The potential of selected South African plants with anti-Klebsiella activity for the treatment and prevention of ankylosing spondylitis

Evaluation of Potential Factors Influencing the Dissemination of Multidrug-Resistant Klebsiella pneumoniae and Alternative Treatment Strategies

The increasing reports of multidrug-resistant Klebsiella pneumoniae have emerged as a public health concern, raising questions about the potential routes for the evolution and dissemination of the pathogenic K. pneumoniae into environmental reservoirs. Potential drivers of the increased incidence of antimicrobial-resistant environmental K. pneumoniae include the eminent global climatic variations as a direct or indirect effect of human activities. The ability of microorganisms to adapt and grow at an exponential rate facilitates the distribution of environmental strains with acquired resistant mutations into water systems, vegetation, and soil which are major intersection points with animals and humans. The bacterial pathogen, K. pneumoniae, is one of the critical-priority pathogens listed by the World Health Organization, mostly associated with hospital-acquired infections. However, the increasing prevalence of pathogenic environmental strains with similar characteristics to clinical-antibiotic-resistant K. pneumoniae isolates is concerning. Considering the eminent impact of global climatic variations in the spread and dissemination of multidrug-resistant bacteria, in this review, we closely assess factors influencing the dissemination of this pathogen resulting in increased interaction with the environment, human beings, and animals. We also look at the recent developments in rapid detection techniques as part of the response measures to improve surveillance and preparedness for potential outbreaks. Furthermore, we discuss alternative treatment strategies that include secondary metabolites such as biosurfactants and plant extracts with high antimicrobial properties.

The genus Alphitonia Reissek ex Endl. (Rhamnaceae): A review of its customary uses, phytochemistry and biological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Alphitonia Reissek ex Endl. is a relatively small genus of the family Rhamnaceae. Plants of this genus are found predominantly in the tropical regions of Southeast Asia, Australia and the Pacific, with some species being widely distributed and others endemic to a region. Almost half of the species of the Alphitonia genus have been reported for their customary (traditional and contemporary) medicinal uses. This includes for the treatment of skin conditions, headache, stomachache, inflammation, and body pain such as joint pain and childbirth.

AIM OF THE REVIEW

The aim of this review is to provide the first comprehensive account on the customary uses including ethnomedicinal uses, and phytochemistry and biological activities of the Alphitonia genus, and to identify gaps in current knowledge and scope for future research of plants of this genus.

MATERIALS AND METHODS

Information relevant to the genus Alphitonia was collected by searching the scientific databases (SciFinder, Google Scholar, ACS publications, PubMed, Wiley Online Library and International Plant name Index). Species names were validated using the World Flora Online database (www.worldfloraonline.org).

RESULTS

Eight plants from the Alphitonia genus have been reported to be used as customary medicines, i.e. A. excelsa, A. ferruginea, A. franguloides, A. incana, A. neocaledonica, A. petriei, A. philippinensis and A. zizyphoides. A. excelsa, A. petriei, A. philippinensis and A. zizyphoides, have been shown to have biological activities that align with their customary uses, including antimicrobial, antioxidant and anti-inflammatory activities. Only five Alphitonia species reported for their medicinal customary uses have been explored for their phytochemistry, i.e. A. excelsa, A. neocaledonica, A. petriei, A. philippinensis and A. zizyphoides. Compounds identified from these plants include those that are well known for their medicinal importance. A. macrocarpa, A. whitei and A. xerocarpus have also been examined for their phytochemistry and have been found to have the same or similar bioactive compounds to those found in customarily used Alphitonia species. No biological activities or phytochemistry studies have been reported for the known customarily used medicinal plants A. ferruginea, A. franguloides and A. incana.

CONCLUSIONS

This review highlights the customary uses, biological activities and phytochemistry of plants of the Alphitonia Reissek ex Endl. genus and highlights the significance of the knowledge systems of Indigenous peoples. Of the plants that have been researched for their biological activities and phytochemistry, there is good correlation with these properties and their customary medicinal uses. However, over half of the plants of the Alphitonia genus, including those that are already reported in the public domain for their customary medicinal uses, have had none or limited biological activities or phytochemistry studies conducted. While only eight species of the Alphitonia genus have been reported as customary medicines, other Alphitonia species also possess medicinally important compounds, and it is possible that they are customary medicines but their uses have not been shared publicly by the Indigenous knowledge custodians. There is clearly much scope for further investigation of this genus with regards to their ethnomedicinal uses and therapeutic potential.

