Antibacterial and antibiotic-modifying activities of fractions and compounds from Albizia adianthifolia against MDR Gram-negative enteric bacteria

Mangiferin potentiates the activity of antifungal agents against fluconazole-resistant Candida spp

Aim: To evaluate the antifungal activity of mangiferin against Candida spp. resistant to fluconazole. Materials & methods: The antifungal activity of mangiferin was assessed using broth microdilution and its interaction with azoles and amphotericin B was evaluated by checkerboard. The activity of mangiferin against Candida spp. biofilms was assessed using the MTT colorimetric assay and its possible mechanism of action was evaluated using flow cytometry. Results: Mangiferin showed activity against Candida albicans, Candida tropicalis and Candida parapsilosis resistant to fluconazole and showed synergism with azoles and amphotericin B. Mangiferin increased the activity of antifungals against Candida biofilms and caused depolarization of the mitochondrial membrane and externalization of phosphatidylserine, suggesting apoptosis. Conclusion: mangiferin combined with antifungals has potential against Candida spp.

Antimicrobial and Cytotoxic Activities of Constituents from the Fruit of Albizia lebbeck L. Benth (Fabaceae)

Twenty-two compounds were isolated from the fruit of Albizia lebbeck including one unprecedented, rare amino acid-derived zwitterionic and one new flavone derivative. The isolation was performed on repeated column chromatography over silica gel and their structures were determined by 1D-, 2D-NMR and HR-ESI-MS spectra together with reported data in the literature. The chemophenetic significance is also discussed. Some isolated compounds were reported for the first time to be found in the species. Additionally, compound 2 showed antibacterial activity and compounds 1 and 2 revealed moderate cytotoxic activity against the Raw 264.7 cancer cell line with IC₅₀ values of 37.19 µM and 29.36 µM, respectively. Furthermore, a proposed biosynthetic pathway of compound 1 is described.

Sesquiterpene Lactones from Vernonia tufnelliae: Structural Characterization and Biological Evaluation

The genus Vernonia is an extremely rich source of biologically active sesquiterpene lactones. The present report describes the spectroscopic structure elucidation and the cytotoxic and antimicrobial properties of five hitherto unknown germacranolide-like sesquiterpenoids and several known compounds. These new derivatives include a compound (1) with an unprecedented 10/5/5/6 tetracyclic framework featuring a hexahydro-1H,3H,7H-furo[3',4':3,4]furo[3,2-c]pyridin-1-one core resulting from an intramolecular cyclization cascade involving a methacrylate substituent and a low molecular weight amine. Furthermore, an elemane-germacranolide hybrid (2) and three amino acid-derived lactones (3-5) were characterized. A plausible biosynthetic pathway to the key alkaloid is presented, while shielding tensor calculations using DFT in combination with the DP4+ method were applied to elucidate its stereostructure. The newly characterized compounds along with ten known sesquiterpene lactones and phenolic compounds have been isolated from Vernonia tufnelliae, a medicinal plant from the western region of Cameroon. Their structures were consistent with spectroscopic and spectrometric data recorded. The present report is the first investigation of the chemistry and biology of V. tufnelliae.

Antibacterial Modes of Herbal Flavonoids Combat Resistant Bacteria

The increasing dissemination of multidrug resistant (MDR) bacterial infections endangers global public health. How to develop effective antibacterial agents against resistant bacteria is becoming one of the most urgent demands to solve the drug resistance crisis. Traditional Chinese medicine (TCM) with multi-target antibacterial actions are emerging as an effective way to combat the antibacterial resistance. Based on the innovative concept of organic wholeness and syndrome differentiation, TCM use in antibacterial therapies is encouraging. Herein, advances on flavonoid compounds of heat-clearing Chinese medicine exhibit their potential for the therapy of resistant bacteria. In this review, we focus on the antibacterial modes of herbal flavonoids. Additionally, we overview the targets of flavonoid compounds and divide them into direct-acting antibacterial compounds (DACs) and host-acting antibacterial compounds (HACs) based on their modes of action. We also discuss the associated functional groups of flavonoid compounds and highlight recent pharmacological activities against diverse resistant bacteria to provide the candidate drugs for the clinical infection.

Medicinal Plants for Anti-neurodegenerative diseases in West Africa

ETHNOPHARMACOLOGICAL RELEVANCE

Neurodegenerative diseases are neuronal diseases that affect the brain components by degenerating the structure and function of the central or peripheral nervous system progressively. It is a leading cause of death and affects huge amount of people worldwide. Plant-based medicines have been utilised in the therapies for many illnesses that have defied western treatments, including neurodegenerative diseases.

AIM OF THIS REVIEW

This review presents an overview of the major neurodegenerative diseases and reported prominent medicinal plants used in managing those diseases in West Africa.

