Flavonoids from Brosimum acutifolium

Biotransformation of the Phenolic Constituents from Licorice and Cytotoxicity Evaluation of Their Metabolites

Biotransformation of four bioactive phenolic constituents from licorice, namely licoisoflavanone (1), glycyrrhisoflavone (2), echinatin (3), and isobavachalcone (4), was performed by the selected fungal strain Aspergillus niger KCCM 60332, leading to the isolation of seventeen metabolites (5-21). Structures of the isolated compounds were determined on the basis of extensive spectroscopic methods, twelve of which (5-7, 10-17 and 19) have been previously undescribed. A series of reactions including hydroxylation, hydrogenation, epoxidation, hydrolysis, reduction, cyclization, and alkylation was observed in the biotransformation process. All compounds were tested for their cytotoxic activities against three different human cancer cell lines including A375P, MCF-7, and HT-29. Compounds 1 and 12 exhibited most considerable cytotoxic activities against all the cell lines investigated, while compounds 2 and 4 were moderately cytotoxic. These findings will contribute to expanding the chemical diversity of phenolic compounds, and compounds 1 and 12 may serve as leads for the development of potential cancer chemopreventive agents.

Betulinic Acid and Brosimine B Hybrid Derivatives as Potential Agents against Female Cancers

Background:

Cancer is a multifactorial disease, representing one of the leading causes of death worldwide. On a global estimate, breast cancer is the most frequently occurring cancer in women and cervical cancer, the fourth most common. Both types of cancer remain the major cause of cancer-related mortality in developing countries. A strategy for rational drug design is hybridization, which aims to bring together in one molecule, two or more pharmacophores in order to reach several biological targets.

Objective:

The objective of this work was to develop new hybrids based on natural pharmacophores: Betulinic acid (1) and brosimine b (2), active in female cancer cell lines.

Methods:

The coupling reactions were carried out by Steglich esterification. Different compounds were designed for the complete and simplified structural hybridization of molecules. The anticancer activities of the compounds were evaluated in human cervical adenocarcinoma (HeLa), human cervical metastatic epidermoid carcinoma (ME-180), and human breast adenocarcinoma (MCF-7) cell lines.

Results:

Hybrid 3 presented higher potency (IC50 = 9.2 ± 0.5μM) and SI (43.5) selectively in MCF-7 cells (in relation to Vero cells) with its cytotoxic effect occurring via apoptosis. In addition, compound 6 showed activity in MCF-7 and HeLa cells with intermediate potency, but with high efficacy, acting via apoptosis as well.

Conclusion:

In this context, we showed that the combination of two complex structures generated the development of hybrids with differing inhibitory profiles and apoptotic modes of action, thus representing potential alternatives in female cancer treatment.

Remarkable capacity of brosimine b to disrupt methicillin-resistant Staphylococcus aureus (MRSA) preformed biofilms

Methicillin-resistant Staphylococcus aureus (MRSA) is a major public health concern representing about 60% of S. aureus isolated from hospitalized patients in countries such as USA and Brazil in the last years. Additionally, the ability to adhere to surfaces and the development of biofilms are important properties of pathogenic bacteria involved in medical device-associated infections, and staphylococci are recognized as the major etiologic agents in these situations. The aim of this study is to evaluate three Brosimum acutifolium flavonoids, 4'-hydroxy-7,8(2″,2″-dimethylpyran)flavan (1), brosimine b (2) and 4-hydroxy-lonchocarpin (3), regarding their antibiofilm, antibacterial and antioxidant activities. Flavonoids 1 and 2 were able to reduce S. aureus viability within preformed biofilms in 73% at 50 μM while 2 also reduced biofilm biomass in 48% at 100 μM. Flavonoid 3 was not able to reduce biofilm biomass at assessed concentrations. When tested against methicillin-resistant S. aureus (MRSA) strains, 2 (100 μM) reduced 70%-98% of viable bacteria within 24h-old biofilms. The minimum inhibitory concentration against the methicillin-sensitive Staphylococcus aureus ATCC 25904 was 50 μM for the three compounds. In preliminary assays to evaluate cytotoxicity, 1 was highly hemolytic at concentrations above 50 μM while 2 and 3 did not cause significant hemolysis at 100 μM. The antioxidant activity was observed only in the ethanolic extract and 2. In vivo toxicity evaluations using Galleria mellonella larvae as alternative host model resulted in 83.3% survival for treatment with 1, 76.7% for 2, and 100% for 3 at 500 mg/kg. This study highlights the potential of these flavonoids, especially 2, as antibiofilm agent to control preformed S. aureus biofilms.

2-Arylbenzofuran, flavonoid, and tyrosinase inhibitory constituents of Morus yunnanensis

Two novel 2-arylbenzofuran dimers, morusyunnansins A and B (1 and 2), two new biflavonoids, morusyunnansins C and D (3 and 4), two new flavans, morusyunnansins E and F (5 and 6), and four known flavans (7-10) were isolated from the leaves of Morus yunnanensis. Compounds 5-8 showed potent inhibitory effects on mushroom tyrosinase with IC(50) values ranging from 0.12 ± 0.02 to 1.43 ± 0.43 μM.

Furanoflavonoids: an overview

The review covers the phytochemistry and pharmacology of furanoflavonoids describing 291 compounds and containing 228 references.

Natural PTP1B inhibitors from Broussonetia papyrifera

Two new compounds, 8-(1,1-dimethylallyl)-5'-(3-methylbut-2-enyl)-3',4',5,7-tetrahydroxyflanvonol (1), 3'-(3-methylbut-2-enyl)-3',4',7-trihydroxyflavane (2) and three known compounds 3,3',4',5,7-pentahydroxyflavone (3), uralenol (4), broussochalcone A (5) were isolated from the roots of Broussonetia papyrifera, and their structures determined by spectroscopic methods. Compounds 1, 3, 4 and 5 significantly show the inhibitory activities against the PTP1B enzyme.

Brosimacutins A-I, nine new flavonoids from Brosimum acutifolium

Nine new flavonoids, brosimacutins A-I (1-9), and four known flavonoids were isolated from the bark of Brosimum acutifolium, a Brazilian folk medicine ("Mururé"). Their structures were elucidated by spectroscopic methods, including 2D NMR. Brosimacutins A-I possess differentially functionalized isoprene units at C-8.

Acutifolins A-F, a new flavan-derived constituent and five new flavans from Brosimum acutifolium

Acutifolin A (1), a novel constituent with a bicyclo[3.3.1]non-3-ene-2,9-dione ring, acutifolins B-F (2-6), five new flavans, and three known flavans were isolated from the bark of Brosimum acutifolium, a Brazilian folk medicine ("Mururé"). Their structures were elucidated by spectroscopic methods, including 2D NMR.