Isolation And Elucidation Of The Alkaloid From The Marine Sponge Phakellia Fusca And Mycale Parishi

Sponges of the genus Axinella are prolific sources of many and varied natural products, mostly pyrrole and guanidine based alkaloids, halistatins, axinastatins, sodwanone triterpenes, nitrogenous sesqiterpenes, A-norsteroids, unusual pregnone steroids, etc. Varieties of pharmacological activities displayed by those metabolites greatly increased their importance. Sponges of the genus Mycale also are rich sources of bioactive natural compounds having different structures, including mycalamides, mycalolides, diterpenoid rotalins, mycalisines, polybromminated C-15 acetogenins, brominated isocoumarines, and norterpene cyclic peroxides, etc. In the course of our systematic studies on marine sponges, we have investigated the chemical constituents of specimen of sponges Phakellia fusca Schimidt (order demosponges, family Axinellidae) and Mycale parishi (Bowerbank, 1875) (order Poecilosclerida, family: Mycalidae) collected around the South China Sea.Three bromopyrroles and a pyrrololactam were isolated from the marine sponge Phakellia fusca Schimidt. The bromopyrroles were determined as: 4, 5-dibromo-l//-pyrrole-2-carboxylic acid methyl ester 1, 4, 5-dibromo-3-cyano-l//-pyrrole-2-carboxylic acid methyl ester 2, 4, 5-dibromo-l//-pyrrole-2-carboxylic acid amide 3 on the basis of the data of GC-MS and some other spectrometric methods. These pyrroles were found for the first time in the marine sponge P. fusca Schmidt. The finding of those alkaloids is of considerable value for chemotaxonomy of the Axinellidae family. Compound 2 is a new compound.The structure of the pyrrololactam alkaloid 4 was established by single-crystal X-ray diffraction, and further characterized by NMR spectroscopy. The crystal belongs to orthorhombic system, space group Pbca with a = 12.984(7), b - 7.429(4), c = 18.580(10) A, V= 1792.2 (16) A3, Z= 8, Mr = 243.07,Dx=1.802 mg/cm3,F(000) = 960, μ(Mo-Ka) = 4.553 mm-1, λ = 0.71073 A. The structure was refined to R = 0.0535 and Rw = 0.0803, S = 1.106, (△p)max= 1.259, (△p)min= -0.706 e/A3.Two pyrimidine and a ceramide were isolated from the marine sponge Mycale parishi Bowerbank. Their structure were elucidated as 1 -(2-deoxy-β-D-ribo-furanosyl)-5-methyl-2,4(lH)-pyrimidinedione 5, 2,4-(1H,3H)-pyrimidinedione 6 and pentacosanok acid (2-hydroxy-1-hydroxymethyl-3-heptadecenyl)-amide 7 by the interpretation of their spectral data. The absolute configuration of compound 5 was established by a single-crystalX-ray diffraction experiments. Its crystal belongs to orthorhombic system, space group P212121 with a = 4.8438(4), b = 13.8689(13), c = 16.2650(14) A, V= 1092.65 (17) A3, Z = 4, Mr = 242.23, Dx= 1.473 mg/m3, F(000)= 512, μ (Mo-Ka) = 4.553 mm-1, X = 0.71073 A. The structure was refined to R = 0.0364 and Rw = 0.0735, S = 0.959, (△p)max=0.155, (△p)min=-0.169 e/A3.It was for the first time to investigate the chemical constituents of this kind of marine sponge Mycale parishi Bowerbank, and the ceramide 7 is a new compound.