Biological activities of extracts from Aspidosperma subincanum Mart. and in silico prediction for inhibition of acetylcholinesterase

Syntheses of Tetracyclic Indoline Derivatives Via Gold(I)-Catalyzed Hydroamination/Cycloisomerization Cascade of 2-Ethynyltryptamides

A gold(I)-catalyzed hydroamination/cycloisomerization cascade reaction was developed to yield indolizino[8,7-b]indole and indolo[2,3-a]-quinolizine derivatives from 2-ethynyltryptamides. The optimal conditions were determined by condition screening, and the functional group tolerances of these reactions were explored based on synthetic substrates. An insight into the explanation on the selectivity of the ring closure was obtained by density functional theory calculations. A plausible mechanism for the cascade reactions was proposed. Derivatization of the indolizino[8,7-b]indole and total synthesis of nauclefidine demonstrated the practicality of this strategy.

Determination of Anti-Alzheimer's Disease Activity of Selected Plant Ingredients

Neurodegenerative diseases, among which one of the more common is Alzheimer’s disease, are the one of the biggest global public health challenges facing our generation because of the increasing elderly population in most countries. With the growing burden of these diseases, it is essential to discover and develop new treatment options capable of preventing and treating them. Neurodegenerative diseases, among which one of the most common is Alzheimer’s disease, are a multifactorial disease and therefore demand multiple therapeutic approaches. One of the most important therapeutic strategies is controlling the level of acetylcholine—a neurotransmitter in cholinergic synapses—by blocking the degradation of acetylcholine using acetylcholinesterase inhibitors such as tacrine, galantamine, donepezil and rivastigmine. However, these drugs can cause some adverse side effects, such as hepatotoxicity and gastrointestinal disorder. Thus, the search for new, more effective drugs is very important. In the last few years, different active constituents from plants have been tested as potential drugs in neurodegenerative disease therapy. The availability, lower price and less toxic effects of herbal medicines compared with synthetic agents make them a simple and excellent choice in the treatment of neurodegenerative diseases. The empirical approach to discovering new drugs from the systematic screening of plant extracts or plant-derived compounds is still an important strategy when it comes to finding new biologically active substances. The aim of this review is to identify new, safe and effective compounds that are potential candidates for further in vivo and clinical tests from which more effective drugs for the treatment of Alzheimer’s disease could be selected. We reviewed the methods used to determine anti-Alzheimer’s disease activity. Here, we have discussed the relevance of plant-derived compounds with in vitro activity. Various plants and phytochemical compounds have shown different activity that could be beneficial in the treatment of Alzheimer’s disorders. Most often, medicinal plants and their active components have been investigated as acetylcholinesterase and/or butyrylcholinesterase activity inhibitors, modifiers of β-amyloid processing and antioxidant agents. This study also aims to highlight species with assessed efficacy, usable plant parts and the most active plant components in order to identify species and compounds of interest for further study. Future research directions are suggested and recommendations made to expand the use of medicinal plants, their formulations and plant-derived active compounds to prevent, mitigate and treat Alzheimer’s disease.

S16020 pyridocarbazole derivatives display high activity to lung cancer cells

BACKGROUND

Despite the dynamic development of medicine, globally cancer diseases remain the second leading cause of death. Therefore, there is a strong necessity to improve chemotherapy regimens and search for new anticancer agents. Pyridocarbazoles are compounds with confirmed antitumor properties based on multimodal mechanisms, i.a. DNA intercalation and topoisomerase II-DNA complex inhibition. One of them, S16020, displayed a wide spectrum of activity.

OBJECTIVE

The aim of the study was to investigate the antitumor potency of six S16020 derivatives, synthesized according to the SAR (structure-activity relationship) method.

METHODS

The biological evaluation included influence on cancer cell viability, proliferation, and migration, as well as P-glycoprotein activity. NHDF, A549, MCF-7, LoVo, and LoVo/DX cell lines were used in the study.

RESULTS

All derivatives displayed low toxicity to normal (NHDF) cells at 1 and 2 µM (≤ 20% of cell growth inhibition). The highest reduction in cell viability was noted in A549 cells which was accompanied by significant disruption of cells proliferation and motility. Compound 1 exhibited the strongest cytotoxic, antiproliferative, and antimigratory effects, higher than the reference olivacine. A significant reduction in P-glycoprotein activity was found for derivatives 6 and 1.

CONCLUSION

S16020 derivatives could be considered as potential candidates for new anticancer drugs.

The toxicity of Aspidosperma subincanum to MCF7 cells is related to modulation of oxidative status and proinflammatory pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Cancer is an inflammatory disease because carcinogenesis and tumor progression depend on intrinsic and extrinsic inflammatory pathways. Although species of the genus Aspidosperma are widely used to treat tumors, and there is ethnopharmacological evidence for traditional use of the species A. subincanum as an anti-inflammatory agent, its antineoplastic potential is unknown.

