Efficacy and toxicity of thirteen plant leaf acetone extracts used in ethnoveterinary medicine in South Africa on egg hatching and larval development of Haemonchus contortus

Anti Gram-Positive Bacteria Activity of Synthetic Quaternary Ammonium Lipid and Its Precursor Phosphonium Salt

Organic ammonium and phosphonium salts exert excellent antimicrobial effects by interacting lethally with bacterial membranes. Particularly, quaternary ammonium lipids have demonstrated efficiency both as gene vectors and antibacterial agents. Here, aiming at finding new antibacterial devices belonging to both classes, we prepared a water-soluble quaternary ammonium lipid (6) and a phosphonium salt (1) by designing a synthetic path where 1 would be an intermediate to achieve 6. All synthesized compounds were characterized by Fourier-transform infrared spectroscopy and Nuclear Magnetic Resonance. Additionally, potentiometric titrations of NH3+ groups 1 and 6 were performed to further confirm their structure by determining their experimental molecular weight. The antibacterial activities of 1 and 6 were assessed first against a selection of multi-drug-resistant clinical isolates of both Gram-positive and Gram-negative species, observing remarkable antibacterial activity of both compounds against Gram-positive isolates of Enterococcus and Staphylococcus genus. Further investigations on a wider variety of strains of these species confirmed the remarkable antibacterial effects of 1 and 6 (MICs = 4-16 and 4-64 µg/mL, respectively), while 24 h-time-killing experiments carried out with 1 on different S. aureus isolates evidenced a bacteriostatic behavior. Moreover, both compounds 1 and 6, at the lower MIC concentration, did not show significant cytotoxic effects when exposed to HepG2 human hepatic cell lines, paving the way for their potential clinical application.

Nematocidal Activity of Ethanol and Aqueous Extracts of Persea americana Seeds against Heligmosomoides polygyrus using the Worm Microtracker Method

Background

Infections with gastrointestinal helminths constitute a serious obstacle to the good health of the local population in most African Countries. The aim of this study was to evaluate the anthelminthic activity of Persea americana ethanol and aqueous extracts against Heligmosomoides polygyrus using the worm microtracker.

Method

Aqueous and ethanolic extracts of P. americana were prepared. Different concentrations of the extracts were tested against the egg and larvae stages of H. polygyrus using an automated high-throughput method. Briefly, embryonated eggs and larvae of this parasite were obtained after the incubation of fresh eggs at 25°C for 24, 48, and 96 hours for embryonated eggs, L1 and L2 larvae, respectively. One hundred microliters of the plant extracts at various concentrations were put in contact in a 96-well microplate with a suspension of 100 embryonated eggs in a total volume of 200 μL and incubated in a worm microtracker where the motility of the worms was recorded every 30 minutes for the ovicidal activity. The final tested extract concentration was 5, 2.5, 1.25, 0.625, and 0.3125 mg/mL, whereas ringer solution (0.95%) and 1.5% Dimethyl sulfoxide (DMSO) were used as negative controls and levamisole as positive control. The same method was used for larvicidal activities. The anthelmintic activity was determined using the average movement of the worms in the tested product compared with the negative control (1.5% DMSO and ringer solution).

Results

The egg hatching rates of H. polygyrus had IC50 of 0.49 mg/mL (95% confidence interval: 71.70-92.03) and 0.22 mg/mL (95% confidence interval: 74.28-86.18) for the ethanol and aqueous extract, respectively. These IC50 indicate that the aqueous extract is more active for the inhibition of hatching at a 95% confidence interval. The aqueous and ethanol extracts presented mean inhibitory hatching rates of 78.33 ± 1.67% and 75.67 ± 1.15% at 5 mg/mL, respectively, with no significant differences. The highest percentage of inhibition of L1 larva was observed at 5 mg/mL with 89 ± 2.3%and 85 ± 2.7% for the ethanol and aqueous extracts, respectively. The lowest percentage of inhibition was observed at 0.3125 mg/mL, with 54.67 ± 3.38% and 49 ± 2.64% for the ethanol and aqueous extract, respectively. No significant differences were observed between the two extracts at 5 mg/mL with an inhibitory percentage of 90.67 ± 3.05% (ethanol) and 89.33 ± 2.08% (aqueous).

Conclusion

Extracts of P. americana seeds possess nematocidal activity, however, further in silico and in vivo investigations are necessary to confirm their anthelminthic activity.

The potential role of alfalfa polysaccharides and their sulphated derivatives in the alleviation of obesity

Sulfated alfalfa polysaccharides (SAPs) as derivatives of alfalfa polysaccharides (APs) showed better in vitro antioxidant activity and potential obesity inhibition. The purpose of this study was to investigate the effect and mechanisms of APs and SAPs on obesity alleviation. Different concentrations of APs and SAPs were tested for effects on body conditions, gut flora, antioxidant capacity, and immunological factors. The results showed that APs and SAPs improved the physical conditions of obese mice, including organ weight, body weight, intraperitoneal fat ratio, and lipid levels. APs and SAPs increased the antioxidant capacity of the obese mice, enhanced the activity of SOD and CAT, and decreased the activity of MDA in the serum, liver, and colon. APs and SAPs upregulated the mRNA expression of IL-4 and IL-10 and downregulated the mRNA expression of NF-κB, IFN-γ, TNF-α, and IL-6 in the liver and colon. Meanwhile, APs and SAPs improved lipid absorption in the jejunum, upregulated LXR and GLP-2, and down-regulated the mRNA expression of NPC1L1. APs and SAPs also contributed to restoring short-chain fatty acid levels in the colon. APs and SAPs improved the structure of the intestinal flora, promoted the proliferation of bacteria associated with short-chain fatty acid metabolism, and inhibited the proliferation of pathogenic bacteria. At the same concentration, the effect of SAPs on the antioxidant capacity was stronger than that of APs. In the AP group, high concentrations of APs showed the best anti-inflammatory effect, while in the SAP group, medium concentrations of SAPs showed the best inhibition of inflammation. Our results suggest that APs and SAPs alleviate obesity symptoms by relieving inflammation, improving the antioxidant capacity, and regulating intestinal flora and therefore could be used as potential probiotic products to alleviate obesity.

Nematicidal Characterization of Newly Synthesized Thiazine Derivatives Using Caenorhabditis elegans as the Model Organism

In humans, animals, and agriculture, parasitic nematode infection is a very serious issue. Many drugs are being used to control nematode infections. Owing to toxicity and nematodes' resistance to the available drugs, special attention is required to synthesize new drugs that are environmentally friendly with high-level efficacy. In the present study, various substituted thiazine derivatives (1 to 15) were synthesized, and the structures were confirmed by infrared, proton (¹H), and ¹³C NMR spectroscopies. The nematicidal potential of the synthesized derivatives was characterized using Caenorhabditis elegans (C. elegans) as a model organism. Among all synthesized compounds, 13 (LD₅₀ = 38.95 μg/mL) and 15 (LD₅₀ = 38.21 μg/mL) were considered the most potent compounds. Most compounds showed excellent anti-egg-hatching activity. Fluorescence microscopy confirmed that compounds 4, 8, 9, 13, and 15 displayed a high apoptotic effect. The expressions of gst-4, hsp-4, hsp16.2, and gpdh-1 genes were high in affected (treated with thiazine derivatives) C. elegans in comparison with normal C. elegans. The present research revealed that modified compounds are highly effective as they showed the gene level changes in the selected nematode. Due to structural modification in thiazine analogues, the compounds showed various modes of action. The most effective thiazine derivatives could be excellent candidates for novel broad-scale nematicidal drugs.

Nematicidal Characterization of Solanum nigrum and Mentha arvensis Leaf Extracts Using Caenorhabditis elegans as a Model Organism

Considering foremost global issues instigated by parasitic nematodes, Solanum nigrum (S. nigrum) and Mentha arvensis (M. arvensis) nematicidal potential at the gene level has been explored herein. Methanol, ethyl acetate, chloroform, n-hexane, and distilled water were used for extract preparation. Caenorhabditis elegans (C. elegans) was used as the model organism. Nematicidal and anti-egg hatching assays, fluorescence microscopy, and quantitative real-time PCR were done. S. nigrum chloroform (LD₅₀ = 1.21 mg/mL) and M. arvensis methanol (LD₅₀ = 2.47 mg/mL) extracts exhibited excellent nematicidal potential. Both plants showed potent anti-egg hatching activity (1 mg/mL). S. nigrum methanol and M. arvensis ethyl acetate extracts showed high apoptotic effect in muscles, gonads, and uterus (eggs). Stress genes, that is, gst-4, hsp-16.2, and gpdh-1 were highly expressed in affected C. elegans (treated with S. nigrum and M. arvensis leaf extracts) when compared with normal C. elegans. Phytochemicals and bioactive compounds present in plants may be the major cause of their excellent nematicidal potential, which further confirmed that both plants could be an alternative candidate(s) for novel broad-scale anthelmintic drug(s).

