Untargeted-based metabolomics analysis and in vitro/in silico antiviral activity of extracts from Phyllanthus brasiliensis (Aubl.) Poir.

INTRODUCTION: This study describes the molecular profile and the potential antiviral activity of extracts from Phyllanthus brasiliensis, a plant widely found in the Brazilian Amazon. The research aims to shed light on the potential use of this species as a natural antiviral agent. METHODS: The extracts were analysed using liquid chromatography-mass spectrometry (LC-MS) system, a potent analytical technique to discover drug candidates. In the meantime, in vitro antiviral assays were performed against Mayaro, Oropouche, Chikungunya, and Zika viruses. In addition, the antiviral activity of annotated compounds was predicted by in silico methods. RESULTS: Overall, 44 compounds were annotated in this study. The results revealed that P. brasiliensis has a high content of fatty acids, flavones, flavan-3-ols, and lignans. Furthermore, in vitro assays revealed potent antiviral activity against different arboviruses, especially lignan-rich extracts against Zika virus (ZIKV), as follows: methanolic extract from bark (MEB) [effective concentration for 50% of the cells (EC50 ) = 0.80 µg/mL, selectivity index (SI) = 377.59], methanolic extract from the leaf (MEL) (EC50 = 0.84 µg/mL, SI = 297.62), and hydroalcoholic extract from the leaf (HEL) (EC50 = 1.36 µg/mL, SI = 735.29). These results were supported by interesting in silico prediction, where tuberculatin (a lignan) showed a high antiviral activity score. CONCLUSIONS: Phyllanthus brasiliensis extracts contain metabolites that could be a new kick-off point for the discovery of candidates for antiviral drug development, with lignans becoming a promising trend for further virology research.

The Roots of Deguelia nitidula as a Natural Antibacterial Source against Staphylococcus aureus Strains.

Deguelia nitidula (Benth.) A.M.G.Azevedo & R.A.Camargo (Fabaceae) is an herbaceous plant distributed in the Brazilian Amazon, and it is called "raiz do sol" (sun roots). On Marajó Island, quilombola communities use its prepared roots to treat skin diseases commonly caused by fungi, viruses, and bacteria. Thus, in this study, the extract, and its fractions from D. nitidula roots were used to perform in vitro cytotoxic and antibacterial assays against Staphylococcus aureus strains. Thereafter, liquid chromatography-mass spectrometry (LC-MS) was used for the metabolite annotation process. The ethanolic extract of D. nitidula roots show significant bactericidal activity against S. aureus with IC50 82 µg.mL-1 and a selectivity index (SI) of 21.35. Furthermore, the SREFr2 and SREFr3 fractions show a potent bactericidal activity, i.e., MIC of 46.8 µg.mL-1 for both, and MBC of 375 and 93.7 µg.mL-1, respectively. As showcased, SREFr3 shows safe and effective antibacterial activity mainly in respect to the excellent selectivity index (SI = 82.06). On the other hand, SREFr2 shows low selectivity (SI = 6.8), which characterizes it as not safe for therapeutic use. Otherwise, due to a limited amount of reference MS2 spectra in public libraries, up to now, it was not possible to perform a complete metabolite annotation. Despite that, our antibacterial results for SREFr3 and correlated substructures of amino acid derivatives show that the roots of D. nitidula are a natural source of specialized metabolites, which can be isolated in the future, and then used as a support for further bio-guided research, as well as natural drug development.

Anticancer potential of limonoids from Swietenia macrophylla: Genotoxic, antiproliferative and proapoptotic effects towards human colorectal cancer.

