Bio-guided isolation of leishmanicidal and trypanocidal constituents from Pituranthos battandieri aerial parts

Antiparasitic activity of Eryngium bourgatii Gouan: Fractionation and isolation of constituents from roots and aerial parts

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants are rich in bioactive compounds with diverse properties that can preserve human health. Eryngium bourgatii is used in traditional medicine to purify the blood. Species of this genus have been used for their antibacterial, antitumor, antifungal or antiparasitic properties among others.

AIM OF THE STUDY

In this work, the antiparasitic properties against Leishmania donovani, Trypanosoma cruzi, and Plasmodium falciparum were evaluated.

MATERIALS AND METHODS

Methyl tert-butyl ether (MTBE), dichloromethane (DCM), and ethyl acetate (EtOAc) extracts of the roots and the non-flowering aerial parts were obtained by maceration at room temperature. Some of them were partitioned with solvents of increasing polarity, specifically n-hexane (n-Hex), dichloromethane (DCM), and ethyl acetate (EA) to isolate different fractions. Growth inhibition assays were performed against the three protozoa (L. donovani, T. cruzi, and P. falciparum). The active fractions were subsequently separated by chromatography to determine the secondary metabolites responsible for the activity. In addition, GC-MS studies were performed to further analyse the composition of the extracts and fractions.

RESULTS

Regarding the roots, the MTBE extract was the most potent leishmanicidal (77.7 % inhibition at 10 μg/mL). The activity increased in its n-Hex fraction (95.3 % inhibition), and in the DCM fraction, both leishmanicidal (93.6 %) and anti-Chagas activity (92.2 %) improved. Furanone 12, a new natural compound, was the main component of the extract and the most potent leishmanicide (96.7 %), sixteen times less than the reference drug, Amphotericin B. 11-Acetoxyfalcarindiol (19) was the most potent anti-Chagas (89.1 % inhibition). Regarding the aerial parts, the DCM extract was the most potent leishmanicide (83.3 %), which improved in its DCM fraction (95.7 %), mainly attributed to compound 12. The DCM fraction of the MTBE extract produced the best antichagasic result (93.3 % inhibition), attributed to falcarindiol (17). Practically, the same compounds were identified in the roots as in the aerial parts, but in different proportions. Nine pure compounds were isolated; 34 were identified in roots and 37 in the aerial parts by GC-MS, with alkyne compounds leading, followed by sesquiterpenes and fatty acids.

Revealing the Therapeutic Potential of Pituranthos scoparius: Phytochemical Composition, Biological Activities, and Abiotic Stress Resilience Through In Vitro and In Silico Analyses From the Algerian Sahara

Although medicinal plants have the potential to be used therapeutically, little is known about the bioactive components and environmental stress reactions of the Algerian Saharan plant Pituranthos scoparius. The biological activity, phytochemical composition, adaptability, and molecular docking of the plant were evaluated in this work, along with dynamics simulations (in silico) that analyze how plant phytochemicals inhibit Pseudomonas aeruginosa LasR. In addition, osmolytes linked to edaphic factors and stresses were investigated in soil samples from Adrar. This latter was characterized by moderate limestone, low salinity, high potassium, and low phosphorus. Glycine betaine, proline, soluble carbohydrates, chlorophyll, and carotenoids were all present in stressed plants. GC-MS analysis revealed 40 major essential oil components, including β-phellandrene and exo-2-hydroxyanisole, while LC-MS detected β-carotene, riboflavin, and ascorbic acid. The ethanolic extract (IC50 = 164.86 ± 29.92 µg/mL) and essential oil (IC50 = 188.46 ± 5.49 µg/mL) exhibited DPPH radical scavenging activity. Furthermore, the anti-inflammatory tests showed inhibition of albumin denaturation by the ethanolic extract (84.46 ± 0.008%) and essential oil (62.25 ± 0.015%) at 10 mg/mL. The ethanolic extract (100 mg/mL) also exhibited antibacterial activity, inhibiting Staphylococcus aureus and Enterococcus faecalis (34 mm zones). On the other hand, the in silico analysis revealed that quercetin, methylbicyclo(4.4.0)decane (cis), and cianidanol effectively bound to and suppressed LasR. This study investigated the adaptability, phytochemical profile, biological activities, and microbial interactions of P. scoparius using in silico methods. The identification of key bioactive compounds and their antioxidant, anti-inflammatory, and antibacterial properties, including LasR inhibition, provides valuable insights for drug development.

