This study is a first contribution on the reproductive biology of Holothuria (Platyperona) sanctori from the Algerian coastline in the southwestern Mediterranean. Sampling was conducted at two sites in central Algeria, one (Ain Taggourait, w. Tipasa) where there is little anthropogenic influence and another (Tamentefoust, w. Alger) where there are two major sources of pollution from Oued el Harrach and Oued el Hamiz effluents which contain particulate organic matter. Significant differences in sea cucumber reproduction were observed between the two sites. This could be due to the difference in organic matter noted in the sediment of the two study sites. However, temporal similarities of the gonad index (GI) and the sexual maturity stages suggest that the reproductive cycle of H. (P.) sanctori is annual with the main spawning event taking place from June to October. Spawning is of high intensity in the Bay of Bou Ismail (Ain Taggourait) and spread out over time in the Bay of Algiers (Tamentefoust), reflecting an environment sufficiently rich in food to insure reproduction. We also show that gonad maturation of males and females was synchronized. Temperature is the most likely factor influencing the reproductive cycle and spawning. At the study sites, H. (P.) sanctori had a winter sexual resting phase, followed by maturation during spring, before spawning in summer. However, there was a slight lag to the start of spawning at the two study sites.

This paper reports for the first time the presence of Holothuria (Roweothuria) arguinensis in the Algerian coastal waters. Individuals of this species were taken from the Tamentefoust area (Bay of Algiers, Algeria, 3°13′E 36°48′N) at 4.5 m depth and examined, using traditional morphological and endoskeletal characters. The general body form and the ossicles are in accordance with the descriptions of the species obtained in the literature.

To promote the nutritional and pharmacological values of four sea cucumber species (Holothuria poli, H. tubulosa, H. arguinensis, and H. sanctori), harvested from the Algerian coast, we aimed to study their proximate composition, fatty acid profile and angiotensin-converting enzyme (ACE) inhibitory activity. Their phospholipids were also used to elaborate nanoliposomes and to encapsulate peptides obtained from the same source. After the physico-chemical characterization of nanoliposomes and peptides, in vitro analyses were realized. The four holothurian species showed a high amount of protein (49.26–69.34%), and an impressive lipid profile of 27 fatty acids, mainly composed of polar fatty acids (91.16–93.85%), with a high polyunsaturated fatty acids (PUFA) content (50.90–71.80%), particularly eicosapentaenoic acid (EPA) (5.07–8.76%) and docosahexaenoic acid (DHA) (4.86–7.25%). A high phospholipids amount was also found (55.20–69.85%), mainly composed of phosphatidylcholine (PC) (51.48–58.56%). Their peptide fractions exhibited a high ACE inhibitory activity (IC₅₀ 0.30 to 0.51 mg/mL). The results also showed that the nanoliposomes do not induce cytotoxicity and cell death in human MSCs and no perturbation of proliferation for all the times and the tested concentrations, as well as the combined nanoliposomes and hydrolysates (HTS) at a concentration of 0.1 mg/mL. All four sea cucumbers show potential as a new source for omega-3, omega-6, and bioactive peptides.