Anti-biofilm, antibacterial, and anti-quorum sensing activities of selected South African plants traditionally used to treat diarrhoea

DATA AVAILABILITY : The original data can be obtained from the corresponding author upon request.The development of resistance of microorganisms to conventional antibiotics is a major global health concern; hence, there is an increasing interest in medicinal plants as a therapeutic option. This study aimed to evaluate the antibacterial, anti-biofilm, and anti-quorum activities of crude extracts prepared using various solvents of nine indigenous South African plants used locally for the treatment of diarrhoea. The minimum inhibitory concentration (MIC) was determined using the broth microdilution method and the crystal violet assay was used to test the anti-biofilm activity of the extracts against a panel of bacteria. Anti-quorum sensing activity of the extracts was assessed via inhibition of violacein production in Chromobacterium violaceum ATCC 12472. Preliminary screening of extracts against E. coli ATCC 25922 revealed that the acetone extracts had significant activity, with MIC values ranging from 0.04 to 0.63 mg/mL. Further screening against a panel of bacterial pathogens showed that the acetone extract of Bauhinia bowkeri was the most active with MIC of 0.01 mg/mL against Salmonella enteritidis, followed by Searsia lancea with MIC of 0.03 mg/mL against Bacillus cereus. All the plant extracts prevented the attachment of biofilms by more than 50% against at least one of the tested bacteria. However, only the mature biofilm of B. cereus was susceptible to the extracts, with 98.22% eradication by Searsia pendulina extract. The minimum quorum sensing inhibitory concentration of the extracts ranged from 0.08 to 0.32 mg/mL with S. lancea having the most significant activity. The extract of S. lancea had the best violacein production inhibitory activity with IC50 value of 0.17 mg/mL. Overall, the results obtained indicate that acetone extracts of S. leptodictya, S. lancea, S. batophylla, S. pendulina, B. galpinii, and B. bowkeri possess antibacterial and anti-biofilm activities and can modulate quorum sensing through the inhibition of violacein production. Therefore, these results signify the potential of the selected plant extracts in treating diarrhoea through inhibition of bacterial growth, biofilm formation inhibition, and quorum sensing antagonism, supporting their medicinal use.The World Academy of Science (NRFTWAS), South Africa, the University of Pretoria, the DAAD and the National Research Foundation (South Africa).http://www.hindawi.com/journals/ecamam2023Paraclinical Science

Extractives from Artemisia afra with anti-bacterial and anti-fungal properties

SUPPLEMENTARY MATERIAL : TABLE S1: 1H ( H; J, Hz) NMR (400 MHZ) data for compounds A–H in CDCl3, MeOD and DMSO; TANLE S2: 13C ( c) (100.6 MHz) NMR data for compounds A–H in CDCl3, MeOD and DMSO and S2, FIGURES SA.1–SH.68: Spectral data for compounds (A–H).Secondary metabolites were isolated using chromatographic techniques after being extracted sequentially from the roots of Artemisia afra using organic solvents such as ethanol, ethyl acetate, dichloromethane, and n-hexane. The isolated compounds were evaluated for anti-fungal, anti-bacterial, and cytotoxicity activities. Spectroscopic techniques, including Nuclear Magnetic Resonance (NMR), Fourier transform infrared (FTIR), and liquid chromatography–mass spectrometry (LC-MS), were used to elucidate the structures of the isolated compounds. The phytochemical investigation of A. afra led to the isolation of eight (A–H) compounds which were identified as 3b-taraxerol (A), 3b-taraxerol acetate (B), dodecyl-p-coumarate (C), ferulic acid (D), scopoletin (E), sitosterol-3-O-b-D-glucopyranoside (F), 3,5-di-O-feruloylquinic acid (G) and Isofraxidin-7-O-b-Dglucopyranoside (H) based on spectroscopic data. Compounds A, B, C, F, G, and H are known but were isolated for the first time from the roots of A. afra. The isolated compounds and extracts from A. afra exhibited good anti-fungal and anti-bacterial activity with dichloromethane and ethyl acetate crude extracts (0.078 mg/mL) and compound E (62.5 g/mL) showed good activities against Escherichia coli. Compounds C and F also showed good activity against Enterococcus faecalis with minimum inhibitory concentration (MIC) values of 62.5 and 31.25 g/mL, respectively. Extracts and compounds (A–H) exhibited anti-fungal and anti-bacterial properties and showed no toxicity when tested on Vero monkey kidney (Vero) cells.The National Research Foundation Research South Africa and Tshwane University of Technology (VJT).https://www.mdpi.com/journal/plantsam2024Paraclinical SciencesSDG-15:Life on lan

Anti-inflammatory activity of seven plant species with potential use as livestock feed additives

