Mass spectrometry as a tool for the dereplication of specialised metabolites from Pterocaulon angustifolium DC

Pterocaulon genus comprises 26 species, half of them have been phytochemical investigations regarding the chemical composition, and coumarins have been considered the chemotaxonomic markers in the genus. Herein Pterocaulon angustifolium DC (Asteraceae), a native plant from Brazil, is investigated for the first time. Twenty-six compounds were isolated from aerial parts of P. angustifolium DC., being 5 triterpenes, 4 phytosterols, 9 flavonoids, 3 phenolic acids, and 5 coumarins. Moreover, a total of 177 compounds were putatively identified using the dereplication technique by UHPLC-HRMS/MS, more than 50% correspond to flavonoids and coumarins. Although 41 different coumarins have already been reported in Pterocaulon genus, 16 were identified for the first time in this study. Crude ethanolic extract and fractions of P. angustifolium were also biologically investigates, and dichloromethane fraction was the most active fraction in the evaluation of antiproliferative, antioxidant, antimicrobial and cholinesterase inhibitory activities.

Efficient synthesis and antitumor evaluation of 4-aminomethyl-N-arylpyrazoles: Discovery of potent and selective agents for ovarian cancer

A new one-pot two-step sequential methodology for synthesis of novel 3-carboxyethyl 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives is reported. One-pot transformation of β-enamino diketones and arylhydrazines generated 4-iminium-N-arylpyrazole salt intermediates in situ, which were easily transformed into 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives by NaBH₃CN. The products could be isolated in the free or hydrochloride salt forms. Also, it was possible to obtain the products in the zwitterionic form by ester group hydrolysis. Furthermore, all synthesised compounds were evaluated in vitro against a panel of eight human tumor cell lines. The 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives were much more powerful than the hydrochloride and zwitterionic forms. Moreover, the results suggest that the N-aryl group at the pyrazole ring is vital for modulating antiproliferative activity. The 3-carboxyethyl 4-[(tert-butylamino)methyl]-N-phenylpyrazoles 3a-g exhibited higher inhibitory activities against OVCAR-3, with GI₅₀ values of 0.013-8.78 μM, and lower inhibitory activities against normal human cell lines. Molecular docking was performed to evaluate the probable binding mode of 3a into active site of CDK2.

In Silico, In Vitro, and In Vivo Antitumor and Anti-Inflammatory Evaluation of a Standardized Alkaloid-Enriched Fraction Obtained from Boehmeria caudata Sw. Aerial Parts

In the context of the cancer-inflammation relationship and the use of natural products as potential antitumor and anti-inflammatory agents, the alkaloid-enriched fraction of Boehmeriacaudata (BcAEF) aerial parts was evaluated. In vitro antiproliferative studies with human tumor cell lines showed high activity at low concentrations. Further investigation on NCI-H460 cells showed an irreversible effect on cell proliferation, with cell cycle arrest at G2/M phase and programmed cell death induction. Molecular docking studies of four alkaloids identified in BcAEF with colchicine’s binding site on β-tubulin were performed, suggesting (−)-C (15R)-hydroxycryptopleurine as the main inductor of the observed mitotic death. In vivo studies showed that BcAEF was able to reduce Ehrlich tumor volume progression by 30 to 40%. Checking myeloperoxidase activity, BcAEF reduced neutrophils migration towards the tumor. The in vivo anti-inflammatory activity was evaluated by chemically induced edema models. In croton oil-induced ear edema and carrageenan (CG)-induced paw edema models, BcAEF reduced edema around 70 to 80% together with inhibition of activation and/or migration of neutrophils to the inflammatory area. All together the results presented herein show BcAEF as a potent antitumor agent combining antiproliferative and anti-inflammatory properties, which could be further explored in (pre)clinical studies.

Novel anticancer PdII complexes: The effect of the conjugation of transferrin binding peptide and the nature of halogen coordinated on antitumor activity

A series of Pd^II complexes with bis-(2-pyridylmethyl)glycine as a ligand of formula [PdX(bis-(2-pyridylmethyl)glycine)] where X = Cl, Br, I were prepared and the effect of the halogen nature in the antitumor activity of eight tumorigenic and one non-tumorigenic cell line was evaluated. The chloride derivative was further functionalized with a transferrin receptor binding peptide, generating the first Pd^II based metallopeptide. Its antitumor activity was also evaluated. However, among all the complexes, the chloride and iodine parent compounds showed the lowest GI₅₀ values in the panel evaluated, and lowest GI₅₀ than cisplatin in several cell lines. In contrast, the bromine derivative showed higher values of GI₅₀ than chloride and iodine (around 30 - 50 μM). The same trend was observed for the bovine serum albumin binding constant with higher values for iodine, chlorine, and bromine in this order. In aqueous solution, the chloride is exchanged by water while the bromine and iodine are not. DNA was evaluated as a target and showed no significative interaction for all the compounds. The results suggest sulfur-rich proteins and not DNA as a target. This report represents the first Pd^II metallopeptide reported, its evaluation in solution and antitumor activity. This work opens the possibilities for further functionalization of Pd^II complexes and the importance of the halogen coordination in the design of novel metallodrugs.