Anthelmintic Agents from African Medicinal Plants: Review and Prospects

Soil-transmitted helminthiasis affects more than 1.5 billion people globally and largely remains a sanitary problem in Africa. These infections place a huge economic burden on poor countries and affect livestock production, causing substantial economic losses and poor animal health. The emergence of anthelmintic resistance, especially in livestock, and the potential for its widespread in humans create a need for the development of alternative therapies. Medicinal plants play a significant role in the management of parasitic diseases in humans and livestock, especially in Africa. This report reviews anthelmintic studies that have been conducted on medicinal plants growing in Africa and published within the past two decades. A search was made in various electronic databases, and only full articles in English were included in the review. Reports show that aqueous and hydroalcoholic extracts and polar fractions obtained from these crude extracts form the predominant (80%) form of the extracts studied. Medicinal plants, extracts, and compounds with different chemical groups have been studied for their anthelmintic potential. Polyphenols and terpenoids are the most reported groups. More than 64% of the studies employed in vitro assays against parasitic and nonparasitic nematode models. Egg hatch inhibition, larval migration inhibition, and paralysis are the common parameters assessed in vitro. About 72% of in vivo models involved small ruminants, 15% rodents, and 5% chicken. Egg and worm burden are the main factors assessed in vivo. There were no reports on interventions in humans cited within the period under consideration. Also, few reports have investigated the potential of combining plant extracts with common anthelmintic drugs. This review reveals the huge potential of African medicinal plants as sources of anthelmintic agents and the dire need for in-depth clinical studies of extracts, fractions, and compounds from African plants as anthelmintic agents in livestock, companion animals, and humans.

A Self-Forming Hydrogel from a Bactericidal Copolymer: Synthesis, Characterization, Biological Evaluations and Perspective Applications

Objects touched by patients and healthcare workers in hospitals may harbor pathogens, including multi-drug resistant (MDR) staphylococci, enterococci (VRE), Escherichia coli, Acinetobacter, and Pseudomonas species. Medical devices contaminated by these pathogens may also act as a source of severe and difficult-to-treat human infections, thus becoming a critical public health concern requiring urgent resolutions. To this end, we recently reported the bactericidal effects of a cationic copolymer (CP1). Here, aiming at developing a bactericidal formulation possibly to be used either for surfaces disinfection or to treat skin infections, CP1 was formulated as a hydrogel (CP1_1.1-Hgel). Importantly, even if not cross-linked, CP1 formed the gel upon simple dispersion in water, without requiring gelling agents or other additives which could be skin-incompatible or interfere with CP1 bactericidal effects in possible future topical applications. CP1_1.1-Hgel was characterized by attenuated-total-reflectance Fourier transform infrared (ATR-FTIR) and UV-Vis spectroscopy, as well as optic and scanning electron microscopy (OM and SEM) to investigate its chemical structure and morphology. Its stability was assessed by monitoring its inversion properties over time at room temperature, while its mechanical characteristics were assessed by rheological experiments. Dose-dependent cytotoxicity studies performed on human fibroblasts for 24 h with gel samples obtained by diluting CP_1.1-Hgel at properly selected concentrations established that the 3D network formation did not significantly affect the cytotoxic profile of CP1. Also, microbiologic investigations carried out on two-fold serial dilutions of CP1-gel confirmed the minimum inhibitory concentrations (MICs) previously reported for the not formulated CP1.Selectivity indices values up to 12 were estimated by the values of LD₅₀ and MICs determined here on gel samples.

Mutual Jellification of Two Bactericidal Cationic Polymers: Synthesis and Physicochemical Characterization of a New Two-Component Hydrogel

Here, a new two-component hydrogel (CP1OP2-Hgel) was developed, simply by dispersing in water two cationic bactericidal polymers (CP1 and OP2) effective against several multidrug-resistant (MDR) clinical isolates of the most relevant Gram-positive and Gram-negative species. Interestingly, while OP2 acts only as an antibacterial ingredient when in gel, CP1 works as both an antibacterial and a gelling agent. To verify whether it would be worthwhile to use CP1 and OP2 as bioactive ingredients of a new hydrogel supposed for a future treatment of skin infections, dose-dependent cytotoxicity studies with CP1 and OP2 were performed on human fibroblasts for 24 h, before preparing the formulation. Although a significant cytotoxicity at concentrations > 2 µM was evidenced for both polymers, selectivity indices (SIs) over 12 (CP1) and up to six (OP2) were determined, due to the powerful antibacterial properties of the two polymers, thus supporting the rationale for their formulation as a hydrogel. The chemical structure and morphology of CP1OP2-Hgel were investigated by PCA-assisted attenuated total reflectance (ATR) Fourier-transform infrared (FTIR) analysis and scanning electron microscopy (SEM), while its rheological properties were assessed by determining its dynamic viscosity. The cumulative weight loss and swelling percentage curves, the porosity, and the maximum swelling capability of CP1OP2-Hgel were also determined and reported. Overall, due to the potent bactericidal effects of CP1 and OP2 and their favorable selectivity indices against several MDR pathogens, good rheological properties, high porosity, and strong swelling capability, CP1OP2-Hgel may, in the future, become a new weapon for treating severe nosocomial skin infections or infected chronic wounds. Further investigations in this sense are currently being carried out.

Potent and Broad-Spectrum Bactericidal Activity of a Nanotechnologically Manipulated Novel Pyrazole

The antimicrobial potency of the pyrazole nucleus is widely reported these days, and pyrazole derivatives represent excellent candidates for meeting the worldwide need for new antimicrobial compounds against multidrug-resistant (MDR) bacteria. Consequently, 3-(4-chlorophenyl)-5-(4-nitrophenylamino)-1H-pyrazole-4-carbonitrile (CR232), recently reported as a weak antiproliferative agent, was considered to this end. To overcome the CR232 water solubility issue and allow for the determination of reliable minimum inhibitory concentration values (MICs), we initially prepared water-soluble and clinically applicable CR232-loaded nanoparticles (CR232-G5K NPs), as previously reported. Here, CR232-G5K NPs have been tested on several clinically isolates of Gram-positive and Gram-negative species, including MDR strains. While for CR232 MICs ≥ 128 µg/mL (376.8 µM) were obtained, very low MICs (0.36–2.89 µM) were observed for CR232-G5K NPs against all of the considered isolates, including colistin-resistant isolates of MDR Pseudomonas aeruginosa and Klebsiella pneumoniae carbapenemases (KPCs)-producing K. pneumoniae (0.72 µM). Additionally, in time–kill experiments, CR232-G5K NPs displayed a rapid bactericidal activity with no significant regrowth after 24 h on all isolates tested, regardless of their difficult-to-treat resistance. Conjecturing a clinical use of CR232-G5K NPs, cytotoxicity experiments on human keratinocytes were performed, determining very favorable selectivity indices. Collectively, due to its physicochemical and biological properties, CR232-G5K NPs could represent a new potent weapon to treat infections sustained by broad spectrum MDR bacteria.

