Bioguided Isolation of Alkaloids and Pharmacological Effects of the Total Alkaloid Fraction from Aspidosperma pyrifolium Mart. (Apocynaceae)

Aspidosperma pyrifolium is used in traditional medicine to treat inflammatory disorders. The aim of the study was to perform phytochemical characterization and evaluate the anti-inflammatory, anti-nociceptive and acute toxicity effects of the total alkaloid fraction (TAF-Ap) from stem barks. Two monoterpenic indole alkaloids were isolated by high performance liquid chromatography coupled with mass spectrometry (HPLC-MS) and the structural elucidation was performed using 1D and 2D NMR analysis. As for toxicity, no animals died at 50 mg kg−1 and this concentration presented mild sedation and forced breathing within the first 24 h. The lethal dose capable of killing 50% of the animals (LD50) was estimated to be 160 mg kg−1. In the pharmacological tests, the models used were 1% carrageenan-induced paw edema and peritonitis, 1% formalin-induced nociception and 1% acetic acid-induced abdominal writhing in Swiss mice. The study made it possible to isolate 15-methoxyaspidospermine and 15-methoxypyrifolidine, corroborating the results of pharmacological assays, which showed anti-inflammatory and analgesic potential, especially at 30 mg kg−1 (p < 0.001). Thus, the species was shown to be a promising source of active substances, with special attention paid to its toxicological potential.

Evaluation of acute and subacute toxicity of ethanolic extract and fraction of alkaloids from bark of Aspidosperma nitidum in mice

This study investigated the acute and subacute toxicity of the ethanolic extract (EE) and alkaloid fraction (FA) from A. nitidum. The EE was obtained from trunk bark with ethanol, FA was obtained from the fractionation of EE. To test the acute toxicity, mice were divided into four groups, and the negative controls received water or aqueous solution of dimethyl sulfoxide, whereas the others received EE or FA (2000 mg/kg, orally, single dose). The same controls were used in the subacute trial. However, the animals were treated for 28 days, and the dose used was 1000 mg/kg per day of EE and FA. Daily clinical evaluations of the animals were performed. At the end of the experiment, hematological, biochemical, and histopathological assessments (liver, lung, heart, and kidney) were performed. In the acute and subacute toxicity studies, mice treated with EE and FA did not show any clinical changes, there were no changes in weight gain, hematological and biochemical parameters compared to the control groups (p > 0.05). In the histopathological examination, there was no abnormality in the organs of the treated animals. Therefore, EE and FA did not produce toxic effects in mice after acute and subacute treatment.

Hepatoprotective Property of Phyllanthus amarus Alkaloid-Rich Fraction with Respect to Oxidative Stress Marker Enzymes

A disruption in the equilibrium between the generation of reactive oxygen species and antioxidant defense enzymes is referred to as oxidative stress. In the present study, we planned to identify the hepatoprotective effect of Phyllanthus amarus alkaloid rich fraction in wistar strain albino male rats. The hepatic damage was induced by the D-galactosamine and ameliorative effect was tested with alkaloid rich fraction of P. amarus by measuring oxidative stress markers such as G6PDH, LDH, SDH, MDH and GDH in the liver tissue. Activity levels of G6PDH, SDH, MDH and GDH were significantly decreased in D-galactosamine induced hepatitis rats when compare to normal control rat group, while their activities were significantly increased in hepatitis rat group that supplemented with alkaloid rich fraction of P. amarus. In contrast, LDH enzyme activity of liver was significantly increased in the hepatitis rat group when compare to normal control rats, while its activity was significantly decreased in hepatitis rats treated with alkaloid fraction. In conclusion, it is very clear that alkaloid fraction of P. amarus has hepatoprotective property with respect of decreasing oxidative stress by regulating oxidative stress marker enzymes. The isolation and identification of specific alkaloid compounds with hepatoprotective properties and anti-oxidative stress will require much further research.