Antitumoral and Anticholinesterasic Activities of the Seven Species from Rubiaceae

BACKGROUND

The genus Psychotria and Palicourea are reported as a source of alkaloids and iridoids, which exhibit biological activities. This study aimed to evaluate antiproliferative and anticholinesterase activities and quantification of the alkaloids of seven species among the genus found in Mato Grosso do Sul region in Brazil.

METHODS

Concentrations of alkaloids were measured spectrophotometrically. The extracts were submitted to antiproliferative activity against ten cell lines. The anticholinesterase activity of the extracts was developed using brain structures of male Wistar rats: cerebral cortex, hippocampus, hypothalamus and striatum by the Ellman method.

RESULTS

Alkaloids from Psychotria and Palicourea species were quantified which showed values of 47.6 to 21.9 µg/g. Regarding the antiproliferative potential, Palicourea crocea demonstrated selectivity against the 786-0 cell line (GI50: 22.87 µg/mL). Psychotria leiocarpa inhibited cell growth against OVCAR-3 (GI50: 3.28 µg/mL), K-562 (GI50: 5.26 µg/mL), HaCaT (GI50: 27.20 µg/mL), PC-3 (GI50: 34.92 µg/mL), MCF-7 (GI50: 35.80 µg/mL) and P. capillacea showed activity against OVCAR-3 (GI50: 2.33 µg/ml) and U251 (GI50: 16.66 µg/ml). The effect of acetylcholinesterase inhibition was more effective in the hippocampus, demonstrating inhibition for Paliourea crocea, Psychotria deflexa, P. brachybotrya and P. leiocarpa of 70%, 57%, 50% and 40%, respectively, followed by P. poeppigiana and P. capillacea, inhibiting 21%, compared to the control.

CONCLUSION

Herein, the present work showed for the first time, anticholinesterasic and antiproliferative activities of extracts of Palicourea and Psychotria seem to be mainly associated with the levels of alkaloids in the leaves of these species.

Sulfonamide-containing copper(II) metallonucleases: Correlations with in vitro antimycobacterial and antiproliferative activities

The bis-(1,10-phenanthroline)copper(I) complex, [Cu(I)(phen)₂]⁺, was the first copper-based artificial nuclease reported in the literature. The biological and ligand-like properties of sulfonamides make them good candidates for fine-tuning the reactivity of the [Cu(phen)₂] motif with biomolecules. In this context, we developed three novel copper(II) complexes containing the sulfonamides sulfameter (smtrH) and sulfadimethoxine (sdmxH) and (N^N)-bidentate ligands (2,2'-biyridine or 1,10-phenantroline). The compounds were characterized by chemical and spectroscopic techniques and single-crystal X-ray crystallography. When targeting plasmid DNA, the phen-containing compounds [Cu(smtr^-)₂(phen)] (1) and [Cu(sdmx^-)₂(phen)] (2) demonstrated nuclease activity even in the absence of reducing agents. Addition of ascorbic acid resulted in a complete cleavage of DNA by 1 and 2 at concentrations higher than 10 μM. Experiments designed to evaluate the copper intermediates involved in the nuclease effect after reaction with ascorbic acid identified at least the [Cu(I)(N^N)₂]⁺, [Cu(I)(sulfa)(N^N)]⁺ and [Cu(I)(sulfa)₂]⁺ species. The compounds interact with DNA via groove binding and intercalation as verified by fluorescence spectroscopy, circular dichroism (CD) and molecular docking. The magnitude and preferred mode of binding are dependent on the nature of both N^N ligand and the sulfonamide. The potent nuclease activity of compounds 1 and 2 are well correlated with their antiproliferative and anti-M. tuberculosis profiles. The results presented here demonstrated the potential for further development of copper(II)-sulfonamide-(N^N) complexes as multipurpose metallodrugs.