In Vitro Potential of the Acetone Leaf Extract and Fractions of Psychotria capensis (Eckl.) Vatke (Rubiaceae) to Combat Co-Infection of Tuberculosis and Helminthiasis

Tuberculosis (TB) is a disease of global importance that affects millions of people. Approximately a quarter of the world’s population is currently infected with M. tuberculosis, and about 10% of those infected will develop into active disease, particularly immune compromised individuals. Helminthiasis is of global health importance, affecting over 2 billion people mostly in resource-poor countries. Co-infection with tuberculosis (TB) and helminths (worms) is an emerging global public health concern with both affecting about one-third of the global population. Chronic infection with helminths can result in impaired immune responses to TB as well as enhancing failure to TB therapy and BCG vaccination. Antimycobacterial and anthelmintic activities of the acetone extract and fractions of Psychotria capensis were evaluated, including their in vitro safety. In addition, the anti-inflammatory and immunomodulatory effect of the fractions and crude extract of P. capensis were assessed. Antimycobacterial activity of the extract and fractions was tested against four non-tuberculous mycobacteria (Mycobacterium smegmatis, M. fortuitum, M. aurum, M. bovis BCG) and pathogenic M. tuberculosis H37Rv while the Egg Hatch Assay (EHA) was used for the anthelmintic test on eggs of Haemonchus contortus. Cytotoxicity was determined against Vero kidney cells while in vitro immune modulation via cytokine production was determined on activated macrophages. The minimum inhibitory concentration (MIC) values of the Psychotria capensis acetone extract and fractions ranged from 39 to 1,250 μg/ml with the crude extract and hexane fraction having the best MIC values (both 39 μg/ml). In the EHA, the inhibitory concentration (IC₅₀) ranged from 160 to 630 μg/ml with the hexane fraction having the best activity. The hexane and chloroform fractions were relatively non-toxic with LC₅₀ values of 290 and 248 μg/ml respectively, while the acetone crude extract (64 μg/ml) and n-butanol fraction (71 μg/ml) were moderately toxic. The SI values (LC₅₀/MIC) ranged from 0.1 to 7.4 with the hexane fraction having the highest value against M. smegmatis (7.4). The hexane fraction had the best dual anthelmintic and antimycobacterial activity. This fraction had the best NO inhibitory activity and was the least cytotoxic, indicating that its activity was not due to general metabolic toxicity, with 96.54% cell viability. Pro-inflammatory cytokines such as IL-12p70 were upregulated while IL-10 expression was inhibited by the extracts. Compounds were detected using GC-MS analysis, and in both the crude acetone extract and the hexane fraction was the diterpene neophytadiene, which has anti-inflammatory and antimicrobial activity. Finding alternative or complementary approaches to dealing with TB infections by, amongst other things, reducing the incidence of helminth infestations may lessen the burden of TB, contributing to slowing the spread of multi-drug resistance.

Pyrazole-Based Water-Soluble Dendrimer Nanoparticles as a Potential New Agent against Staphylococci

Although the antimicrobial potency of the pyrazole nucleus is widely reported, the antimicrobial effects of the 2-(4-bromo-3,5-diphenyl-pyrazol-1-yl)-ethanol (BBB4), found to be active against several other conditions, have never been investigated. Considering the worldwide need for new antimicrobial agents, we thought it noteworthy to assess the minimum inhibitory concentration (MICs) of BBB4 but, due to its scarce water-solubility, unequivocal determinations were tricky. To obtain more reliable MICs and to obtain a substance also potentially applicable in vivo, we recently prepared water-soluble, BBB4-loaded dendrimer nanoparticles (BBB4-G4K NPs), which proved to have physicochemical properties suitable for clinical application. Here, with the aim of developing a new antibacterial agent based on BBB4, the BBB4-G4K NPs were tested on several strains of different species of the Staphylococcus genus. Very low MICs (1.5–3.0 µM), 15.5–124.3-fold lower than those of the free BBB4, were observed against several isolates of S. aureus and S. epidermidis, the most pathogenic species of this genus, regardless of their resistance patterns to antibiotics. Aiming at hypothesizing a clinical use of BBB4-G4K NPs for staphylococcal skin infections, cytotoxicity experiments on human keratinocytes were performed; it was found that the nano-manipulated BBB4 released from BBB4-G4K NPs (LD₅₀ 138.6 µM) was 2.5-fold less cytotoxic than the untreated BBB4 (55.9 µM). Due to its physicochemical and biological properties, BBB4-G4K NPs could be considered as a promising novel therapeutic option against the very frequent staphylococcal skin infections.

Efficacy of Ursolic Acid-Enriched Water-Soluble and Not Cytotoxic Nanoparticles against Enterococci

Ursolic acid (UA), a pentacyclic triterpenoid acid found in many medicinal plants and aromas, is known for its antibacterial effects against multi-drug-resistant (MDR) Gram-positive bacteria, which seriously threaten human health. Unfortunately, UA water-insolubility, low bioavailability, and systemic toxicity limit the possibilities of its application in vivo. Consequently, the beneficial activities of UA observed in vitro lose their potential clinical relevance unless water-soluble, not cytotoxic UA formulations are developed. With a nano-technologic approach, we have recently prepared water-soluble UA-loaded dendrimer nanoparticles (UA-G4K NPs) non-cytotoxic on HeLa cells, with promising physicochemical properties for their clinical applications. In this work, with the aim of developing a new antibacterial agent based on UA, UA-G4K has been tested on different strains of the Enterococcus genus, including marine isolates, toward which UA-G4K has shown minimum inhibitory concentrations (MICs) very low (0.5-4.3 µM), regardless of their resistance to antibiotics. Time-kill experiments, in addition to confirming the previously reported bactericidal activity of UA against E. faecium, also established it for UA-G4K. Furthermore, cytotoxicity experiments on human keratinocytes revealed that nanomanipulation of UA significantly reduced the cytotoxicity of UA, providing UA-G4K NPs with very high LD₅₀ (96.4 µM) and selectivity indices, which were in the range 22.4-192.8, depending on the enterococcal strain tested. Due to its physicochemical and biological properties, UA-G4K could be seriously evaluated as a novel oral-administrable therapeutic option for tackling difficult-to-treat enterococcal infections.

Anthelmintic, antimycobacterial, antifungal, larvicidal and cytotoxic activities of acetone leaf extracts, fractions and isolated compounds from Ptaeroxylon obliquum (Rutaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Ptaeroxylon obliquum (Thunb.) Radlk, sneezewood, is a commonly used medicinal plant in South Africa for the treatment of parasitic infections in animals, tuberculosis (TB) and related symptoms, and other microbial infections.

AIM OF THE STUDY

In this study anthelmintic, antifungal, antimycobacterial, larvicidal and cytotoxic activities of the acetone leaf extract of P. obliquum, solvent-solvent derived fractions of the extract and isolated compounds (obliquumol and a mixture of lupeol and β-amyrin) were determined.

MATERIALS AND METHODS

The in vitro anthelmintic activity was tested against Haemonchus contortus ova and larvae using the egg hatch inhibition and larval development assays. The antifungal activity was investigated using a serial microplate dilution method against Aspergillus fumigatus, Cryptococcus neoformans and Candida albicans. Antimycobacterial activity was evaluated by a tetrazolium violet-based broth microdilution method against pathogenic Mycobacterium tuberculosis and Mycobacterium bovis. The larvicidal activity was evaluated against Aedes aegypti. Cytotoxicity was determined using human liver (C3A) and Vero African green monkey kidney cell lines.

RESULTS

Obliquumol (ptaeroxylinol acetate) was more effective than the crude acetone extract against H. contortus ova and larvae with an LC₅₀ of 95 μg/mL against the larvae. Obliquumol had very good antifungal activity with minimal inhibitory concentrations (MIC) values from 2 to 16 μg/mL. Lupeol and β-amyrin mixture also had good activity against C. neoformans and C. albicans with an MIC of 16 μg/mL against both fungi. The crude extract and fractions had average to weak antimycobacterial activity against the two pathogenic mycobacteria with MICs of 313-625 μg/mL for the extract and fractions tested. Obliquumol had good activity with an MIC of 63 μg/mL against pathogenic M. tuberculosis ATCC 27115. The acetone crude extract was toxic against Vero cells with an CC₅₀ of 14.2 μg/mL. Obliquumol and the mixture of lupeol and β-amyrin were not toxic against both Vero and C3A cells at the highest concentration tested of 200 μg/mL and had good selectivity index values against the opportunistic fungal pathogens. No tested samples had any larvicidal activity against A. aegypti at the concentrations tested.

CONCLUSION

The activity noted against H. contortus may support the ethnoveterinary use of this plant against animal parasites in South Africa although aqueous extracts were not active. The activity of obliquumol against opportunistic fungal pathogens was also promising. The cytotoxicity of the acetone leaf extract, however, raises concerns about the traditional use of P. obliquum to treat a wide range of diseases although if an aqueous extract is used the toxicity concern may not be relevant.