Please read abstract in the article.The National Research Council (NRF) South Africa, Onderstepoort Veterinary Institute (OVI), the University of Pretoria and Red Meat Research and Development South Africa.http://www.elsevier.com/locate/sajbhj2024ChemistryParaclinical SciencesSDG-03:Good heatlh and well-beingSDG-15:Life on lan

Optimizing extraction of pelargonium sidoides roots : impact of ethanol concentration on biological activity of extracts

Pelargonium sidoides DC. (Geraniaceae) is an important indigenous medicinal plant in South Africa, historically employed by various ethnic groups to treat respiratory and gastrointestinal ailments. The proprietary herbal tincture, Umckaloabo , utilizes an ethanolic extract (EPs 7630) from the roots of P. sidoides, and has demonstrated effectiveness in alleviating symptoms of respiratory infections. P. sidoides roots contain numerous highly oxygenated coumarins and phenolic metabolites, notably the marker compound umckalin. While Umckaloabo is prepared using 11 % ethanol extraction, the South African commercial market predominantly employs 60 % ethanol extraction due to its consistent umckalin yield and antimicrobial activity. The effects of these extraction methods on chemical composition and in vitro pharmacological activity remain poorly understood. This study confirmed superior antibacterial and antifungal activity in the 60 % ethanol extracts prepared from six root samples compared to the 11 % ethanol extracts. MIC values for both Gram-negative and Gram-positive bacteria ranged from 0.078 to 2.5 mg/mL in the 60 % extracts. Remarkably, two of the root extracts exhibited excellent to very good activity against C. albicans and C. neoformans with MIC values of 0.039 and 0.078 mg/mL, respectively. A positive correlation was identified between total minimum inhibitory concentration (MIC) levels and polyphenol content, rather than umckalin levels. The influence of these extracts on the pro-inflammatory cytokine IL-6 was assessed. Both 60 % and 11 % root extracts of P. sidoides at 100 mg/mL significantly reduced IL-6 production, with the 60 % extracts demonstrating a more pronounced effect (p = 0.008). Statistical analysis revealed significant differences between 11 % and 60 % ethanol extractions in terms of average MIC overall, average Gram-negative MIC, average Gram-positive MIC, fungal MIC, and IL-6 levels. Extracts with higher polyphenol values exhibited superior antimicrobial activity and antioxidant potential, suggesting that polyphenol content may serve as a more reliable indicator of antimicrobial activity than umckalin levels. Additionally, polyphenol levels in the roots may vary with altitude and other environmental factors, warranting further research.The National Research Foundation and Nativa (Pty) Ltd, South Africa.http://www.elsevier.com/locate/sajbam2024ChemistryParaclinical SciencesNon

Antimycobacterial, hepatoprotective and cytotoxicity effects of selected plant species from the Menispermaceae family

Tuberculosis, caused by Mycobacterium tuberculosis, is a worldwide disease affecting millions of people. The rise of resistant strains, coupled with toxicity of current chemotherapy, requires effective alternatives against mycobacterial infections. Some plants from the Menispermaceae family have been used to treat tuberculosis and cough related symptoms. In this study, acetone, methanol:water (4:1), dichloromethane:methanol (1:1) and hot water extracts of different plant parts of Cissampelos owariensis, Cissampelos mucronata and Tinospora fragosa were tested against M. aurum, M. bovis, M. fortuitum, M. smegmatis and M. tuberculosis using a two-fold serial microdilution assay. Cytotoxicity of the active extracts was determined against Vero and HepG2 cells. The hepatoprotective effect of the active extracts was evaluated using rifampicin and acetaminophen as toxic drugs against HepG2 cells. The hot water leaf extracts were most active with promising minimum inhibitory concentration (MIC) values of 20 and 40 µg/mL against M. smegmatis and M. fortuitum respectively. The acetone extracts of C. owariensis, C. mucronata and T. fragosa had the lowest MIC values (0.03 – 1.67 mg/mL). The root extract of C. owariensis was not toxic to Vero cells while the leaf extract was more toxic. The acetone extract of C. mucronata leaves was toxic to Vero cells but the other extracts had low toxicity. The active leaf and root extracts had protective effects on rifampicin-induced toxicity on HepG2 cells. The root extract also had a protective effect on acetaminophen-induced toxicity on HepG2 cells but the leaf extract had no protective effect. The hot water extracts of C. owariensis, C. mucronata and T. fragosa had a more protective effect on the toxin-induced cells than the acetone extracts. These results support further investigation on the bioactive compounds in these plant extracts.The National Research Foundation (NRF, South Africa),http://www.elsevier.com/locate/sajbhj2024Paraclinical SciencesSDG-03:Good heatlh and well-bein

Influence of selected plant extracts on bacterial motility, aggregation, hydrophobicity, exopolysaccharide production and quorum sensing during biofilm formation of enterohaemorrhagic Escherichia coli O157:H7

