An in vitro investigation of indigenous South African medicinal plants used to treat oral infections

Biofilm formation in food industries: Challenges and control strategies for food safety

Various pathogens have the ability to grow on food matrices and instruments. This grow may reach to form biofilms. Bacterial biofilms are community of microorganisms embedded in extracellular polymeric substances (EPSs) containing lipids, DNA, proteins, and polysaccharides. These EPSs provide a tolerance and favorable living condition for microorganisms. Biofilm formations could not only contribute a risk for food safety but also have negative impacts on healthcare sector. Once biofilms form, they reveal resistances to traditional detergents and disinfectants, leading to cross-contamination. Inhibition of biofilms formation and abolition of mature biofilms is the main target for controlling of biofilm hazards in the food industry. Some novel eco-friendly technologies such as ultrasound, ultraviolet, cold plasma, magnetic nanoparticles, different chemicals additives as vitamins, D-amino acids, enzymes, antimicrobial peptides, and many other inhibitors provide a significant value on biofilm inhibition. These anti-biofilm agents represent promising tools for food industries and researchers to interfere with different phases of biofilms including adherence, quorum sensing molecules, and cell-to-cell communication. This perspective review highlights the biofilm formation mechanisms, issues associated with biofilms, environmental factors influencing bacterial biofilm development, and recent strategies employed to control biofilm-forming bacteria in the food industry. Further studies are still needed to explore the effects of biofilm regulation in food industries and exploit more regulation strategies for improving the quality and decreasing economic losses.

Evaluation of the antifungal effect of plant extracts on oral Candidaspp. - a critical methodological analysis of the last decade

INTRODUCTION

In 2022, the World Health Organization published a report encouraging researchers to focus on Candida spp. to strengthen the global response to fungal oral infections and antifungal resistance. In the context of innovative research, it seems pertinent to investigate the antifungal potential of natural extracts of plants and the methodology involved in the recent reports. The aim of this systematic review is to identify the current state of in vitro research on the evaluation of the ability of plant extracts to inhibit Candida spp.

MATERIAL AND METHODS

A bibliographic search has been developed to on a 10-year period to identify which plant extracts have an antifungal effect on the Candida spp. found in the oral cavity.

RESULTS

A total of 20 papers were reviewed and fulfilled all the selection criteria and were included in the full data analysis.

DISCUSSION

Plants have been tested in a wide range of states - whole extracts, extraction of particular components such as flavonoids or polyphenols, or even using the plant to synthesize nanoparticles. Of forty-five plants tested, five of them did not show any effect against Candida spp., which weren't part of the same family. There is a wide range of plant that exhibit antifungal proprieties.

CONCLUSION

Many plants have been tested in a wide range of states - whole extracts, extraction of components such as flavonoids or polyphenols, or even using the plant to synthetize nanoparticles. The combination of plants, the addition of plants to a traditional antifungal and the interference with adhesion provided by some plants seem to be promising strategies. Nonetheless, on contrary to drugs, there is a critical lack of standardization on methodologies and protocols, which makes it difficult to compare data and, consequently, to conclude, beyond doubts, about the most promising plants to fight Candida spp. oral infections.

Evaluation of the Antioxidant, Cytotoxicity, Antibacterial, Anti-Motility, and Anti-Biofilm Effects of Myrothamnus flabellifolius Welw. Leaves and Stem Defatted Subfractions

The formation of biofilms underscores the challenge of treating bacterial infections. The study aimed to assess the antioxidant, cytotoxicity, antibacterial, anti-motility, and anti-biofilm effects of defatted fractions from Myrothamnus flabellifolius (resurrection plant). Antioxidant activity was assessed using DPPH radical scavenging and hydrogen peroxide assays. Cytotoxicity was screened using a brine shrimp lethality assay. Antibacterial activity was determined using the micro-dilution and growth curve assays. Antibiofilm potential was screened using the crystal violet and tetrazolium reduction assay. Liquid-liquid extraction of crude extracts concentrated polyphenols in the ethyl acetate and n-butanol fractions. Subsequently, these fractions had notable antioxidant activity and demonstrated broad-spectrum antibacterial activity against selected Gram-negative and Gram-positive bacteria and Mycobacterium smegmatis (MIC values < 630 μg/mL). Growth curves showed that the bacteriostatic inhibition by the ethyl acetate fractions was through the extension of the lag phase and/or suppression of the growth rate. The sub-inhibitory concentrations of the ethyl acetate fractions inhibited the swarming motility of Pseudomonas aeruginosa and Klebsiella pneumoniae by 100% and eradicated more than 50% of P. aeruginosa biofilm biomass. The polyphenolic content of M. flabellifolius plays an important role in its antibacterial, anti-motility, and antibiofilm activity, thus offering an additional strategy to treat biofilm-associated infections.