A Review of Ethnoveterinary Knowledge, Biological Activities and Secondary Metabolites of Medicinal Woody Plants Used for Managing Animal Health in South Africa

Globally, the use of ethnoveterinary medicine as remedies for animal health among different ethnic groups justify the need for a systematic exploration to enhance their potential. In addition, the increasing popularity and utilisation of woody plants remain common in traditional medicine, which may be attributed to their inherent benefits. The current review was aimed at analysing ethnoveterinary surveys, biological activities, and secondary metabolites/phytochemical profiles of the woody plants of South Africa. Eligible literature (period: 2000 to 2020) were retrieved from different databases such as Google Scholar, PubMed, Sabinet, and Science Direct. Based on the inclusion and exclusion criteria, 20 ethnoveterinary surveys were eligible and were subjected to further analysis. We identified 104 woody plant species from 44 plant families that are used in the treatment of different diseases in animals, particularly cattle (70%) and goats (20%). The most mentioned (with six citations) woody plants were Terminalia sericea Burch. ex DC and Ziziphus mucronata Willd., which were followed by plants with five (Cussonia spicata Thunb., Pterocarpus angolensis DC and Vachellia karroo (Hayne) Banfi & Galasso) or four (Acokanthera oppositifolia (Lam.) Codd, Cassia abbreviata Oliv., and Strychnos henningsii Gilg) individual mentions. The most dominant families were Fabaceae (19%), Apocynaceae (5.8%), Rubiaceae (5.8%), Anacardiaceae (4.8%), Combretaceae (4.8%), Euphorbiaceae (4.8%), Malvaceae (4.8%), Rhamnaceae (4.8%), and Celastraceae (3.8%). Bark (33%), leaves (29%), and roots (19%) were the plant parts dominantly used to prepare remedies for ethnoveterinary medicine. An estimated 20% of woody plants have been screened for antimicrobial, anthelmintic, antioxidant, and cytotoxicity effects. Phytochemical profiles established a rich pool of valuable secondary metabolites (phenolic, flavonoids and condensed tannins) that may be responsible for the exerted biological activities. Overall, the significant portion of woody plants lacking empirical evidence on their biological effects indicates a major knowledge gap that requires more research efforts.

Bactericidal Activity of Non-Cytotoxic Cationic Nanoparticles against Clinically and Environmentally Relevant Pseudomonas spp. Isolates

Difficult-to-treat bacterial infections caused by resistant human and plant pathogens severely afflict hospitals, and concern the agri-food sectors. Bacteria from the Pseudomonadaceae family, such as P. aeruginosa, P. putida, P. fluorescens, and P. straminea, can be responsible for severe nosocomial infections in humans. P. fragi is the major cause of dairy and meat spoilage, while P. syringae can infect a wide range of economically important plant species, including tobacco, kiwi, and tomato. Therefore, a cationic water-soluble lysine dendrimer (G5-PDK) was tested on several species of Pseudomonas genus. Interestingly, G5-PDK demonstrated variable minimum inhibitory concentrations (MICs), depending on their pigment production, on Pseudomonas aeruginosa (1.6-> 6.4 µM), MICs = 3.2-6.4 µM on P. putida clinical isolates producing pyoverdine, and very low MICs (0.2-1.6 µM) on strains that produced non-pigmented colonies. Time-kill experiments established the rapid bactericidal activity of G5-PDK. In the cytotoxicity experiments on human keratinocytes, after 4 h of treatment with G5-PDK at concentrations 16-500 × MIC, more than 80% of viable cells were observed, and after 24 h, the selectivity indices were maintained above the maximum value reported as acceptable. Due to its proven bactericidal potency and low cytotoxicity, G5-PDK should be seriously considered to counteract clinically and environmentally relevant Pseudomonas isolates.

Investigation of anthelmintic activity of the acetone extract and constituents of Typha capensis against animal parasitic Haemonchus contortus and free-living Caenorhabditis elegans

This study aimed to determine in vitro anthelmintic activity of plant extracts of eleven plant species used traditionally in South Africa to treat various disorders including symptoms related to nematode infections, and to isolate bioactive compounds from the most active plant extract. Crude plant extracts were tested on different life-cycle stages of Haemonchus contortus. The cytotoxicity of the most active extracts, fractions and compounds was evaluated on Vero cells and the most potent extract, fractions and compounds were tested for their ability to kill the parasitic H. contortus and the free-living nematode Caenorhabditis elegans. Typha capensis acetone extract had the strongest egg hatching inhibitory effect with an EC₅₀ of 184.94 μg/mL, and this extract also halted larval development of H. contortus with an EC₅₀ of 83.30 μg/mL compared to the positive control (albendazole) with an EC₅₀ of 2.66 μg/mL. Typha capensis crude extract and its butanol fraction had promising anthelmintic activity against both parasitic H. contortus and free-living C. elegans. Two compounds isolated from T. capensis, namely, isorhamnetin-3-O-β-D-glucoside and isorhamnetin 3-O-rutinoside, had antioxidant activity with IC₅₀ values of 3.16 μg/mL and 0.96 μg/mL respectively, and good anthelmintic activity against H. contortus with IC₅₀ values of 55.61 μg/mL and 145.17 μg/mL respectively. Identification of bioactive compounds from the T. capensis crude extract supports development of this extract as a complementary or alternative treatment against haemonchosis. However, further research is necessary to confirm the anthelmintic efficacy of the plant, including in vivo studies.

Chemical characterization and in vitro anthelmintic activity of Citrus bergamia Risso and Citrus X paradisii Macfad essential oil against Haemonchus contortus Kirby isolate

Haemonchus contortus, a blood-sucking parasite of small ruminants, produces very important economic losses in the productive sector. This abomasum parasite has become resistant to most commercial drugs worldwide, and alternatives to fight this problem are urgently needed. Essential oils (EO) are a complex mixture of volatile secondary metabolites, composed mainly by terpenoids and phenolic compounds, from plants that have several pharmacological properties, including anthelmintic activity. Particularly, citrus peel is a source of cold-pressed EO, where limonene is its major component, and can be used as an additional food component for ruminants. The aim of the present work was to determine the in vitro anthelmintic activity of EO from Citrus bergamia (EOB), C. x paradisii (EOG) and limonene against the benzimidazole-susceptible Kirby isolate of H. contortus, using the egg hatch test (EHT) and the exsheathed third stage larval motility test (XLMT) using a WMicroTracker equipment. Albendazole (ABZ) and monepantel (MON) were used as positive controls. The 50% inhibitory concentrations (IC₅₀) in XLMT were 8.77 and 13.88 µg/ml for EOB and EOG respectively, after an incubation of 72 h. An interesting observation on XLMT resulted when the positive controls were tested on the same plate, but in different well of the EOB. The volatile components of the EO significantly influenced (P < 0.05) the percentage of larval motility, reducing values from 66.9 to 19.6% for ABZ, and from 72.8 to 33.7% for MON, when comparing the activity of positive controls in a control plate without EO. The in vitro anthelmintic activity of EOB and EOG shows that they could be interesting candidates for nematode control. It is still necessary additional studies against the adult stage of H. contortus in efficacy trials in infected animals to validate their anthelmintic activity.

Differential Morphological, Structural and Biological Characteristics of Cysts in Heterodera Species in Korea

Morphological (cyst shape, color, and sizes [length (L), maximum width (W), volume and "a" (L/W)]), structural (vulvar cone slope angle [VCSA], surface wrinkle [VCSW], cyst wall thickness, composition, and texture) and biological characteristics (fecundity, hatching, and emergence [number of second-stage juveniles (J2) from a cyst]) in preceding Heterodera glycines (Hg), currently-recorded H. sojae (Hs) and H. trifolii (Ht) were examined by microscopy. Cysts were lemon-shaped, indicating the genus is Heterodera except for Hs that formed frequently globular cysts with significantly flatter VCSA (102.2°) with smooth VCSW than Hg (50.6°) and Ht (82.0°), but not genus Globodera because of the presence of vulvar cone in Hs. Ht was significantly larger in all morphological characteristics than Hg and Hs, suggesting Ht may be diagnosed differentially by cyst sizes and also host plant preferences. Hs showed smaller "a" value with more globular shape and stronger structures with more thickened and strengthened collagen-like texture of cyst wall than Hg and Ht. This suggests Hs may be diagnosed differently by structural characteristics from the others, especially Hg with similar cyst sizes. There were no significant differences in emergence (inoculum potential) among cyst nematodes due to the offset of fecundity and hatching rate; however, the inoculum potential of Hs may be not so persistent as Hg and Ht in fields because of its lower fecundity and higher hatching rate (causing rapid inoculum loss) than the others. These characteristics of cysts provide information useful for simple and differential diagnoses and reliable management of cyst nematodes.