Diarrhoeagenic Escherichia coli is a serious threat to human and animal health, with antimicrobial drug resistance contributing to the problem. Alternative mechanisms of prevention and treatment of E. coli-induced diarrhoea include those targeting biofilm production and quorum sensing, properties that have been associated with some investigated plant extracts. Plants were selected from various genera, including Vachellia, Senegalia, Morus, Leucaena, Salix, Grewia, Ziziphus, Searsia, Dichrostachys and Ceratonia, based on their known antimicrobial activity. The antibacterial effects of leaf extracts against multidrug-resistant E. coli O157:H7 were investigated using a broth microdilution method, and cytotoxicity to normal mammalian cell lines was studied using a tetrazolium colorimetric assay. Subsequently, antibiofilm activity and inhibition of extracellular polymeric substance (EPS) production by plant extracts against E. coli O157:H7 was investigated using crystal violet as a staining dye after 0 and 24 h incubation and carbohydrate estimation 5 % phenol-sulfuric assay. The biosensor strain Chromobacterium violaceum ATCC 12472 was used to study the anti-quorum sensing potential of the selected plant extracts. Cell motility, cell surface hydrophobicity (CSH), and aggregation were also investigated. All plant extracts had weak antibacterial activity (MIC > 0.62 mg/ml) with relatively low cytotoxicity. The acetone extracts of Salix babylonica and Leucaena leucocephala prevented bacterial cell attachment (0 h) by 81.21 % and 89.36 %, respectively. Approximately 28 % of plant extracts eradicated established biofilms by more than 50 %, however, they were unable to inhibit EPS production above 30 %. The half-maximal concentration of extracts generally inhibited violacein production (ranging from 0.01 to 0.02 mg/ml), with V. erioloba acetone extract being the most effective at quorum quenching. Some plant extracts exhibited a significant difference (p<0.05) in motility, aggregation and hydrophobicity compared to untreated cells. This study highlights the potential of selected plant extracts to act via different mechanisms of action to decrease virulence of enteric E. coli, motivating further investigation of the bioactive compounds in the leaves.The National Research Foundation and Red Meat Research Development South Africa.http://www.elsevier.com/locate/sajbhj2024Paraclinical SciencesNon

Invasive alien species as a potential source of phytopharmaceuticals : phenolic composition and antimicrobial and cytotoxic activity of Robinia pseudoacacia L. leaf and flower extracts

DATA AVAILABILITY STATEMENT : Data are presented in the manuscript.SUPPLEMENTARY MATERIAL : TABLE S1: Pearson’s correlation coefficients (two-tailed) between total phenolic (TP), total non-flavonoids (TNF) and total flavonoids (TF) contents and antioxidant capacity (obtained by DPPH, ABTS, and FRAP assays).Black locust (Robinia pseudoacacia L.), an invasive tree in Europe, commonly known for its negative impact on biodiversity, is a rich source of phenolic compounds recognized in traditional medicine. Since the metabolite profile depends on the environment and climate, this study aimed to provide the first LC-MS phytochemical screening of the black locust from the Istria region (Croatia). The compounds were extracted from leaves and flowers with 70% ethanol and 80% methanol. Total phenolics (TP) and flavonoids (TF), as well as antioxidant capacity (AC) measured by ABTS (17.49–146.41 mg TE/g DW), DPPH (24.67–118.49 mg TE/g DW), and FRAP (7.38–77.53 mg TE/g DW) assays, were higher in leaf than in flower extracts. Higher TP and total non-flavonoid (TNF) values were displayed in ethanolic than in methanolic extracts. In total, 64 compounds were identified, of which flavonols (20) and hydroxycinnamic acid derivatives (15) were the most represented. Flavanols such as catechin dominated in leaf extracts, followed by flavonols, with kaempferol glucuronyl rhamnosyl hexosides as the main compound, respectively. Flower extracts had the highest share of flavones, followed by ellagitannins, with luteolin dirhamnosyl hexosides and vescalagin, respectively, being predominant. The extracts had good quorum sensing, biofilm formation prevention, and eradicating capacity. The results provided new insights into the phytochemical properties of R. pseudoacacia as the first step toward its potential pharmaceutical use.The Croatian Science Foundation and the Slovenian Research Agency (ARRS).https://www.mdpi.com/journal/plantsam2024Paraclinical SciencesSDG-03:Good heatlh and well-beingSDG-15:Life on lan

A water-soluble polymer-lumefantrine conjugate for the intravenous treatment of severe malaria

