The metastasis suppressor gene KiSS-1 encodes kisspeptins, the natural ligands of the orphan G protein-coupled receptor GPR54.

Natural peptides displaying agonist activity on the orphan G protein-coupled receptor GPR54 were isolated from human placenta. These 54-, 14,- and 13-amino acid peptides, with a common RF-amide C terminus, derive from the product of KiSS-1, a metastasis suppressor gene for melanoma cells, and were therefore designated kisspeptins. They bound with low nanomolar affinities to rat and human GPR54 expressed in Chinese hamster ovary K1 cells and stimulated PIP(2) hydrolysis, Ca(2+) mobilization, arachidonic acid release, ERK1/2 and p38 MAP kinase phosphorylation, and stress fiber formation but inhibited cell proliferation.

Photocytotoxicity of hypericin in normoxic and hypoxic conditions.

The normoxic and hypoxic photocytotoxicity of hypericin has been examined on A431 cells as assessed by the Neutral Red method, using cell-culture flasks made of polystyrene and glass, different hypericin concentrations and light fluences. Using polystyrene flasks, lower hypoxic photoactivities of hypericin than those in normoxic conditions are seen under low fluence. In these conditions the hypoxic photocytotoxic effect can be (partially) rescued by increasing the fluence.

Evidence that total extract of Hypericum perforatum affects exploratory behavior and exerts anxiolytic effects in rats.

Clinical trials have extensively reported the ability of Hypericum perforatum extracts to exert a significant antidepressant activity. Hypericin, the main constituent of H. perforatum extract, is no more regarded as the active principle of the antidepressant activity of the drug.

Photocytotoxicity of protohypericin after photoconversion to hypericin.

In the present study, protohypericin was synthesised in order to compare its intrinsic photocytotoxicity with that of hypericin. The experimental work was performed in specific filtered light conditions that prevented both an unintended photoconversion of protohypericin and photosensitization of the cells. Assessing the photocytotoxicity as a function of irradiation time, it was found that the photocytotoxicity of both compounds converged after a long irradiation time (i.

Confluence dependent resistance to photo-activated hypericin in HeLa cells.

Hypericin is a natural photo-active pigment produced by plants of the genus Hypericum. The compound exhibits a potent photocytotoxic activity in vitro and in vivo. Using HeLa cells we further investigated whether the photocytotoxic in vitro effect of hypericin is influenced by the cell density.