Alkaloidal fraction of Diospyros mespiliformis protect against Trypanosoma evansi-mediated haematological and hepatic impairment in infected rats

The present study investigated the antitrypanosomal activities of crude and an alkaloidal fraction of Diospyros mespiliformis in Trypanosoma evansi - infected rats. A total of twenty-one (21) rats were divided into seven (7) groups of three (3) rats each. Groups 1-6 were infected with the T. evansi parasite and were treated with 100 and 200 mg/kg BW crude extract, 200 and 400 mg/kg BW of the alkaloid fraction of D. mespiliformis, 3.5mg/kg of berenil (standard control) and 0.2 mL/kg BW of normal saline (negative control) respectively. Group 7 serves as the normal control (non-infected and non-treated) rats. Results revealed that the crude extract at 400 mg/kg BW and alkaloid fraction at all doses tested (100 and 200 mg/kg BW) significantly (P<0.05) increased the RBC, PCV, MCH, MCHC, WBC, and reduced the elevated bilirubin when compared with the untreated control. The extract also significantly increased the reduced total proteins. In conclusion, an alkaloid from Diospyros mespiliformis ameliorative effect on T. evansi-induced biochemical and hematological alterations in rats, thus could be considered a novel agent for the development of a new drug against trypanosomiasis

New alkaloids from Ocotea duckei vattimo (Lauraceae)

Ocotea duckei Vattimo, popularly known as “louro-de-cheiro”, “louro-pimenta”, and “louro-canela” is a member of the Lauraceae family found in the Northeast region of Brazil. It is popularly used to treat neuralgia, dyspepsia, anorexia and pain. This current study aimed to promote the isolation and the identification / determination of new secondary metabolites of the species O. duckei Vattimo. In order to obtain the vegetable drug of O. duckei, its stem barks were harvested and submitted to a drying process followed by pulverization. The Crude Ethanolic Extract (BSE), obtained from the vegetable drug, was then subjected to an alkaloid extraction protocol in order to generate its Total Alkaloid Fraction (TAF). The isolation and identification of chemical compounds were carried out by chromatographic and spectroscopic methods respectively. The chemical investigation of O. duckei resulted in the isolation of three compounds: Ocoteaduccin A (OD-1, 0.020 g), Ocoteaduccin B (OD-2, 0.015 g), and N-methylcoclaurine (OD-3, 0.008 g). O. duckei proved to be a promising species, due to the variety of isolated chemical compounds. Further chemical, pharmacological and toxicological studies must be conducted in order to improve the phytochemical knowledge about this plant.

Green Synthesis of Platinum and Palladium Nanoparticles Using Peganum harmala L. Seed Alkaloids: Biological and Computational Studies

This study reports a facile and eco-friendly method for the green synthesis of platinum and palladium nanoparticles (Pt NPs and Pd NPs) using Peganum harmala seed alkaloid fraction. The ζ-potential of the synthesized Pt NPs, Pd NPs and Pt–Pd NPs were −11.2 ± 0.5, −9.7 ±1.2, and −12.7 ± 2.1 mV; respectively. Transmission electron microscopy (TEM) revealed the formation of spherical-shaped nanoparticles with smooth margins. The mean diameters of the synthesized Pt NPs, Pd NPs, and Pt–Pd NPs were determined using TEM analysis and were found to be 20.3 ± 1.9, 22.5 ± 5.7, and 33.5 ± 5.4 nm, respectively. The nanoparticles’ bioreduction was confirmed by ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, and their organic contents were determined by thermal gravimetric analysis (TGA). The Pt–Pd NPs mixture showed more pronounced antioxidant activity of 843.0 ± 60 μM Trolox equivalent (TE)/mg NPs compared to the individual Pt NPs (277.3 ± 13.5 μM TE/mg NPs) and Pd NPs (167.6 ± 4.8 μM TE/mg NPs). Furthermore, the Pt–Pd NPs exhibited significant cytotoxic activities against lung cancer (A549) and breast adenocarcinoma (MCF-7) cells, IC50 of 8.8 and 3.6 µg/mL, respectively; as compared to Pt NPs (IC50 of 10.9 and 6.7 µg/mL, respectively) and Pd NPs (IC50 of 31 and 10.8 µg/mL, respectively and compared to carboplatin (IC50 of 23 and 9.5 µg/mL, respectively). Moreover, molecular docking studies were conducted to explore the possible anticancer and antioxidant mechanisms of the biogenic nanoparticles. Pt NPs, Pd NPs, and their mixture showed inhibitory activity against cysteine proteinase, which supports their high antitumor activity, but moderate antioxidant activity. In conclusion, Pd-Pt NPs mixture prepared using harmala seed alkaloid fraction showed potential as effective antineoplastic agents.