METHODS

Scientific articles regarding medicinal plants and their usefulness in managing neurodegenerative diseases in West Africa were pooled from different scientific databases. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses to filter articles based on their relevance. Pharmacological activity, plant parts used, experimental models, and some isolated chemical compounds of those plants were summarised.

RESULTS

In the West Africa region, Fabaceae (19%) and Solanaceae (13%) have the highest representation of plant families used to treat neurological diseases, while Apocynaceae, Asteraceae, Euphorbiaceae have also been utilised. Flavonoids, alkaloids, phenolic compounds, terpenoids, coumarins present in those plants and their derivatives are reported to possess neuro-protective effects. Biochemical enzymes correlating to antioxidants, anti-inflammatory effects are the potential targets against neurodegenerative diseases.

CONCLUSION

Medicinal plants for anti-neurodegenerative diseases in West Africa have been documented with their neuropharmacological activities. Plant families such as Fabaceae, Solanaceae, Apocynaceae, Asteraceae, and Euphorbiaceae could be a major natural source for discovery of anti-neurodegenerative drugs, thus the metabolites from them should be given priority for neurological research. This review will provide clues for further investigations on the screening and development of anti-neurodegenerative natural products from West African medicinal plants.

Virtual screening and in vitro experimental verification of LuxS inhibitors from natural products for Lactobacillus reuteri

The rapid proliferation and colonization of probiotics in the intestines are essential for human health. Quorum sensing (QS) is a communication mechanism among bacteria, which can regulate various bacterial crowd behavior. This study aimed to enhance the viability of Lactobacillus reuteri 1-12 by regulating QS. Herein, we built a database containing 72 natural products (previously reported) that can improve intestinal flora. Virtual screening (VS) was subsequently conducted to screen four potential active compounds. After that, molecular docking was conducted to analyze the binding mode of the four natural products to S-Ribosylhomocysteinase (LuxS). The results showed that norathyriol, mangiferin, baicalein, and kaempferol had good binding ability to LuxS. The validation experiment showed that norathyriol, mangiferin, baicalein, and kaempferol could inhibit the production of autoinducer-2 (AI-2). Moreover, mangiferin significantly increased L. reuteri 1-12 biomass and promoted L. reuteri 1-12 biofilm formation and structure. Besides, only mangiferin inhibited luxS expression, thus increasing L. reuteri 1-12 biomass. This research indicated that mangiferin may be a potential inhibitor of LuxS, promoting the probiotic properties of L. reuteri and human health.

Toward the Allelopathy of Peganum sp. and Related Chemical Constituents in Agriculture

The genus Peganum constitutes one of the perennial groups of plants of semi-arid regions across the world. It produces diverse classes of metabolites with claimed valuable pharmacological applications. Despite the key chemical and biological properties of the genus, its allelopathy or that of one of its species has not been reviewed yet. Thus, the present survey aims to report the agricultural applications of extracts, fractions, and compounds from the genus Peganum. This work was based on the available literature related to both the Peganum genus and agriculture, which were generated from available high-impact scientific engines. The plants in this genus contain a large group of secondary metabolites including phenolic compounds, terpenes, and N-containing compounds. Alkaloids, as the main components of the extracts from plants in the genus, were identified as the major active principles. The toxicity of Peganum isolates against plants and related pest organisms was also reviewed. Extract preparations from species of Peganum were listed among insecticidal and herbicidal allelochemicals used for crop protection. The review also tried to contextualize natural products in agriculture. Peganum plant extracts and fractions have showed significant potential in weed and crops management, soil health, and biopesticide production.

Alkenylbenzoquinones and other compounds from the fruit of Maesa lanceolata exhibited potent cytotoxic, antibacterial, and antiradical scavenging activities§

A phytochemical study of the methanol extract of the fruit of Maesa lanceolata resulted in the isolation of a new alkenylbenzoquinone (1), alongside the known compounds (Z)-2,5-dihydroxy-6-methyl-3-(pentadec-10'-enyl)-1,4-benzoquinone (2), 2,5-dihydroxy-6-methyl-3-(nonadec-14'-enyl)-1,4-benzoquinone (3), 2,5-dihydroxy-6-methyl-3-(tridecyl)-1,4-benzoquinone (4), (2S,3S,4R,2'R,9E)-[2'-hydroxytetraeicosanoyl]-2-aminooctadec-9-ene-1,3,4-triol (5), monopalmitin (glyceryl palmitate) (6), lupeol (7), and 3-O-(β-D-glucopyranoside)-β-sitosterol (8). The structures of the compounds were established by the means of spectroscopic (1 D- and 2 D-NMR) and spectrometric techniques (MS). The isolated compounds were assessed for their antibacterial, cytotoxic, and antiradical activities. Compound 2 showed moderate activity against Staphylococcus warneri (DSMZ 20036), while the other compounds were inactive. The two quinones 1 and 2 were significantly cytotoxic, with IC₅₀ values of 0.005 µM and 12.5 µM respectively, and were weakly active towards DPPH radical (IC₅₀ >250 µg/mL).

