Spinochrome synthesis

Naphthoquinones of the spinochrome class: occurrence, isolation, biosynthesis and biomedical applications

Quinones are widespread in nature and have been found in plants, fungi and bacteria, as well as in members of the animal kingdom. More than forty closely related naphthoquinones have been found in echinoderms, mainly in sea urchins but occasionally in brittle stars, sea stars and starfish. This review aims to examine controversial issues on the chemistry, biosynthesis, functions, stability and application aspects of the spinochrome class, a prominent group of secondary metabolites found in sea urchins. The emphasis of this review is on the isolation and structure of these compounds, together with evaluation of their relevant biological activities, source organisms, the location of origin and methods used for isolation and identification. In addition, the studies of their biosynthesis and ecological function, stability and chemical synthesis have been highlighted. This review aims to establish a focus for future spinochrome research and its potential for benefiting human health and well-being.

Marine Waste Utilization as a Source of Functional and Health Compounds

Consumer demand for convenience has led to large quantities of seafood being value-added processed before marketing, resulting in large amounts of marine by-products being generated by processing industries. Several bioconversion processes have been proposed to transform some of these by-products. In addition to their relatively low value conventional use as animal feed and fertilizers, several investigations have been reported that have demonstrated the potential to add value to viscera, heads, skins, fins, trimmings, and crab and shrimp shells by extraction of lipids, bioactive peptides, enzymes, and other functional proteins and chitin that can be used in food and pharmaceutical applications. This chapter is focused on reviewing the opportunities for utilization of these marine by-products. The chapter discusses the various products and bioactive compounds that can be obtained from seafood waste and describes various methods that can be used to produce these products with the aim of highlighting opportunities to add value to these marine waste streams.

Preparative Synthesis of Spinochrome D, a Pigment of Different Sea Urchin Species

A simple and effective synthesis of spinochrome D (1) (2,3,5,6,8-pentahydroxy-1,4-naphthoquinone), a pigment of different sea urchin species, has been developed starting from 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone (13), easily available by cycloacylation of 1,4-dimethoxybenzene (11) with dichloromaleic anhydride (12). Bromination of 13 with either bromine or dioxane dibromide to 6-bromo-2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone (21), followed by nucleophilic substitution of the halogen atoms by methoxy groups in 21 and hydrolysis of trimethyl ether 10 produce the target compound in overall yield from 62 to 65%.

Preparative Production of Spinochrome E, a Pigment of Different Sea Urchin Species

A concise route to spinochrome E (1) (2,3,5,6,7,8-hexahydroxy-1,4-naphthoquinone), a pigment isolated from sea urchins of different species, has been developed starting from either commercially available 5,8-dihydroxy-1,4-naphthoquinone (11) or 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone (12). The protocol involves 3 steps, the chlorination of either 11 or 12 to tetrachloronaphthazarin (13), the total nucleophilic substitution of the chlorine atoms in 13 by methoxy groups, and hydrolysis of tetramethyl ether14; this makes possible the preparation of the target compound in overall yields from 41 to 46%.

A Convenient and Efficient Synthesis of Naphthazarin

A convenient and efficient synthetic method of the important intermediate naphthazarin is presented starting from 1, 4, 5, 8-tetramethoxynaphthalene in an overall yield of 87%. Compared with the reported synthesis, this method has several advantages. Firstly, the reaction conditions are milder; secondly, the workup of each step is simpler and the yield is considerably higher; thirdly, all the reactions involved in the method are more suitable for large-scale preparations.

Synthesis of some hydroxynaphthazarins and their cardioprotective effects under ischemia-reperfusion in vivo

A series of hydroxynaphthazarins has been synthesized. Some of them were found in in vivo experiments to be protectors of myocardium under ischemia-reperfusion and to reduce the infarction zone by 50% without any adverse effect. All compounds exhibit a moderate or small toxicity and are active in low doses.