The aim of this study was to determine the palynological origin, phenolic and flavonoid content, and antioxidant properties of twenty-five samples of bee pollen harvested during a nine-month period (February–November) from the Canavieiras municipality (northeastern Brazil). Of the 25 samples analyzed, only two (February 01 and 02) were heterofloral. The predominant pollens in the samples analyzed during that month were: Cecropia, Eucalyptus, Elaeis, Mimosa pudica, Eupatorium, and Scoparia. Ethyl acetate fractions were analyzed by HPLC-DAD. The flavonoids isoquercetin, myricetin, tricetin, quercetin, luteolin, selagin, kaempferol, and isorhamnetin were detected. The flavonoid present in all 22 samples was isolated and identified as isorhamnetin 3-O-β-neohesperidoside. The total phenolic contents determined using the Folin-Ciocalteu reagent ranged from 41.5 to 213.2 mg GAE/g. Antioxidant activities based on the 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2-azinobis 3-ethylbenzothiozoline-6-sulfonic acid (ABTS), and Fe2+ ion chelating activity assays were observed for all extracts, and correlated with the total phenolic content.

Stingless bees in Brazil are indigenous and found all over the country. Bee pollen is used for its nutritional value in the human diet. It is made up of natural flower pollen mixed with nectar and bee secretions. In order to evaluate the chemical composition, free radical scavenging activity, and botanical origin, sample of pollen loads from stingless bee, Melipona rufiventris (Uruçu amarela) was studied. The EtOAc extract of pollen of Melipona rufiventris yielded the following compounds: p-hydroxycinnamic acid, dihydroquercetin, isorhamnetin, isorhamnetin-3-O-(6"-O-E-pcoumaroyl)-β-D-glucopyranoside, luteolin, and quercetin. This is the first report of the isolation of isorhamnetin-3-O-(6"-O-E-p-coumaroyl)-β-D-glucopyranoside from pollen. The free radical-scavenging activities of different solvent extracts of pollen were determined using DPPH assay. This activity decreases in the order: EtOAc>EtOH>Hexane extract. It appears that the EtOAc extract of the pollen is a good scavenger of active oxygen species. The botanical evaluation of pollen loads showed the composition by two pollen types, with the dominant type (97.3%) being Scoparia dulcis (L.) (Scrophulariaceae) and the minor one Senna obtusifolia (L.) Irwin & Barneby (Fabaceae). This suggests a specific foraging behavior in Melipona rufiventris bees, even in an environment with such a rich botanical diversity as the Northeastern Brazil.

__________________________________________________________________ ResumoPólen de abelhas é uma mistura de pólens florais coletados pelas abelhas com ampla variação na sua composição. Investigação do pólen coletado pela abelha sem ferrão Scaptotrigona bipunctata levou a quatro agliconas de flavonóides: miricetina, dihidromiricetina, quercetina e isoramnetina. As estruturas foram estabelecidas a partir de dados espectroscópicos (NMR) das substâncias naturais. AbstractBee pollen is a mix of bee-collected floral pollens which varies widely in composition. Investigation of pollen collected by the stingless bee Scaptotrigona bipunctata yielded four flavonoid aglycones: myricetin, dihydromyricetin, quercetin and isorhamnetin. The structures were established from spectroscopic data (NMR) of the natural substances. __________________________________________________________________ Os meliponíneos caracterizam-se por serem abelhas sociais e possuírem o ferrão atrofiado, impossibilitando seu uso, daí serem conhecidas popularmente como abelhas sem ferrão. Estas abelhas constituem um grupo formado por mais de 300 espécies conhecidas em todo mundo, sendo muitas destas nativas do Brasil 1 . Várias espécies de abelhas nativas encontramse ameaçadas de extinção devido à exploração predatória dos enxames, às queimadas e desmatamentos. Dentre os vários produtos das abelhas sem ferrão, encontra-se o pólen 1,2 . O "pólen de abelhas" é o resultado da aglutinação do pólen das flores com néctar e substâncias salivares das abelhas. Este pólen é acumulado em "cargas polínicas" nas corbículas (estruturas semelhantes a pequenas bolsas) e pode ser utilizado pelo homem 3 . Há séculos o pólen das abelhas vem sendo utilizado na medicina popular para aliviar e curar constipações, gripes, úlceras, envelhecimento precoce e outros 4,5 e atualmente existem diversos trabalhos de pesquisa sobre as potencialidades e interesse terapêutico do pólen de abelhas do gênero Apis, que vão desde o tratamento de rinites alérgicas 6,7 , hepatoprotetor 8 e antiteratogênico 9,10 . Este trabalho relata o resultado obtido da investigação química do pólen coletado pela abelha sem ferrão Scaptotrigona bipunctata.Os flavonóides encontrados no pólen são geralmente glicosilados, apenas alguns trabalhos citam os flavonóides do tipo aglicona 11,12,13,14 . O presente trabalho mostra a presença de quatro flavonóides agliconas, sendo o flavonóide diidromiricetina relatado pela primeira vez em pólen de abelhas. Estes dados mostrando duas variedades do padrão flavonoídico (miricetina e quercetina) sugerem que as abelhas podem estar visitando espécies de plantas diferentes.Pesquisas futuras serão feitas comparando os padrões dos flavonóides isolados do pólen da abelha com os flavonóides de origem botânica, o que permitirá usar estas substâncias fenólicas como marcadores em associação à análise palinológica. OH

In recent decades, the essential oils of plants have drawn great interest as sources of natural products. Essential oil from the fruits of Vismia guianensis was tested for its chemical constituents and antimicrobial and antioxidant activities. Gas chromatography/mass spectrometry (GC-MS) analysis of the essential oil revealed the presence of 38 sesquiterpenoids. The major components were βcaryophyllene (25.8%), α-copaene (13.1%), and δ-cadinene (11.6%). Antimicrobial activities were measured against six species of Gram negative and seven species of Gram positive bacteria and showed antibacterial activity against the human pathogenic Gram-positive bacteria Staphylococcus lentus with minimum inhibitory concentration (MIC) values of 78 μg/ml. The antioxidant activity of the essential oil was evaluated using the beta carotene/linoleic acid assay and showed antioxidant activity.

A modified and efficient Knoevenagel condensation procedure was developed to synthesize the title compounds using β-alanine and acetic acid as catalysts, showing good to excellent yields. We used lawsone with suitable aliphatic aldehydes including isobutyraldehyde, 3-methylbutyraldehyde, 2-ethylbutyraldehyde, phenylacetaldehyde, 2-phenyl-propionaldehyde, among others. These compounds were submitted to cytotoxic screening against three tumor cell lines presenting good to excellent cytotoxic profiles.

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