Red Seaweed “Rhodophyta” are an important group of macroalgae that include approximately 7000 species. They are a rich source of structurally diverse bioactive constituents, including protein, sulfated polysaccharides, pigments, polyunsaturated fatty acids, vitamins, minerals, and phenolic compounds with nutritional, medical, and industrial importance. Polysaccharides are the main components in the cell wall of red algae and represent about 40–50% of the dry weight, which are extensively utilized in industry and pharmaceutical compounds, due to their thickening and gelling properties. The hydrocolloids galactans carrageenans and agars are the main red seaweed cell wall polysaccharides, which had broad-spectrum therapeutic characters. Generally, the chemical contents of seaweed are different according to the algal species, growth stage, environment, and external conditions, e.g., the temperature of the water, light intensity, nutrient concentrations in the ecosystem. Economically, they can be recommended as a substitute source for natural ingredients that contribute to a broad range of bioactivities like cancer therapy, anti-inflammatory agents, and acetylcholinesterase inhibitory. This review touches on the main points of the pharmaceutical applications of red seaweed, as well as the exploitation of their specific compounds and secondary metabolites with vital roles.

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Biochemical constituents and master elements (Pb, Cr, Cd, Fe, Cu, Zn, Hg, B, Al, SO, Na, K, Li, Ca, Mg, and F) were investigated in six different seaweed species from Abu Qir Bay in the Egyptian Mediterranean Sea coast. The moisture level ranged from 30.26% in Corallina mediterranea to 77.57% in Padina boryana. On dry weight basis, the ash contents varied from 25.53% in Jania rubens to 88.84% in Sargassum wightii. The protein contents fluctuated from 8.26% in S. wightii to 28.01% in J. rubens. Enteromorpha linza showed the highest lipids (4.66%) and carbohydrate contents (78.95%), whereas C. mediterranea had the lowest lipid (0.5%), and carbohydrate contents (38.12%). Chlorophylls and carotenoid contents varied among the species. Total antioxidant capacity of the tested green seaweeds had the highest activities followed by brown and red seaweeds which had a similar trend of phenol and tannins contents. High reducing power was observed in all tested seaweeds extract except Ulva lactuca. Brown species had the highest amount of elements followed by red and green seaweeds. Notably, SO recorded the highest level in the tested green species (108.05 mg/g dry weight (DW)). The Ca/Mg and K/Na ratios reflected highly significant difference between seaweed species. This study keeps an eye on 29 parameters and by applying stepwise multiple regression analysis, prospective equations have been set to describe the interactions between these parameters inside seaweeds. Accordingly, the tested seaweeds can be recommended as a source of healthy food with suitable ion quotient and estimated daily intake values.

This study aims to assess the bioactive compounds and antioxidant activities of three selected seaweeds [Cladophora pellucida (Chlorophyta), Padina tetrastromatica (Phaeophyta) and Laurencia papillosa (Rhodophyta)] collected from Abo Qir bay, Alexandria, Egypt. L. papillosa demonstrated the greatest DPPH radical scavenging activity (52.1 ± 1.23 %) and β carotene content (3675.6 ± 134.6 IU/100 g) in comparison with the other seaweed species. The highest contents of phenol (0.26 ± 0.005 mg/g DW) and flavonoid (5.6 ± 0.8 mg CE/ 100 g DW) were observed in P. tetrastromatica and C. pellucida, respectively. P. tetrastromatica showed the highest ascorbic acid content (26.0 ± 0.98 mg%). Nineteen fatty acid methyl esters were detected in the tested seaweeds by gas chromatography, while C. pellucida had the highest total concentrations of fatty acids and the highest omega 3 and omega 6 fatty acids. Polysaccharides (cladophoran, fucoidan and agar) were identified in C. pellucida, P. tetrastromatica and L. papillosa, respectively, by Fourier transform infrared with attenuated total reflectance. These findings recommend the studied seaweeds to be used as a novel source of natural bioactive compounds and antioxidant agents for food supplements, cosmetics and pharmaceutical industries.

Abstract:The synthesis of 4-chloro-8-methylquinolin-2(1H)-one and its thione analogue is described. Some nucleophilic substitution reactions of the 4-chloro group were carried out to get new 4-substituted 2-quinolinones and quinolinethiones, such as 4-sulfanyl, hydrazino, azido and amino derivatives, which are of important synthetic use. The structure of the new compounds was established by their elemental analysis, IR and 1 H-NMR spectra. Also the mass fragmentation pattern of some products is discussed.

Resumen.-Se investigaron los cambios estacionales en la composición de pigmentos [Clorofila a (Cl-a), carotenoides totales (Car.), ficobiliproteínas (ficoeritrina (PE), ficocianina (PC), aloficocianina (APC))], en 5 especies de Rhodophyta. Los niveles de clorofila a, carotenoides y ficobiliproteínas presentaron altos contenidos durante invierno, y disminuyeron en verano, mostrando decoloración de tejidos de rojo a verde o amarillo. Los resultados muestran que los contenidos de pigmentos variaron estacionalmente con respecto a las especies de algas, y a los cambios de los parámetros físico-químicos, mientras que el pH, oxígeno disuelto, NO 3 -, NO 2 -, NH 4 + , nitrógeno total (TN) y fósfato total (TP) tuvieron un impacto directo sobre el contenido de pigmentos fotosintéticos, y la temperatura tuvo una correlación negativa significativa sobre los pigmentos fotosintéticos. Palabras clave: Parámetros ambientales, clorofila, ficobiliproteínas, algas rojas, variación estacionalAbstract.-Seasonal changes of pigment composition [Chlorophyll a (Chl-a), total carotenoid (Car.), phycobiliproteins (phycoerythrin (PE), phycocyanin (PC), allophycocyanin (APC))], in the 5 species of Rhodophyta were investigated. Chl-a, carotenoids and phycobiliproteins levels showed high contents during winter, whereas decreased in summer showing discoloration tissue from deep red to green or yellow. The results show that the pigment contents were varied seasonally with respect to the algal species and physical and chemical parameters changes, while pH, dissolved oxygen, NO 3 -, NO 2 -, NH 4 + , total nitrogen (TN) and total phosphorus (TP) had direct impact on photosynthetic pigments content, and temperature had significant negative correlation on photosynthetic pigments.

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