Study of chemical constituents, antioxidants and antimicrobial activities of Tamarindus indica L. seed.

The fruits of Tamarindus indica L. are consumed worldwide, with various parts of the plant being used for medicinal purposes. The residues (pericarp and seeds) generated during cellulose processing are of significant value as they contain bioactive compounds with diverse biological activities. The objective of this study was to evaluate the chemical constituents of the ethyl acetate fraction as possible substitutes for synthetic compounds with biological properties using ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS/MS) analysis and the evaluation of the antioxidant activity (ferric reducing antioxidant power [FRAP], 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid [ABTS], and 1-diphenyl-2-picrylhydrazyl [DPPH]), total phenolic compounds (TPC), and antimicrobial activity of the hydroalcoholic extract and tamarind seed fractions were also performed. The chemical investigation of the acetate fraction using UHPLC-HRMS/MS resulted in the putative identification of 14 compounds, including flavonoids, (+)-catechin/(-)-epicatechin, procyanidin B2, procyanidin C2, isoquercetin, quercetin, luteolin, rutin, taxifolin, eriodictyol, kaempferide, hydroxybenzoic acid, protocathecuic acid, and protocathecuic acid methyl and ethyl esters derivatives. The crude hydroalcoholic extract exhibited the best results in terms of TPC: 883.87 gallic acid equivalent (GAE; mg/g) and antioxidant activity: FRAP: 183.29 GAE (mg/g), ABTS: 39.67%, and DPPH: 91.08%. The extract exhibited excellent antibacterial activity against gram-positive bacteria, specifically Staphylococcus aureus minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC; 62.5/125 g/mL) and Bacillus cereus MIC/MBC (125/250 g/mL), and gram-negative bacteria, specifically Aeromonas hydrophila MIC/MBC (125/250 µg/mL) and Pseudomonas aeruginosa MIC/MBC (250/500 g/mL). Morphological damage to cells was observed using flow cytometry and scanning electron microscopy. Tamarind seeds contain unique bioactive compounds that should be explored for their use as novel food preservatives. PRACTICAL APPLICATION: Original data were obtained regarding the Tamarindus indica L. seed extract and the ethyl acetate and hexane fractions. This research aimed to investigate the potential of these for food preservation and as alternatives to additives and synthetic compounds added to cattle feed. This paper reports novel findings regarding the chemical composition of the extract and its antioxidant activity, along with its antimicrobial activity against bacteria (gram-positive: Staphylococcus aureus, Bacillus cereus, and gram-negative: Salmonella enterica serovar Enteritidis, Escherichia coli, Pseudomonas aeruginosa, and Aeromonas hydrophila) and yeasts (Candida albicans and Saccharomyces cerevisiae).

The chemistry of Vernonanthura nudiflora (Less.) H. Rob. flowers and its antimicrobial activities.

Twenty-one known specialised metabolites were isolated from the flowers of Vernonanthura nudiflora (Less.) H. Rob., the structures of the compounds were established based on 1 D and 2 D NMR spectroscopic experiments. Others 28 compounds were putatively identified using the dereplication technique by UHPLC-HRMS/MS. Twenty-three of the compounds are being reported for the first time in this species. The mixture of sesquiterpene lactones piptocarphins A and B (17 + 18), and the flavone velutin (14) were tested against several microorganisms and showed promising activity against Mycobacterium tuberculosis with MIC of 15.6 µg/mL and 31.2 µg/mL, respectively. Furthermore, 17 + 18 showed greater cytotoxicity against VERO cells (IC50 = 7.0 ± 1.73) compared to compound 14 (IC50 85.0 ± 10.6 µg/mL). These findings reveal the feasibility of using the UHPLC-ESI-HRMS/MS-based dereplication strategy in complex fractions to identify specialised metabolites, moreover to V. nudiflora flowers being a source of compounds with antimycobacterial potential.

Low-cost alternative for the bioproduction of bioactive phenolic compounds of callus cultures from Cereus hildmannianus (K.) Schum.

The aim of this study was to establish a sustainable alternative callus culture of Cereus hildmannianus for the production and bioactive determination of phenolic compounds from this species. The conventional callus was cultivated using agar and Murashige and Skoog (MS) medium, while for the alternative culture the agar was replaced with a cotton support covered with filter paper and MS medium (incubated at 32 °C with photoperiod of 16 h), and the morphological characteristics and growth index were assessed (8 weeks). Extracts were obtained by maceration followed by partition, characterized by nuclear magnetic resonance - NMR and ultra-high performance liquid chromatography - UHPLC, quantified (phenolic compounds) by UV-Vis methods, and their antioxidant, antitumor activities, as well as cytotoxicity, were evaluated. The establishment of an alternative callus culture was carried out successfully. Characteristic signals of phenolic compounds were determined by NMR, and 46 compounds with fragment ions were identified using UHPLC analysis. The highest concentrations of phenolic compounds, and greatest antioxidant and antitumor activities, were obtained with the dichloromethane fractions of both callus tissue cultures, which were not cytotoxic. The callus culture from C. hildmannianus has shown promise as a source for the sustainable production of phenolic compounds with antioxidant and antiproliferative activities and thus, has potential use as a natural antitumor product.