DATA AVAILABILITY STATEMENT : The data that support the findings of this study are available from the corresponding author upon reasonable request.Uncomplicated malaria is effectively treated with oral artemisinin-based combination therapy (ACT). Yet, there is an unmet clinical need for the intravenous treatment of the more fatal severe malaria. There is no combination intravenous therapy for uncomplicated due to the nonavailability of a water-soluble partner drug for the artemisinin, artesunate. The currently available treatment is a two-part regimen split into an intravenous artesunate followed by the conventional oral ACT . In a novel application of polymer therapeutics, the aqueous insoluble antimalarial lumefantrine is conjugated to a carrier polymer to create a new water-soluble chemical entity suitable for intravenous administration in a clinically relevant formulation . The conjugate is characterized by spectroscopic and analytical techniques, and the aqueous solubility of lumefantrine is determined to have increased by three orders of magnitude. Pharmacokinetic studies in mice indicate that there is a significant plasma release of lumefantrine and production its metabolite desbutyl-lumefantrine (area under the curve of metabolite is ≈10% that of the parent). In a Plasmodium falciparum malaria mouse model, parasitemia clearance is 50% higher than that of reference unconjugated lumefantrine. The polymer-lumefantrine shows potential for entering the clinic to meet the need for a one-course combination treatment for severe malaria.World Health Organization; South African Medical Research Council; National Research Foundation of South Africa.http:// www.mbs-journal.deam2024ChemistryParaclinical SciencesSDG-03:Good heatlh and well-bein

Evaluation of minerals, trace elements, and antinutritional factors in selected legume fodder species (Fabaceae) with the potential to improve cattle nutrition and gastrointestinal health

The study aimed to investigate the nutritional composition, trace elements and anti-nutritional factors of fodder species belonging to the family Fabaceae potentially used as an alternative feed for cattle. The proximate composition, particularly dry matter, moisture, fats, crude proteins (CP), carbohydrates, crude fibre (CF), and neutral detergent fiber (NDF), were analysed, thereby, nonfibre carbohydrate (NFC) and gross energy (GE) were calculated. Thirty-three trace elements were determined from chemically digested dried plant material using ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and ICP-OES (ICP-Optical Emission Spectrophotometry). The tannin levels, a known antinutritional factor, were estimated using Folin–Ciocalteu method. The methods were validated by the relative standard deviation (RSD) values and acceptable recovery percentage, linearity, limit of quantification (LoQ), and limit of detection (LoD). The proximate composition analysis estimated levels of dry matter (> 90 %), ash (3.77–26.98 %), crude proteins (8.22–22.19 %), carbohydrates (54.00–86.79 %), crude fibre (10.54–40.10 %), NDF (22.26–59.20 %) and GE (< 100 Kcal kg−1 DM) in leguminous species. Essential elements were detected in recommended levels including Zn (21.20–50.30 mg/kg), Co (0.06–0.045 mg kg), Cr (0.5–5.08 mg kg−1), Mn (9.02–197 mg kg−1), Mg (0.10–0.52 mg kg−1), Fe (42.40–812 mg kg−1) and Na (72.00–1721 mg kg−1). The concentration of toxic elements was below critical levels and tannin occurred at a safe level (< 50 mgTAE kg−1) for ruminant consumption. Therefore, the selected fodder can effectively contribute to cattle dietary requirements for smallscale farmers in Onderstepoort,Agriculture Research Council-Onderstepoort Veterinary Research (South Africa) and National Research Foundation (South Africa). The University of Pretoria funded the postdoctoral fellowship of IMF.http://www.elsevier.com/locate/sajb2025-06-08hj2024Paraclinical SciencesSDG-02:Zero Hunge

LC–DAD–MS phenolic characterisation of six invasive plant species in Croatia and determination of their antimicrobial and cytotoxic activity

Invasive plants’ phytochemicals are important for their invasiveness, enabling them to spread in new environments. However, these chemicals could offer many pharmaceutical compounds or active ingredients for herbal preparations. This study provides the first LC–MS phytochemical screening of six invasive alien plant species (IAPS) in the Istria region (Croatia): Ailanthus altissima, Ambrosia artemisiifolia, Conyza canadensis, Dittrichia viscosa, Erigeron annuus, and Xanthium strumarium. The study aims to identify and quantify the phenolic content of their leaf extracts and assess their antimicrobial and cytotoxic potential. A total of 32 species-specific compounds were recorded. Neochlorogenic, chlorogenic, and 5-p-coumaroylquinic acids, quercetin-3-glucoside, and kaempferol hexoside were detected in all the tested IAPS. Hydroxycinnamic acid derivatives were the main components in all the tested IAPS, except in E. annuus, where flavanones dominated with a share of 70%. X. strumarium extract had the best activity against the tested bacteria, with an average MIC value of 0.11 mg/mL, while A. altissima and X. strumarium extracts had the best activity against the tested fungi, with an average MIC value of 0.21 mg/mL in both cases. All the plant extracts studied, except X. strumarium, were less cytotoxic than the positive control. The results provided additional information on the phytochemical properties of IAPS and their potential for use as antimicrobial agents