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Brazilian green and red propolis stand out as commercial products for different medical applications. In this article, we report the antimicrobial activities of the hydroalcoholic extracts of green (EGP) and red (ERP) propolis, as well as guttiferone E plus xanthochymol (8) and oblongifolin B (9) from red propolis, against multidrug-resistant bacteria (MDRB). We undertook the minimal inhibitory (MIC) and bactericidal (MBC) concentrations, inhibition of biofilm formation (MICB 50 ), catalase, coagulase, DNase, lipase, and hemolysin assays, along with molecular docking simulations. ERP was more effective by displaying MIC and MBC values <100 μg mL -1 . Compounds 8 and 9 displayed the lowest MIC values (0.98 to 31.25 μg mL -1 ) against all tested Gram-positive MDRB. They also inhibited the biofilm formation of S. aureus (ATCC 43300 and clinical isolate) and S. epidermidis (ATCC 14990 and clinical isolate), with MICB 50 values between 1.56 and 6.25 μg mL -1 . The molecular docking results indicated that 8 and 9 might interact with the catalase's amino acids. Compounds 8 and 9 have great antimicrobial potential., (© 2021 Wiley-VHCA AG, Zurich, Switzerland.)

Three new caged polyprenylated benzophenone derivatives named burlemarxiones D-F (1-3) were isolated from the hexane extract of Clusia burle-marxii trunks. Burlemarxione D (1) contains the tetracyclo[8.3.1.0 3,11 .0 5,10 ]tetradecane core skeleton also observed for burlemarxione A, its probable immediate precursor. However, two additional rings are formed to produce an unprecedented complex-caged core skeleton. These additional rings could be formed by a radical cyclization reaction of one prenyl group at C-5 with C-1 and C-33, followed by oxidative dehydrogenation (rearomatization) or by an intramolecular [4 + 2] radical cycloaddition (Diels-Alder reaction), followed by an enolization reaction (rearomatization). Burlemarxiones E and F were isolated after methylation with diazomethane that was necessary to avoid the interconversion of the pair of β-diketones in tautomeric equilibrium. The proposed biosynthetic pathway for burlemarxiones D-F involves the condensation of either lavandulyl pyrophosphate or 2-(1-methylvinyl)-hexa-5-enyl pyrophosphate with the acylphloroglucinol derivative 6-benzoyl-5-hydroxy-5-cyclohexen-1,3-dione, followed by consecutive prenylation reactions. Therefore, Clusia burle-marxii reinforces the claim that the genus Clusia is an important source of sophisticated caged polyprenylated benzophenone derivatives., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The overexposure of the skin to ultraviolet (UV) radiation may lead to oxidative stress, resulting in severe damage. The prevention of skin injuries through the topical application of natural compounds rich in antioxidants, such as propolis extracts, has shown promising results. In Brazil, the "red propolis" extract has stood out due to its complex constitution, based mainly on polyprenylated benzophenones (BZP). However, although the use of red propolis extracts has been shown to be encouraging, their addition in topical formulations is limited by the low solubility of BZP. For this reason, this study aimed to develop topical nanoemulgels containing Brazilian red propolis (BRP) extract to increase the potential of topical application, and the evaluation of skin protection against UVA/UVB radiation damage by means of protein carbonylation, protein thiol content and TBARS assays. The nanoemulgels were obtained by adding gelling polymer to nanoemulsions that were previously prepared by spontaneous emulsification. In this sense, a nanoemulgel containing BRP extract-loaded nanoemulsions (H-NE) and a nanoemulgel containing BRP extract-loaded nanoemulsions with DOTAP (H-NE/DT) were prepared. The physicochemical characterization of nanoemulgels showed monodisperse populations of 200-300 nm. The H-NE zeta potential was -38 mV, while that of H-NE/DT was +36 mV. BZP content in the formulations was around 0.86 mg g-1. These parameters remained stable for 90 days under cold storage. H/NE and H-NE/DT presented a non-Newtonian pseudoplastic rheological behavior. Permeation/retention studies, through porcine ear skin, showed the highest BZP retention (18.11 μg cm-2 after 8 h) for H-NE/DT, which also demonstrated, in an in vitro study, the highest ability to protect skin against oxidative damage after UVA/UVB radiation exposure. The results concerning the antioxidant activity revealed that formulations containing the BRP n-hexane extract were the most promising in combating oxidative stress, probable due to the presence of polyprenylated BZP. Altogether, the outcomes of this study suggest that nanoemulgels have suitable characteristics for topical application, and may be an alternative for the prevention of oxidative skin damage caused by UVA/UVB radiation.

The Brazilian red propolis (BRP) constitutes an important commercial asset for northeast Brazilian beekeepers. The role of Dalbergia ecastaphyllum (L.) Taub. (Fabaceae) as the main botanical source of this propolis has been previously confirmed. However, in addition to isoflavonoids and other phenolics, which are present in the resin of D. ecastaphyllum , samples of BRP are reported to contain substantial amounts of polyprenylated benzophenones, whose botanical source was unknown. Therefore, field surveys, phytochemical and chromatographic analyses were undertaken to confirm the botanical sources of the red propolis produced in apiaries located in Canavieiras, Bahia, Brazil. The results confirmed D. ecastaphyllum as the botanical source of liquiritigenin ( 1 ), isoliquiritigenin ( 2 ), formononetin ( 3 ), vestitol ( 4 ), neovestitol ( 5 ), medicarpin ( 6 ), and 7- O -neovestitol ( 7 ), while Symphonia globulifera L.f. (Clusiaceae) is herein reported for the first time as the botanical source of polyprenylated benzophenones, mainly guttiferone E ( 8 ) and oblongifolin B ( 9 ), as well as the triterpenoids β -amyrin ( 10 ) and glutinol ( 11 ). The chemotaxonomic and economic significance of the occurrence of polyprenylated benzophenones in red propolis is discussed.

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 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.