AIM OF THE STUDY

To evaluate toxic effects of the indole alkaloid-rich fraction (IAF) of A. subincanum on the MCF7 cell line and identify some of the anti-inflammatory mechanisms involved.

MATERIALS AND METHODS

Chromatographic analyses were performed by ultra-high-performance liquid chromatography with electrospray ionization mass spectrometry, and cytotoxic and antiproliferative effects of IAF were verified by MTT and clonogenic assays. Cell cycle alterations were analyzed by measuring DNA content, while propidium iodide and acridine orange staining was performed to determine the type of induced cell death. The expression of apoptosis markers and proteins involved in cell proliferation and survival pathways was analyzed by immunoblotting, RT-qPCR, and ELISAs. Interference with redox status was investigated using a DCFH-DA probe and by measuring catalase activity.

RESULTS

Chromatographic analyses showed that IAF is a complex mixture containing indole alkaloids. IAF selectively exerted toxic and antiproliferative effects, elevating the Bax/Bcl-xL ratio and inducing apoptosis in MCF7 cells. IAF decreased intracellular reactive oxygen species levels and increased catalase activity, while reducing the IL-8 level and suppressing COX-2 expression.

CONCLUSIONS

IAF induces apoptosis in MCF7 cells by suppressing COX-2 expression while reducing IL-8 levels and intracellular content of reactive oxygen species.

Application of the metabolomics approach to the discovery of active compounds from Brazilian trees against resistant human melanoma cells

INTRODUCTION

The chemical diversity of plants plays an essential role in the development of new drugs. However, new bioactive compound identification and isolation are challenging due to the complexity and time-consuming nature of the traditional process. Recently, alternative strategies have become popular, such as the statistical approach to correlate compounds with biological activities, overcoming bottlenecks in bioactive natural product research.

OBJECTIVE

We aimed to determine bioactive compounds against resistant human melanoma cells from leaves of Aspidosperma subincanum, Copaifera langsdorffii, Coussarea hydrangeifolia, Guarea guidonea and Tapirira guianensis, using a metabolomics approach.

MATERIAL AND METHODS

The extracts and fractions were obtained by accelerated solvent extraction (ASE) and tested against resistant melanoma cells SK-MEL-28 and SK-MEL-103. Chemical analysis was performed by high-performance diode array detector tandem mass spectrometry (HPLC-DAD-MS/MS). Chemical and biological data were analysed through univariate and multivariate analysis.

RESULTS

The species present high chemical diversity, including indole alkaloids, glycosylated flavonoids, galloylquinic acid derivatives, cinnamic acid derivatives, and terpenes. The ASE fractionation separated the compounds according to the physicochemical properties; only C. langsdorffii and T. guianensis extracts were active. Both results from the chemical profile and the biological assay were treated using a metabolomics approach to identify the contribution of different classes of secondary metabolites in the viability of human melanoma cells. The analyses showed the metabolites from C. langsdorffii and T. guianensis, such as polyphenols and terpenes, were the main compounds correlated with the biological response.

CONCLUSION

These findings afford alternative pathways that are trustworthy and less time-consuming to identify new bioactive compounds against multidrug-resistant human melanoma cells.

Biological Activities of Extracts from Ageratum fastigiatum: Phytochemical Study and In Silico Target Fishing Approach

In the present study, the ethanolic extract from aerial parts of Ageratum fastigiatum was evaluated in vitro against epimastigote forms of Trypanosoma cruzi (Y strain), promastigote forms of Leishmania amazonensis (PH8 strain), and L. chagasi (BH400 strain). The extract was also evaluated against Staphylococcus aureus (ATCC 25 923), Escherichia coli (ATCC 11 775), Pseudomonas aeruginosa (ATCC 10 145), and Candida albicans (ATCC 36 802). The phytochemical screening was performed by thin-layer chromatography and high-performance liquid chromatography. The extract was fractionated using flash preparative chromatography. The ethanolic extract showed activity against T. cruzi, L. chagasi, and L. amazonensis and antimicrobial activity against S. aureus, E. coli, P. aeruginosa, and C. albicans. The phytochemical screening revealed coumarins, terpenes/sterols, and flavonoids in the ethanolic extract. In addition, the coumarin identified as ayapin was isolated from this extract. We also performed in silico prediction of potential biological activities and targets for compounds previously found in A. fastigiatum. Several predictions were confirmed both retrospectively and prospectively by experimental results described here or elsewhere. Some activities described in the in silico target fishing approach were validated by the ethnopharmacological use and known biological properties. Some new activities and/or targets were predicted and could guide future studies. These results suggest that A. fastigiatum can be an interesting source of substances with antiparasitic and antimicrobial activities.