Assessment of in vitro anthelmintic activity and bio-guided chemical analysis of BRS Boyrá pineapple leaf extracts

Species of the Bromeliaceae are known for their pharmacological actions, including anthelmintic effects. The aim of this study was to investigate the in vitro anthelmintic activity of extracts and fractions of BRS Boyrá pineapple leaf against the eggs and infective larvae of gastrointestinal nematodes (Trichostrongylidae) of goats and to identify the compounds involved in this activity. Crude methanol, hexane, dichloromethane, ethyl acetate and residual hydromethanol extracts were investigated by quantitative analysis of phenolic and flavonoid contents, antioxidant activity, anthelmintic activity against gastrointestinal nematodes of goats. The extracts were submitted to chromatographic methods for substance isolation and spectrometric techniques to identify their structures. The anthelmintic activity was performed by in vitro assays with eggs and larvae of nematodes obtained from naturally infected donor goats. All extracts contained phenolic (2.22-14.12 g of gallic acid equivalent per 100 g of dry extract) and flavonoid compounds (0.13-1.45 g of quercetin equivalent per 100 g of dry extract). Bio-guided fractionation of the BRS Boyrá pineapple leaves showed high antioxidant activity (EC₅₀ for DPPH of 2.16-21.38 mg mL^-1 and inhibition of co-oxidation of β-carotene of 36.40-74.86%) and anthelmintic activity (15.69-100% inhibition of egg hatching). The ethyl acetate extract exhibited greatest activity in all assays. Through chromatographic column analysis it was possible to isolate three substances: β-sitosterol and stigmasterol mixture in dichloromethane and hexane extracts, identified by NMR and p-coumaric acid in the ethyl acetate extract, identified by HPLC-DAD. The isolated p-coumaric acid exhibited high ovicidal effect against goat gastrointestinal nematodes (IC₅₀: 0.12 mg mL^-1) and can be considered the active substance of the ethyl acetate extract. This study revealed for the first time that the pineapple BRS Boyrá possesses inhibitory activity against gastrointestinal nematodes (Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp.), and that p-coumaric acid is an important bioactive.

Validation of in-vitro bioassay methods: Application in herbal drug research

This present review described the validation method of in-vitro bioassay for its application in herbal drug research. Seven sequencing steps that can be taken for performing a valid bioassay include: literature survey, sample stability evaluation, Biosystem performance testing, Sample performance evaluation, determination of 50% effective concentration or cytotoxic concentrations, selective index evaluation, and determination of accurate relative potency of sample. Detailed methods and acceptance criteria for each step are described herein. Method calculations of the relative potency of sample using European Pharmacopeia 10.0, 5.3 (2020) were recommended instead of using United States Pharmacopeia 42 (2019). For having reliable data and conclusions, all methods (chemical and bioassay) need to be first validated before any data collection. Absence of any validation method may results in incorrect conclusions and bias.

Review: Southern African medicinal plants used as blood purifiers

ETHNOPHARMALOGICAL RELEVANCE

Blood purification practices, also referred to as blood cleansing or detoxification, is an ancient concept which is widespread amongst African traditional medicine, but for which no modern scientific basis exists. There prevails considerable ambiguity in defining what a blood purifier is.

AIM OF THE STUDY

The purpose of this review is to firstly define what a blood purifier is in the context of African traditional medicine and compare to other cultural and westernized interpretations. Thereafter, this study identifies traditionally used medicinal plants used as blood purifiers in southern Africa and correlates these species to scientific studies, which may support evidence for these "blood purifying plant species".

MATERIALS AND METHODS

Ethnobotanical books and review articles were used to identify medicinal plants used for blood purification. Databases such as Scopus, ScienceDirect, PubMed and Google Scholar were used to source scientific articles. An evaluation was made to try correlate traditional use to scientific value of the plant species.

RESULTS

One hundred and fifty nine plant species have been documented as traditional remedies for blood purification. Most of the plant species have some pharmacological activity, however, very little link to the traditional use for blood purification. There has been some justification of the link between blood purification and the use as an antimicrobial and this has been explored in many of the plant species identified as blood purifiers. Other pharmacological studies specifically pertaining to the blood require further attention.

CONCLUSION

Irrespective of the ambiguity of interpretation, medicinal plants used to "cleanse the blood", play an important holistic role in traditional medicine and this review with recommendations for further study provides some value of exploring this theme in the future.

Antihelminthic action of the Anethum graveolens essential oil on Haemonchus contortus eggs and larvae

Gastrointestinal nematodes are responsible for great economic losses in sheep raising, and their control has long been carried out almost exclusively by the administration of anthelmintics, which have led to serious resistance problems. In the search for alternative control measures, phytotherapic research is highlighted. The aim of this study was to evaluate the action of Anethum graveolens (dill) essential oil on different stages of Haemonchus contortus life cycle, as well its cytotoxicity MDBK (Madin-Darby bovine kidney) cells. H. contortus larvae and eggs were obtained from infected sheep feces, and essential oil extracted from plant seeds through the Clevenger apparatus. 9.4, 4.7, 2.35, 1.17. 0.58 and 0.29 mg/mL concentrations were evaluated. The Egg Hatch Inhibition (HI), Larval Development Inhibition (LDI) and Larval Migration Inhibition (LMI) techniques were used. Thybendazole 0.025 mg/mL in HI and Levamisole 0.02 mg/mL in the LDI and LMI tests were used as positive controls, while distilled water and a Tween 80 solution were used as positive negative controls. The inhibition results obtained for the highest oil concentration were: HI 100%, LDI 98.58% and LMI 63.7%, differing (𝑝 <0.05) from negative controls. Main A. graveolens oil components present in 95.93% of the total oil were Dihydrocarvone (39.1%), Carvone (22.24%), D-Limonene (16.84%), Apiol (10.49%) and Trans-dihydrocarvone (7.26%). Minimum A. graveolens essential oil concentrations required to inhibit 50% (IC50) of egg hatching, larval development and larval migration were 0.006 mg/mL, 2.536 mg/mL and 3.963 mg/mL, respectively. Cell viability in MDBK (Madin-Darby bovine kidney) cells, when incubated with A. graveolens essential oil, was 86% for the highest (9.4 mg/mL) and 99% for the lowest concentration (0.29 mg/mL). A. graveolens essential oil, according to the results obtained in this study, is a promising alternative in sheep gastrointestinal nematode control.

Addition of a surfactant to water increases the acaricidal activity of extracts of some plant species used to control ticks by Zimbabwean smallholder farmers

Background

Many studies have revealed that bioactive compounds for different indications are not extracted from plants with water, the only extractant practically available to rural communities. We compared the acaricidal activity of acetone extracts of 13 species used traditionally to protect cattle against ticks. We also investigated if the extraction of biologically active compounds against Rhipicephalus (Boophilus) decoloratus ticks could be enhanced by adding a liquid soap that is locally available to smallholder farmers.

Methods

A total of 13 plant species selected based on reported traditional use in Zimbabwe, were dried and finely ground before extraction with water, or water plus a surfactant, or acetone. The adapted Shaw Larval Immersion Test (SLIT) method was used to determine the activity of acetone and crude water extracts with or without liquid soap against the tick larvae. The activity of four fractions of crude acetone extracts (extracted using solvents of different polarity), of the most active plant species, Maerua edulis (tuber and leaf) was also compared to identify the most active fraction.

Results

Aqueous plant extracts were not toxic to ticks, but the addition of 1% liquid soap as a surfactant increased mortality of the R. (B) decoloratus larvae significantly. With the Maerua edulis tuber extract, the efficacy of the 1% liquid soap was comparable to that of the amitraz based commercial synthetic acaricide. The use of acetone as an extractant, also increased the mortality of the tick larvae in all the plant species. With M. edulis (tuber and leaf), Monadenium lugardae and Kleinia sp. acetone extracts, the activity was comparable to that of the positive control (a commercially available amitraz-based synthetic acaricide). The non-polar fractions of the acetone extract of leaf and tuber of M. edulis caused up to 100% mortality. This indicates that non-polar to intermediate polarity compounds are responsible for the acaricidal activity.