Antimicrobial activity of medicinal plants used for urinary tract infections in pastoralist community in Ethiopia

BACKGROUND

Medicinal plants have wide medicament application used to prevent and management of many ailments. These plants are used for primary health care in pastoralist communities who are deprived of modern medical care. They possess extensive therapeutics bioactive coupled with varied chemical structures. However, scientific validation of efficacy and safety of plants used to treat the urinary tract infections haven't been fully exploited. The aim of this study was to evaluate antimicrobial activity and screening phytochemicals of medicinal plants used to treat urinary tract infections.

METHODS

In-vitro experimental study was carried out to evaluate the antimicrobial effect and screening phytochemical of Rumex abyssinicus, Cucumis pustulatus, Discopodium penninervium, Lippia adoensis, Euphorbia depauperata, and Cirsium englerianum. Against drug resistance microbes. 80% methanol was used for extraction of the plant parts. The susceptibility tests were investigated using disc diffusion and broth micro-dilution methods.

RESULTS

The majority of tested extracts showed antimicrobial activity on two or more drug-resistant bacteria with MIC value (1.0-128.0 μg/ml) and 9-27 mm inhibition zone in diameter. Extracts obtained from C.englerianum and E. depauperate showed more potent antibacterial activity on MRSA and Enterococcus faecalis with IZ 25 and 27 mm respectively. E. coli and K. pneumoniae were inhibited by those extracts with IZ ranging 9-25 mm and 11-27 mm respectively. E.faecalis and K. pneumoniae were more susceptible bacteria to the respective extracts. R. abyssinicus showed promising antifungal effect with had 21 mm IZ and MIC range 16-32 μg/ml on C.albicans. Alkaloids, flavonoids, phenolic and terpenoid were common phytochemical characterized in majority of screened plants.

CONCLUSION

Tested extracts exhibited significant antibacterial and antifungal activity. Hence, further structural elucidation of bioactive that inhibited the growth of microbes aforementioned plants may be used as precursors for the synthesis of new antibiotics in the future.

β-Sitosterol Attenuates High Grain Diet-Induced Inflammatory Stress and Modifies Rumen Fermentation and Microbiota in Sheep

β-sitosterol (BSS) is a plant-derived natural bioactive compound, its cellular mechanism of anti-inflammatory activity has been proven recently. Little information is available regarding the application of BSS on ruminants under high grain diet. The objective of this study was to evaluate the effects of dietary BSS supplementation on inflammatory response, ruminal fermentation characteristics and the composition of the ruminal bacterial community under high grain diet. Eight rumen-cannulated Hu sheep (59.7 ± 4.8 kg of initial body weight) were randomly assigned into a replicated 4 × 4 Latin square design trial. Sheep were fed a high grain diet (non-fiber carbohydrate: neutral detergent fiber = 2.03) supplemented either with 0.25 (LBS), 0.5 (MBS), 1.0 (HBS) or without (CON) g BSS /kg dry matter diet. On day 21 of each period, rumen content samples were obtained at 6 h postfeeding, and blood samples were obtained before morning feeding. The data showed that compared with control group, Dietary BSS supplementation decreased serum concentrations of tumor necrosis factor, interleukin (IL)-6, and IL-1β. The ruminal pH and acetate concentration for BSS treatment were improved, while concentration of propionate, butyrate and lactate was decreased. The result of Illumina MiSeq sequencing of 16S rRNA gene revealed that BSS addition can increase the proportion of Prevotella_1, Rikenellaceae_RC9_gut_group, Prevotella_7, and Selenomonas_1, and decrease the proportion of Lachnospiraceae_NK3A20_group. These results indicated that BSS attenuates high grain diet-induced inflammatory response and modifies ruminal fermentation. In addition, the BSS dietary supplementation at the level of 0.5 g/kg is recommended in sheep.

Saponin with antibacterial activity from the roots of Albizia adianthifolia

An unprecedented saponin is being reported herein together with five known compounds from the methanol extract of the roots of Albizia adianthifolia. The metabolites were obtained over repeated open column chromatography methods and spectroscopic followed by spectrometric techniques. The isolated compounds were tested against eleven Gram-negative bacteria including multidrug resistant strains. The results revealed considerable inhibition of the new saponin against the studied bacteria with MIC values ranging from 16 to 128 μg/mL.