Ethnomedicinal Uses, Phytochemistry, and Anticancer Potentials of African Medicinal Fruits: A Comprehensive Review

Africa is home to diverse medicinal plants that have been used for generations for the treatment of several different cancers and, presently, they are gaining interest from researchers as promising approaches to cancer treatment. This review aims to provide a comprehensive review of dietary and medicinal African fruits including their traditional uses, botanical description, ethnobotanical uses, bioactive phytochemical compositions, and anticancer properties investigated to date in vitro, in vivo, and in clinical studies. Data on recent updates concerning the traditional uses and anticancer properties of these fruits were collected from a myriad of available publications in electronic databases, such as Web of Science, PubMed, ScienceDirect, Scopus, SpringerLink, and Google Scholar. The results suggest that approximately 12 native or commercially grown African fruits belonging to different plant species, including Tribulus terrestris, Xanthium strumarium, Withania somnifera, Xylopia aethiopica, Abelmoschus esculentus, Carissa macrocarpa, Carpobrotus edulis, Syzygium cumini, Kigelia Africana, Annona muricata, Persea americana, and Punica granatum, have been reported for their potential as treatment options for the management of cancer. We further found that approximately eight different fruits from native plant species from Africa, namely, Sclerocarya birrea, Dovyalis caffra, Parinari curatellifolia, Mimusops caffra, Carpobrotus edulis, Vangueria infausta, Harpephyllum caffrum, and Carissa macrocarpa, have been widely used for the traditional treatment of different ailments but somehow failed to gain the interest of researchers for their use in anticancer research. In this review, we show the potential use of various fruits as anticancer agents, such as Tribulus terrestris, Xanthium strumarium, Withania somnifera, Xylopia aethiopica, Abelmoschus esculentus, Carissa macrocarpa, Carpobrotus edulis, Syzygium cumini, Kigelia Africana, Annona muricata, Persea americana, and Punica granatum; unfortunately, not enough reported research data have been published to gain thorough mechanistic insights and clinical applications. Additionally, we discuss the possibility of the utilization of potential phytochemicals from fruits like Persea americana and Punica granatum in anticancer research, as well as future directions.

Avocado seed by-product uses in emulsion-type ingredients with nutraceutical value: Stability, cytotoxicity, nutraceutical properties, and assessment of in vitro oral-gastric digestion

The avocado industry obtains 20-30% of the total by-products (peels and seeds). However, byproducts can be uses as sources of economic nutraceutical ingredients with functional potential. This work developed emulsion-type ingredients from avocado seed to evaluate its quality, stability, cytotoxicity, and nutraceutical properties before/after in vitro oral-gastric digestion. Ultrasound lipid extraction achieved an extraction yield of up to 95.75% compared with Soxhlet conventional extraction (p > 0.05). Six ingredients' formulations (E1-E6) were stable for up to day 20 during storage, preserving their antioxidant capacity and displaying low in vitro oxidation compared to control. None of the emulsion-type ingredients were considered cytotoxic according to the shrimp lethality assay (LC₅₀ > 1000 µg/mL). Ingredients E2, E3, and E4 generated low lipoperoxides' concentrations and high antioxidant capacity during the oral-gastric stage. The 25 min-gastric phase showed the highest antioxidant capacity and low lipoperoxidation. Results suggested avocado seed-derived could be used to develop functional ingredients with nutraceutical properties.

Ethnopharmacology and biological activities of the Aizoaceae

ETHNOPHARMACOLOGICAL RELEVANCE

The Aizoaceae is one of the largest succulent plant families. Most members of the family are ornamental and form part of specialist succulent collections. The exceptional diversity of the Aizoaceae is not only limited to its growth forms, habitat, and chemistry, but is also reflected in its many traditional uses. Selected species are well known for their use in traditional medicines, with recent scientific studies validating their biological activity.

AIM OF THE STUDY

Herein, this review aimed to articulate foundational and current global research endeavors related to the traditional uses and pharmacological activities of the Aizoaceae.

MATERIALS AND METHODS

Research articles and search terms related to the ethnopharmacology and bioactivities of the Aizoaceae between 1940 and 2022 were evaluated using electronic databases such as Google Scholar, PubMed, ScienceDirect, Scopus, JSTOR, and Web of Science.

RESULTS

Popular Aizoaceae genera including Mesembryanthemum, Trianthema, and Tetragonia are noted for their cultural value and are key components in herbal medicines for the treatment of a myriad of disorders. Isolated bioactive compounds isolated from selected species demonstrated varied antimicrobial, antioxidant, and neuroprotective functions in basic pharmacological studies. However, most studies lacked reliable correlation to in vivo activity and did not adequately validate the safety and efficacy of potential therapeutic compounds.

CONCLUSIONS

While the cultural and therapeutic value of popular Aizoaceae species have been highlighted in the literature, there remains glaring inconsistencies among other related species. Data deficiency may be ameliorated by further studies focused on taxonomic markers, chemical characterization and underlying molecular mechanisms of activity of a wider pool of species to enhance our knowledge of this hyperdiverse family.

Cytotoxicity and antimicrobial activity of isolated compounds from Monsonia angustifolia and Dodonaea angustifolia

ETHNOPHARMACOLOGICAL RELEVANCE

Monsonia angustifolia is traditionally used to treat anthrax, heartburn, diarrhea, eye infections and hemorrhoids. Dodonaea angustifolia is frequently used as a treatment for dental pain, microbial infections and jungle fever. The two plant species were selected due to the presence of secondary metabolites such as coumarins, flavonoids, terpenoids, saponins and polyphenolics from the crude extracts, which exhibit pharmacological significance. The pure isolated compounds from the crude extracts are known for their diverse structures and interesting pharmacophores.