Bacteriospermia and Male Infertility: Role of Oxidative Stress

Male infertility is one of the major challenging and prevalent diseases having diverse etiologies of which bacteriospermia play a significant role. It has been estimated that approximately 15% of all infertility cases are due to infections caused by uropathogens and in most of the cases bacteria are involved in infection and inflammation leading to the development of bacteriospermia. In response to bacterial load, excess infiltration of leukocytes in the urogenital tract occurs and concomitantly generates oxidative stress (OS). Bacteria may induce infertility either by directly interacting with sperm or by generating reactive oxygen species (ROS) and impair sperm parameters such as motility, volume, capacitation, hyperactivation. They may also induce apoptosis leading to sperm death. Acute bacteriospermia is related with another clinical condition called leukocytospermia and both compromise male fertility potential by OS-mediated damage to sperm leading to male infertility. However, bacteriospermia as a clinical condition as well as the mechanism of action remains poorly understood, necessitating further research in order to understand the role of individual bacterial species and their impact in male infertility.

Comparison of the antibacterial activity of Australian Terminalia spp. extracts against Klebsiella pneumoniae: a potential treatment for ankylosing spondylitis

Traditional medicines prepared using Terminalia species have been used globally to treat inflammation and pathogenic infections. Recent studies have demonstrated that multiple Asian and African Terminalia spp. inhibit bacterial triggers of some autoimmune inflammatory diseases, including ankylosing spondylitis. Despite this, the effects of Australian Terminalia spp. on a bacterial trigger of ankylosing spondylitis (K. pneumoniae) remain unexplored. Fifty-five extracts from five Australian Terminalia spp. were investigated for K. pneumoniae growth inhibitory activity. Methanolic, aqueous and ethyl acetate extracts of most species and plant parts inhibited K. pneumoniae growth, with varying potencies. Methanolic leaf extracts were generally the most potent bacterial growth inhibitors, with minimum inhibitory concentration (MIC) values of 66 μg/mL (T. ferdinandiana), 128 μg/mL (T. carpenteriae) and 83 μg/mL (T. petiolares). However, the aqueous leaf extract was the most potent T. grandiflora extract (MIC = 87 μg/mL). All T. catappa extracts displayed low growth inhibitory activity. The Terminalia spp. methanolic leaf extracts were examined by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS). All contained a relative abundance of simple gallotannins (particularly gallic and chebulic acids), the flavonoid luteolin, as well as the monoterpenoids cineole and terpineol. Notably, all Terminalia spp. were non-toxic or of low toxicity in ALA and HDF toxicity assays, highlighting their potential for preventing the onset of ankylosing spondylitis and treating its symptoms once the disease is established, although this needs to be verified in in vivo systems.

Carpobrotus edulis (L.) N.E.Br. extract as a skin preserving agent: From traditional medicine to scientific validation

OBJECTIVE

Carpobrotus edulis (L.) N.E.Br. is a succulent perennial plant native to South Africa and grows invasively in the Mediterranean basin. It is commonly used for the treatment of various diseases, including skin wound healing and regeneration, for which experimental validation is lacking. We therefore evaluated the skin healing properties by testing a C. edulis aqueous leaf extract (CAE) on cell cultures and in enzymatic assays.

METHODS

Micro-morphological analysis of leaves was carried out using scanning electron microscopy and light microscopy. Phytochemical features and antioxidant activity of CAE were evaluated by reversed-phase liquid chromatography coupled with diode array detection and electrospray ion trap mass spectrometry (RP-LC-DAD-ESI-MS), and in vitro cell-free assays. Biological activities were evaluated using keratinocytes and fibroblasts, as well as elastase, collagenase, and hyaluronidase.

RESULTS

CAE showed high carbohydrates (28.59% ± 0.68%), total phenols ([101.9 ± 6.0] g gallic acid equivalents/kg dry extract [DE]), and flavonoids ([545.9 ± 26.0] g rutin equivalents/kg DE). RP-LC-DAD-ESI-MS revealed the predominant presence of hydroxycinnamic acids (51.96%), followed by tannins (14.82%) and flavonols (11.32%). The extract was not cytotoxic, had a strong and dose-dependent antioxidant activity, and inhibited collagenase (> 90% at 500 µg/mL) and hyaluronidase (100% at 1000 µg/mL). In cell culture experiments, CAE increased wound closure and collagen production, which was consistent with its high polyphenol content.

