Insecticidal efficacy and possibility of Combretum trifoliatum Vent. (Myrtales: Combretaceae) extracts in controlling Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae).

BACKGROUND: The fall armyworm Spodoptera frugiperda (J.E. Smith), is an important pest of agronomical crops. It is interesting to discover secondary metabolites in plants that are environmentally safer than synthetic pesticides. For this purpose, Combretum trifoliatum crude extract and its isolated compounds were investigated for their insecticidal activities against S. frugiperda. RESULTS: The median lethal dose (LD50 ) was evaluated in the second-instar larvae using the topical application method. The isolated compounds, apigenin and camphor, demonstrated a highly toxic effect on larvae at a lower LD50 dose than crude extract. Moreover, when the larvae were exposed to crude extract concentrations, the development to pupa and adult stages was reduced by more than 50%. The ovicidal toxicity was examined using a hand sprayer. The extract concentration 5, 10, and 20 µg/egg significantly decreased the egg hatchability. In addition, crude extract showed a significant difference in inhibiting acetylcholinesterase (AChE) activity while crude extract and camphor showed significant inhibitory effects on carboxylesterase (CE) and glutathione-S-transferase (GST) activities. CONCLUSION: The crude ethanol extract of Combretum trifoliatum was toxic to S. frugiperda in terms of larval mortality, negatively affecting biological parameters, and decreasing egg hatchability. Additionally, the activities of cholinergic and detoxifying enzymes were affected by crude extract and its isolated compounds. These results highlight that Combretum trifoliatum might be efficient as a bioinsecticide to control S. frugiperda. © 2023 Society of Chemical Industry.

Calcicole behaviour of Callisthene fasciculata Mart., an Al-accumulating species from the Brazilian Cerrado.

Most aluminium (Al)-accumulating species are found on soils with high Al saturation and low Ca availability (Ca poor). Callisthene fasciculata Mart. (Vochysiaceae), however, is an Al-accumulating tree restricted to Ca-rich soils with low Al saturation in the Brazilian Cerrado savanna. Here we tested its calcicole behaviour, and the possible role of organic acids in detoxification of Al during the early stages of plant development. We assessed growth, dry mass, nutrients, Al and organic acids in seedlings grown for 50 days on two contrasting Cerrado soils; one with high Ca concentrations and low Al saturation and the other with low Ca availability and high Al saturation. Relative to plants on Ca-rich soil, plants on Ca-poor soil had necrotic spots and bronzing of leaves. Roots and shoots contained reduced concentrations of P and Cu, but higher concentrations of Fe, Al and citrate. Despite lower concentrations in the soil, Ca and Mg increased in shoots. Shoot concentrations of oxalate were also higher. We confirmed C. fasciculata as an Al-accumulating species with calcicole behaviour. The increased concentrations of organic acids in plants with higher Al accumulation suggest that high availability of soluble Al does not prevent occurrence of this species on soils with high Al saturation. Instead, the absence of C. fasciculata from Ca-poor soils is probably due to imbalances in tissue Fe, Cu and Zn imposed by this soil type.

Caffeoyloxy-5,6-dihydro-4-methyl-(2H)-pyran-2-one isolated from the leaves of Olinia usambarensis attenuates LPS-induced inflammatory mediators by inactivating AP-1 and NF-κB.

We have previously reported the isolation of four compounds, caffeoyloxy-5,6-dihydro-4-methyl-(2H)-pyran-2-one (CDMP), olinioside, caffeic acid and 3-hydroxylup-12-en-28-oic acid, from the leaves of Olinia usambarensis. Here, we evaluated the inhibitory effects of these compounds on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and prostaglandin E2 (PGE2) in RAW 264.7 macrophages, and found that CDMP is the most potent of these two pro-inflammatory mediators (IC50; 12.12 µM and 10.78 µM, respectively). Consistent with these results, CDMP also down-regulated inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), and interleukin 6 (IL-6) at the protein and mRNA levels in LPS-treated RAW 264.7 macrophages. Furthermore, CDMP suppressed LPS-induced nuclear factor κB (NF-κB) activation by decreasing p65 nuclear translocation through the phosphorylation and degradation of the inhibitory κBα (IκBα). CDMP also attenuated LPS-induced transcriptional and DNA-binding activities of activator protein 1 (AP-1) by suppressing the phosphorylation and expression of c-Fos and c-Jun. Finally, CDMP considerably suppressed the LPS-induced phosphorylation of c-Jun N-terminal kinase (JNK), but did not affect the phosphorylation of p38 or extracellular signal-regulated kinase (ERK). Taken together, our data suggest that CDMP down-regulates genes encoding pro-inflammatory mediators and cytokines, such as iNOS, COX-2, TNF-α, IL-1ß, and IL-6 via NF-κB and JNK/AP-1 inactivation in LPS-induced RAW 264.7 macrophages.

