Ethnopharmacological relevanceThe plant arctic root (Rhodiola rosea, L.) is growing in northern regions of Europe, Asia and North America. Extracts of R. rosea are used in traditional medicine for various conditions related to nervous system function. According to scientific studies from the last decades, the plant might have potential for use in the treatment of memory impairments, stress and depression, but reports concerning other neuropsychiatric disorders are scarce.Aim of the studyIn this context, our study aimed to examine potential antipsychotic-like effects of R. rosea root extract.Materials and MethodsWe tested the effects of R. rosea root extract on prepulse inhibition in rats and mice. Prepulse inhibition is an established operational measure of sensorimotor gating, which is impaired in schizophrenia and other psychotic disorders.ResultsR. rosea root extract increased prepulse inhibition in rats and mice. Interestingly, the R. rosea extract had stronger effects in those individual animals that had low baseline levels of prepulse inhibition. Therefore, we performed further experiments in which we pharmacologically induced a prepulse inhibition deficit by two different psychostimulants, either the dopamine D2 receptor agonist apomorphine or the NMDA receptor antagonist dizocilpine (MK-801). Pre-treatment with the R. rosea extract significantly restored both, apomorphine- and dizocilpine-induced prepulse inhibition deficits.ConclusionsThe present study demonstrates that R. rosea extract robustly reverses prepulse inhibition deficits in rodents. This suggests antipsychotic-like effects of R. rosea extract. Future studies should focus on the pharmacological mechanisms underlying these effects.

Ethnopharmacological relevanceProstate cancer is one of the most diagnosed forms of cancer among men in western regions. Many traditional applications or phytotherapeutic concepts propose to inhibit the proliferation of prostate cancer cells. In order to detect influences of plant or fungal extracts and derived fractions on androgen receptor signaling pathways, a differentiating cell proliferation assay was established, which enables the simultaneous detection of hormonal and cytotoxic effects.Material and methodsThe well characterized prostate cancer cell lines LNCaP and PC-3 were used in a multiple readout assay. In all, 186 fractions of 23 traditionally used organisms were screened regarding their effects on proliferation of the two prostate cancer cell lines. The fractions were prepared by accelerated solvent extraction followed by gradient extrography. Extracts of the potential hormonally active plants Cibotium barometz, Heteropterys chrysophylla, and Sideroxylon obtusifolium (= Bumelia sartorum) were phytochemically investigated.ResultsFractions from Cibotium barometz, Cortinarius rubellus, Cyrtomium falcatum, Heteropterys chrysophylla, Nephrolepis exaltata, Salvia miltiorrhiza, Sideroxylon obtusifolium, Trichilia emetica, and Trimeria grandifolia exhibited hormonal influences on prostate cancer cells. Cytotoxic activity towards human cell lines was detected for the first time for fractions from Aglaia spectabilis (A. gigantea), Nephrolepis exaltata and Cortinarius brunneus.ConclusionsThe differential behavior of the two prostate cancer cell lines allows the discrimination between potential androgenic or antiandrogenic activities and effects on the estrogen or glucocorticoid receptor as well as cytotoxic activities. The combined cell lines assay can help to assess the biological activities of material used in traditional medicine.

Aim of the studyFor identification of the active constituents we investigated the anticancer activity of cardenolides from Streptocaulon tomentosum Wight & Arn. (Asclepiadaceae) and from Nerium oleander L. (Apocynaceae) which are both used against cancer in the traditional medicine in their region of origin.Material, methods and resultsThe antiproliferative activity of cardenolides isolated from roots of Streptocaulon tomentosum (IC50 < 1–15.3 μM after 2 days in MCF7) and of cardenolide containing fractions from the cold aqueous extract of Nerium oleander leaves (“Breastin”, mean IC50 0.85 μg/ml in a panel of 36 human tumor cell lines), their influence on the cellular viability and on the cell cycle (block at the G2/M-phase or at the S-phase in tumor cells, respectively) were determined using different cell lines. The murine cell line L929 and normal non-tumor cells were not affected. Bioactivity guided fractionation of Breastin resulted in the isolation of the monoglycosidic cardenolides oleandrine, oleandrigeninsarmentoside, neritaloside, odoroside H, and odoroside A (IC50-values between 0.010 and 0.071 μg/ml).ConclusionsThe observed anticancer activities of extracts and isolated cardenolides are in agreement with the ethnomedicinal use of Streptocaulon tomentosum and Nerium oleander. The most active anticancer compounds from both species are monoglycosidic cardenolides possessing the 3β,14β-dihydroxy-5β-card-20(22)-enolide structure with or without an acetoxy group at C-16. The results indicate that the cytotoxic effects are induced by the inhibition of the plasma membrane bound Na+/K+-ATPase.