Roberto Carlos Campos Martins

The increasing prevalence of multidrug-resistant bacteria highlights the urgent need for novel antimicrobial agents from natural sources. This study investigated the antibacterial, antibiofilm, and antioxidant activities of Metrodorea nigra leaves through a bioassay-guided approach combined with UHPLC-MS/MS and feature-based molecular networking (FBMN). The dichloromethane fraction and its subfraction Sp1D exhibited the highest antibacterial activity, with minimum inhibitory concentrations as low as 16–32 µg/ml against Gram-positive strains, including Staphylococcus aureus . Sp1D also demonstrated bactericidal effects and strong inhibition of biofilm formation. Metabolomic analysis revealed a predominance of flavonoids and identified pinostrobin, supported by NMR and MS/MS data, as a major constituent, along with the annotation of rhodomyrtone. FBMN analysis suggested a positive correlation between antibacterial activity and aglycone flavanones, whereas glycosylated flavonoids were mainly associated with inactive samples, indicating the influence of structural features on bioactivity. Antioxidant assays confirmed significant radical scavenging and reducing capacities, particularly for the crude extract and dichloromethane fraction. These findings expand the phytochemical knowledge of M. nigra , including the first report of flavanones in the genus, and highlight its potential as a source of bioactive compounds for the development of new antimicrobial agents.

Brazilian native seaweed Canistrocarpus cervicornis (Ochrophyta, Dictyotaceae) is recognized for its chemodiversity, particularly cyclic diterpenes and polysaccharides, yet its relevance to neurological disorders remains unexplored. This study evaluated the neuroprotective potential of a hydroethanolic extract (ECCH), its polar fraction (CCFPol), a dichloromethane extract (ECCD), and eight derived fractions (CCF1–2, CCF3, CCF4, CCF5–6, CCF7, CCF8–10, and CCF11–15). Cytotoxicity was evaluated in SH-SY5Y neuroblastoma cells, and neuroprotection was examined against 6-OHDA–induced toxicity. The mitochondrial membrane potential, ROS and H₂O₂ generation assays were conducted to explore the mechanisms underlying the observed effects. Among the key findings, the CCF3 fraction exhibited a high content (75.04%) of dolastane-type diterpenoids. Both CCFPol (100 µg/mL) and CCF3 (1 µg/mL) increased cell viability to 68.43 ± 4.60% and 60.61 ± 0.80%, respectively, compared with 6-OHDA–treated cells (50.70 ± 2.71%). Additionally, CCF3 and CCFPol reduced H₂O₂ levels (200.0 ± 18.19% and 195.5 ± 16.13%, respectively, vs. 6-OHDA-treated cells: 302.2 ± 17.07%) and lowered intracellular ROS (122.6 ± 22.7% and 129.6 ± 19.4%, respectively, vs. 6-OHDA-treated cells: 153.0 ± 32.7%). This is the first study to demonstrate the neuroprotective potential of the C. cervicornis in a 6-OHDA-induced neurotoxicity cellular model, contributing to the understanding of marine bioactive resources and their relevance for neurological research. Additional studies aimed at isolating the active constituents and clarifying their mechanisms of action will further strengthen and expand the biological relevance of this specie as source of neuroprotective agents.

This study aimed to assess the antimicrobial potential of Bp1-AdE, produced by Bacillus pumilus 64-1, and to investigate its mode of action against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Bp-1AdE, derived from sponge-associated B. pumilus, exhibited bactericidal activity at 1,550 µg ml⁻¹ against S. aureus ATCC29213 and MRSA strains. Light and fluorescence microscopy revealed drastic cell lysis of S. aureus treated with Bp-1AdE. Scanning and transmission electron microscopy suggested that Bp-1AdE disrupts the cytoplasmic membrane. Toxicity assays showed that Bp-1AdE was non-toxic to Tenebrio molitor larvae. Liquid chromatography-mass spectrometry (LC-MS) and Global Natural Product Social (GNPS) spectral libraries identified four substances within Bp-1AdE, including aliphatic alcohols [3,4-dipentylhexane-2,5-diol and 1,1'-(4,5-dibutyl-3,6-dimethylcyclohexane-1,2-diyl)bis(ethan-1-one)] and terpenoids (cholic acid and canrenone). Bp-1AdE demonstrated selective toxicity and bactericidal activity, highlighting its potential for controlling infections caused by multidrug-resistant S. aureus strains.