Phenolic compounds and anticancer activity of commercial sugarcane cultivated in Brazil

The cultivation of sugarcane hybrids (X Saccharum officinarum L.) is an important revenue source for the Brazilian economy. Herein it is reported the evaluation of the cytotoxic activity of mid-polarity sugarcane extracts against human cancer cell lines, as well as the isolation of steroids sitosterol, stigmasterol and campesterol, phenolic acids p-hydroxybenzoic, p-hydroxycinnamic, vanillic and ferulic acid, terpenoids α-tocopherol and β-carotene and a novel substance in sugarcane, the flavonoid aglycone tricin (5,7,4-trihydroxy-3,5-dimethoxyflavone). The presence of large amounts of phenolic acids and the flavonoid tricin may explain the cytostatic activity observed for the mid-polarity crude extract and filtrates.

Antiproliferative activity of buttermilk lipid fractions isolated using food grade and non-food grade solvents on human cancer cell lines

Buttermilk is a dairy by-product with a high content of milk fat globule membranes (MFGMs), whose protein constituents are reported to be antiproliferative. Lipids represent about half of the composition of MFGM. The aim of this study was to isolate buttermilk lipid fractions and evaluate their potential antiproliferative effect. Selective extraction with food grade or non-food grade solvents was performed. Antiproliferative effectiveness of lipid extracts and their neutral and polar fractions was evaluated on nine human cancer cell lines. Fractions obtained using food grade ethanol gave a higher yield than those obtained using non-food grade solvents, and they effectively inhibited cell viability of the cancer cell lines investigated. These fractions, rich in phospho- and sphingolipids, were strongly antiproliferative against human ovary and colon cancer cells. This observation allowed us to hypothesize further analyses aimed at promoting the use of buttermilk polar lipid fractions as functional food additives.

Bioguided identification of antifungal and antiproliferative compounds from the Brazilian orchid Miltonia flavescens Lindl

The Orchidaceae family is appreciated worldwide for the beauty of its flowers, and hundreds of species of this family occur in Brazil. Yet little is known about the potential of orchids for therapeutic application. We have investigated bioactive compounds produced by the South Brazilian orchid Miltonia flavescens Lindl. Bioguided studies with the fungus Cladosporium herbarum allowed the identification of hydrocinnamic acid as the active antifungal compound. In addition, the chloroform fraction exhibited an interesting activity against human cancer cells, and 5,7-dihydroxy-6,4'-dimethoxyflavone isolated from this fraction was found to be active against seven human cancer cell lines, including NCI/ADR-RES ovary sarcoma, with an IC50 value of 2.6 microg/mL. This is the first report on the cytostatic activity of this flavone against human ovary sarcoma.

In vitro and in vivo antitumor activity of crude extracts obtained from Brazilian Chromobacterium sp isolates

Natural products produced by microorganisms have been an important source of new substances and lead compounds for the pharmaceutical industry. Chromobacterium violaceum is a Gram-negative β-proteobacterium, abundant in water and soil in tropical and subtropical regions and it produces violacein, a pigment that has shown great pharmaceutical potential. Crude extracts of five Brazilian isolates of Chromobacterium sp (0.25, 2.5, 25, and 250 µg/mL) were evaluated in an in vitro antitumor activity assay with nine human tumor cells. Secondary metabolic profiles were analyzed by liquid chromatography and electrospray ionization mass spectrometry resulting in the identification of violacein in all extracts, whereas FK228 was detected only in EtCE 308 and EtCE 592 extracts. AcCE and EtCE 310 extracts showed selectivity for NCI/ADR-RES cells in the in vitro assay and were evaluated in vivo in the solid Ehrlich tumor model, resulting in 50.3 and 54.6% growth inhibition, respectively. The crude extracts of Chromobacterium sp isolates showed potential and selective antitumor activities for certain human tumor cells, making them a potential source of lead compounds. Furthermore, the results suggest that other compounds, in addition to violacein, deoxyviolacein and FK228, may be involved in the antitumor effect observed.

Synthesis, antiproliferative activity in cancer cells and theoretical studies of novel 6α,7β-dihydroxyvouacapan-17β-oic acid Mannich base derivatives

Natural products are great prototypes for the design of new anticancer agents. The plant-derived natural product 6α,7β-dihydroxyvouacapan-17β-oic acid (1) is promising for the development of more potent antiproliferative agents against human cancer cells. Indeed, its lactone derivative 6α-hydroxyvouacapan-7β,17β-lactone (2), a non-natural furanoditerpene, exhibited higher anticancer activity than compound 1. Herein, we describe the synthesis and antiproliferative activity of six new Mannich derivatives of compound 2 against nine cancer cell lines. Overall, our results revealed that Mannich derivatives 3-8 were more potent than compound 2 in inhibiting the proliferation of cancer cells. Theoretical studies also supported our findings, revealing the nucleophilic character of furan ring as an important feature for antiproliferative activity of the studied Mannich derivatives.