Biomedical subjects
Publications and source records attributed to Anna Piovan.
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The biologically active naphthodianthrones hypericin and pseudohypericin were detected by electrospray ionization mass spectrometry (ESI-MS/MS) in microsamples from the sepals of Hypericum elodes (Hypericaceae) containing the so-called "red glands", i.e. stipitate glands with red-coloured heads. The occurrence of hypericins in the red glands of H. elodes supports the taxonomic position of the section Elodes within the genus Hypericum and provides evidence that the ability of carrying out the biosynthetic pathway leading to the naphthodianthrone compounds, rather than the absolute amounts produced, should be regarded as a chemical marker of the phylogenetically more advanced sections of genus Hypericum. The biologically active phloroglucinol derivatives hyperforin and adhyperforin, so far found only in H. perforatum, were also detected and evidence for their localization in the sepal secretory canals with large lumen, is given.
A widespread occurrence of melatonin in plant kingdom has been reported. The circadian rhythm in the level of melatonin observed in both unicellular algae and higher plants, suggests a role in regulation of photoperiodic and rhythmic phenomena, i.e. a similar function for melatonin in both plants and animals. Evidence has been obtained for a role of melatonin in plant morphogenesis, but more research is needed to ascertain other suggested physiological roles in higher plants (seed dormancy regulation, radical scavenger activity, interaction with calmodulin) as well the ecological significance of the high melatonin levels recorded in alpine plants. Setting-up more reliable analytical methods for melatonin detection and quantification is a basic requirement to get more insight into melatonin roles in plant physiology and ecology.
To search for antitumor agents from plants, we studied Polygala vulgaris since cytotoxic lignans are known to occur in some Polygala species. Preliminary data on plant petrol ether, chloroform, and methanol extracts from the roots and aerial parts, showed in vitro cytotoxic activity against the solid tumor LoVo cell line. Fractionation of the active extracts led to the isolation of three new compounds, a derivative of aucuparine and two xanthones, as well as a known methylsinapate. All compounds were tested for in vitro cytotoxic activity using two cell lines, LoVo and its strain, which express resistance to common antitumor agents.