Publicado em 10 de novembro de 2022. Esta cartilha é resultado de uma motivação pessoal dos autores em proporcionar uma apresentação e divulgação de conhecimentos científicos sobre a linha de pesquisa de cultivo de macroalgas marinhas, sob condições controladas em laboratório, de forma didática e compilada. As informações apresentadas neste documento foram obtidas através de uma revisão bibliográfica de estudos publicados nos últimos 20 anos sobre cultivo de macroalgas em condições laboratoriais. Apresentamos conceitos como: o que são macroalgas, porque são cultivadas e quais são os tipos de cultivo. Além disso, relatamos quais as espécies de algas marinhas que têm sido objeto de estudos por pesquisadores de todo o mundo. Ademais, apresentamos dados referentes aos fatores abióticos que influenciam a manutenção de macroalgas em laboratórios, as principais aplicações biotecnológicas atuais e as algas cultivadas no Brasil. Dessa forma, o documento é destinado a toda comunidade acadêmica incluindo alunos e professores das áreas de ficologia, aquacultura e química de produtos naturais. Espera-se, portanto, que este material agregue conhecimento científico a todos aqueles que tenham interesse pela área de cultivo de algas marinhas.

A rare dihydoxyflavan-epicatechin proanthocyanidin, entcassiflavan-(4β→8)-epicatechin, was isolated from Dalbergia monetaria, a plant widely used by traditional people from the Amazon to treat urinary tract infections. The constitution and relative configuration of the compound were elucidated by HR-MS and detailed 1D- and 2D-NMR measurements. By comparing the experimental electronic circular dichroism (ECD) spectrum with the calculated ECD spectra of all 16 possible isomers, the absolute configuration, the interflavan linkage, and the atropisomers could be determined.

Terpenes are one of the most abundant classes of secondary metabolites produced by plants and can be divided based on the number of isoprene units (C₅) in monoterpenes (2 units—C₁₀), sesquiterpenes (3 units—C₁₅), diterpenes (4 units—C₂₀), triterpenes (6 units—C₃₀), etc. Chemically, triterpenes are classified based on their structural skeleton including lanostanes, euphanes, cycloartanes, ursanes, oleananes, lupanes, tirucallanes, cucurbitanes, dammaranes, baccharanes, friedelanes, hopanes, serratanes etc. Additionally, glycosylated (saponins) or highly oxidated/degraded (limonoids) triterpenes could be found in nature. The antiinflammatory effect and action as immunomodulators of these secondary metabolites have been demonstrated in different studies. This review reports an overview of articles published in the last 15 years (from 2006 to 2021 using PubMed and SciFinder database) describing the antiinflammatory effects of different triterpenes with their presumed mechanism of action, suggesting that triterpenes could be appointed as natural products with future pharmaceutical applicability.

Porifera, commonly referred to as marine sponges, are acknowledged as major producers of marine natural products (MNPs). Sponges of the genus Phorbas have attracted much attention over the years. They are widespread in all continents, and several structurally unique compounds have been identified from this species. Terpenes, mainly sesterterpenoids, are the major secondary metabolites isolated from Phorbas species, even though several alkaloids and steroids have also been reported. Many of these compounds have presented interesting biological activities. Particularly, Phorbas sponges have been demonstrated to be a source of cytotoxic metabolites. In addition, MNPs exhibiting cytostatic, antimicrobial, and anti-inflammatory activities have been isolated and structurally characterized. This review provides an overview of almost 130 secondary metabolites from Phorbas sponges and their biological activities, and it covers the literature since the first study published in 1993 until November 2021, including approximately 60 records. The synthetic routes to the most interesting compounds are briefly outlined.