Ibukun Michael Famuyide

Breast and colon cancers are leading causes of death worldwide. There is a need for improved treatment strategies. South African medicinal plants, including Clerodendrum glabrum (C. glabrum) and Combretum nelsonii (C. nelsonii), are known for their cytotoxic properties. This study aimed to isolate and characterize terpenoids and stilbenes from the roots of C. glabrum and C. nelsonii and evaluate their anticancer potential against colorectal adenocarcinoma (Caco-2) and hormone receptor-positive breast cancer (MCF-7) cell lines. Spectroscopic techniques including nuclear magnetic resonance spectroscopy (NMR) were used to characterize the isolated compounds. Repeated column chromatography of C. glabrum extract led to the isolation of ferruginol (1), royleanone (2), and β-amyrin palmitate (3). C. nelsonii extract afforded combretastatin A-1 (4), a mixture of combretastatin A-1-2′-O-β-D-glucopyranoside (5a) and combretastatin B-1-2′-O-β-D-glucopyranoside (5b). Compounds 1, 2, 4, 5a, and 5b were isolated for the first time from the plant species. C. glabrum extract showed good anticancer properties with LC₅₀ of 1.30 × 10³ µg/mL (CaCo-2) and 2790 µg/mL (MCF-7). Compound (1) exhibited high toxicity against the Caco-2 at LC₅₀ of 24.3 µg/mL and moderate activity against MCF-7 at 48.4 µg/mL. Compound (4) and the mixture (5a and 5b) showed moderate activity against the MCF-7 at LC₅₀ 72.0 and 44.1 µg/mL, respectively. These findings highlight C. glabrum and C. nelsonii as promising sources of anticancer lead compounds.

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 3β-taraxerol (A), 3β-taraxerol acetate (B), dodecyl-p-coumarate (C), ferulic acid (D), scopoletin (E), sitosterol-3-O-β-D-glucopyranoside (F), 3,5-di-O-feruloylquinic acid (G) and Isofraxidin-7-O-β-D-glucopyranoside (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 µg/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 µg/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.

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.

Bovine mastitis in dairy livestock production is a serious economic problem causing milk production losses and increased management costs. Staphylococcus aureus and non-aureus staphylococcus (NAS) are important causes of bovine mastitis. Antimicrobial resistance can limit the control of mastitis pathogens. Antibacterial and cytotoxic activities of acetone and ethanol extracts of nine South African plants were determined against reference and drug-resistant staphylococci isolated from clinical cases of bovine mastitis. The nine plants, namely, Antidesma venosum, Elaeodendron croceum, Erythrina caffra, Indigofera frutescens, Pleurostylia capensis, Searsia lancea, Searsia leptodictya, Trichilia emetica, and Ziziphus mucronata, were chosen for research material. The antibacterial activity of extracts was determined using a serial microdilution method, while a tetrazolium-based assay was used to determine their cytotoxicity against Vero cells. The values of antibacterial minimum inhibitory concentration (MIC) obtained were promising, with MIC ranging between 0.01 and 1.41 mg/mL. Generally, acetone extracts of most plants had better activity than their ethanol counterparts. The S. aureus strains were more susceptible to all the extracts than the NAS strains. The plant extracts’ half-maximal toxicity (LC₅₀) was higher than 0.02 mg/mL, which is the recommended cytotoxic cut-off concentration. The ethanol extract of E. caffra, which showed better MIC values than its acetone extract, had the highest mean selectivity index (SI) of 8.30. Among the plants tested, S. lancea exhibited the most potent antibacterial activity, suggesting its potential usefulness as a broad-spectrum antibacterial agent against staphylococci associated with bovine mastitis, at relatively non-cytotoxic concentrations. Therefore, it is recommended for further investigation.

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.

Selenium (Se) is an essential trace nutrient for humans and animals owing to its role in redox regulation, thyroid hormone control factors, immunity, inflammatory reactions, brain activities, and carbohydrate regulation. It is also important to support muscle development, as well as for reproductive and cardiovascular well-being. Furthermore, sulfur is known to be a healing element, due to the remarkable function of specialized and secondary S-containing compounds. The scope of the current study was to determine the impact of Se and S enrichment on the secondary metabolite accumulation and antibacterial and NO inhibition activities in green and red leaf lettuce (V1 and V2, respectively). The plants were grown in a hydroponic system supplied with different S concentrations (S0: 0, S1: 1 mM and S2: 1.5 mM K₂SO₄) via the nutrient solution and foliar-applied varying levels of Se (0, 0.2 and 2.6 µM). Electrospray ionization–quadrupole time-of-flight mass spectrometry (ESI-QTOF/MS) combined with ultra-performance liquid chromatography (UPLC) was used to identify the secondary metabolites in green and red lettuce. The results indicated that extracts of the biofortified lettuce were not cytotoxic to Vero kidney cells at the highest concentration tested of 1 mg/mL. The ESI/MS of the tentatively identified metabolites showed that the response values of 5-O-caffeoylquinic acid, cyanidin 3-O-galactoside, quercetin 3-O-(6′′-acetyl-glucoside) and quercetin 3-O-malonylglucoside were induced synergistically under higher Se and S levels in red lettuce plants. The acetone extract of red lettuce had antibacterial activity against Pseudomonas aeruginosa, with a minimum inhibitory concentration (MIC) of 0.156 and 0.625 μg/mL under S2/Se1 and S2/Se2 treatments, respectively. As with antibacterial activity, the acetone extract of green (V1) lettuce treated with adequate (S1) and higher S (S2) under Se-limiting conditions showed the ability to inhibit nitric oxide (NO) release from macrophages. NO production by macrophages was inhibited by 50% at respective concentrations of 106.1 ± 2.4 and 101.0 ± 0.6 μg/mL with no toxic effect on the cells, in response to S1 and S2, respectively, under Se-deficient conditions (Se0). Furthermore, the red cultivar (V2) exhibited the same effect as the green cultivar (V1) regarding NO inhibition, with IC₅₀ = 113.0 ± 4.2 μg/mL, in response to S1/Se2 treatments. Collectively, the promising NO inhibitory effect and antibacterial activity of red lettuce under the above-mentioned conditions might be attributed to the production of flavonoid glycosides and phenylpropanoic acid esters under the same condition. To the best of our knowledge, this is the first report to show the novel approach of the NO inhibitory effect of Se and S enrichment in food crops, as an indicator for the potential of Se and S as natural anti-inflammatory agents.

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 0.63mg/mL. Further screening against a panel of bacterial pathogens showed that the acetone extract of Bauhinia bowkeri was the most active with MIC of 0.01mg/mL against Salmonella enteritidis, followed by Searsia lancea with MIC of 0.03mg/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 0.32mg/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 0.17mg/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.