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The south Brazilian Hypericum species have revealed the presence of a series of biologically active phloroglucinol derivatives. In this study, a mixture of japonicine A and an isomer with an unreported structure, named japonicine E, was isolated from the roots of H. polyanthemum. Additionally, uliginosin A from H. myrianthum, isouliginosin B from H. polyanthemum, hyperbrasilol B and isohyperbrasilol B from H. caprifoliatum and cariphenone A from H. carinatum were also isolated. The structures were elucidated using 1D- and 2D-NMR experiments and by comparison with previously reported data. The compounds japonicines A/E, uliginosin A, isouliginosin B, hyperbrasilol B and cariphenone A exhibited antinociceptive activity in the mice hot-plate test and did not induce motor impairment in the rotarod apparatus., (© 2018 Wiley-VHCA AG, Zurich, Switzerland.)

Bioactivity-guided fractionation of the EtOH extract of the branches of Kielmeyera variabilis led to the isolation of a new acylphoroglucinol (1), which was active against all the MRSA strains tested herein, with pronounced activity against strain EMRSA-16. Compound 1 displayed an MIC of 0.5 mg/L as compared with an MIC of 128 mg/L for the control antibiotic norfloxacin. The structure of the new compound was elucidated by 1D and 2D NMR spectroscopic analysis and mass spectrometry, and experimental and calculated ECD were used to determine the absolute configurations. The compounds β-sitosterol (2), stigmasterol (3), ergost-5-en-3-ol (4), and osajaxanthone (5) also occurred in the n-hexane fraction. The EtOAc fraction contained nine known xanthones: 3,6-dihydroxy-1,4,8-trimethoxyxanthone (6), 3,5-dihydroxy-4-methoxyxanthone (7), 3,4-dihydroxy-6,8-dimethoxyxanthone (8), 3,4-dihydroxy-2-methoxyxanthone (9), 5-hydroxy-1,3-dimethoxyxanthone (10), 4-hydroxy-2,3-dimethoxyxanthone (11), kielcorin (12), 3-hydroxy-2-methoxyxanthone (13), and 2-hydroxy-1-methoxyxanthone (14), which showed moderate to low activity against the tested MRSA strains.

Three dimeric acylphloroglucinols, austrobrasilol A, austrobrasilol B and isoaustrobrasilol B were isolated from the flowers of Hypericum austrobrasiliense (Hypericaceae, section Trigynobrathys). Their structures were elucidated using mass spectrometry and NMR experiments (1D and 2D), and by comparison with previously reported data for other dimeric acylphloroglucinols isolated from Hypericum and Elaphoglossum genera. The three compounds were orally administered in mice at equimolar doses to uliginosin B (15mg/kg, p.o.) displaying antinociceptive activity in the hot-plate test. The compounds did not induce motor impairment in the rotarod apparatus., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

A large number of plants are known to possess strong antitumor properties. Previous studies have verified the antiproliferative activity of the extracts and fractions from six species of Hypericum spp. growing in southern Brazil. In the present study, the in-vitro antiproliferative effects of two dimeric phloroglucinols (japonicin A and uliginosin B, isolated from Hypericum myrianthum) and two benzophenones (cariphenone A and cariphenone B, isolated from H. carinatum) were investigated against three tumor cell lines (HT-29 - human colon carcinoma cells; U-251 - human glioma cell line, and OVCAR-3 - human ovarian carcinoma cells). In addition, different doses of these compounds were associated with cytotoxic drugs commonly used as chemotherapy in the clinic. Cariphenone A and cariphenone B showed moderate antiproliferative activity against all tumor cell lines at a dose of 100 μg/ml. Unlike benzophenones, japonicin A and uliginosin B exerted antiproliferative effects only in the OVCAR-3 cell line. Moreover, a very strong synergistic effect was demonstrated by the association of subeffective doses of japonicin A with the chemotherapeutic drug paclitaxel, decreasing cellular proliferation of the OVCAR-3 cell line. These preliminary results provide a scientific basis to further pursue these compounds as potential combined therapy for certain tumor types.

Two new polyprenylated acylphloroglucinols, spiranthenones A (1) and B (2), a sesquiterpenoid, 6 α-acetoxy,1 β-hydroxyeudesm-4(15)-ene (3), along with sesamin and β-sitosterol, were isolated from the EtOAc extract of the leaves of Spiranthera odoratissima, and shown to display antiprotozoal activity. Their structures and relative stereochemistry were elucidated by NMR and mass spectrometry. These compounds exhibited moderate antiprotozoal activity, but without significant cytotoxicity against fibroblasts cell line NIH-3T3. Compound 3 was the most selective towards parasites., (© Georg Thieme Verlag KG Stuttgart · New York.)

Two new benzophenones were isolated from the leaves of Hypericum carinatum. Their structures were established on the basis of 2D NMR spectroscopic analyses and mass spectrometry as cariphenone A (6-benzoyl-5,7-dihydroxy-2,2,8-trimethyl-2H-chromene) (1) and cariphenone B (8-benzoyl-5,7-dihydroxy-2,2,6-trimethyl-2H-chromene) (2). Five known compounds, the phloroglucinol derivative uliginosin B (3), 1-eicosanol, sitosterol, stigmasterol, and campesterol, were also characterized. Compounds 1-3 were evaluated for their total antioxidant capacity through a total radical-trapping parameter assay. Only compound 1 showed moderate antioxidant activity, exhibiting inhibition of chemiluminescence similar to that of quercetin at the same concentration.