Margarida Maria dos Santos Humberto

Bio: Margarida Maria dos Santos Humberto is an academic researcher from Federal University of Alagoas. The author has contributed to research in topics: Triterpene & Syzygium. The author has an hindex of 2, co-authored 2 publications receiving 24 citations.

Estudo fitoquímico e avaliação das atividades moluscicida e larvicida dos extratos da casca do caule e folha de Eugenia malaccensis L. (Myrtaceae)

Abstract: Eugenia malaccensis L. (Syzygium malaccensis Merr. & Perry), popularly known in Brazil as jambo vermelho, is a very common tree and one of the medicinal plants of Alagoas State, Brazil. Previous chemical studies with E. malaccensis have been carried out with native plants from Asia, Oceania, and Central America. This work describes the chemical study of E. malaccensis L., a specimen collected in Alagoas State. Considering that studies on the molluscicidal and larvicidal potential of E. malaccensis were not reported, this work aimed to test its molluscicidal activity against Biomphalaria glabrata snails and larvicidal activity against Aedes aegypti mosquitos. The ethanolic stem bark and leaf extracts were inactive towards Aedes aegypti larvae. The ethanolic stem bark and leaf extract were active against Biomphalaria glabrata with CL50 = 42.53 and 41.90 mg/mL, respectively. 5,7,3',4',5'-Penta-hydroxy-flavonol (1), 5,7,3',5'-tetra-hydroxy-4'-methoxy-flavonol (2), 3,4,5-tri-hydroxybenzoic acid (3) and 3-acetyl-urs-12-en-28-oic acid (4) were isolated and identified from the leaves and stem bark. The acid 3b-O-acetyl-urs-12-en-28-oic is for the first time isolated from the genus Eugenia. The structures of the compounds have been established by IR, 1H and 13C NMR spectral analysis and by comparison with literature data.

Pentacyclic triterpene 5‐phenylpenta‐2,4‐dienoyl esters from Peltastes peltatus (Vell.) Woodson

Abstract: Two new pentacyclic triterpene esters, peltastine A [3beta-[5-phenyl-(2E,4E)-penta-2,4-dienoyloxy]-urs-12-ene] and peltastine B [3beta-[5-phenyl-(2E,4E)-penta-2,4-dienoyloxy]-lup-20(29)-ene], have been isolated from the stem of Peltastes peltatus (Vell.) Woodson along with the previously reported beta-amyrin juarezate [3-[5-phenyl-(2E,4E)-penta-2,4-dienoyloxy]-olean-12-ene]. The structures of these compounds were established by MS, 1D- and 2D-NMR experiments as well as by chemical degradation.

Phylogeny and systematics of the rauvolfioideae (apocynaceae) based on molecular and morphological evidence1

Abstract: To elucidate deeper relationships within Rauvolfioideae (Apocynaceae), a phylogenetic analysis was conducted using sequences from five DNA regions of the chloroplast genome (matK, rbcL, rpl16 intron, rps16 intron, and 3′ trnK intron), as well as morphology. Bayesian and parsimony analyses were performed on sequences from 50 taxa of Rauvolfioideae and 16 taxa from Apocynoideae. Neither subfamily is monophyletic, Rauvolfioideae because it is a grade and Apocynoideae because the subfamilies Periplocoideae, Secamonoideae, and Asclepiadoideae nest within it. In addition, three of the nine currently recognized tribes of Rauvolfioideae (Alstonieae, Melodineae, and Vinceae) are polyphyletic. We discuss morphological characters and identify pervasive homoplasy, particularly among fruit and seed characters previously used to delimit tribes in Rauvolfioideae, as the major source of incongruence between traditional classifications and our phylogenetic results. Based on our phylogeny, simple style-heads, sync...

Antioxidant Capacity and Phenolic Content of four Myrtaceae Plants of the South of Brazil

Abstract: Antioxidant compounds can be useful to prevent several degenerative diseases or as preservative in food and toiletries. Species of the Myrtaceae family are able to accumulate phenolic substances and those are closely related to the antioxidant activity due to their capacity to scavenge free radicals, protect against lipid peroxidation and quench reactive oxygen species. These facts prompted us to investigate the antioxidant capacity of the ethanolic extracts of the leaves of four Myrtaceae plants collected of the south of Brazil: Eugenia chlorophylla O. Berg., Eugenia pyriformis Cambess, Myrcia laruotteana Cambess and Myrcia obtecta (Berg) Kiacrsk. The antioxidant potential was performed using the DPPH (a single electron transfer reaction based assay) and ORAC (Oxygen Radical Absorbance Capacity, a hydrogen atom transfer reaction based assay) assays. Moreover, the total soluble phenolic content was also measured using the Folin-Ciocalteu reagent. A preliminary evaluation of the ethanolic extracts of these Myrtaceae plants revealed high levels of phenolic compounds (343.7-429.3 mg GAE) as well as high antioxidant activity according to both methods (1338 a 3785 micromol of TE/g of extract in ORAC and SC50 in the range of 1.70 and 33.7 microg/mL in the DPPH). The highest antioxidant activity obtained by DPPH assay was exhibited by ethanol extract of the leaves of E. pyriformis (1.70 microg/mL), followed by extracts of M. laruotteana (3.38 microg/mL) and M. obtecta (6.66 microg/mL). In comparison with controls, in the DPPH assay, the extract of E. pyriformis was more active than trolox (SC50 = 2.55 microg/mL), while the extracts of M. laruotteana and M. obtecta were more actives than quercetin (SC50 = 7.80 microg/mL). In the ORAC assay, all species also show good antioxidant capacity (>1000 micromol of TE/g). Initial HPLC-UV/DAD and ESI-MS confirmed the presence of phenolic acids constituents in the ethanol extracts. The results indicate the presence of compounds possessing promising antioxidant/free-radical scavenging activity in the analyzed extracts of Myrcia and Eugenia plants of the south of Brazil.

Ecological phytochemistry of Cerrado (Brazilian savanna) plants

Abstract: The Cerrado (the Brazilian savanna) is one of the vegetation formations of great biodiversity in Brazil and it has experienced strong deforestation and fragmentation. The Cerrado must contain at least 12,000 higher plant species. We discuss the ecological relevance of phytochemical studies carried out on plants from the Cerrado, including examples of phytotoxicity, antifungal, insecticidal and antibacterial activities. The results have been classified according to activity and plant family. The most active compounds have been highlighted and other activities are discussed. A large number of complex biochemical interactions occur in this system. However, only a small fraction of the species has been studied from the phytochemical viewpoint to identify the metabolites responsible for these interactions.