CONCLUSION

Our data support the use of the C. edulis for skin care and the treatment of skin problems. Moreover, use of C. edulis for skin care purposes could be an eco-friendly solution to reduce its invasiveness in the environment.

A Review of Plant-Based Therapies for the Treatment of Urinary Tract Infections in Traditional Southern African Medicine

Urinary tract infections (UTIs) are amongst the most common bacterial infections globally, with ∼11% of the world's population contracting at least one infection annually. Several South African plants are used in traditional healing systems to treat UTIs, yet the therapeutic potential of these plants against bacteria that cause UTI remains poorly explored. This study documents southern African plant species used traditionally to treat UTIs. An extensive literature review was undertaken to document the southern African plant species that are used in traditional South African medicine to treat UTIs, thereby highlighting gaps in the current research that require further study. One hundred and fifty-three southern African plant species that are used to treat UTIs were identified. Eighty-five southern African plants were identified as having noteworthy inhibitory activity against the major UTI-causing bacteria. Few of those studies screened against all of the bacterial causes of UTIs, and none of those studies examined the mechanism of action of the plant preparations. Furthermore, many of those studies did not test the toxicity of the plant extracts, so an evaluation of the safety for therapeutic usage was lacking. Substantial further research is to determine their potential for therapeutic use.

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.

The traditional use of southern African medicinal plants for the treatment of bacterial respiratory diseases: A review of the ethnobotany and scientific evaluations

ETHNOPHARMACOLOGICAL RELEVANCE

Multiple plant species were used traditionally in southern Africa to treat bacterial respiratory diseases. This review summarises this usage and highlights plant species that are yet to be verified for these activities.

AIM OF THE STUDY

This manuscript reviews the traditional usage of southern African plant species to treat bacterial respiratory diseases with the aim of highlighting gaps in the literature and focusing future studies.

MATERIALS AND METHODS

An extensive review of ethnobotanical books, reviews and primary scientific studies was undertaken to identify southern African plants which are used in traditional southern African medicine to treat bacterial respiratory diseases. We also searched for southern African plants whose inhibitory activity against bacterial respiratory pathogens has been conmfirmed, to highlight gaps in the literature and focus future studies.

RESULTS

One hundred and eighty-seven southern African plant species are recorded as traditional therapies for bacterial respiratory infections. Scientific evaluations of 178 plant species were recorded, although only 42 of these were selected for screening on the basis of their ethnobotanical uses. Therefore, the potential of 146 species used teraditionally to treat bacterial respiratory diseases are yet to be verified.

CONCLUSIONS

The inhibitory properties of southern African medicinal plants against bacterial respiratory pathogens is relatively poorly explored and the antibacterial activity of most plant species remains to be verified.

Unravelling the Antibacterial Activity of Terminalia sericea Root Bark through a Metabolomic Approach

Terminalia sericea Burch. ex. DC. (Combretaceae) is a popular remedy for the treatment of infectious diseases. It is widely prescribed by traditional healers and sold at informal markets and may be a good candidate for commercialisation. For this to be realised, a thorough phytochemical and bioactivity profile is required to identify constituents that may be associated with the antibacterial activity and hence the quality of raw materials and consumer products. The aim of this study was to explore the phytochemistry and identify the antibacterial constituents of T. sericea root bark, using a metabolomic approach. The chemical profiles and antibacterial activities of 42 root bark samples collected from three districts in the Limpopo Province, South Africa, were evaluated. Dichloromethane:methanol (1:1) extracts were analysed using ultraperformance liquid chromatography (UPLC)-mass spectrometry (MS), and chemometric models were constructed from the aligned data. The extracts were tested against Bacillus cereus (ATCC 11778), Staphylococcus epidermidis (ATCC 12223), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 8739), Klebsiella pneumoniae (ATCC 13883), Pseudomonas aeruginosa (ATCC 27853), Shigella sonnei (ATCC 9292) and Salmonella typhimurium (ATCC 14028), using the minimum inhibition microdilution assay. Nine compounds; sericic acid, sericoside, resveratrol-3-O-β-rutinoside, ellagic acid, flavogallonic acid dilactone, methyl-flavogallonate, quercetin-3-(2′′-galloylrhamnoside), resveratrol-3-(6′′-galloyl)-O-β-d-glucopyranoside and arjunetin, were isolated from the root bark. All the compounds, with the exception of sericic acid, sericoside and resveratrol-3-O-β-rutinoside, were isolated for the first time from the root bark of T. sericea. Chemometric analysis revealed clustering that was not population specific, and the presence of three groupings within the samples, characterised by sericic acid, sericoside and an unidentified compound (m/z 682/4.66 min), respectively. The crude extracts from different populations displayed varied antibacterial activities against S. typhimurium (minimum inhibitory concentrations (MICs) 0.25–1.0 mg/mL), but similar activity towards Bacillus cereus (1.0 mg/mL). Several compounds present in the root bark were highly active towards all or most of the pathogens tested, but this activity was not reflected by the chemical profiles of extracts prepared from the individual samples. Among the pure compounds tested, only flavogallonic acid dilactone and methyl-flavogallonate exhibited broad-spectrum activity. A biochemometric analysis indicated that there was no consistent association between the levels of phytochemicals and the activity of the active or non-active extracts. Although it was deduced that the major constituents of T. sericea root bark contributed to the chemotypic variation, further investigation of the interactions of compounds present in the root bark may provide antibacterial efficacies not evident when examining compounds singularly. The data reported herein will provide information that is fundamentally important for the development of quality control protocols.