Conclusion

Organic solvents such as acetone extracted active compounds but water did not. By adding commonly available dishwashing soap to water active compounds were extracted leading to a high acaricidal activity of the plant extracts. In some cases, it was as active as non-polar extracts and a synthetic commercial acaricide (positive control). This approach makes it possible for the smallholder farmers and traditional healers to extract biologically active compounds from plants by using water.

Ultrastructure changes induced by the phloroglucinol derivative agrimol G isolated from Leucosidea sericea in Haemonchus contortus

Plant extracts used for the treatment of helminth infections in sheep are an alternative to chemical anthelmintic drugs. Previous studies have reported the anthelmintic activity of acetone leaf extracts of Leucosidea sericea. For this study, we evaluate the ultrastructure changes induced by the acetone leaf extract of L. sericea and the component agrimol G (AG) that was isolated for the first time on adult haemonchus parasites. Adult haemonchus parasites harvested from sheep were incubated with the plant extract and AG for 3 h and evaluated by both scanning and transmission electron microscopy in comparison and in combination with albendazole or ivermectin. In all cases the method of evaluation shows ultrastructural changes, with albendazole inducing mitochondrial damage and ivermectin inducing muscle degeneration, both as previously described. Incubation with the plant extract and AG resulted in the formation of numerous non-membrane bound multi-vesicular like bodies and evenly spread disruptions/erosion in the epicuticle. Combining AG with ivermectin or albendazole resulted in an absence of effect of AG. Based on the structural changes induced by AG, together with the absence of an effect in combination with ivermectin and albendazole would suggest a disrupted microtubular network. The latter does however require biochemical confirmation.

Anthelmintic activity of plants against gastrointestinal nematodes of goats: a review

The gastrointestinal nematodes (GIN) stand out as an important cause of disease in small ruminant, especially on goat farm. Widespread resistance to synthetic anthelminthics has stimulated the research for alternative strategies of parasite control, including the use of medicinal plants. The present work summarizes the in vitro and in vivo studies of plants with activity against GIN of goats, focusing on the description of chemical constituents related to this effect. This review retrieved 56 scientific articles from 2008 to 2018 describing more than 100 different plant species. The most frequently investigated family was Fabaceae (30.7%). Most in vitro studies on the activity of plant extracts and fractions were carried out with of free-living stages nematodes. In vivo studies were conducted mainly with the use of plants in animal feed and generally showed lower effectiveness compared to in vitro assays. The main plant secondary metabolites associated with anthelmintic effect are condensed tannins, saponin and flavonoids. However, the studies with compounds isolated from plants and elucidation of their mechanisms of action are scarce. Herbal medicines are thought to be promising sources for the development of effective anthelmintic agents.

In vitro anthelmintic activity and safety of different plant species against the ovine gastrointestinal nematode Teladorsagia circumcincta

The present study was conducted to evaluate the in vitro anthelmintic activity and safety of methanolic and aqueous extracts of 9 plants against the ovine GIN Teladorsagia circumcincta. Initially the ovicidal efficacy of all extracts was tested at 50 mg/ml and at 1%, this last concentration for the methanolic extract of Elettaria cardamomum, by the Egg Hatch Assay. In those extracts with efficacy higher than 95%, the effective concentration required to inhibit 50% of egg hatching (EC₅₀) and their cytotoxicity, as the lethal dose 50 (LC₅₀), was also measured. The aqueous extracts of Aesculus hippocastanum, Isatis tinctoria, Chelidonium majus, E. cardamomum and Sisymbrium irio, with EC₅₀ values ranging 1.30-2.88 mg/ml, and the aqueous extract of Jasminum polyanthum with a value of 6.41 mg/ml, showed the highest activities. The aqueous extract of J. polyanthum was the safest extract, followed by methanolic extract of E. cardamomum and aqueous extract of S. irio, all of them with a Selective Index higher than 1. According to our results, there is no correlation between the amount of total phenols or total tannins with the anthelmintic activity of the plants tested. Although results need to be interpreted with caution, as in vitro activity may not automatically translate into in vivo efficacy, those extracts with SI equal or higher than 1 and EC₅₀ equal or lower than 6 mg/ml, could be taken into account for being used subsequently as feed or food additives in infected sheep.

In vitro ovicidal effect of a Senecio brasiliensis extract and its fractions on Haemonchus contortus

Background

Haemonchosis affects sheep husbandry and its treatment is often compromised due to the development of anthelminthic resistance. Plant-derived bioactive compounds have been studied as alternative to control Haemonchus contortus. The objective of this study was to evaluate the effect of Senecio brasiliensis extracts on H. contortus egg hatching and infective larvae migration.

Results

The aqueous extract from dried and fresh plant and alkaloid-enriched fraction of the previously dried leaves of S. brasiliensis inhibited H. contortus egg hatching. The main plant compound in alkaloid fraction was integerrimine, a pyrrolizidine alkaloid (PA). However, the aqueous extract from dried plant displayed higher efficacy when compared to their alkaloid enriched or non-polar fractions, meaning that, although PAs contributed to the ovicidal effect, other compounds in the plant can also contribute to their effect. Furthermore, the aqueous extract from dried plant also had higher efficacy than aqueous extract from fresh plant in larvae migration inhibition. Finally, extract from dried plant presented low in vitro cytotoxic effect.

Conclusion

Taken together our results suggest a good anthelmintic effect of S. brasiliensis, especially when aqueous extract is prepared from dried plant. Further in vivo studies should be performed focused on forms of administration of this extract in rearing sheep.

In vitro anthelmintic effects of Bridelia ferruginea, Combretum glutinosum, and Mitragyna inermis leaf extracts on Haemonchus contortus, an abomasal nematode of small ruminants

Gastrointestinal nematodes remain a major constraint on the health, welfare, and production of small ruminants. This study was conducted to evaluate three plant extracts (from Bridelia ferruginea, Combretum glutinosum, and Mitragyna inermis) as effective remedies against gastrointestinal parasites of small ruminants. Phytochemical screening was conducted on the plant leaves, and the potential anthelmintic properties of these plants were tested in vitro on Haemonchus contortus using the egg hatch, larval migration, and adult worm motility assays. The phytochemical screening of the leaves revealed the presence of several bioactive components in all the plants. The number of eggs that hatched was reduced in a concentration-dependent manner (p < 0.01) upon treatment with the methanol extract of B. ferruginea and the acetone extracts of C. glutinosum and M. inermis. The inhibitory effect of the acetone extract of B. ferruginea and the methanol extracts of C. glutinosum and M. inermis was not concentration-dependent (p > 0.05). There was a significant difference (p < 0.05) in the reduction in larval migration between the lowest concentrations (75 to 150 μg/mL) and the highest concentrations (300 to 1200 μg/mL) of plant extracts. The ability of plant extracts to affect the mobility of the adult worms was not concentration-dependent (p > 0.05); however, it was dependent on the time of incubation (p < 0.01). At the highest concentration (2400 μg/mL), all adult worms were motionless after 24 h of exposure, while at the lowest concentration (< 150 μg/mL), this occurred after 48 h of exposure. M. inermis and C. glutinosum extracts were more effective than B. ferruginea extracts (p < 0.05). Overall, these results suggest that these plants used by small-scale farmers possess antiparasitic properties useful for helminthiasis control. However, the effects of the plants remain to be confirmed via in vivo assays and toxicity tests in further studies.

In Vitro Anthelmintic Activity of Four Plant-Derived Compounds against Sheep Gastrointestinal Nematodes

By using the egg hatch test (EHT), the larval development test (LDT) and the larval mortality/paralysis test (LMT), the in vitro anthelmintic activity on sheep gastrointestinal strongyles (GIS) of four plant-derived pure compounds, mangiferin (at 0.25%, 0.125% and 0.0625%), rutin (at 1%, 0.75%, 0.5%), quercetin (at 1%), and β-sitosterol (at 1%, 0.75%, 0.5%), was investigated. For comparison, untreated and treated (0.1% thiabendazole, 0.1% TBZ) controls were used. Six repetitions were made throughout the experiment. Data were statistically elaborated using the χ² test. The concentration able to inhibit the development of the 50% of L1s to L3s and causing the mortality of the 50% of L3s (EC50) was also calculated. L3s recovered from untreated Petri dishes were identified at the genus level. In EHT, all tested compounds at all concentrations significantly (p < 0.01) inhibited the hatch of the eggs when compared to the untreated controls, but none of them was as effective as 0.1% TBZ. In LDT, rutin (at 1%, 0.75% and 0.5%), mangiferin (at 0.25% and 0.125%), β-sitosterol (at 1%) and 0.1% TBZ completely prevented the larval development from L1 to L3 in respect to the untreated controls (p < 0.01). In LMT, all tested compounds significantly (p < 0.01) increased the death of L3s compared to the untreated controls, except for β-sitosterol at 0.5%. However, only rutin at all concentrations and 0.25% and 0.125% mangiferin were as effective as 0.1% TBZ. Haemonchus, Trichostrongylus, Chabertia and Teladorsagia/Ostertagia GIS genera, were identified.

