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(searched for: doi:10.1016/j.jep.2017.09.002)
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Zenande K.S. Mcotshana, Lyndy J. McGaw, Douglas Kemboi, Gerda Fouche, Ibukun M. Famuyide, Rui W.M. Krause, Xavier Siwe-Noundou, Vuyelwa Jacqueline Tembu
Published: 1 January 2023
Journal of Ethnopharmacology, Volume 301; https://doi.org/10.1016/j.jep.2022.115170

Mildred A. Chauke, Motetelo A. Mogale, Ladislaus K. Mdee,
Journal of Medicinal Plants for Economic Development, Volume 6; https://doi.org/10.4102/jomped.v6i1.149

Abstract:
Background: The search for bioactive organic products for the treatment of various diseases is a growing concern worldwide, because these bioactive natural products are associated with fewer side effects and are easily accessible.Aim: The present study analysed the phytochemical constituents and cytotoxic effects of the leaf, bark and fruit extracts of Cordia grandicalyx Oberm.Setting: Plant samples were collected from Ga-Mashishimale village in Ba-Phalaborwa Municipality, South Africa.Methods: Antioxidant activity was determined through 1,1-diphenyl-2-picrylhydrazyl radical scavenging method, whilst cytotoxic assay was assessed using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide method. Plant extracts were subjected to phytochemical profiling using both qualitative and quantitative methods. The extracts were also subjected to fractionation using column chromatography and thin-layer chromatography, and the sub-fractions with considerable yields were identified using nuclear magnetic resonance (NMR).Results: The aqueous extracts of the bark and leaves had significant (p 0.001) antioxidant activity as compared to negative controls and ascorbic acid. Additionally, appreciable amounts of total phenolic and alkaloid contents were recorded on polar extracts, notably 200 mg/GAE and 140 mg/quercetin equivalents for leaf cold water and leaf hot water extracts, respectively. All extracts were not toxic to cells, whilst the positive control (H2O2) led to almost 100% demise of cells. Two compounds were isolated from the leaf acetone extracts collected from fraction 20 to 30 and fraction 101 to 120 and identified as α˗amyrin and β-amyrin by NMR spectral analysis.Conclusion: The study provided evidence supporting the screening of plants for the discovery of therapeutic compounds. The study also revealed that all the different C. grandicalyx extracts were less toxic to cells and may provide scientific backing for continued use of the plant in mixtures for the treatment of diseases.
, Joseph Mwanzia Nguta, James Mucunu Mbaria, Mitchel Otieno Okumu
Published: 28 September 2021
Future Journal of Pharmaceutical Sciences, Volume 7, pp 1-11; https://doi.org/10.1186/s43094-021-00342-z

Abstract:
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.
Published: 18 June 2021
by MDPI
Journal: Molecules
Abstract:
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.
Published: 28 April 2021
by MDPI
Journal: Applied Sciences
Applied Sciences, Volume 11; https://doi.org/10.3390/app11094020

Abstract:
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.
Lucas E. S. Oliveira, Lucas A. Moita, Bruna S. Souza, Naylla M. V. Oliveira, Ana C. S. Sales, Mayck S. Barbosa, Francisca D. S. Silva, Alan L. C. Farias, Victor L. R. Lopes, Luiz F. C. França, et al.
Published: 23 February 2021
Journal: Oral Diseases
Oral Diseases, Volume 28, pp 786-795; https://doi.org/10.1111/odi.13803

Abstract:
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. 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. Significant reduction of GBI, PPD and gingival MPO activity and ABH was seen in animals treated with LPPp compared to periodontitis. Values of GSH, MDA, ALT and histopathological evaluation were preserved in animals treated with LPPp. 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.
Published: 19 November 2020
by MDPI
Journal: Antibiotics
Abstract:
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.
Salmon A. Adebayo, , Salmina N. Mokgehle, Adeyemi O. Aremu
Published: 8 October 2020
Journal of Ethnopharmacology, Volume 266; https://doi.org/10.1016/j.jep.2020.113459

Abstract:
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 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 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 potentials 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 necessitate 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.
Fekade Beshah, Yilma Hunde, Mesfin Getachew, , , Archana Bachheti
Published: 1 October 2020
Current Research in Biotechnology, Volume 2, pp 103-119; https://doi.org/10.1016/j.crbiot.2020.09.002

The publisher has not yet granted permission to display this abstract.
Published: 16 September 2020
by MDPI
Scientia Pharmaceutica, Volume 88; https://doi.org/10.3390/scipharm88030039

Abstract:
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.
, Priscila Do N. Bezerra, , Wanessa A. da Costa, Gracialda C. Ferreira, Raul N. de Carvalho
Current Bioactive Compounds, Volume 16, pp 383-393; https://doi.org/10.2174/1573407215666181122103511

Abstract:
Background: Croton species are widely spread around the world, and present a varied chemical composition distributed in many classes of secondary metabolites, such as terpenoides, alkaloids, phenolic compounds and phenylpropanoids. These compounds can be obtained by different extraction methods, and more recently, with supercritical fluids. The crude and isolated extracts may have applications due to their biological activities in animals and humans. Methods: The text was written based on literature data from 1996 onwards. Results: The research showed in a concise way the botanical and taxonomic aspects of Croton and the success of its application is in studies related to the biological activities of the plant parts. It was also related to the chemical composition of its extracts and isolated compounds, obtained by many methods. Conclusion: In summary, the review feature studies reported the use of extracts and isolated Croton compounds due to their biological effects with antioxidant, antimicrobial, anti-inflammatory, neuroprotective, antitumor, anticancer, cytotoxic, insecticidal and allelopathic activities, with potential application in food, cosmetics, pharmaceuticals, and agrochemicals products.
Johnatan Wellisson Da Silva Mendes, Walmir Emanuel Miranda Cunha, Fábio Fernandes Galvão Rodrigues, Edilberto Rocha Silveira, Roberta Dávila Pereira De Lima,
Published: 8 June 2020
Phytochemistry Reviews, Volume 19, pp 1-28; https://doi.org/10.1007/s11101-020-09695-4

The publisher has not yet granted permission to display this abstract.
N.I. Mongalo, S.S. Mashele,
Published: 1 April 2020
Journal: Heliyon
Abstract:
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.
Published: 14 February 2020
by MDPI
Journal of Clinical Medicine, Volume 9; https://doi.org/10.3390/jcm9020517

Abstract:
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.
Published: 9 December 2019
by MDPI
Journal: Antibiotics
Abstract:
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.
Published: 17 March 2019
by MDPI
Journal: Biomolecules
Biomolecules, Volume 9; https://doi.org/10.3390/biom9030106

Abstract:
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.
Published: 12 January 2019
by MDPI
Scientia Pharmaceutica, Volume 87; https://doi.org/10.3390/scipharm87010002

Abstract:
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.
, Wilfred Otang Mbeng
Published: 1 January 2019
Indian Journal of Pharmacology, Volume 51, pp 140-149; https://doi.org/10.4103/ijp.ijp_262_18

Abstract:
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.
Published: 28 August 2018
by MDPI
Journal: Antioxidants
Antioxidants, Volume 7; https://doi.org/10.3390/antiox7090113

Abstract:
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.
Amir Roointan, , Mohammad Fathalipour, Zohreh Hashemi, Mohammad Mehdi Zarshenas, Mohammad Soleimani,
Published: unknown date
Abstract:
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. 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. 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. For the first time, we demonstrated the antibacterial activity of the P. scoparia root against MRSA isolates and other common burn wound pathogens.
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