Invasive Plants: Turning Enemies into Value

In this review, a brief description of the invasive phenomena associated with plants and its consequences to the ecosystem is presented. Five worldwide invasive plants that are a threat to Portugal were selected as an example, and a brief description of each is presented. A full description of their secondary metabolites and biological activity is given, and a resume of the biological activity of extracts is also included. The chemical and pharmaceutical potential of invasive species sensu lato is thus acknowledged. With this paper, we hope to demonstrate that invasive species have potential positive attributes even though at the same time they might need to be controlled or eradicated. Positive attributes include chemical and pharmaceutical properties and developing these could help mitigate the costs of management and eradication.

Bioactive compounds sourced from Terminalia spp. in bacterial malodour prevention: an effective alternative to chemical additives

OBJECTIVE

Recently, our group reported that extracts prepared from the Australian native plant Terminalia ferdinandiana Exell. are potent inhibitors of the growth malodorous bacteria with similar efficacy to triclosan and through these results, we highlighted a potential biological alternative to the current chemical additives. Other members of the genus Terminalia are also well documented for their antibacterial potential and tannin contents and thus were investigated as potential deodorant additives.

METHODS

Solvent extractions prepared from of selected Indian, Australian and South African Terminalia spp. were screened by disc diffusion and liquid dilution assays against C. jeikeium, S. epidermidis, P. acnes and B. linens. The antibacterial activity was quantified by liquid dilution MIC assays. The extracts were screened for toxicity using Atremia franciscana nauplii and HDF cell viability bioassays. High-resolution time-of-flight (TOF) LC-MS and GC-MS headspace fingerprint analysis was used to detect tannin, flavonoid and terpenoid components in the extracts.

RESULTS

Bacterial growth inhibition was observed in all Terminalia extracts with the methanolic T. chebula, T. carpenteriae and T. sericea extracts the most promising bacterial growth inhibitors, yielding MIC values as low as 200 µg mL^-1 . Toxicity analyses of the extracts were favourable, and we determined that the methanolic T. chebula, T. carpenteriae and T. sericea extracts were all non-toxic. Using previously detected T. ferdinandiana antimicrobials as benchmarks, LC-MS and GC-MS fingerprint analyses revealed similar compounds in the methanolic T. chebula, T. carpenteriae and T. sericea extracts.

CONCLUSION

Through these results, we propose that Terminalia spp. extracts may be useful deodorant additives to inhibit the growth of axillary and plantar malodorous bacteria, offering a biological alternative to their chemically synthesized counterparts.

