissues due to a defect of the metabolic pathway for phytanic acid [43]. [PERSON] _et al._[50] demonstrated that albino rats fed with lucerne--but not with ryegrass--protein concentrate, develop photosensitization. This allergy to sunlight could be due to the accumulation of pheophorbide and related pigments in tissues [51]. Similar sunlight allergic reactions were reported in humans having ingested dried laver enriched with pheophorbides and pyropheophorbides [52]. [PERSON] _et al._[53] have shown that these deesterified tetrapyrcles are more strongly absorbed than the phytylated ones from the food matrix by the intestinal epithelial cells, allowing a larger accumulation in the patient body. Therefore, there is a need for information on the effects of processes on tetrapyrcle bioaccessibility and bioavailability. For instance, conservation industrial processes such as freezing and canning along with cooking have a positive effect on Chl bioavailability [54, 55], making the pigment's quantity after processing exceeding 100% of the value measured before processing (e.g., [56, 57]). Non-natural Chls, such as Cu-Chls, Cu-pheophorbide, Cu-pheophytin, or Chlins, are digested similarly to natural Chl molecules, that is, the phytol chain is cleaved but the Cu ion is not leached from the porphyrin ring because the chelate is much more stable. The stability is only relative because an increase in Cu has been measured in the plasma following Chlin ingestion [58]. Several tests suggested that oral or parenteral administration of Chlins did not produce any gross adverse effect on health [59, 60]. Phytoplankton contains also other types but usually minor tetrapyrcles such as hemes. Heme-protein complexes are degraded in the lumen of the stomach and small intestine [61]. Hemes being soluble in alkaline environment, they do not need to bind proteins for the luminal absorption, which is indeed facilitated by the presence of specific heme transporters such as the heme carrier protein 1 (HCP1) at the apical surface of enterocytes [62].