AIM

To isolate and identify antibacterial and antifungal chemical constituents from Monsonia angustifolia and Dodonaea angustifolia plant extracts and evaluate the cytotoxicity of pure compounds from the crude extracts.

MATERIALS AND METHODS

Extractives from M. angustifolia and D. angustifolia plants were isolated using chromatographic techniques and structures were elucidated based on NMR, IR and MS spectroscopic techniques. A microplate serial dilution method was used to evaluate the antibacterial activity of extracts and pure compounds against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and antifungal activity against Candida albicans and Cryptococcus neoformans. The cytotoxicity was determined using the 3-(4, 5-dimethylthiazol)-2, 5-diphenyl tetrazolium bromide (MTT) assay.

RESULTS

The dichloromethane, ethyl acetate and methanol crude extracts from the plants exhibited significant inhibition of microbial growth. The phytochemical investigation of these active crude extracts led to the isolation of five pure active compounds, 5-methoxyjusticidin A (1), cis-phytyl diterpenoidal fatty acid ester (2), stigmasterol (3), β-sitosterol (4) and 5-hydroxy-7,4'-dimethoxyflavone (5). Stigmasterol (3) showed good antifungal activity against Cryptococcus neoformans with a minimum inhibition concentration (MIC) of 25 μg/mL and Candida albicans (MIC = 50 μg/mL).

CONCLUSION

Compounds (1-5) isolated from Monsonia angustifolia and Dodonaea angustifolia showed antibacterial and antifungal activities and were non-toxic against Madin-Darby canine kidney (MDCK) cells and VERO monkey kidney (VERO) cells.

Digestive and gastroprotective effects of Achillea erba-rotta subsp. moschata (Wulfen) I.Richardson (syn. A. moschata Wulfen) (Asteraceae): From traditional uses to preclinical studies

ETHNOPHARMACOLOGICAL RELEVANCE

Achillea erba-rotta subsp. moschata (Wulfen) I.Richardson (syn. A. moschata Wulfen) (Asteraceae) is an alpine endemic plant whose aerial parts are harvested by the locals mainly for the digestive properties. Despite its widespread use, few studies have been conducted to date to verify its bioactivity.

AIM OF THE STUDY

The purpose of the work was to meet the tradition confirming with experimental data the popular belief that the consumption of this species offers beneficial effects to the gastrointestinal system.

MATERIALS AND METHODS

Using Soxhlet apparatus, the dried aerial parts of A. erba-rotta subsp. moschata were successively extracted with petroleum ether (PET), dichloromethane (DCM) and methanol (MeOH). The essential oil (EO) was obtained by hydrodistillation using a Clevenger apparatus while infusion (AE) was prepared following the traditional local recipe. Their chemical characterization was performed by various techniques including SPME-GC/MS, GC/MS and HPLC/MS-MS. An in vitro biological screening was carried out. The influence of AE on lipid digestion was monitored by titration of free fatty acids (FFA) during pancreatic lipase activity with the pH-stat method. For all extracts and EO, the anti-Helicobacter pylori activity was assessed by the broth microdilution method, the influence on cell viability was evaluated against NCI-N87, OE21 and Caco-2 cell lines and a preliminary toxicity evaluation was done using Brine Shrimp lethality (BSL) assay. The anti-inflammatory potential was evidenced by interleukin IL-1- induced IL8 expression on Caco-2 cells.

RESULTS

AE increased by 15% the FFA releasing compared to the pancreatic lipase alone. PET, DCM and MeOH extracts as well as AE and EO were considered active against the growth of both antimicrobial susceptible and resistant strains of H. pylori with MIC values starting from 16 μg/mL. PET and DCM (IC₅₀ = 89 μg/mL and 96 μg/mL, respectively, against Caco-2 cell line) extracts showed the high effect on cell viability while the EO reduced in 50% of cell viability at 1.48 μL/mL (NCI-N87 cells), 1.42 μL/mL (OE21 cells), and 3.44 μL/mL (Caco-2 cells) corroborating the BSL results. In different degrees, all extracts and EO inhibited the IL-1β-stimulated IL-8 production in Caco-2 cells.

CONCLUSIONS

The obtained data are encouraging and provide a scientific basis for the traditional use of A. erba-rotta subsp. moschata as a digestive agent although they need to be further corroborated by studies involving the investigation of both the in vivo activities and the role of the compounds detected in the extracts.

Cytotoxicity of Cymbopogon citratus (DC) Stapf fractions, essential oil, citral, and geraniol in human leukocytes and erythrocytes

ETHNOPHARMACOLOGY RELEVANCE

Our recently published paper demonstrated that ethyl acetate fractions obtained from Cymbopogon citratus (DC.) Stapf (C. citratus) leaves, which are consumed as infusion in folk medicine due to their therapeutic properties, are rich in polyphenols and exhibit promising antioxidant activity by acting through different mechanisms in vitro. However, studies regarding the toxicity of these fractions are necessary to investigate their safe use in future biomedical applications.

AIM OF THE STUDY

This study aimed to investigate the toxicity of ethyl acetate (obtained in acidic and basic conditions and after the essential oil removal from the leaves) and chloroform fractions, essential oil, and its pure constituents, citral and geraniol.

MATERIALS AND METHODS

The toxicity of C. citratus samples was evaluated by using Artemia salina (A. salina) and human blood cells (leukocytes and erythrocytes).