Dissecting the Underlying Pharmaceutical Mechanism of Chinese Traditional Medicine Yun-Pi-Yi-Shen-Tong-Du-Tang Acting on Ankylosing Spondylitis through Systems Biology Approaches

Traditional Chinese Medicine (TCM) has been served as complementary medicine for Ankylosing Spondylitis (AS) treatment for a long time. Yun-Pi-Yi-Shen-Tong-Du-Tang (Y-Y-T) is a novel empirical formula designed by Prof. Chengping Wen. In this study, a retrospective investigation supported efficacy of Y-Y-T and then we deciphered the underlying molecular mechanism of the efficacy. Herbal ingredients and targeting proteins were collected from TCMID. PPI networks were constructed to further infer the relationship among Y-Y-T, drugs used for treating AS, differentially expressed genes of AS patients and AS disease proteins. Finally, it was suggested that TLR signaling pathway and T cell receptor signaling pathway may involve in the biological processes of AS progression and contribute to the curative effect and proteins such as JAK2, STAT3, HSP90AA1, TNF and PTEN were the key targets. Our systemic investigation to infer therapeutic mechanism of Y-Y-T for AS treatment provides a new insight in understanding TCM pharmacology.

Inhibition of Shewanella spp. growth by Syzygium australe and Syzygium luehmannii extracts: natural methods for the prevention of fish spoilage

Syzygium australe and Syzygium luehmannii fruit and leaf were investigated for their ability to inhibit Shewanella spp. growth. Extracts of both Syzygium spp. displayed potent growth inhibitory properties against all Shewanella spp. tested in disc diffusion and liquid diffusion assays. In general, S. australe extracts were more potent inhibitors of Shewanella spp. growth, and the fruit extracts were generally better than the corresponding leaf extracts. The methanolic S. australe fruit extract was a particularly potent inhibitor of all Shewanella spp. growth, with MIC values as low as 87 µg/mL. The aqueous and ethyl acetate S. australe fruit extracts were similarly potent inhibitors of Shewanella spp. growth, albeit with slightly higher MIC values. Several other Syzygium spp. extracts also were potent bacterial growth inhibitors, albeit with MIC values generally >1000 µg/mL. The most potent S. australe fruit extracts were nontoxic in the Artemia franciscana bioassay, with LC₅₀ values substantially >1000 µg/mL. The potent bacterial growth inhibitory activity and lack of toxicity of the S. australe fruit extracts indicate their potential as natural fish and seafood preservatives.

Antimicrobial natural product research: A review from a South African perspective for the years 2009-2016

ETHNOPHARMACOLOGICAL RELEVANCE

This review provides information on the antimicrobial research which has taken place on South African natural products for the last eight years (2009-2016). This important field is the backbone of all studies involving the use of medicinal plants against infectious diseases and hence can form the mainstay for future studies.

MATERIALS AND METHODS

All publications within the years 2009-2016 were considered. Exclusion criteria were studies not involving South African medicinal natural products and those publications where full articles could not be accessed. An overview of the most common experimental methods used and new advances in terms of antimicrobial investigations are provided. Disease categories selected for further investigation were skin and wounds, respiratory, gastrointestinal, sexually transmitted and ophthalmic infections amongst others. Alternate natural products and combinations studies were also included.

RESULTS

The minimum inhibitory concentration (MIC) was the most commonly used experimental method to determine antimicrobial activity. Staphylococcus aureus was the most commonly tested skin pathogen and Klebsiella pneumoniae was the most common pathogen implicated in respiratory disorders. Only 20% of gastrointestinal studies included commonly implicated pathogens such as Shigella flexneri and Campylobacter species.

CONCLUSION

Multidisciplinary studies have emerged as a strong support for antimicrobial investigations and show the importance of including toxicity when studying antimicrobial efficacy. Alternate approaches (for example biofilms and quorum sensing) at examining antimicrobial effects are encouraged. Studies on resistant strains require more insight and future recommendations should look at consistent dosing and investigations on compound interactions amongst others.

A Possible Role of Intestinal Microbiota in the Pathogenesis of Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the sacroiliac joints and the spine, for which the pathogenesis is thought to be a result of the combination of host genetic factors and environmental triggers. However, the precise factors that determine one’s susceptibility to AS remain to be unraveled. With 100 trillion bacteria residing in the mammalian gut having established a symbiotic relation with their host influencing many aspects of host metabolism, physiology, and immunity, a growing body of evidence suggests that intestinal microbiota may play an important role in AS. Several mechanisms have been suggested to explain the potential role of the microbiome in the etiology of AS, such as alterations of intestinal permeability, stimulation of immune responses, and molecular mimicry. In this review, the existing evidence for the involvement of the microbiome in AS pathogenesis was discussed and the potential of intestinal microbiome-targeting strategies in the prevention and treatment of AS was evaluated.