Raimundo Braz-Filho

Bio: Raimundo Braz-Filho is an academic researcher from Universidade Federal Rural do Rio de Janeiro. The author has contributed to research in topics: Carbon-13 NMR & Proton NMR. The author has an hindex of 32, co-authored 377 publications receiving 4923 citations. Previous affiliations of Raimundo Braz-Filho include State University of Norte Fluminense & Federal University of São Carlos.

Antibacterial and antioxidant activities of ursolic acid and derivatives.

Abstract: Ursolic acid, an important bioactive compound, was isolated from ethanol extract of aerial parts of Sambucus australis. In order to develop bioactive ursolic acid derivatives, two semi-synthetic compounds were obtained through modification at C-3. The antibacterial activity of the ursolic acid and its derivatives was investigated. The microdilution method was used for determination of the minimal inhibitory concentration (MIC), against twelve bacterial strains. The influence of ursolic acid and its derivatives on the susceptibility of some bacterial pathogens to the aminoglycosides antibiotics neomycin, amikacin, kanamycin and gentamicin was evaluated. The most representative synergistic effect was observed by 3β-formyloxy-urs-12-en-28-oic acid at the concentration of 64 μg/mL in combination with kanamycin against Escherichia coli (27), a multidrug-resistant clinical isolate from sputum, with reduction of MIC value from 128 μg/mL to 8 μg/mL. Ursolic acid and its derivatives were examined for their radical scavenger activity using the DPPH assay, and showed significant activity.

Coconut water (Cocos nucifera L.)—A new biocatalyst system for organic synthesis

Abstract: A series of aliphatic and aromatic aldehydes and ketones was reduced using plant cell preparations from coconut juice, Cocos nucifera, also called ACC (agua-de-coco do Ceara). The reduced products were typically obtained in excellent yields (%) and with very high enantiomeric excess. Esters, amides, and nitrobenzene, yielded acids, amines and an azoxyderivative with satisfactory results.

Terpenoids from Endophytic Fungi

Abstract: This work reviews the production of terpenoids by endophytic fungi and their biological activities, in period of 2006 to 2010. Sixty five sesquiterpenes, 45 diterpenes, five meroterpenes and 12 other terpenes, amounting to 127 terpenoids were isolated from endophytic fungi.

Bioatividade de ácidos húmicos: efeitos sobre o desenvolvimento radicular e sobre a bomba de prótons da membrana plasmática

Abstract: – The bioactivity of humic acids (HA) isolated from sludge of the station of sewer treatment(HAL) and from vermicompost (HAV) was evaluated through the action of those substances onprimary transport of protons of the plasma membrane of coffee and corn root cells and its relationshipwith the development of those species. A stimulation in the superficial area of roots was observed forboth species cultivated with both humic acids, exhibiting an optimum concentration, about 40 mg L -1 ofHA. In this condition the treatment with HAL and HAV stimulated the plasma membrane H + -ATPaseof corn and coffee roots. HAL were more effective to promote those effects than HAV. The modifica-tion of the chromatographic profile of the HA in solution before and after the cultivation of theseedlings revealed that the interaction plant-HA promoted a rearrangement of the average molecularweight of those substances suggesting a dynamic mobilization of bioactive subunits of the HA by plantexudates. The structural analysis of the HA has detected the presence of auxin groups. A comparativeanalysis of the action of those HA on the monocotyledonous (corn) and dicotyledonous (coffee) plantsindicates to the activation of plasmallema H

Antimicrobial activity of wax and hexane extracts from Citrus spp. peels.

Abstract: Antibacterial and antifungal properties of wax and hexane extracts of Citrus spp. peels were tested using bioautographic and microdilution techniques against three plant pathogenic fungi (Penicillium digitatum, Curvularia sp., and Colletotrichum sp.), two human pathogens (Trichophyton mentagrophytes and Microsporum canis), and two opportunistic bacteria (Escherichia coli and Staphylococcus aureus). Two polymethoxylated flavonoids and a coumarin derivative, were isolated and identified from peel extracts, which presented antimicrobial activity especially against M. canis and T. mentagrophytes: 4',5,6,7,8-pentamethoxyflavone (tangeritin) and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin) from C. reticulata; and 6,7-dimethoxycoumarin (also known as escoparone, scoparone or scoparin) from C. limon.

A review on the dietary flavonoid kaempferol.

Abstract: Epidemiological studies have revealed that a diet rich in plant-derived foods has a protective effect on human health. Identifying bioactive dietary constituents is an active area of scientific investigation that may lead to new drug discovery. Kaempferol (3,5,7-trihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) is a flavonoid found in many edible plants (e.g. tea, broccoli, cabbage, kale, beans, endive, leek, tomato, strawberries and grapes) and in plants or botanical products commonly used in traditional medicine (e.g. Ginkgo biloba, Tilia spp, Equisetum spp, Moringa oleifera, Sophora japonica and propolis). Some epidemiological studies have found a positive association between the consumption of foods containing kaempferol and a reduced risk of developing several disorders such as cancer and cardiovascular diseases. Numerous preclinical studies have shown that kaempferol and some glycosides of kaempferol have a wide range of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anticancer, cardioprotective, neuroprotective, antidiabetic, anti-osteoporotic, estrogenic/antiestrogenic, anxiolytic, analgesic and antiallergic activities. In this article, the distribution of kaempferol in the plant kingdom and its pharmacological properties are reviewed. The pharmacokinetics (e.g. oral bioavailability, metabolism, plasma levels) and safety of kaempferol are also analyzed. This information may help understand the health benefits of kaempferol-containing plants and may contribute to develop this flavonoid as a possible agent for the prevention and treatment of some diseases.

Chalcone: A Privileged Structure in Medicinal Chemistry.

Abstract: Privileged structures have been widely used as an effective template in medicinal chemistry for drug discovery. Chalcone is a common simple scaffold found in many naturally occurring compounds. Many chalcone derivatives have also been prepared due to their convenient synthesis. These natural products and synthetic compounds have shown numerous interesting biological activities with clinical potentials against various diseases. This review aims to highlight the recent evidence of chalcone as a privileged scaffold in medicinal chemistry. Multiple aspects of chalcone will be summarized herein, including the isolation of novel chalcone derivatives, the development of new synthetic methodologies, the evaluation of their biological properties, and the exploration of the mechanisms of action as well as target identification. This review is expected to be a comprehensive, authoritative, and critical review of the chalcone template to the chemistry community.