AIMS: Swietenia macrophylla have been considered for the treatment of various diseases, including anticancer activity. This study aimed to investigate the anticancer activity of S. macrophylla leaves extract and its isolated compound towards human colorectal cancer cell line. MAIN METHODS: Hexanic extract of S. macrophylla leaves demonstrated relevant cytotoxicity only against colon cancer cell line HCT116. KEY FINDINGS: Our results showed significant DNA damage and apoptosis after treatment with the hexanic extract of S. macrophylla. Moreover, no toxicity was noticed for the animal model. The isolated compound limonoid L1 showed potent cytotoxicity against cancer cell lines with IC50 at 55.87 µg mL-1. Limonoid L1 did not trigger any cell membrane rupture in the mice erythrocytes suggesting no toxicity. The antiproliferative effect of L1 was confirmed in colorectal cancer cells by clonogenic assay, inducing G2/M arrest, apoptosis, and DNA damage in cancer-type cells. SIGNIFICANCE: L1 reduced BCL2 and increased ATM, CHK2, TP53, ARF, CDK1, CDKN1A, and CASP3 in the colorectal cancer cell line. These findings suggest that limonoid L1 isolated from S. macrophylla can be a promising anticancer agent in managing colorectal cancer.

In vitro biological action of aqueous extract from roots of Physalis angulata against Leishmania (Leishmania) amazonensis.

BACKGROUND: Leishmaniasis is an infectious disease caused by various species of the protozoan parasites of the Leishmania genus and transmitted by phlebotomine sandflies. The protozoa multiply in phagocytic cells, mainly macrophages, which play an important role defending the organism from pathogens. The most effective treatment for leishmaniasis is the chemotherapy and besides the high cost, these drugs are toxic and require a long period of treatment. Currently, some herbal products are considered an important alternative source of a new leishmanicidal agent, which includes the plant Physalis angulata, . We evaluated effects of an aqueous extract from roots of Physalis angulata (AEPa) on Leishmania proliferation, morphology and also determined whether physalins were present in the extract contributing to the knowledge of its pharmacological efficacy. METHODS: Morphological alterations were determined by light microscopy, transmission and scanning electron microscopy. Host cell viability was evaluated by MTT, and propidium iodide. AEPa were submitted in full HRESITOF analysis. RESULTS: AEPa promoted a dose-dependent reduction on promastigotes (IC50 = 39.5 µg/mL ± 5.1) and amastigotes (IC50 = 43.4 µg/mL ± 10.1) growth. This growth inhibition was associated with several morphological alterations observed in promastigote forms. No cytotoxic effect in mammalian cells was detected (IC50 > 4000 µg/mL). Furthemore, the presence of physalins A, B, D, E, F, G and H were described, for the first time, in the P. angulata root. CONCLUSIONS: Results demonstrate that AEPa effectively promotes antileishmanial activity with several important morphological alterations and has no cytotoxic effects on host cells.

Flavonoids from leaves of Derris urucu: assessment of potential effects on seed germination and development of weeds.

In some previous studies, we described the isolation of nine compounds from leaves of Derris urucu, a species found widely in the Amazon rainforest, identified as five stilbenes and four dihydroflavonols. In this work, three of these dihydroflavonols [urucuol A (1), urucuol B (2) and isotirumalin (3)] were evaluated to identify their potential as allelochemicals, and we are also reporting the isolation and structural determination of a new flavonoid [5,3'-dihydroxy-4'-methoxy-(7,6:5″,6″)-2″,2″-dimethylpyranoflavanone (4)]. We investigated the effects of the dihydroflavonols 1-3 on seed germination and radicle and hypocotyl growth of the weed Mimosa pudica, using solutions at 150 mg.L-1. Urucuol B, alone, was the substance with the greatest potential to inhibit seed germination (26%), while isotirumalin showed greater ability to reduce the development of the hypocotyl (25%), but none of the three substances showed the potential to inhibit radicle. When combined in pairs, the substances showed synergism for the development of root and hypocotyl and effects on seed germination that could be attributed to antagonism. When tested separately, the trend has become more intense effects on seed germination, while for the substances tested in pairs, the intensity of the effect was greater on development of weed.

Inhibition of α-glucosidase and hypoglycemic effect of stilbenes from the Amazonian plant Deguelia rufescens var. urucu (Ducke) A. M. G. Azevedo (Leguminosae).