RESULTS

The A. salina lethality assay demonstrated that C. citratus fractions were moderately toxic with LC₅₀ values ranging from 146.12 to 433.15 μg mL^-1, whereas the essential oil and isolated compounds were highly toxic with LC₅₀ lower than 100 μg mL^-1. Leukocyte viability decreased after incubation in the presence of the fractions obtained after the essential oil removal from the plant leaves, as well as in the presence of essential oil, citral and geraniol. The same samples increased the osmotic fragility of erythrocytes, and field emission gun scanning electron microscopy (FESEM) analysis revealed significant changes in cell morphology. Interestingly, our results suggest that the previous removal of essential oil from plant leaves facilitated the extraction of cytotoxic compounds from C. citratus.

CONCLUSIONS

It was demonstrated that C. citratus ethyl acetate and chloroform fractions, essential oil, as well citral and geraniol were considered toxic to A. salina, cytotoxic to human blood cells and showed to induce alterations in the erythrocyte membrane at higher concentrations. These fractions will be further investigated to identify the phytochemicals involved in the observed cytotoxic effects and explored using in vivo models.

Qualitative and quantitative phytochemical composition, antimicrobial activity, and brine shrimp cytotoxicity of different solvent extracts of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans

Background

The root, root bark, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans are used for managing bacterial and fungal infections among the Luo community of Kisumu East Sub County in Kenya. However, data on the efficacy of these plants against common bacterial and fungal pathogens is not available. The safety of these plants is also not known. This study aimed to investigate the phytochemical composition, antimicrobial properties, and safety of different solvent extracts of the roots, root barks, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans. The broth microdilution method evaluated the antimicrobial activities of the root, root bark, and root tuber extracts (water, acetone, and methanol) of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans. Gram-positive (Bacillus cereus, Staphylococcus aureus), gram-negative (Escherichia coli), and fungal (Candida albicans) microorganisms were used in the evaluation. The safety of the extracts was evaluated in Artemia salina. The phytochemical composition of the extracts was determined using qualitative and quantitative assays.

Results

In general, the extracts of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans displayed poor antimicrobial properties relative to conventional antimicrobial agents including Amoxicillin, Gentamicin, and Nystatin. The aqueous extract of Acanthus polystachyus and the aqueous, acetone, and methanol extracts of Keetia gueinzii were safe in Artemia salina but all other extracts were cytotoxic to Artemia salina.

Conclusions

These findings suggest that the use of the roots, root barks, and root tubers of Acanthus polystachyus, Keetia gueinzii, and Rhynchosia elegans is limited by poor antimicrobial efficacy and cytotoxicity.

The Botanical, Chemical and Ethnobotanical Diversity of Southern African Lamiaceae

The Lamiaceae is undoubtedly an important plant family, having a rich history of use that spans the globe with many species being used in folk medicine and modern industries alike. Their ability to produce aromatic volatile oils has made them valuable sources of materials in the cosmetic, culinary, and pharmaceutical industries. A thorough account of the taxonomic diversity, chemistry and ethnobotany is lacking for southern African Lamiaceae, which feature some of the region’s most notable medicinal and edible plant species. We provide a comprehensive insight into the Lamiaceae flora of southern Africa, comprising 297 species in 42 genera, 105 of which are endemic to the subcontinent. We further explore the medicinal and traditional uses, where all genera with documented uses are covered for the region. A broad review of the chemistry of southern African Lamiaceae is presented, noting that only 101 species (34%) have been investigated chemically (either their volatile oils or phytochemical characterization of secondary metabolites), thus presenting many and varied opportunities for further studies. The main aim of our study was therefore to present an up-to-date account of the botany, chemistry and traditional uses of the family in southern Africa, and to identify obvious knowledge gaps.

Antimicrobials from Medicinal Plants: An Emergent Strategy to Control Oral Biofilms

Oral microbial biofilms, directly related to oral diseases, particularly caries and periodontitis, exhibit virulence factors that include acidification of the oral microenvironment and the formation of biofilm enriched with exopolysaccharides, characteristics and common mechanisms that, ultimately, justify the increase in antibiotics resistance. In this line, the search for natural products, mainly obtained through plants, and derived compounds with bioactive potential, endorse unique biological properties in the prevention of colonization, adhesion, and growth of oral bacteria. The present review aims to provide a critical and comprehensive view of the in vitro antibiofilm activity of various medicinal plants, revealing numerous species with antimicrobial properties, among which, twenty-four with biofilm inhibition/reduction percentages greater than 95%. In particular, the essential oils of Cymbopogon citratus (DC.) Stapf and Lippia alba (Mill.) seem to be the most promising in fighting microbial biofilm in Streptococcus mutans, given their high capacity to reduce biofilm at low concentrations.

Latex proteins from Plumeria pudica reduce ligature-induced periodontitis in rats

BACKGROUND

Previous studies have shown that latex proteins from Plumeria pudica (LPPp) have anti-inflammatory and antioxidant activity. Therefore, the aim of this study was to evaluate the effects in rats of LPPp on ligature-induced periodontitis, an inflammatory disease.

