Role of temperature and nutrients on the growth and toxin production of Prorocentrum hoffmannianum (Dinophyceae) from the Florida Keys.

The benthic dinoflagellate Prorocentrum hoffmannianum M.A. Faust is typical of tropical warm waters and produces biotoxins responsible for diarrhetic shellfish poisoning (DSP). In this study, the effect of temperature and nutrient limitation on growth and toxin production of P. hoffmannianum isolated from field samples collected in the Florida Keys was investigated. Batch culture experiments were ran at two temperatures (i.e. 21 ± 0.1 and 27 ± 0.1 °C) and under nitrogen-limited (14.7 µmol L-1 N-NO3- and 18.1 µmol L-1 P-PO43-) and phosphorus-limited (441 µmol L-1 N-NO3- and 0.6 µmol L-1 P-PO43-) levels with respect to control nutrient conditions (441 µmol L-1 N-NO3-and 18.1 µmol L-1 P-PO43-). Both temperature and nutrient conditions significantly affected growth rates and maximum yield of P. hoffmannianum with the maximum values being recorded at the higher temperature and in the replete medium. Production of okadaic acid was induced under all conditions (from 13.5 to 859.8 pg cell-1), with values up to one order of magnitude higher than those observed in other DSP toxin producing species. Toxin production was enhanced under P limitation at 27 °C, corroborating the theory that toxin production is modulated by cell physiological conditions, which are in turn affected by a wide spectrum of factors, including environmental stressors such as nutrient availability. Toxin fraction released in the growth medium was negligible. No okadaic acid esters were detected in this strain of P. hoffmannianum.

NMR-based phytochemical analysis of Vitis vinifera cv Falanghina leaves. Characterization of a previously undescribed biflavonoid with antiproliferative activity.

Vitis vinifera cv Falanghina is an ancient grape variety of Southern Italy. A thorough phytochemical analysis of the Falanghina leaves was conducted to investigate its specialised metabolite content. Along with already known molecules, such as caftaric acid, quercetin-3-O-ß-d-glucopyranoside, quercetin-3-O-ß-d-glucuronide, kaempferol-3-O-ß-d-glucopyranoside and kaempferol-3-O-ß-d-glucuronide, a previously undescribed biflavonoid was identified. For this last compound, a moderate bioactivity against metastatic melanoma cells proliferation was discovered. This datum can be of some interest to researchers studying human melanoma. The high content in antioxidant glycosylated flavonoids supports the exploitation of grape vine leaves as an inexpensive source of natural products for the food industry and for both pharmaceutical and nutraceutical companies. Additionally, this study offers important insights into the plant physiology, thus prompting possible technological researches of genetic selection based on the vine adaptation to specific pedo-climatic environments.

Effects of N and P availability on carbon allocation in the toxic dinoflagellate Ostreopsis cf. ovata.

Blooms of the toxic dinoflagellate Ostreopsis cf. ovata are usually associated with shallow and calm coastal waters, characterized by low nutrient concentrations. The algal cells typically cover the benthic substrates, such as the macroalgal and invertebrate communities and rocks, forming a mucilaginous film. Data reported on O. cf. ovata toxin production observed under both field and culture conditions show high variability in terms of toxic profile and cellular content; little is known about the environmental and physiological aspects which regulate the toxin dynamics. In this study, O. cf. ovata physiology was investigated using batch cultures supplied with nutrient concentrations similar to those found in the Adriatic Sea during the recurrent blooms and the observed cellular dynamics were compared with those found in a culture grown under optimal conditions, used as a reference. Data on the cellular C, N and P content during the growth highlighted a possible important role of the cellular nutritional status in regulating the toxin production that resulted to be promoted under specific intervals of the C:N and C:P ratios. The variable toxicity found for O. cf. ovata in various geographic areas could be related to the different in situ prevalent environmental conditions (e.g., nutrient concentrations) which affect the cellular elemental composition and carbon allocation. The obtained results strongly suggest that in the environment toxin production is steadily sustained by a low and constant nutrient supply, able to maintain appropriate cellular C:N (>12) or C:P (>170) ratios for a long period. These results explain to some extent the variability in toxicity and growth dynamics observed in blooms occurring in the different coastal areas.

NMR-based identification of the phenolic profile of fruits of Lycium barbarum (goji berries). Isolation and structural determination of a novel N-feruloyl tyramine dimer as the most abundant antioxidant polyphenol of goji berries.

Biological properties of fruits of Lycium barbarum (goji berries) have been ascribed to their high content of nutrients and phenolics. Comprehensive studies aimed at unambiguously identifying the phenolic components in goji berries are still lacking. In this paper, we report on the isolation and NMR-based identification of the major phenolics in commercially available goji berries. Together with already known phenolics, including caffeic acid, p-coumaric acid, rutin, scopoletin, N-trans-feruloyl tyramine, and N-cis-feruloyl tyramine, an unreported N-feruloyl tyramine dimer was characterized as the most abundant polyphenol isolated from the berries. Usually divalent molecules show enhanced biological activities than their corresponding monomers.

(1S,3R,4S,5R)5-O-Caffeoylquinic acid: isolation, stereo-structure characterization and biological activity.

Sorbus domestica fruits (sorbs) are commonly harvested and consumed for their nutritious qualities and have long been used as natural remedy against diabetes in the popular medicine. Recently, sorbs have been described as sources of antioxidant compounds including polyphenols. Chemical analyses carried out on sorbs collected in Southern Italy have led to the isolation of a chlorogenic acid isomer as the main antioxidant compound contained in the fruit butanol extract. NMR studies have identified the isolated compound as (1S,3R,4S,5R)5-O-Caffeoylquinic acid. In comparison to chlorogenic acid, the isolated isomer features an inverted configuration at C4. Such configurational inversion causes the chlorogenic acid stereoisomer acid to assume a preferential conformation remarkably different from that of chlorogenic acid. This seems to account for the enhanced potency of (1S,3R,4S,5R)5-O-Caffeoylquinic acid to reduce both the glucose and cholesterol uptakes by the cell line HepG2 when compared to chlorogenic acid.