Natural and Bioinspired Lipidic Alkynylcarbinols as Leishmanicidal, Antiplasmodial, Trypanocidal, Fungicidal, Antibacterial, and Antimycobacterial Agents

The present review article recapitulates for the first time the antipathogenic biological data of a series of lipidic natural products and synthetic analogues thereof characterized by the presence in their structure of an alkynylcarbinol unit. The cytotoxic properties of such natural and bioinspired compounds have been covered by several literature overviews, but to date, no review article detailing their activity against pathogens has been proposed. This article thus aims at providing a comprehensive overview of the field including early studies from the 1970s and 1980s with a specific focus on results published from the late 1990s until nowadays. Publications presenting the data of almost 50 different natural products are reported. Detailed activities encompass the fields of leishmanicidal, antiplasmodial, trypanocidal, fungicidal, and mainly antibacterial and antimycobacterial compounds. The few published studies aimed at exploring the structure-activity relationship in these series are also described. Around 15 different synthetic analogues of natural products, selected among the most active reported, are also presented. The rare data available regarding the antipathogenic mode of action of these products are recalled, and finally, a comparative analysis of the available biological data is proposed with the aim of identifying the key structural determinants for the bioactivity against pathogens of these unusual compounds.

The preventive effects of Centaurea maroccana Ball. extract against oxidative stress induced by cisplatin in mice brains: in vitro and in vivo studies

Since antiquity, Centaurea species have been used in folk medicine to treat several diseases owing to their potential biological activities that distinguish this genus such as antioxidant, anticancer, and anti-inflammatory effect. The current study aimed to investigate the possible neuroprotective effects of the n-butanol extract of Centaurea maroccana (BECM) against cisplatin (CP) induced neurotoxicity in mice. BECM's potential neuroprotective properties were studied in vitro and in vivo models. Male Swiss albino mice were orally received BECM (200 mg/kg) for 10 days before a single intraperitoneal injection of cisplatin (8 mg/kg). Vitamin E (100 mg/kg) was given daily by gavage as a positive control. In vitro results revealed that BECM inhibited lipid peroxidation (LPO) levels and acetylcholinesterase (AChE) activity. In vivo findings showed that BECM pretreatment was able to regulate lactate dehydrogenase (LDH) levels and to improve CP-induced cholinergic dysfunction by inhibiting AChE activity in mice brains. Moreover, BECM attenuated CP-provoked oxidative stress by suppressing LPO levels, increasing total antioxidant capacity (TAC) and enhancing the activities of antioxidant enzymes (catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx) and glutathione S-transferase (GST)) in both brain cytosolic and mitochondrial fractions. The histological analysis exhibited neurotoprotective effect of BECM by protecting the cerebral cortex and reducing the histomorphological alterations resulted by cisplatin. Interestingly, our extract achieved neuroprotection comparable to vitamin E in most evaluated parameters. It appears that protective potency of BECM against CP-induced neurotoxicity could be related to its richness in polyphenols confirmed by liquid-chromatography tandem mass spectrometry analysis (LC-MS/MS).

Trypanocidal effect of alcoholic extract of Castanedia santamartensis (Asteraceae) leaves is based on altered mitochondrial function

The deficit of effective treatments for Chagas disease has led to searching for new substances with therapeutic potential. Natural products possess a wide variety of chemical structural motifs and are thus a valuable source of diverse lead compounds for the development of new drugs. Castanedia santamartensis is endemic to Colombia, and local indigenous communities often use it to treat skin sores from leishmaniasis; however, its mechanism of action against the infective form of Trypanosoma cruzi has not been determined. Thus, we performed chemical and biological studies of two alcoholic leaf extracts of C. santamartensis to identify their active fractions and relate them to a trypanocidal effect and evaluate their mechanism of action. Alcoholic extracts were obtained through cold maceration at room temperature and fractionated using classical column chromatography. Both ethanolic and methanolic extracts displayed activity against T. cruzi. Chemical studies revealed that kaurenoic acid was the major component of one fraction of the methanolic extract and two fractions of the ethanolic extract of C. santamartensis leaves. Moreover, caryophyllene oxide, kaurenol, taraxasterol acetate, pentadecanone, and methyl and ethyl esters of palmitate, as well as a group of phenolic compounds, including ferulic acid, caffeic acid, chlorogenic acid, myricetin, quercitrin, and cryptochlorogenic acid were identified in the most active fractions. Kaurenoic acid and the most active fractions CS400 and CS402 collapsed the mitochondrial membrane potential in trypomastigotes, demonstrating for the first time the likely mechanism against T. cruzi, probably due to interactions with other components of the fractions.

Identification of lobetyolin as a major antimalarial constituent of the roots of Lobelia giberroa Hemsl

Lobelia giberroa Hemsl. is an endogenous Ethiopian medicinal plant with a long history of use in the treatment of malaria, bacterial and fungal diseases, and cancer. Here, we present the in vivo bioassay-guided fractionation of the 80% methanol extract of L. giberroa roots, which led to the isolation of lobetyolin. L. giberroa roots were extracted with 80% methanol, and the dried 80% methanol extract was fractionated with hexane, ethyl acetate, methanol, and water. Acute oral toxicity study was conducted according to the Organisation for Economic Co-operation and Development Guideline 425 by using female Swiss albino mice. Antimalarial activity was assessed in Plasmodium berghei-infected Swiss albino mice. Through in vivo bioassay-guided fractionation processes lobetyolin, a C14-polyacetylene glucoside, was isolated from the methanol fraction by silica gel column chromatography as the main active ingredient from the plant. The chemical structure of lobetyolin was elucidated by interpretation of spectroscopic data (¹HNMR, ¹³CNMR, IR. MS) including two dimensional NMR. The plant extract was considered safe for administration up to 2000 mg/kg. In the four-day suppressive test, the 80% methanol extract (400 mg/kg), methanol fraction (400 mg/kg), and lobetyolin (100 mg/kg) exhibited antimalarial activity, with chemosuppression values of 73.05, 64.37, and 68.21%, respectively. Compared to the negative control, which had a mean survival time of 7 days, the lobetyolin (100 mg/kg) and methanol fraction (400 mg/kg) treated groups had mean survival times of 18 and 19 days, respectively. The current study supports the traditional use of the plant for the treatment of malaria. The structural differences between lobetyolin and existing antimalarials, as well as its previously unknown antimalarial activity, make it of interest as an early lead compound for further chemical optimization.