METHODS

The animals were divided into groups: saline (animals without induction of periodontitis), periodontitis (induced periodontitis and untreated) and LPPp (induced periodontitis and treated with 40 mg/kg). The following parameters were evaluated after 20 consecutive days of treatment: gingival bleeding index (GBI), probing pocket depth (PPD), alveolar bone height (ABH) and gingival myeloperoxidase (MPO) activity. In the hepatic tissue, malondialdehyde (MDA), glutathione (GSH) and histopathological alterations were evaluated. Blood levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured.

RESULTS

Significant reduction in GBI, PPD and gingival MPO activity and ABH was seen in animals treated with LPPp compared with periodontitis. Values of GSH, MDA, ALT and histopathological evaluation were preserved in animals treated with LPPp.

CONCLUSIONS

Treatment with LPPp improved clinical aspects of periodontitis, reduced the blood and hepatic alterations and prevented alveolar bone loss. Data suggest that LPPp have potential for treatment of periodontitis.

Ethnomedicinal uses, biological activities, phytochemistry and conservation of African ginger (Siphonochilus aethiopicus): A commercially important and endangered medicinal plant

ETHNOPHARMACOLOGICAL RELEVANCE

In sub-Saharan Africa, African ginger (Siphonochilus aethiopicus) is used for treating common illnesses including colds, coughs, inflammation and related symptoms. The available literature survey on this plant provided scarce anecdotal information, particularly in western and eastern Africa, with a few reports on its bioactivity. In addition, the indigenous knowledge and conservation strategies of this economically important and critically endangered species are currently fragmented.

AIM OF THE REVIEW

This review entails a critical appraisal of existing literature on the ethnomedicinal uses, biological activities, phytochemicals, research opportunities and prospects for the sustainable use of S. aethiopicus.

MATERIALS AND METHODS

This review was conducted using a comprehensive literature search on the ethnomedicinal uses, biological activities and phytochemistry of S. aethiopicus throughout its distributional range. The conservation status and associated bio-economy potential of African ginger were also assessed. We searched different online databases (e.g. Google Scholar, ScienceDirect, PubMed and Scopus) for peer-reviewed journals, conference outputs, international, regional and national organizational reports, published books and theses.

RESULTS

We established that S. aethiopicus is used to treat a wide variety of ailments such as respiratory problems (including cough, influenza), pain, inflammation and malaria. Extracts of African ginger are used as an ingredient in some commercialised products for nutraceutical, cosmeceutical and pharmaceutical purposes. The rhizome extract demonstrated anti-asthmatic, anti-inflammatory, and antiplasmodial activities, which led to the development of a patented novel extract for treating asthma and allergies. Phytochemical analysis of leaf, root and rhizome extracts of African ginger revealed the presence of flavonoids, phenolic acids, volatile and essential oils as the major constituents. These phytochemicals are known to possess bioactivities such as antimicrobial and anti-inflammatory activities. Particularly, the bioactive compounds, siphonochilone and eucalyptol, found in the roots and rhizomes have demonstrated potential to be used in remedies for treating asthma and allergic reactions. Furthermore, extracts of S. aethiopicus contained natural anti-inflammatory mediators with potential to combat and manage chronic inflammation. This plant is classified on the Red List of South African Plants as a critically endangered plant. Its high risk of extinction due to its unsustainable harvesting and exploitation necessitates its rapid propagation and cultivation to meet its increasing demand.

CONCLUSIONS

The review highlights the therapeutic potential of S. aethiopicus and rational prioritization of this plant species with the potential for isolating new bioactive compounds. In the light of the use of this plant extract in traditional medicine and many commercial products, there is a heightened need to explore the mechanism(s) of action of the identified extracts and bioactive compounds in order to fully understand their pharmacokinetics and probably elucidate the pathways of their activities.

African Plant-Based Natural Products with Antivirulence Activities to the Rescue of Antibiotics

The worldwide emergence of antibiotic-resistant bacteria and the thread of widespread superbug infections have led researchers to constantly look for novel effective antimicrobial agents. Within the past two decades, there has been an increase in studies attempting to discover molecules with innovative properties against pathogenic bacteria, notably by disrupting mechanisms of bacterial virulence and/or biofilm formation which are both regulated by the cell-to-cell communication mechanism called ‘quorum sensing’ (QS). Certainly, targeting the virulence of bacteria and their capacity to form biofilms, without affecting their viability, may contribute to reduce their pathogenicity, allowing sufficient time for an immune response to infection and a reduction in the use of antibiotics. African plants, through their huge biodiversity, present a considerable reservoir of secondary metabolites with a very broad spectrum of biological activities, a potential source of natural products targeting such non-microbicidal mechanisms. The present paper aims to provide an overview on two main aspects: (i) succinct presentation of bacterial virulence and biofilm formation as well as their entanglement through QS mechanisms and (ii) detailed reports on African plant extracts and isolated compounds with antivirulence properties against particular pathogenic bacteria.

Antibacterial Activity of Prunus Scoparia Root Methanol Extract against Most Common Burn Wound Pathogens

BACKGROUND

Burn wound infection and sepsis are serious medical conditions requiring prompt intervention. Plants are a good natural source for the development of novel, safe, and cost-effective antibacterial agents. The objective of the present study was to assess the antibacterial potential of aqueous, chloroform, and methanol extracts of the Prunus scoparia (P. scoparia) root against the most common burn wound pathogens.