In vitro ovicidal and larvicidal activities of some saponins and flavonoids against parasitic nematodes of goats

This study assessed the anthelmintic activity of plant-derived compounds against gastrointestinal nematodes of goats using the egg hatch and larval motility assays. The compounds tested were saponins (digitonin and aescin) and their respective sapogenins (aglycones), hecogenin acetate and flavonoids (catechin, hesperidin, isocordoin and a mixture of isocordoin and cordoin). Additionally, cytotoxicity of active substances was analysed on Vero cell through 3-4,5-dimethylthiazol-2-yl,2,5diphenyltetrazolium bromide (MTT) and propidium iodide (PI) tests. Significant reduction on the egg hatching (P 90%). Nevertheless, higher cytotoxicity was observed in the MTT assay, with IC50 of 0.20 mg mL-1 (aescin) and 0.0074 mg mL-1 (digitonin). Aescin and digitonin have a pronounced in vitro anthelmintic effect and the glycone portion of these saponins plays an important role in this activity.

In vitro effects of aqueous extract from Maytenus senegalensis (Lam.) Exell stem bark on egg hatching, larval migration and adult worms of Haemonchus contortus

Background

Maytenus senegalensis is a common shrub which is scattered in tropical Africa. Different parts of this plant have been reported to be useful in traditional medicine against gastrointestinal disorders and intestinal worms. This study evaluated the anthelmintic activity of the aqueous stem bark extract of M. senegalensis using egg hatch assay (EHA), larval migration inhibition assay (LMIA) and adult worms’ motility inhibition assay (AMIA).

Results

On EHA, the extract concentrations tested resulted in a significant (p < 0.01) inhibition of egg hatching in concentration-dependent manner and ranged between 31.86% at 75 μg.mL^− 1 to 54.92% at 2400 μg.mL^− 1 after a 48 h post-exposure with eggs. For the LMI assays, the aqueous extract of M. senegalensis showed a significant (p < 0.05) inhibition of larval migration in a concentration-dependent manner. The highest concentration used (2400 μg.mL^− 1) showed a 37.77% inhibition. The use of polyvinyl polypyrrolidone (PVPP) indicated that tannins and flavonoids were partly involved in the effect since the larval migration was inhibited by 15.5%, but other biochemical compounds were also implicated. On AMIA, M. senegalensis was associated with a reduced worm motility after a 24 h post exposure compared to phosphate buffered saline as control (p < 0.05). By this time 66.66% of the worms’ were found immotile or dead in the wells containing plant extract at 2400 μg.mL^− 1. The Phytochemical analysis of aqueous extract of M. senegalensis by HPLC-ESI-MSⁿ detected the presence of proanthocyanidins (20%) and flavonoids (> 50%).

Conclusions

These in vitro results suggest the presence of some anthelmintic properties in M. senegalensis extract, which is traditionally used by small farmers in west and central Africa. These effects may be due to the flavonoids and proanthocyanidins present in the extract and need to be studied under in vivo conditions.

In vitro Anthelmintic Activity of Two Aloe-derived Active Principles against Sheep Gastrointestinal Nematodes

The in vitro anthelmintic activity on sheep gastrointestinal strongyle (GIS) eggs and larvae of 0.5% aloin and 0.1% aloe-emodin was investigated. From fresh faecal samples collected by ewes naturally infected by Haemonchus, Trichostrongylus and Teladorsagia nematodes, GIS eggs were isolated and cultivated in Petri dishes (100 eggs/dish). For the in vitro evaluation of the anthelmintic activity of tested compounds, the Egg hatch test (EHT), the Larval development test (LDT) and the Larval mortality/paralysis test (LMT) were used. In each assay, the activity of tested compounds was compared to untreated and treated (0.1% thiabendazole, TBZ) controls. Six repetitions were made through the experiment. Obtained data were statistically elaborated using the X2 test. In EHT, 0.5% aloin gave highly significantly different (P<0.01) results from the untreated controls. In LDT, both 0.1% aloe-emodin and 0.5% aloin almost completely prevented the larval development from L1 to L3, showing no significant differences (P<0.01) when compared to TBZ. In LMT, larval mortality observed in 0.5% aloin treated plates was significantly higher (P<0.01) than that observed in TBZ treated controls. These results show the in vitro anthelmintic properties on sheep GIS of the examined plant secondary metabolites. In LDT and/or LMT, the activity of 0.5% aloin and 0.1% aloe-emodin was comparable to or higher than that of the reference drug.

In vitro anthelmintic and cytotoxic activities of extracts of Persea willdenovii Kosterm (Lauraceae)

This study describes the effects of extracts and fractions of Persea willdenovii leaves against goat gastrointestinal nematodes and their cytotoxicity on Vero cells. The in vitro ovicidal and larvicidal activities of the crude ethanolic, hexane, ethyl acetate (EAE), butanolic and residual hydroethanolic extracts were assessed through the inhibition of egg hatching and larval motility assays. The most active extract (EAE) was then fractionated by chromatography in an open column containing silica gel, to furnish six fractions (Fr1–Fr6), which were also tested. The cytotoxicity of active extracts and fractions was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue exclusion assay. The EAE and two fractions (Fr1 and Fr2) showed inhibitory activity in the egg hatching of gastrointestinal nematodes of goats in a concentration-dependent manner. The effective concentrations for 50% inhibition (EC50) of egg hatching were 2.3, 0.12 and 2.94 mg/ml for EAE, Fr1 and Fr2, respectively. All extracts and fractions were not effective in inhibiting 50% of motility of infective larvae. EAE and Fr2 had IC50 values (50% inhibitory concentration) of 4.95 and 2.66 mg/ml, respectively. Fr1 showed a slight cytotoxic effect (cellular inviability <30%) only after 48 h of treatment (MTT test). Gas chromatography–mass spectrometry (GC–MS) analysis showed the presence of six fatty acid ethyl esters, a fatty acid methyl ester and a long-chain ketone in the most active fraction. These constituents identified in P. willdenovii can be related to the high ovicidal activity and relatively non-toxic effect of the extracts.

The use of <i>Lespedeza cuneata</i> for natural control of gastrointestinal nematodes in Merino sheep

Lespedeza cuneata (poorman’s lucerne; sericea lespedeza), a tannin-rich perennial legume, was offered as hay to dry Merino ewes in a confined feeding experiment to evaluate the effect on the level of gastrointestinal parasite infection in sheep. Medicago sativa (a low tannin containing perennial legume) was used as the control treatment. Parameters faecal egg count (FEC), FAMACHA^© scores and rectal temperatures were used. FECs were substantially lower (p = 0.05) in the Lespedeza group after 35 days, together with a trend of higher rectal temperatures, compared with the Medicago group. Although non-significant (p > 0.05), the higher rectal temperatures suggested a lower level of anaemia in the sheep on the Lespedeza ration and, therefore, a lower parasite-worm burden. However, FAMACHA^© scores showed no significant (p > 0.05) differences between treatments despite the differences in FEC that were recorded, indicating that host homeostasis was possibly mediated by improved nutrition as a result of the high protein content of both experimental diets.

