Pietro Monaco

Antialgal compounds from Zantedeschia aethiopica

Two cycloartane triterpenes and 10 sterols present in Zantedeschia aethiopica along with three lignans and 10 phenylpropanoids were identified by spectroscopic means. 3-(4-hydroxy-3-methoxy)-phenyl-1,2-propandiol and 1-(4-hydroxy-3-methoxy)-phenyl-2-[4-(2,3-dihydroxypropyl)-2-methoxy]-phenoxy-1,3-propandiol have been isolated for the first time. Antialgal assays show good activity for some aromatic compounds.

Potential allelochemicals fromPistia stratiotes L.

Among the substances isolated from ethyl ether extract ofPistia stratiotes L., linoleic acid,γ-linolenic acid, (12R,9Z,13E,15Z)-l2-hydroxy- 9,13,15-octadecatrienoicacid, (9S,10E,12Z,15Z)-9-hydroxy-10,12,15-octadecatrienoic acid, α-asarone, and 24S-ethyl-4,22-cholestadiene-3,6-dione were found to inhibit the growth of some microalgae in solid medium. Toxicity of α-asarone on the growth of sensitive algal strains in liquid medium is discussed.

Cycloartane triterpenes from Juncus effusus

Abstract A new triterpene, cycloart-23Z-enfe-3β,25-diol and other oxygenated cycloartanes have been isolated from Juncus effusus. The configurations at C-24 of the epimeric 24,25-epoxycycloartan-3β-ols, cycloart-25-ene-3β,24-diols and cycloartane-3β,24,25-triols have been attributed on the basis of chemical correlations. The 1H and 13C NMR chemical shifts of the 24R- and 24S-stereomers are also reported.

In vitro algal growth inhibition by phytotoxins ofTypha latifolia L.

The ether extract ofTypha latifolia L. inhibited the growth of some microalgae. Among the substances chromatographically isolated and characterized from the ether extract, three steroids [β-sitosterol, (20S) 24-methylenlophenol, and stigmast-4-ene-3,6-dione] and three fatty acids [α− linolenic, linoleic, and an unidentified C8∶2] were found to inhibit the growth of some microalgae tested. A selective effect of these substance on blue-green algae (particularly on T 625Synechococcus leopoliensis and on T 1444Anabaena flosaquae) was observed.

Lignans from Arum italicum

Abstract Two new 8- O -3′ neolignans and two new 8- O -4′ neolignan glucosides have been isolated from Arum italicum . The structures and the absolute configurations have been attributed on the basis of the physical data of the compounds and of their peracetylated derivatives.

Potential allelochemicals from Sambucus nigra

Twenty-four aromatic metabolites belonging to cyanogenins, lignans, flavonoids, and phenolic glycosides were obtained from Sambucus nigra. Structures were determined on the basis of their spectroscopic features. Two compounds have been isolated and identified as (2S)-2-O-beta-D-glucopyranosyl-2-hydroxyphenylacetic acid and benzyl 2-O-beta-D-glucopyranosyl-2,6-dihydroxybenzoate. All the compounds have been assayed on dicotyledons Lactuca sativa (lettuce) and Raphanus sativus (radish) and monocotyledon Allium cepa (onion) to test their stimulatory or inhibitory effects on seed germination and radicle elongation. Cyanogenins have a mainly inhibiting effect while lignans stimulate the growth. Some compounds show different effects on dicotyledons and monocotyledons.

Allelochemical activity of phenylpropanes from Acorus gramineus

Abstract Six phenylpropanes have been isolated from the aquatic plant Acorus gramineus and characterized on the basis of their physical features. The most abundant compounds, tested for their allelochemical properties, were found to inhibit some green and blue-green algae.

Phenanthrenoids from the wetland Juncus acutus

Nine 9,10-dihydrophenanthrenes, three phenanthrenes and a related pyrene have been isolated from the wetland plant Juncus acutus. The structures have been attributed by means of their spectral data and chemical correlation. 5-(1-Ethoxy-ethyl)-2-hydroxy-7-methoxy-1,8-dimethyl-9,10-dihydrophenanthrene and 5-(1-phytoxy-ethyl)-2-hydroxy-7-methoxy-1,8-dimethyl-9,10-dihydrophenanthrene, 2,7-dihydroxy-1-methyl-5-vinylphenanthrene, 2,7-dimethoxy-1,6-dimethyl-5-vinylphenanthrene and 2,7-dihydroxy-1,6-dimethylpyrene are described for the first time. Many of the compounds showed in vitro phytotoxicity against Selenastrum capricornutum, a microalga used in aquatic tests.

Chemical Constituents of the Aquatic Plant Schoenoplectus lacustris: Evaluation of Phytotoxic Effects on the Green Alga Selenastrum capricornutum

Forty-nine secondary metabolites were isolated from aqueous and alcoholic extracts of the aquatic plant Shoenoplectus lacustris. All compounds were characterized based on spectroscopic data. Eleven free and glycosylated low-molecular polyphenols, 17 cinnamic acid and dihydrocinnamic acid derivatives, 11 flavonoids, and 10 C13nor-isoprenoids were identified. The structure of the new compound, 1-benzoyl-glycerol-2-α-l-arabinopyranoside, was elucidated by 2D NMR experiments (COSY, HSQC, HMBC, NOESY). To evaluate potential phytotoxic effects, all compounds were tested on the green alga Selenastrumcapricornutum, a unicellular organism commonly used in tests of toxicity as a bioindicator of eutrophic sites. The most active compound was (−)-catechin, showing an inhibition similar to that of the algaecide CuSO4.

Antialgal ent-labdane diterpenes from Ruppia maritima

Seven ent-labdane diterpenes have been isolated from Ruppia maritima. The structures 15,16-epoxy-ent-labda-8(17),13(16),14-trien-19-al; 15,16-epoxy-ent-labda-8(17),13(16),14-trien-19-ol acetate; methyl 15,16-epoxy-12-oxo-ent-labda-8(17),13(16),14-trien-19-oate; 15,16-epoxy-ent-labd-8(17),13E-dien-15-ol and 13-oxo-15,16-bis-nor-ent-labd-8(17)-ene have been assigned to the five new compounds by spectroscopic means and chemical correlations. The phytotoxicity of the diterpenes has been assessed using the alga Selenastrum capricornutum as organism test.