Alkaloids from Siparuna (Siparunaceae) are predicted as the inhibitors of proteolysis and plasma coagulation caused by snake venom and potentially counteract phospholipase A2 activity of Bothrops jararaca.

ETHNOPHARMACOLOGICAL RELEVANCE: Snakebite envenomation (SBE) is the world's most lethal neglected tropical disease. Bothrops jararaca is the species that causes the greatest number of SBEs in the South and Southeastern of Brazil. The main symptoms are local (inflammation, edema, hemorrhage, and myonecrosis) and systemic (hemorrhage, hemostatic alterations with consumptive coagulopathy, and death) effects. Species of the genus Siparuna, Siparunaceae, are used in folk and traditional medicine to treat SBE. However, limited information is available concerning Brazilian Siparuna species against SBE. AIM OF THE STUDY: To investigate the correlation between the compounds present in the extracts of five Siparuna species as potential agents against proteolytic activity, plasma coagulation, and phospholipase A2 (PLA2) activity caused by B. jararaca venom, using data obtained by UHPLC-MS/MS, biological activity, and multivariate statistics. MATERIALS AND METHODS: The ethanol extracts from leaves of S. ficoides, S. decipiens, S. glycycarpa, S. reginae, and S. cymosa were fractionated by liquid-liquid extraction using different solvents of increasing polarity (hexane, dichloromethane, ethyl acetate, and n-butanol), affording their respective extracts, totaling 25 samples that were assayed through in vitro plasma coagulation and proteolytic activity assays. Moreover, the extracts were analyzed by UHPLC-MS/MS, using electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) in negative and positive ionization modes. The data was processed in MZmine v. 2.53 and evaluated by multivariate statistical tests (PLS) using the software UnscramblerX v. 10.4. These data were also used to build molecular networks (GNPS), and some ions of interest could be annotated using the library of molecules on the GNPS platform. RESULTS: A total of 19 extracts inhibited B. jararaca-induced plasma coagulation, with emphasis on S. cymosa and S. reginae (800 s). The inhibition of the proteolytic activity was also promising, ranging from 16% (S. glycycarpa) to 99% (S. cymosa, S. decipiens, and S. reginae). In addition, most extracts from S. cymosa and S. reginae inhibited 70-90% of PLA2 activity. Based on data from positive mode APCI analyses, it was possible to obtain a statistic model with reliable predictive capacity which exhibited an average R2 of 0.95 and a Q2 of 0.88, indicating a robust fit. This process revealed five ions, identified as the alkaloids: coclaurine (1), stepholidine (2) O-methylisopiline (3), nornantenine (4) and laurolitsine (5). This is the first study to evidence the potential antivenom of alkaloids from Siparuna species. CONCLUSIONS: Altogether, our results give support to the popular use of Siparuna extracts in SBE accidents, suggesting their potential as an alternative or complementary strategy against envenoming by B. jararaca venom. The predicted ions in the chemometric analysis for the assayed activities can also be correlated with the blocking activity and encourage the continuation of this study for possible isolation and testing of individual compounds on the used models.

Myrtucommulones and Related Acylphloroglucinols from Myrtaceae as a Promising Source of Multitarget SARS-CoV-2 Cycle Inhibitors.

The LABEXTRACT plant extract bank, featuring diverse members of the Myrtaceae family from Brazilian hot spot regions, provides a promising avenue for bioprospection. Given the pivotal roles of the Spike protein and 3CLpro and PLpro proteases in SARS-CoV-2 infection, this study delves into the correlations between the Myrtaceae species from the Atlantic Forest and these targets, as well as an antiviral activity through both in vitro and in silico analyses. The results uncovered notable inhibitory effects, with Eugenia prasina and E. mosenii standing out, while E. mosenii proved to be multitarget, presenting inhibition values above 72% in the three targets analyzed. All extracts inhibited viral replication in Calu-3 cells (EC50 was lower than 8.3 µg·mL-1). Chemometric analyses, through LC-MS/MS, encompassing prediction models and molecular networking, identified potential active compounds, such as myrtucommulones, described in the literature for their antiviral activity. Docking analyses showed that one undescribed myrtucommulone (m/z 841 [M - H]-) had a higher fitness score when interacting with the targets of this study, including ACE2, Spike, PLpro and 3CLpro of SARS-CoV-2. Also, the study concludes that Myrtaceae extracts, particularly from E. mosenii and E. prasina, exhibit promising inhibitory effects against crucial stages in SARS-CoV-2 infection. Compounds like myrtucommulones emerge as potential anti-SARS-CoV-2 agents, warranting further exploration.