METHODS

The present experimental study was conducted at Shiraz University of Medical Sciences (Shiraz, Iran) during 2018-2019. The antibacterial activity of the total plant extract was assayed using the broth microdilution method. Fractionation was performed using a separation funnel and solvents with different polarities. Broth microdilution and agar well diffusion assays were performed to determine the antibacterial potential of the obtained fractions. Quantitative and qualitative phytochemical analyses were performed to confirm the presence of secondary metabolites in both the total extract and the fractions.

RESULTS

Methanolic extract of P. scoparia root exhibited antibacterial activity against all tested bacterial strains, especially against Methicillin-resistant Staphylococcus aureus (MRSA) isolates. This extract, compared to the aqueous and chloroformic extracts, exhibited the presence of active antibacterial compounds. The quantitative and qualitative results of phytochemical screening showed that phenols and flavonoids were the main antibacterial compounds in the methanolic extract of the plant.

CONCLUSION

For the first time, we demonstrated the antibacterial activity of the P. scoparia root against MRSA isolates and other common burn wound pathogens.

Ethnopharmacology, Therapeutic Properties and Nutritional Potentials of Carpobrotus edulis: A Comprehensive Review

Carpobrotus edulis, formerly known as Mesembryanthemum edule L, belongs to the Aizoaceae family of plants. It is a facultative halophytic invasive medicinal and edible succulent plant that is native to South Africa and is distributed worldwide. Hitherto, this plant appears to be mainly known for its ornamental use in decorations, soil stabilization, and erosion control, and not for its many potential medicinal and nutritional benefits, thus suggesting its underutilization. This review presents cogent and comprehensive information on the distribution, ethnomedicinal use, phytochemistry, pharmacology, toxicology, and nutritional value of Carpobrotus edulis and provides the rationale for further pharmacognostic research that will validate its many folkloric medicinal and nutraceutical claims, and promote its standardization into a commercially available product. The reported traditional use of this plant for the treatment of sinusitis, diarrhoea, tuberculosis, infantile eczema, fungal and bacterial infections, oral and vaginal thrush, high blood pressure, diabetes, wound infections, spider and tick bites, sore throat as well as mouth infections are well documented. Its therapeutic activities such as anti-proliferative, antioxidant, antifungal, antibacterial, antidiabetic, anti-inflammatory, cytotoxicity, and nutritional value have also been reported to be attributable to the array of phytoconstituents present in the plant. These have promoted renewed research interests into this valuable medicinal plant with a view to repositioning and expanding its uses from the current predominantly ornamental and environmental management role to include phytotherapeutical applications through scientific validation studies that will improve its value for the drug discovery process as well as its contribution to food security.

Ethnopharmacological importance and medical applications of Myrothamnus flabellifolius Welw. (Myrothamnaceae)-A review

ETHNOPHARMACOLOGICAL RELEVANCE

Myrothamnus flabellifolius Welw. (resurrection plant) is a desiccant-tolerant, woody, and shrubby plant. It is popularly used as a local medicinal herbal tea in South Africa, other Southern Africa nations, and Central Africa. M. flabellifolius is used in treating several ailments including epilepsy, mental disorder, cough, pain, stroke, shingles, diabetes, hypertension, wounds, asthma, kidneys and chest ailments.

AIM OF THIS REVIEW

This review focuses on the botanical description, distribution, conservation status, ethnobotany, chemistry and pharmacological properties of M. flabellifolius to spur further research that will promote its sustainable harvesting and commercialization.

MATERIAL AND METHODS

A literature search on diverse scientific databases, including Google, Google Scholar, Science Direct, PubMed, Scopus, theses, dissertations and ethnobotanical textbooks, were conducted.

RESULTS

The conducted search reveals that M. flabellifolius has many traditional uses that can be categorized into infectious diseases, Well-being, respiratory, inflammation, wound and kidney ailments. M. flabellifolius is a natural caffeine-free medicinal herbal tea reported to have antioxidant, anticancer, antiviral, antidiabetic and antimicrobial properties. Toxicological tests on M. flabellifolius were found scarce with gaps in genotoxicological and in vivo studies. Essential oils and isolated compounds were identified from M. flabellifolius with biological activities such as anticancer, antiinflammation, antimicrobial, antiarthritic, antiulcer, antioxidant and antiviral properties.

CONCLUSION

It is envisaged that the current review will add value to more scientific research on M. flabellifolius and enhance/promote the increased interest in the sustainable commercialization of M. flabellifolius herbal tea as well as lead to the validation of unverified ethnobotanical claims.

Ziziphus mucronata Willd. (Rhamnaceae): it's botany, toxicity, phytochemistry and pharmacological activities