The antibacterial activity of extracts of nine plant species with good activity against Escherichia coli against five other bacteria and cytotoxicity of extracts

Background

The development of antibiotic resistant bacteria stems from a number of factors, including inappropriate use of antibiotics in human and animal health and their prolonged use as growth promoters at sub-clinical doses in poultry and livestock production. We were interested in investigating plants that could be useful in protecting humans or animals against diarrhoea. We decided to work on extracts of nine plant species with good activity against Escherichia coli based on earlier work in the Phytomedicine Programme. Leaves of nine medicinal plant species with high antibacterial activity against Escherichia coli were extracted with acetone and their minimal inhibitory concentration (MIC) values determined using a microplate serial dilution technique against Gram-positive (Staphylococcus aureus, Enterococcus faecalis and Bacillus cereus) and Gram-negative (Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa) bacteria. Bioautography was used to determine the number of bioactive compounds in each extract. In vitro safety of the extracts was determined using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide reduction assay on Vero cells.

Results

The extracts were active against all the pathogens with average MICs ranging from 0.02 to 0.52 mg/ml. As expected E. coli was relatively sensitive, while E. faecalis and S. Typhimurium were more resistant to the extracts (average MICs of 0.28 mg/ml and 0.22 mg/ml respectively). Cremaspora triflora and Maesa lanceolata leaf extracts had higher activity than the other extracts against Gram-positive and Gram-negative pathogens with mean MICs of 0.07 mg/ml and 0.09 mg/ml respectively. Extracts of Maesa lanceolata and Hypericum roeperianum had the highest total antibacterial activity (TAA) at 1417 and 963 ml/g respectively. All extracts with the exception of that of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea had relatively low cytotoxicity with LC₅₀ > 20 μg/ml. Cremaspora triflora had the best selectivity index (SI) against S. aureus and E. coli of 2.87 and 1.15 respectively. Hypericum roeperianum had a SI of 1.10 against B. cereus. Bioautography revealed 1–6 visible antimicrobial compounds that were generally non-polar.

Conclusions

There was a weak positive, but statistically non-significant correlation between the potency of the extracts and their cytotoxicity (R = 0.45, ρ > 0.05). The activity of the extracts on the test bacteria was in some cases not correlated with cytotoxicity, as shown by selectivity indices >1. This means that cellular toxicity was probably not due to compounds with antibacterial activity. Some of the extracts had a good potential for therapeutic use against the bacterial pathogens or for application in treating diarhoea. It does not appear that activity against E. coli is a good predictor of activity against Gram-negative rather than Gram-positive bacteria. Further investigation is in progress on C. triflora and H. roeperianum, both of which had promising activities and potential safety based on cytotoxicity.

Anthelmintic activity of acetone extracts from South African plants used on egg hatching of <I>Haemonchus contortus</I>

The nematode, Haemonchus contortus, is responsible for major economic losses in the livestock industry. The management of parasites such as H. contortus has been through the use of synthetic parasiticides. This has resulted in the presence of residues in meat and milk, which affects food safety. The development of resistance to available anthelmintics coupled with their high cost has further complicated matters. This has led to the investigation of alternative methods to manage nematodes, including the use of plants and plant extracts as a potential source of novel anthelmintics. Acetone extracts were prepared from 15 South African plant species and their anthelmintic activity determined using the egg hatch assay (EHA). The leaf extract of Cleome gynandra had the best inhibitory activity (68% ± 3%) at a concentration of 2.5 mg/mL, followed by the stem extract of Maerua angolensis (65% ± 5%). The extracts had a relatively low toxicity on Vero cells determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide) cellular assay.

Evaluation of anthelmintic activity of biologically synthesized silver nanoparticles against the gastrointestinal nematode, Haemonchus contortus

The present study focuses on the in vitro anthelmintic activity of silver nanoparticles (AgNPs) synthesized using the aqueous extract of Azadirachta indica against Haemonchus contortus. The synthesized AgNPs were characterized by ultraviolet-visible (UV-Vis) spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) studies. The UV-Vis spectrum exhibited a sharp peak at 420 nm, which was validated by electron microscopy, indicating the preparation of spherical nanoparticles measuring 15-25 nm in size. The in vitro study was based on an egg hatch assay (EHA) and adult motility inhibition assays. Six concentrations of AgNPs were used for EHA, ranging from 0.00001 to 1.0 μg/ml, and a range of 1-25 μg/ml was used for adult worms. The highest concentration induced 85 ± 2.89% egg hatch inhibition. The IC50 value for EHA was 0.001 μg/ml, whereas in vitro adult H. contortus motility inhibition was produced at 7.89 μg/ml (LC50). The effectiveness of A. indica leaf extract (aqueous) was also evaluated, which showed an IC50 value for EHA of 115.67 μg/ml, while the LC50 against adult H. contortus was 588.54 μg/ml. The overall findings of the present study show that the experimental plant extract contains reducing properties for the synthesis of AgNPs which, in turn, showed potent anthelmintic properties. This is the first report where AgNPs have been tested for their anthelmintic properties in an in vitro model.

The efficacy and safety of nine South African medicinal plants in controlling Bacillus anthracis Sterne vaccine strain

BACKGROUND

Anthrax is a zoonotic disease caused by Bacillus anthracis, a Gram-positive spore-forming bacterium. The presence of the bacteria and the toxins in the blood of infected hosts trigger a cascade of pathological events leading to death. Nine medicinal plants with good activities against other bacteria were selected to determine their in vitro antibacterial activity against Bacillus anthracis Sterne strain. The cytotoxicity of the extracts on Vero kidney cells was also determined.

RESULTS

The minimum inhibitory concentration (MIC) values of the extracts against Bacillus anthracis Sterne strain ranged from 0.02 to 0.31 mg/ml. Excellent MIC values were observed for the following plant species: Maesa lanceolata (0.02 mg/ml), Bolusanthus speciosus, Hypericum roeperianum, Morus mesozygia (0.04 mg/ml) and Pittosporum viridiflorum (0.08 mg/ml). The total antibacterial activity of the extracts ranged from 92 to 5562 ml/g. Total activity presents the volume to which the extract from 1 g of plant material can be diluted and still inhibit microbial growth. Maesa lanceolata and Hypericum roeperianum had the highest total activity with values of 5562 and 2999 ml/g respectively. The extracts of Calpurnia aurea had the lowest total activity (92 ml/g). The cytotoxicity determined on Vero cells indicated that most of the extracts were relatively non-toxic compared to doxorubicin (LC50 8.3 ± 1.76 μg/ml), except for the extracts of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea with LC50 values at 2.38 ± 0.25, 5.20 ± 0.24 and 13 ± 2.26 μg/ml respectively. The selectivity index (SI) ranged from 0.02 to 1.66. Hypericum roeperianum had the best selectivity index, (SI = 1.66) and Elaeodendron croceum had lowest value (SI = 0.02).

CONCLUSIONS

The crude acetone extracts of the selected plant species had promising antibacterial activity against Bacillus anthracis. Maesa lanceolata extracts could be useful as a disinfectant and Hypericum roeperianum could be useful to protect animals based on its high total activity and selectivity index. Further investigation of these plant extracts may lead to the development of new therapeutic agents to protect humans or animals against anthrax.

The antibacterial activity, antioxidant activity and selectivity index of leaf extracts of thirteen South African tree species used in ethnoveterinary medicine to treat helminth infections

BACKGROUND

Diseases caused by bacteria remain a major challenge globally and particularly in sub-Saharan Africa. The plants used in this study have been used in South Africa to treat helminth infections in livestock and humans. In a previous study we found a correlation between antifungal and anthelmintic activity in some cases. In this study we examined other potential uses of these thirteen plant species by determining the antibacterial and antioxidant activity of the leaf acetone extracts.The antibacterial activity was determined by using a serial microdilution method against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis. Bioautography was used to determine the number of antibacterial compounds. The antioxidant activity was determined using the ABTS and DPPH methods.

RESULTS

Maesa lanceolata and Leucosidea sericea with an MIC of 0.02 mg/ml had excellent antibacterial activity against Enterococcus faecalis and Pseudomonas aeruginosa. There was a poor correlation between antioxidant activity and antibacterial activity with R2 = 0.143. This is because antibacterial activity is mainly related to non-polar compounds and antioxidant activity to polar compounds. Maesa lanceolata extracts had a low cytotoxicity with a selectivity index of 5.2, 2.6, 2.6 and 1.3 for P. aeruginosa, E. faecalis, E. coli and S. aureus respectively. Strychnos mitis extracts had a therapeutic index of 1.1 for E. coli.

CONCLUSIONS

This study shows that plant extracts of some species used in ethnoveterinary medicine as anthelmintic may also have excellent antibacterial activity.