Bactericidal and anti-inflammatory effects of Moquilea tomentosa Benth. flavonoid-rich leaf extract.

BACKGROUND: Natural products are an important source of bioproducts with pharmacological properties. Here we investigate the components of leaves from M. tomentosa Benth. (Fritsch) (Chrysobalanaceae) and its effects on bacterial cell growth, biofilm production and macrophage activity. METHODS: The effect of the different leaf extracts against bacterial cell growth was performed using the microdilution method. The most active extract was analyzed by mass spectrometry, and its effect on bacterial biofilm production was evaluated on polystyrene plates. The extract effect on macrophage activity was tested in the RAW264.7 cell line, which was stimulated with different concentrations of the extract in the presence or absence of LPS. RESULTS: We show that the ethyl acetate (EtOAc) extract was the most effective against bacterial cell growth. EtOAc extract DI-ESI (-)MSn analysis showed the presence of a glycosylated flavonoid tentatively assigned as myricetin 3-O-xylosyl-rhamnoside (MW 596). Also, the EtOAc extract increased biofilm formation by S. aureus and inhibited cytokine and NO production induced by LPS in RAW macrophages. CONCLUSION: M. tomentosa flavonoid-enriched EtOAc extract presented a bactericidal and anti-inflammatory pharmacological potential.

Amazonian Siparuna extracts as potential anti-influenza agents: Metabolic fingerprinting.

ETHNOPHARMACOLOGICAL RELEVANCE: Siparuna species are used in Brazilian Folk Medicine for the treatment and prophylaxis of colds, fever, headache, gastrointestinal disorders and rheumatic pain. AIM OF THE STUDY: This study aimed to investigate a possible anti-influenza activity of 25 extracts from leaves of Amazonian S. cristata, S. decipiens, S. glycycarpa, S. reginae and S. sarmentosa based on their folk medicinal uses as well as to investigate their metabolic fingerprinting. The chemical composition of the active extracts was further dereplicated. MATERIAL AND METHODS: The chemical composition of the crude EtOH extracts from five Siparuna species were investigated by ESI (±) LC-QTOF-MS2. Organic extracts were obtained by liquid-liquid partition with solvents of increasing polarity, generating 25 extracts which were subjected to a quick DI-ESI (±) IT-MS fingerprint analysis. These extracts were tested against influenza virus replication and cellular toxicity using MDCK cells and influenza A/Michigan/45/2015 (H1N1)pdm09 virus. The compounds in the active BuOH extracts from S. glycycarpa and S. sarmentosa were annotated by ESI (±) LC-QTOF-MS2. RESULTS: Analysis of the EtOH extracts revealed the presence of alkaloids and flavonoids, in the positive and negative ionization modes. Out of the 25 organic extracts screened for their antiviral activity, the BuOH extracts from S. glycycarpa and S. sarmentosa were the most active, inhibiting 96.0 ± 1.3% and 89.5 ± 0.8% of influenza virus replication 24 h post-infection. These inhibitory effects were maintained until 72hpi. Alkaloids, O- and C-flavonoid glycosides, dihydrochalcones and a procyanidin dimer were annotated in these extracts. CONCLUSIONS: The inhibitory effect against influenza A(H1N1)pdm09 virus replication shown by Amazonian Siparuna species corroborates the use of these plants in Brazilian Folk Medicine, showing their potential as anti-influenza agents. These promising results stimulate the continuation of this study with the aim of isolating the compound(s) responsible for this bioactivity, thus contributing to a better knowledge of those species and to the research of natural products with potential anti-influenza activity.