Ziziphus mucronata is an important multi-purpose plant species that has been used in African traditional medicine for ages in the treatment of various devastating human and animal infections. The current paper is aimed at providing an overview of uses, toxicology, pharmacological properties and phytochemistry of Z. mucronata. The information used in the current work was retrieved using various search engines, including Pubmed, Science Direct, Google Scholar, Scielo, SciFinder and Scopus. The key words used included Ziziphus mucronata, secondary metabolites, chemistry, biological activity and pharmacology, anti-inflammatory, antimicrobial, antifungal, antiviral, ethnobotanical survey, medicinal uses, safety, toxicology and other related words. Out of the 46 infections which the plant species is used to treat, the most common uses includes sexually transmitted infections, skin infections, diarrhoea and dysentery, respiratory and chest complaints and gynaecological complaints (citations ≥6). Pharmacologically, the plant species exhibited a potential antimicrobial activity yielding a minimum inhibitory concentration of <1 mg/ml against important pathogens which includes Mycobacterium tuberculosis, Moraxella catarrhalis, Staphylococcus aureus, Escherichia coli, Propionibacterium acnes, Candida albicans, Cryptoccoos neoformans amongst other microorganisms. Furthermore, the extracts and compounds from Z mucronata revealed potent antiviral, antioxidant, anti-inflammatory and other activities in vitro. Phytochemically, cyclo-peptide alkaloids (commonly called mucronines) dominates and in conjunction with triterpenes, flavonoids, phenolic acids and anthocyanins. Besides these compounds, the plant species exhibited the presence of important in minerals. These phytoconstituents may well explain the reported biological activities. Although the extracts revealed no cytotoxic effect to Vero cells, further toxicological characteristics of the plant species still needs to be explored. There is also a need to carry out the comprehensive safety profiles of the plant species, including heavy metal detection. Although the plant species revealed important biological activities, which includes antimicrobial, antiviral, anti-diabetic, anti-inflammatory, anti-oxidant, anti-plasmodial, anthelmintic, and anti-anaemic activity in vitro, further research is needed to explore the in vivo studies, other compounds responsible for such activities and the mechanisms of action thereof. Such activities validates the use of the plant species in traditional medicine. The data on the possible use of the plant species in the treatment of diarrhoea, sexually transmitted infections, skin related and gynaecological complaints are scant and still needs to be explored and validated both in vitro and in vivo. Furthermore, the anticancer and anthelmintic activity of the plant species also needs to be explored.

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.

Management of Streptococcus mutans-Candida spp. Oral Biofilms' Infections: Paving the Way for Effective Clinical Interventions

Oral diseases are considered the most common noncommunicable diseases and are related to serious local and systemic disorders. Oral pathogens can grow and spread in the oral mucosae and frequently in biomaterials (e.g., dentures or prostheses) under polymicrobial biofilms, leading to several disorders such as dental caries and periodontal disease. Biofilms harbor a complex array of interacting microbes, increasingly unapproachable to antimicrobials and with dynamic processes key to disease pathogenicity, which partially explain the gradual loss of response towards conventional therapeutic regimens. New drugs (synthesized and natural) and other therapies that have revealed promising results for the treatment or control of these mixed biofilms are presented and discussed here. A structured search of bibliographic databases was applied to include recent research. There are several promising new approaches in the treatment of Candida spp.-Streptococcus mutans oral mixed biofilms that could be clinically applied in the near future. These findings confirm the importance of developing effective therapies for oral Candida-bacterial infections.

Efficacy and Mechanism of Traditional Medicinal Plants and Bioactive Compounds against Clinically Important Pathogens

Traditional medicinal plants have been cultivated to treat various human illnesses and avert numerous infectious diseases. They display an extensive range of beneficial pharmacological and health effects for humans. These plants generally synthesize a diverse range of bioactive compounds which have been established to be potent antimicrobial agents against a wide range of pathogenic organisms. Various research studies have demonstrated the antimicrobial activity of traditional plants scientifically or experimentally measured with reports on pathogenic microorganisms resistant to antimicrobials. The antimicrobial activity of medicinal plants or their bioactive compounds arising from several functional activities may be capable of inhibiting virulence factors as well as targeting microbial cells. Some bioactive compounds derived from traditional plants manifest the ability to reverse antibiotic resistance and improve synergetic action with current antibiotic agents. Therefore, the advancement of bioactive-based pharmacological agents can be an auspicious method for treating antibiotic-resistant infections. This review considers the functional and molecular roles of medicinal plants and their bioactive compounds, focusing typically on their antimicrobial activities against clinically important pathogens.

Are plants used in the Eastern Cape province for cosmetics fully commercialized?

Plants have been used for years for various cosmetic purposes. In the Eastern Cape province of South Africa, a large proportion of the population reliant (to some extent) on botanical resources for beauty and health. Despite the use of these botanical resources for various cosmetic purposes, only a few have been fully commercialized or used as ingredients in cosmetic formulation. The present study aimed to review plant species that are fully explored commercially for cosmetic products in the Eastern Cape province. A survey of cosmetic products with plant-based ingredients was done covering the major supermarkets (SPAR, Shoprite, and Pick n Pay), cosmetic shops (Clicks), and pharmacies in the Eastern Cape province, and electronic databases including Embase, Google Scholar, Medline, PubMed, Scopus, SciFinder^®, Springer, Science Direct, and Web of Science were used as data sources for ethnobotanical information. Surprisingly, out of 150 plant species used by both Xhosa men and women for various cosmeceutical purposes, only six plant species have been used commercially with regard to cosmeceutical application. These plants species belong to five major plant families, namely Lamiaceae (two species), Asphodelaceae (one species) Cucurbitaceae (one species), Oleaceae (one species), and Verbenaceae (one species). The findings revealed that the use of Eastern Cape plants for cosmetic purposes has not been fully explored commercially. Thus, there is a need for cosmeceutical industries to explore these species commercially in order to develop new possible cosmetic products for local and international markets.