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Multi-drug resistant malaria parasites urge the discovery of newer drugs.

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Lobelia giberroa is an indigenous traditional antimalarial plant of Ethiopia.

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In vivo antimalarial-activity-guided fractionation led to the isolation of lobetyolin.

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Lobetyolin exhibits a promising antimalarial activity with an ED₅₀ of 36.8 mg/kg.

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Lobetyolin is a potential lead compound to develop a new class of antimalarial drugs.

In Vitro Anti-Trypanosoma cruzi Activity of Halophytes from Southern Portugal Reloaded: A Special Focus on Sea Fennel (Crithmum maritimum L.)

Marine halophytes are an outstanding reservoir of natural products and several species have anti-infectious traditional uses. However, reports about their potential use against neglected tropical ailments, such as Chagas disease, are scarce. This work evaluated for the first time the in vitro anti-Trypanosoma cruzi activity of extracts from the aromatic and medicinal species Helichrysum italicum subsp. picardii (Boiss. & Reut.) Franco (Asteraceae, everlasting) and Crithmum maritimum L. (Apiaceae, sea fennel). For that purpose, decoctions, tinctures, and essential oils from everlasting's flowers and sea fennel's stems, leaves, and flowers were tested against intracellular amastigotes of two T. cruzi strains. The extract from the sea fennel flower decoction displayed significant anti-trypanosomal activity and no toxicity towards the host cell (EC50 = 17.7 µg/mL, selectivity index > 5.65). Subsequent fractionation of this extract afforded 5 fractions that were re-tested in the same model of anti-parasitic activity. Fraction 1 was the most active and selective (EC50 = 0.47 μg/mL, selectivity index = 59.6) and was submitted to preparative thin-layer chromatography. One major compound was identified, falcarindiol, which was likely the one responsible for the observed anti-trypanosomal activity. This was confirmed using a commercially sourced molecule. Target-fishing studies showed falcarindiol as a ligand of T. cruzi spermidine synthase, pointing to a potential enzyme-inhibiting anti-trypanosomal mechanism of action. Overall, this work shows that sea fennel can provide effective anti-parasitic molecule(s) with potential pharmacological applications in the treatment of CD.

Chemical Composition and Antioxidant, Antiparasitic, Cytotoxicity and Antimicrobial Potential of the Algerian Limonium Oleifolium Mill. Essential Oil and Organic Extracts

This work aimed to investigate, for the first time, the chemical composition, antioxidant, antiparasitic, cytotoxicity, and antimicrobial activities of the aromatic plant Limonium oleifolium Mill. essential oil (EO) and organic extracts. L. oleifolium aerial parts essential oil was analyzed by GC-FID and GC-MS, and 46 constituents representing 98.25±1.12 % of the oil were identified. γ-Muurolene (10.81±0.07 %), cis-caryophyllene (7.71±0.06 %), o-cymene (7.07±0.01 %) and α-copaene (5.02±0.05 %) were the essential oil main compounds. The antioxidant activity of L. oleifolium EO and organic extracts (MeOH, CHCl₃ , AcOEt, BuOH) was explored using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ABTS, β-carotene/linoleic acid, cupric reducing antioxidant capacity (CUPRAC), and ferric reducing power assays. The results showed that L. oleifolium EO exhibit antioxidant capacity (IC₅₀ =17.40±1.32 μg/mL for DPPH assay, IC₅₀ =29.82±1.08 μg/mL for β-carotene assay, IC₅₀ =25.23±1.01 μg/mL for ABTS assay, IC₅₀ =9.11±0.08 μg/mL for CUPRAC assay and IC₅₀ =19.41±2.06 mg/mL for reducing power assay). Additionally, the EO showed significant activity against trophozoite form of Acanthamoeba castellanii (IC₅₀ =7.48±0.41 μg/mL) and promastigote form of Leishmania amazonensis (IC₅₀ =19.36±1.06 μg/mL) and low cytotoxicity on murine macrophages (LC₅₀  90.23±1.09 μg/mL), as well as good antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella oxytoca, and Pseudomonas aeruginosa. These results suggest that L. oleifolium essential oil is a valuable source of bioactive compounds presenting antioxidant, antiparasitic, and antimicrobial activities. Furthermore, it is considered nontoxic.