Recent Developments in New Therapeutic Agents against Alzheimer and Parkinson Diseases: In-Silico Approaches

Neurodegenerative diseases (ND), including Alzheimer's (AD) and Parkinson's Disease (PD), are becoming increasingly more common and are recognized as a social problem in modern societies. These disorders are characterized by a progressive neurodegeneration and are considered one of the main causes of disability and mortality worldwide. Currently, there is no existing cure for AD nor PD and the clinically used drugs aim only at symptomatic relief, and are not capable of stopping neurodegeneration. Over the last years, several drug candidates reached clinical trials phases, but they were suspended, mainly because of the unsatisfactory pharmacological benefits. Recently, the number of compounds developed using in silico approaches has been increasing at a promising rate, mainly evaluating the affinity for several macromolecular targets and applying filters to exclude compounds with potentially unfavorable pharmacokinetics. Thus, in this review, an overview of the current therapeutics in use for these two ND, the main targets in drug development, and the primary studies published in the last five years that used in silico approaches to design novel drug candidates for AD and PD treatment will be presented. In addition, future perspectives for the treatment of these ND will also be briefly discussed.

Assessment of antidiabetic potential and phytochemical profiling of Rhazya stricta root extracts

Background

Diabetes mellitus is a chronic disease characterized by hyperglycemia that may occur due to genetic, environmental or lifestyle factors. Natural remedies have been used to treat diabetes since long and many antidiabetic compounds of varied efficacies have been isolated from medicinal plants. Rhazya stricta has been used for decades for the treatment of diabetes mellitus and associated ailments. Considering the folkloric use of R. stricta against diabetes, it was aimed to investigate the effectiveness of its root extracts against diabetes through in vitro assays and in vivo studies using animal model along with phytochemical profiling through GCMS.

Methods

Various fractions of Rhazya stricta obtained through column chromatography were evaluated for a variety of assays including α-glucosidase, Dipeptidyl peptidase-IV (DPP-IV), β-secretase and Glucagon-like peptide-1 (GLP-1) secretion studies. For the in vivo studies the alloxan-induced diabetic mice were treated with root extracts and blood glucose levels, HbA1C, and other biochemical markers along with the histological study of the liver were done. The phytochemical identification was performed using an Agilent 7890B GC coupled to a 7010 Triple Quadrupole (MS/MS) system. GraphPad Prism software version 5.01 was used for statistical analysis.

Results

Majority of the extract fractions showed excellent results against diabetes by inhibiting enzymes DPP-IV (Up to 61%) and β-secretase (Up to 83%) with IC_50s 979 μg/ml and 169 μg/ml respectively with increase in the GLP1 secretion. The results of in vivo studies indicated a marked reduction in blood glucose and HbA1c levels along with positive effects on other parameters like lipid profile, liver functions and renal functions of extract-treated mice as compared to control. The histological examination of the liver demonstrated hepatoprotective effects against diabetes led changes and various classes of phytochemicals were also identified through GCMS in different fractions.

Conclusion

The results revealed strong antidiabetic activity of R. stricta root with the potential to protect body organs against diabetic changes. Moreover, a variety of phytochemicals has also been identified through GCMS that might be responsible for the antidiabetic potential of Rhazya stricta root.

Graphical abstract

Phenolic profiling and in vitro bioactivity of Moringa oleifera leaves as affected by different extraction solvents

In this work the (poly)-phenolic profile of Moringa oleifera leaves was comprehensively investigated through untargeted metabolomics, following a homogenizer-assisted extraction (HAE) using three solvent systems, i.e. methanol (HAE-1), methanol-water 50:50 v/v (HAE-2) and ethyl acetate (HAE-3). This approach allowed to putatively annotate 291 compounds, recording mainly flavonoids and phenolic acids. Thereafter, antioxidant capacity, antimicrobial activity and enzyme inhibition were assayed in the different extracts. HAE-1 extract showed the highest total phenolic content (31.84 mg/g), followed by HAE-2 (26.95 mg/g) and HAE-3 (14.71 mg/g). In addition, HAE-1 and HAE-2 extracts exhibited an expressive activity against Bacillus cereus and Listeria innocua. The HAE-2 leaf extract was characterized by the highest DPPH and ABTS values (being 49.55 and 45.26 mgTE/g), while ferric reducing antioxidant power was found to be higher in HAE-1 (58.26 mgTE/g). Finally, the enzyme inhibitory effects of M. oleifera leaf extracts were investigated against five enzymes, namely acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-amylase and α-glucosidase. All of the tested extracts exhibited inhibitory effects on AChE and BChE with a higher activity for HAE-3 and HAE-1, whilst HAE-1 showed the higher impact on tyrosinase, glucosidase and amylase activities. Taken together, these findings suggest that M. oleifera leaf extracts are a good source of bioactive polyphenols with a potential use in food and pharma industries.