The control of blood glucose levels is critical in the treatment of diabetes mellitus. α-Glucosidase inhibitors are of great importance in reducing hyperglycemia, and plants have provided many of these agents. The present study aimed at investigating the effect of two stilbenes, lonchocarpene and 3,5-dimethoxy-4'-O-prenyl-trans-stilbene (DPS), isolated from the Amazonian plant Deguelia rufescens var. urucu, on α-glucosidase activity and on mice postprandial hyperglycemia. Lonchocarpene and DPS inhibited α-glucosidase in vitro, with pIC(50) values of 5.68 ± 0.12 and 5.73 ± 0.08, respectively. In addition, when given orally, DPS produced a significant reduction of hyperglycemia induced by an oral tolerance test, while lonchocarpene did not. Data suggest that DPS may have a potential use as an antidiabetic drug.

Trypanocidal agents with low cytotoxicity to mammalian cell line: a comparison of the theoretical and biological features of lapachone derivatives.

Starting from alpha- and beta-lapachones, in this work we compared the biological and theoretical profile of several oxyran derivatives of lapachone as potential trypanocidal agents. Our biological results showed that the oxyrans tested act as trypanocidal agents against Trypanosoma cruzi with minimal cytotoxicity in the VERO cell line compared to naphthoquinones. The oxyran derivative of alpha-lapachone (7a) showed to be one of the most potent compounds. In our molecular modeling study, we analyzed the C-ring moiety and the redox center of beta-lapachone molecule as the moieties responsible for the trypanocidal and cytotoxic effects on mammalian cell line. The computational methods used to delineate the structural requirements for the trypanocidal profile pointed out that the transposition of the C-ring moiety of beta-lapachone, combined with its oxyran ring, introduced important molecular requirements for trypanocidal activity in the HOMO energy, HOMO orbital coefficient, LUMO density, electrostatic potential map, dipole moment vector, and calculated logP (clogP) parameter. This study could lead to the development of new antichagasic medicines based on alpha-lapachone analogs.

Oxyrane derivative of alpha-lapachone is potent growth inhibitor of Trypanosoma cruzi epimastigote forms.

The investigation of trypanocidal effects against Trypanosoma cruzi and cytotoxicity in VERO cell line of several oxyranes structurally related to beta-lapachone, nor-beta-lapachone, alpha-lapachone, and 4-methoxy-1,2-naphthoquinone is described. It was found that the oxyranes 10 derived from alpha-lapachone showed an approximately the same trypanocidal activity of beta-lapachone. In addition, all the oxyranes showed less cytotoxicity than the corresponding naphthoquinones.

Preparation of alpha-diazocarbonyl compounds from beta-lapachone derivatives and other 1,2-naphthoquinones: use of the 2D NMR 1H,15N and 1H,13C HMBC techniques in assigning regiochemistry.

The assignment of the diazo site in products of the reaction of p-toluenesulfonylhydrazine with beta-lapachone, 3,4-dihydro-2,2-dimethyl-2H-naphtho[1,2-b]pyran-5,6-dione, and other 1,2-naphthoquinones in methanol solution at room temperature has been accomplished using 1H,13C HMBC and 1H,15N HMBC NMR experiments. Only one diazo-naphthalenone product was isolated in yields ranging from 50-100% from each reaction. The site of diazo substitution of beta-lapachone and derivatives is the 1-position, in contrast to substitution at the 2-position in 4-MeO-1,2-naphthoquinone. Steric factors, rather than electronic factors, control the reaction site. Along with 2-diazo-1(2H)-naphthalenone, an additional product isolated from the reaction of p-toluenesulfonylhydrazide with 1,2-naphthoquinone was 2-diazo-4-hydroxy-1(2H)-naphthalenone. Confirmation of the formation of 6-diazo-2,2-dimethyl-2,3,4,6-tetrahydro-2H-benzo[h]cromen-5-one, obtained from beta-lapachone, was achieved using single crystal X-ray diffraction.

2,3-Dihydro-3,3-dimethylspiro[1H-4-oxanthracene-5,2'-oxiran]-10(5H)-one.

The central six-membered ring in the title compound, C(16)H(16)O(3), is almost planar (and almost coplanar with the aromatic ring), despite one of its C atoms being formally sp(3) hybridized. The planarity is a consequence of the C atom at the centre of the spirocyclic system also being part of the three-membered epoxide ring. The molecules are linked by pi-pi and C-H.pi interactions.