Plant-Derived Bioactives in Oral Mucosal Lesions: A Key Emphasis to Curcumin, Lycopene, Chamomile, Aloe vera, Green Tea and Coffee Properties

Oral mucosal lesions have many etiologies, including viral or bacterial infections, local trauma or irritation, systemic disorders, and even excessive alcohol and tobacco consumption. Folk knowledge on medicinal plants and phytochemicals in the treatment of oral mucosal lesions has gained special attention among the scientific community. Thus, this review aims to provide a brief overview on the traditional knowledge of plants in the treatment of oral mucosal lesions. This review was carried out consulting reports between 2008 and 2018 of PubMed (Medline), Web of Science, Embase, Scopus, Cochrane Database, Science Direct, and Google Scholar. The chosen keywords were plant, phytochemical, oral mucosa, leukoplakia, oral lichen planus and oral health. A special emphasis was given to certain plants (e.g., chamomile, Aloe vera, green tea, and coffea) and plant-derived bioactives (e.g., curcumin, lycopene) with anti-oral mucosal lesion activity. Finally, preclinical (in vitro and in vivo) and clinical studies examining both the safety and efficacy of medicinal plants and their derived phytochemicals were also carefully addressed.

Preliminary Phytochemical Analysis of Berberis goudotii Triana & Planch. ex Wedd. (Berberidaceae) with Anticariogenic and Antiperiodontal Activities

Berberis goudotii is an endemic Colombian plant found in the paramo ecosystem. It has been used in food preparation and as a medicinal plant for diverse treatments. Additionally, it is used as a mouthwash to strengthen the gums and combat throat irritations and periodontitis. The present research evaluated Berberis goudotii aerial parts extract and fractions antimicrobial activities. Ultrasonic-assisted extraction was used to attain total ethanol-water extract. Solid-liquid fractionation was used to obtain hexane fraction. The residue was dispersed in water and liquid-liquid fractionation was carried-out to acquire dichloromethane, butanol and water fractions. Preliminary phytochemical analysis was performed on total extract and phenol, polyphenol, flavonoid, and proanthocyanidin, while tannin content was quantified. Antimicrobial activity assessment was performed by agar diffusion method using disks and wells employing Ceftazidime as a positive control against Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus casei, Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum. Antimicrobial activity was determined as relative percentage inhibition (RPI), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Phenols (92.5 ± 7.7 mg GA/10 g), polyphenols (87.7 ± 8.1 mg PG/10 g) and tannins (44.1 ± 4.3 mg PG/10 g) were among the highest secondary metabolites observed. Total extract presented an MBC of 1.0 µg/µL against cariogenic bacteria (Streptococcus mutans and Streptococcus sobrinus) and 0.12 µg/µL against bacteria associated with periodontal disease (Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum). Butanol and hexane fractions showed antiperiodontal activity with MBC of 0.12 and 1.0 µg/µL, respectively. In conclusion, Berberis goudotii total extract demonstrated antimicrobial activity against cariogenic and periodontal microorganisms, on the other hand, hexane and butanol fractions displayed antiperiodontal activity.

Investigation into the Thermal Response and Pharmacological Activity of Substituted Schiff Bases on α-Amylase and α-Glucosidase

The emphasis of previous studies has targeted the development of insulin mimic with little attention given to the development of metabolic enzyme inhibitors. Our focus is to synthesise nine o-hydroxy and p-nitro-azomethine analogues, investigate their digestive enzyme inhibitory capacity, as well as the antioxidant and antimicrobial activities. The substituted Schiff bases were analysed using thermal gravimetric analyser (TGA), X-ray diffractometer (XRD), nuclear magnetic resonance spectroscopy (NMR), elemental analyser, and Fourier-transform infrared spectroscopy (FT-IR). Determination of synthetic yield revealed that the o-hydroxy analogues produced the highest yield of ≥77.1% compared to p-nitro and unsubstituted analogues. Spectra study showed the presence of azomethine stretching vibration at 1698⁻1613 cm^-1, proton signals at δ 8.46⁻9.81, and carbon signals at δ 145.95⁻159.53 ppm. Investigation into the thermal property indicated an elevated melting point for the o-hydroxy analogue, compared to the p-nitro derivative which showed high stability to heat. There are similarities in crystalline structure with few unique patterns suggesting different substituent group. The antioxidant activities of the substituted analogues registered low half maximal inhibitory concentration (IC₅₀), with exception to the ferric reducing power; indicating that the Schiff bases are weak siderophores. All nine Schiff bases were bacteriostatic or fungistatic at the screened concentrations; however, the nitro-substituted analogues have an enhanced activity with Minimum Inhibitory Concentration (MIC) values of 0.03⁻2.54 µM. Both o-hydroxy and p-nitro-substitution does not improve the antifungal activity of the compounds against A. niger. The o-hydroxyl and p-nitro Schiff base derivatives showed enhanced activity towards the inhibition of α -amylase and α-glucosidase by hydroxylation and glycosylation, respectively. Although, hydroxy derivatives of sulphonic acid derived Schiff base slightly decreased the activities on α-glucosidase and α-amylase. Our findings suggest that p-nitro substitution enhances the in vitro nonenzymatic activity while the o-hydroxy derivatives are good hydrolase inhibitors. Therefore, substituent modification can be used as an enhancement technique in designing novel pharmacophore.