Screening of six medicinal plant species for antileishmanial activity.

This study is aimed to investigate the in vitro anti-leishmanial activity of ethanolic, aqueous or dichloromethane extracts of leaves, flowers, fruits or roots, of six medicinal plant species, namely, Nectandra megapotamica, Brunfelsia uniflora, Myrcianthes pungens, Anona muricata, Hymenaea stigonocarpa and Piper corcovandesis. After isolation and analysis of chemical components by ultra-high performance liquid chromatography-high-resolution tandem mass spectrometry (UHPLC-HRMS/MS), the extracts were also tested for toxicity in J774.A1 macrophages and human erythrocytes. Phenolic acids, flavonoids, acetogenins, alkaloids and lignans were identified in these extracts. Grow inhibition of promastigotes forms of Leishmania amazonensis and Leishmania braziliensis and the cytotoxicity in J774.A1 macrophages were estimated by the XTT method. The most promising results for L. amazonensis and L. braziliensis were shown by the ethanolic extract of the fruits of Hymenaea stigonocarpa and dichloromethane extract of the roots of Piper corcovadensis, with IC 50 of 160 and 150 µg mL-1, resp. Ethanolic extracts of A. muricata (leaf), B. uniflora (flower and leaf), M. pungens (fruit and leaf), N. megapotamica (leaf), and aqueous extract of H. stigonocarpa (fruit) showed IC 50 > 170 µg mL-1 for L. amazonensis and > 200 µg mL-1 for L. braziliensis. The extracts exhibited low cytotoxicity towards J774.A1 macrophages with CC 50 > 1000 µg mL-1 and hemolytic activity from 0 to 46.1 %.

Secondary metabolites of Curvularia sp. G6-32, an endophyte of Sapindus saponaria, with antioxidant and anticholinesterasic properties.

In the present study, the biological activity of an extract of the secondary metabolites (E-G6-32) produced by the Curvularia sp. G6-32 endophyte (isolated from the medicinal plant Sapindus saponaria L.) was investigated. The antioxidant potential was confirmed by the DPPH (22.5%) and ABTS (62.7%) assays, and the total phenolic compound content was 40 µg gallic acid equivalents/mg. The extract E-G6-32 displayed good inhibitory activity toward butyrylcholinesterase (BuChE; IC50 = 110 ± 0.05 µg mL-1). The extract E-G6-32 was subjected to spectroscopic and mass spectrometry analyses. Comparison with the literature data confirmed that (-)-asperpentyn (1) was a major component. Asperpentyn belongs to the epoxyquinone family, which has attractive structural complexity, diverse functional groups, and a broad range of biological activities, including specific enzyme inhibitory activity. Our results suggest that Curvularia sp. G6-32 is a promising source of bioactive secondary metabolites and contains (-)-asperpentyn, which has potential pharmaceutical interest.[Figure: see text].

New cadinene-sesquiterpene from Chromolaena laevigata (lam.) R. M. King & H. Rob (Asteraceae) aerial parts and biological activities.

Phytochemical investigation of Chromolaena laevigata led to the isolation of a new cadinene-sesquiterpene, chromolaevigone glucoside (1), along with nine known compounds: daucosterol (2), stigmasterol glycoside (3), stigmasterol (4), ß-sitosterol (5), pilloin (6), gonzalitosin I (7), quercetin-3-O-α-rhamnopyranoside (8), 7,7-dihydroxy-calamen-12-oic acid lactone (9) and trachelanthic acid (10). Others 11 known compounds were identified by UHPLC-HRMS/MS. These compounds are being described for the first time in this species, with the exception of cadinene 9. Furthermore, due to the limitation of pharmacological studies, antiproliferative, antiviral, and antimicrobial activities of C. laevigata were evaluated. The best results in the cytotoxicity, antimicrobial and antiproliferative tests, presenting GI50 values on ovarian tumour cells (OVCAR-03) of 1.9 µg mL-1 and kidney (786-0) of 2.5 µg mL-1 were observed for the hexanic fraction.[Figure: see text].