Anti-Adhesion Activity of Tannins Isolated from the Mangrove Laguncularia racemosa.

In the search of new compounds with biofilm-inhibiting properties, mangroves with their richness of secondary metabolites can be a valuable resource. Crude methanolic leaf extracts from the mangrove Laguncularia racemosa enriched in phenolic substances cause a reduction in initial cell adhesion of Candida glabrata and Candida albicans, but not on Escherichia coli. LC/MS-guided fractionation of the phenolic compounds resulted in 19 fractions, of which ten were analyzed for their bioactivity against cell adhesion. Effects on cell adhesion and planktonic growth of Escherichia coli, Candida glabrata and Candida albicans were measured in 96-well microtiter plates in the presence of 0.2 mg ml-1 of the isolated fractions. Two fractions caused a reduction of cell adhesion of Candida albicans. These fractions containing bioactive compounds were analyzed by LC/MS and NMR spectroscopy. Casuarinin and digalloyl-hexahydroxydiphenoyl-glucose were identified in the active fractions, in addition to three signals of ellagitannins. These results indicate a specific mode of action of hydrolysable tannins against cell adhesion of Candida albicans, which needs to be further analyzed.

Red galls: the different stories of two gall types on the same host.

Several studies have suggested reasons why galls have conspicuous colours, but none of the ideas have been confirmed. However, what if the vibrant colours of some galls are explained simply by the effect of light exposure? This may lead to anthocyanin accumulation, functioning as a defence mechanism against the effects of high light. We studied the globoid galls induced by Cecidomyiidae (Diptera) on Qualea parviflora (Vochysiaceae), relating anthocyanin accumulation and chlorophyll fluorescence parameters to light incidence in abaxial and adaxial galls. We also tested if the anthocyanin accumulation patterns apply to another Cecidomyiidae-induced gall morphotype (intralaminar) within the same plant. Adaxial galls are exposed to higher incident light, with more anthocyanin accumulation and therefore red coloration. In galls from angled leaves, the greater the angle of the leaf, the higher the difference between anthocyanins on the sun and shade sides of galls. Photosynthetic pigment concentrations did not differ between abaxial and adaxial galls. However, we found higher (Fm ' - F')/Fm ' and Fv /Fm in the abaxial galls. Conversely, NPQ and Rfd were higher in adaxial galls. Finally, the pattern of anthocyanin accumulation was not found in the intralaminar gall. Anthocyanin accumulation in galls functions as a photoprotective strategy, maintaining tissue vitality in regions exposed to high light conditions. However, this mechanism may vary even among galls within the same host, indicating idiosyncrasy when it comes to coloration in galls. To date, this is the first study to demonstrate quantitatively why the galls of a specific species may be coloured: the variation in light regimes creates differential anthocyanin accumulation, influencing coloration.

Phaeophleospora vochysiae Savi & Glienke sp. nov. Isolated from Vochysia divergens Found in the Pantanal, Brazil, Produces Bioactive Secondary Metabolites.

Microorganisms associated with plants are highly diverse and can produce a large number of secondary metabolites, with antimicrobial, anti-parasitic and cytotoxic activities. We are particularly interested in exploring endophytes from medicinal plants found in the Pantanal, a unique and widely unexplored wetland in Brazil. In a bio-prospecting study, strains LGMF1213 and LGMF1215 were isolated as endophytes from Vochysia divergens, and by morphological and molecular phylogenetic analyses were characterized as Phaeophleospora vochysiae sp. nov. The chemical assessment of this species reveals three major compounds with high biological activity, cercoscosporin (1), isocercosporin (2) and the new compound 3-(sec-butyl)-6-ethyl-4,5-dihydroxy-2-methoxy-6-methylcyclohex-2-enone (3). Besides the isolation of P. vochysiae as endophyte, the production of cercosporin compounds suggest that under specific conditions this species causes leaf spots, and may turn into a pathogen, since leaf spots are commonly caused by species of Cercospora that produce related compounds. In addition, the new compound 3-(sec-butyl)-6-ethyl-4,5-dihydroxy-2-methoxy-6-methylcyclohex-2-enone showed considerable antimicrobial activity and low cytotoxicity, which needs further exploration.