Marina DellaGreca

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.

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.

Unusual products of the aqueous chlorination of atenolol

The reaction of the drug atenolol with hypochlorite under conditions that simulate wastewater disinfection was investigated. The pharmaceutical reacted in 1h yielding three products that were separated by chromatographic techniques and characterized by spectroscopic features. Two unusual products 2-(4-(3-(chloro(2-chloropropan-2-yl)amino)-2-hydroxypropoxy)phenyl) acetamide and 2-(4-(3-formamido-2-hydroxypropoxy)phenyl) acetamide were obtained along with 2-(4-hydroxyphenyl) acetamide. When the reaction was stopped at shorter times only 2-(4-(3-amino-2-hydroxypropoxy)phenyl) acetamide and the dichlorinated product were detected. Tests performed on the seeds of Lactuca sativa show that chlorinated products have phytotoxic activity.

Antialgal furano-diterpenes from Potamogeton natans L.

Six furano-ent-labdanes, 19-acetoxy-15,16-epoxy-8(17),13(16),14-ent-labdatrien-20-al, 15,16-epoxy-12-oxo-8(17),13(16),14-ent-labdatrien-20,19-olide, 12(S)-hydroxy-15,16-epoxy-8(17),13(16),14-ent-labdatrien-20,19-olide, 10alpha,19-dihydroxy-15,16-epoxy-8(17),13(16),14-nor-ent-labdatriene, 19,20-dihydroxy-15,16-epoxy-8(17),13(16),14-ent-labdatriene, 15,16-epoxy-12-oxo-8(17),13(16),14-ent-labdatrien-19,20-olide, were isolated, together with the known potamogetonin, from the aquatic plant Potamogeton natans. Their structures were determined on the basis of their chemical and spectral data. The compounds showed in vitro phytotoxicity against Raphidocelis subcapitata, a microalga used in aquatic tests.

Fatty Acids Released by Chlorella vulgaris and Their Role in Interference with Pseudokirchneriella subcapitata: Experiments and Modelling

The role of extracellular fatty acids in the interference between two algae, Chlorella vulgaris Beijerink and Pseudokirchneriella subcapitata (Korshikov) Hindak, was assessed by the co-cultivation of the two selected strains, as well as by the chemical analysis of exudates from the culture media of single strain cultures. The effect of culture age and phosphate limitation was evaluated. The experiments showed that the composition and amount of fatty acids, released by C. vulgaris and by P. subcapitata, both in a batch and in a continuous monoculture, depend on the culture age and on the phosphate concentration in the culture medium. We also found that the amount of chlorellin generated in the two algae co-culture increased and was almost exclusively constituted by a mixture of C18 fatty acids. By using the evaluated concentrations of these fatty acids, an artificial chlorellin was prepared. The toxicity of this mixture to P. subcapitata appears to be similar to that of the natural chlorellin. For both algae, a stimulation of growth was observed at low concentrations of the natural chlorellin, whereas higher concentrations produced inhibitory effects on both species. However, P. subcapitata was much more sensitive than C. vulgaris. By using some of these new experimental results, two new mathematical models have been used to describe the toxicity of chlorellin to C. vulgaris and to the interference between C. vulgaris and P. subcapitata, respectively.

New dimeric phenanthrenoids from the rhizomes of Juncus acutus. Structure determination and antialgal activity

In a study of the allelochemical interactions between the wetland plant Juncus acutus and microalgae some dimeric dihydrophenanthrenoids have been isolated. The structures have been determined on the basis of their spectroscopic properties and their phytotoxicity was evaluated on Selenastrum capricornutum.

Effect of ent-labdane diterpenes from Potamogetonaceae on Selenastrum capricornutum and other aquatic organisms.

Twenty ent-labdane diterpenes, isolated from the aquatic plants Ruppia maritima and Potamogeton natans, were tested to detect their effects on aquatic organisms from different trophic levels. Toxicity tests were performed on aquatic producers (the alga Selenastrum capricornutum), and consumers including a rotifer (Brachionus calyciflorus), a cladoceran crustacean (Daphnia magna), and two anostracan crustaceans (Thamnocephalus platyurus and Artemia salina). Furano-ent-labdanes exhibited high toxicity toward all of these organisms. 15,16-Epoxy-12(S)-hydroxy-8(17),13(16),14-ent-labdatrien-20,19-olide had a high toxicity only toward the algae and the rotifers. It was inactive for the crustaceans.

Bioactivity of Phenanthrenes from Juncus acutus on Selenastrum capricornutum

Twenty-five 9,10-dihydrophenanthrenes, four phenanthrenes, a dihydrodibenzoxepin, and a pyrene, isolated from the wetland plant Juncus acutus, were tested to detect their effects on the green alga Selenastrum capricornutum. Nine of the compounds were isolated and identified for the first time. Most of the compounds caused inhibition of algal growth. The 9,10-dihydrophenanthrenes 1, 5, 21, and 22 were the most active.