In vitro antileishmanial activity of leaf and stem extracts of seven Brazilian plant species

ETHNOPHARMACOLOGICAL RELEVANCE

Leishmaniasis is a parasitic disease that affects people all over the world. The number of cases of leishmaniasis is increasing and the drugs used for its treatment are toxic and not always effective. The recognition of the global nature of this disease and its direct or indirect effects on health economics and actions focuses attention on the development of new therapeutic options. In Brazil, this parasitic disease is endemic in many regions. The plants used by the population against leishmaniasis can be good starting points in the search of new lead compounds for antileishmanial drugs.

AIM OF THE STUDY

The aim of the present study was to investigate the antileishmanial activity of extracts from leaves and stems of seven Brazilian plant species used by the population to treat leishmaniasis, and symptoms that might be related to Leishmania infections.

MATERIALS AND METHODS

Twenty two extracts from seven plants belonging to five different botanical families were prepared by different methods and evaluated for their effect on the viability of promastigote forms of Leishmania infantum (MHOM/BR/1967/BH46) using the resazurin-based colorimetric assay. The extracts were considered active when they inhibited the growth of promastigotes in a percentage greater than or equal to 50% at 100 and 200 µg/mL. The active samples were further investigated to determine IC₅₀, CC₅₀ and SI values against promastigote forms of L. infantum. The active and non-cytotoxic extracts (SI> 10) were evaluated against amastigote forms of L. infantum. In addition, the active extracts against the amastigote forms were analyzed by TLC and HPLC, while the EtOAc extract of stems from Aspidosperma tomentosum was also evaluated by GC/MS.

RESULTS

Among the twenty two extracts evaluated, two were considered active against L. infantum. The EtOH extract of leaves from Dyospiros hispida (IC₅₀ 55.48 ± 2.77 µg/mL and IC₅₀ 80.63 ± 13.17 µg/mL, respectively) and the EtOAc extract of stems from Aspidosperma tomentosum (IC₅₀ 9.70 ± 2.82 µg/mL and IC₅₀ 15.88 ± 1.53 µg/mL, respectively) inhibited significantly the growth of promastigote and amastigote forms of L. infantum. Some extracts, although active in the initial screening, were considered toxic since the SI was lower than 10. In TLC and HPLC analysis the leaf extract of Dyospiros hispida showed the presence of anthraquinones, terpenes and saponins, and in the EtOAc extract of stems from Aspidosperma tomentosum alkaloids and flavonoids were detected. In addition, in the latter extract the indole alkaloids uleine and dasycarpidone could be identified by GC/MS.

CONCLUSIONS

The ethnopharmacological data of Aspidosperma tomentosum and Dyospiros hispida in part support the results found in the biological models used. Extracts of Aspidosperma tomentosum and Dyospiros hispida presented promising results against L. infantum.

Gold(i)-catalyzed pathway-switchable tandem cycloisomerizations to indolizino[8,7-b]indole and indolo[2,3-a]quinolizine derivatives

A common strategy was developed to access both indolizino[8,7-b]indole and indolo[2,3-a]quinolizine derivatives from tryptamine-N-ethynylpropiolamide substrates in a switchable fashion via tuning both the electronic effects and steric effects.

Combined In Vitro Studies and in Silico Target Fishing for the Evaluation of the Biological Activities of Diphylleia cymosa and Podophyllum hexandrum

This paper reports the in silico prediction of biological activities of lignans from Diphylleia cymosa and Podophyllum hexandrum combined with an in vitro bioassays. The extracts from the leaves, roots and rhizomes of both species were evaluated for their antibacterial, anticholinesterasic, antioxidant and cytotoxic activities. A group of 27 lignans was selected for biological activities prediction using the Active-IT system with 1987 ligand-based bioactivity models. The in silico approach was properly validated and several ethnopharmacological uses and known biological activities were confirmed, whilst others should be investigated for new drugs with potential clinical use. The extracts from roots of D. cymosa and from rhizomes and roots of P. hexandrum were very effective against Bacillus cereus and Staphylococcus aureus, while podophyllotoxin inhibited the growth of Staphylococcus aureus and Escherichia coli. D. cymosa leaves and roots showed anticholinesterasic and antioxidant activities, respectively. The evaluated extracts showed to be moderately toxic to THP-1 cells. The chromatographic characterization indicated that podophyllotoxin was the major constituent of P. hexandrum extract while kaempferol and its hexoside were the main constituents of D. cymosa leaves and roots, respectively. These results suggest that the podophyllotoxin could be the major antibacterial lignan, while flavonoids could be responsible for the antioxidant activity.