The Alkaloid-Enriched Fraction of Pachysandra terminalis (Buxaceae) Shows Prominent Activity against Trypanosoma brucei rhodesiense

In the course of our studies on antiprotozoal natural products and following our recent discovery that certain aminosteroids and aminocycloartanoid compounds from Holarrhena africana A. DC. (Apocynaceae) and Buxus sempervirens L. (Buxaceae), respectively, are strong and selective antitrypanosomal agents, we have extended these studies to another plant, related to the latter—namely, Pachysandra terminalis Sieb. and Zucc. (Buxaceae). This species is known to contain aminosteroids similar to those of Holarrhena and structurally related to the aminocycloartanoids of Buxus. The dicholoromethane extract obtained from aerial parts of P. terminalis and, in particular, its alkaloid fraction obtained by acid–base partitioning showed prominent activity against Trypanosoma brucei rhodesiense (Tbr). Activity-guided fractionation along with extended UHPLC-(+)ESI QTOF MS analyses coupled with partial least squares (PLS) regression modelling relating the analytical profiles of various fractions with their bioactivity against Tbr highlighted eighteen constituents likely responsible for the antitrypanosomal activity. Detailed analysis of their (+)ESI mass spectral fragmentation allowed identification of four known constituents of P. terminalis as well as structural characterization of ten further amino-/amidosteroids not previously reported from this plant.

Anti-malarial activity and toxicity of Aspidosperma nitidum Benth: a plant used in traditional medicine in the Brazilian Amazon

The objective of this work was to evaluate the antiplasmodial activity and toxicity of the extract and fractions obtained from the bark of Aspidosperma nitidum. The ethanol extract obtained from the powdered bark of plants was acid-base partitioned and phytochemically analyzed. The antiplasmodial activity, in vivo antimalarial activity and in vitro cytotoxicity were acessed. The selectivity index (SI) was calculated. The acute oral toxicity and pathological effects, of the ethanol extract was evaluated in mice. The major constituent of the ethanol extract was suggestive of a β-carboline chromophore. The alkaloid and neutral fractions contained compounds with an aspidospermine core as the major constituent. The ethanol extract (IC50 = 3.60 µg/mL), neutral fraction (IC50 = 3.34 µg/mL) and alkaloid fraction (IC50= 2.32 µg/mL) showed high activity against P. falciparum (W2 strain). The ethanol extract and the alkaloid fraction reduced 80% of the parasitemia of P. berghei (ANKA)-infected mice (dose of 500 mg/kg) in the 5th day, which was not sustainable at the 8th day. A similar result was obtained for chloroquine. The ethanol extract (CC50 = 410.65 µg/mL; SI = 114.07), neutral fraction (CC50 = 452.53 µg/mL; SI = 135.49), and alkaloid fraction (CC50 =346.73 µg/mL; SI 149.45) demonstrated low cytotoxicity and high SI. The ethanol extract (5000 mg/kg; gavage) presented low acute oral toxicity, with no clinical or anatomopathological modifications being observed (in comparison to the control group). In vitro studies with a chloroquine-resistant clone of P. falciparum confirmed the antiplasmodial activity of the A. nitidum ethanol extract, and its fractions had low cytotoxicity for HepG2 cells. In vivo studies with P. berghei–infected mice and acute toxicity studies corroborated these results.