Green synthesized silver nanoparticle from Allium ampeloprasum aqueous extract: Characterization, antioxidant activities, antibacterial and cytotoxicity effects

Antibacterial carotenoids of three Holothuria species in Hurghada, Egypt

Several echinoderms, including sea urchins, are valuable sources of bioactive compounds but their nutraceutical potential is largely unexplored. In fact, the gonads of some sea urchin species contain antioxidants including carotenoids and polyhydroxylated naphthoquinones (PHNQ’s), such as echinochrome A. Astaxanthin is known to have particular bioactivity for the prevention of neurodegenerative diseases. This carotenoid is produced by microalgae, while several marine invertebrates can bioaccumulate or synthetize it from metabolic precursors. We determined the carotenoid content and analyzed the bioactivity potential of non-harvested Atlantic-Mediterranean sea urchin Arbacia lixula. The comparison of methanol crude extracts obtained from eggs of farmed and wild specimens revealed a higher bioactivity in farmed individuals fed with a customized fodder. HPLC-analysis revealed a high concentration of astaxanthin (27.0 μg/mg), which was the only pigment observed. This study highlights the potential of farmed A. lixula as a new source of the active stereoisomer of astaxanthin.

https://www.mdpi.com/1660-3397/15/6/187/pdf

The Sea Urchin Arbacia lixula: A Novel Natural Source of Astaxanthin.

Background and purpose: Measurement of DPPH free radical scavenging is a valid, accurate, and easy method with high repeatability in evaluating the in vitro antioxidant activity of plant extracts. A positive correlation is reported between antioxidant activity and antimicrobial activity. The aim of this study was to evaluate the correlation between antioxidant and antimicrobial activity of medicinal plant extracts. Materials and methods: The extracts were prepared and DPPH was used to determine free radical-scavenging activity. Antimicrobial effects of hydro-ethanol extract on the bacteria was surveyed using diffusion method in a culture medium Mueller-Hinton agar by paper discs (6 mm) based on Bauer and Kirby instructions. Results: The ability of medicinal plant extracts in scavenging free radicals was found to be higher in the extracts of Myrtus (89.583 μg/mL) and rosemary (80.921 μg/mL). The antioxidant activity of the extracts increased by increase in concentration of the extract. Meanwhile, in low concentrations of the extract (16 and 32 μg/mL) the highest antioxidant activity of the extract was found in Myrtus and then Rosemary, but at high concentrations (64 μg/mL) it was seen in Teucrium polium extract. Rosemary extract was found to be effective against Escherichia coli and Myrtus extract was the most effective on Listeria bacteria, Salmonella typhimurium, and Staphylococcus aureus. Conclusion: The results showed that plants with high antioxidant properties have high antimicrobial activity too, such as the extract of Myrtus and rosemary that were the most effective extracts on bacteria.

Correlation between antioxidant activity and antibacterial activity of nine medicinal plant extracts

Chemical investigation of pharmacologically active compounds from the Echinoidea sea urchin Stomopneustes variolaris resulted in the separation of an unreported cembrane type of diterpenoid, which was characterised as 4-hydroxy-1-(16-methoxyprop-16-en-15-yl)-8-methyl-21,22-dioxatricyclo[11.3.1.15,8]octadecane-3,19-dione by spectroscopic experiments. The compound exhibited greater inhibitory potential against inflammatory agent 5-lipoxygenase (IC50 2.01 mM) than that exhibited by synthetic ibuprofen (IC50 4.50 mM). The selectivity ratio of cyclooxygenase-1 to cyclooxygenase-2 for the studied compound was found to be greater (1.25) than that of ibuprofen (0.43), which could be accounted for the prospective anti-inflammatory property of the cembrane-type diterpenoid against inducible pro-inflammatory cyclooxygenase-2. Potent antioxidant activity of the studied compound was characterised by its greater scavenging effects on 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis-3-ethylbenzothiozoline-6-sulfonic acid radicals (IC50 1.41 and 1.61 mM, respectively) than the standard antioxidative agent α-tocopherol (IC50 1.51 and 1.70 mM, respectively). The greater electronic parameters (topological polar surface area of 82.06) together with two hydrogen bonded interactions at the active site of cyclooxygenase-2 and lesser binding energy (−8.91 kcal/mol) corroborated its prospective anti-inflammatory activity. Therefore, the presently studied cembrane-type diterpenoid could be utilised in medicinal formulations as an effective anti-inflammatory agent.

Antioxidant and anti-inflammatory cembrane-type diterpenoid from Echinoidea sea urchin Stomopneustes variolaris attenuates pro-inflammatory 5-lipoxygenase

The recent appearance of a growing number of bacteria resistant to conventional antibiotics has stimulated the search for novel antimicrobial agents or lead compounds from a variety of sources, including natural sources  crustaceans, molluscs and echinoderms, with particular interest on their secondary metabolites with desirable antimicrobial properties (Haug et al, 2002, Casas et al, 2010). Antimicrobial activity in several species of echinoderms collected from Gulf of California, Mexico, Caribbean and Coast of Norway has been reported (Rinehart et al, 1981; Bryan et al, 1994; Haug et al, 2002). In addition, a variety of antimicrobial factors, including steroidal glycosides (Andersson et al, 1989), polyhydroxylated sterols (Iorizzi et al, 1995), naphthoquinone pigments (Service and Wardlaw, 1984), lysozymes (Canicatti and Roch, 1989; Stabili and Pagliara, 1994), complement like substances (Leonard et al, 1990) and antimicrobial peptides (Beauregard et al, 2001) have also been isolated from echinoderms. These findings suggest that marine echinoderms are a potential source of new types of antibiotics for pharmaceutical development. Tripneustes gratilla (Echinoidea) collected from the Kenyan Coast. Unfortunately, in most of these studies on antimicrobial activity in echinoderms, whole bodies or body walls have been tested for activity. Recently, Haug et al. (2002) observed wide differences in antibacterial activities between different extracts and organs/tissues, as well as between species, of three echinoderms. Whether the same antibacterial factors are responsible for the activity in all organs or tissues remains unclear. The present work focused on screening and comparing antimicrobial and hemolytic activities in different organs/tissues of the sea urchin

Laila A. Abubakar

Papers

Antimicrobial activity of various extracts of the sea urchin Tripneustes gratilla (Echinoidea)