In vitro Antimycobacterial, Apoptosis-Inducing Potential, and Immunomodulatory Activity of Some Rubiaceae Species

Tuberculosis (TB), a disease caused by microorganisms of the Mycobacterium tuberculosis complex, infects almost one-third of the world’s population. The TB epidemic has been further exacerbated by the emergence of multi, extensively, and totally-drug-resistant (MDR, XDR, and TDRTB) strains. An effective immune response plays a crucial role in determining the establishment of TB infection. Therefore, the modulation of the immune system has been considered as a vital approach for the treatment or control of various immune-related diseases such as TB. In this study, the antimycobacterial, immunomodulatory, and apoptosis-inducing effects of six Rubiaceae species were evaluated. A twofold serial dilution method was used to determine the minimum inhibitory concentration values of the plant extracts. The effect of the extracts on the activity of 15-lipoxygenase was investigated. The levels of six different cytokines, IL-2, IL-4, IL-5, IL-10, IFN-γ, and TNF-α, were measured in LPS-activated U937 cell line while the apoptosis-inducing effect of the extracts was evaluated using an annexin V/PI assay using a flow cytometer. The results obtained revealed that all the six extracts tested had antimycobacterial activity against M. tuberculosis H37Rv, M. tuberculosis ATCC 25177, and Mycobacterium bovis ATCC 27299 strains, with MIC values ranging from 39 to 312 μg/mL. The extracts of Cremaspora triflora and Cephalanthus natalensis were the most active against M. tuberculosis (MIC = 39 μg/mL), followed by Pavetta lanceolata and Psychotria zombamontana against M. bovis (MIC = 78 μg/mL). The extracts of P. zombamontana and Psychotria capensis had remarkable IC50 values of 4.32 and 5.8 μg/mL, respectively, better than that of quercetin. The selected extracts promoted Th1/Th2 balances in an in vitro model at the tested concentration which may suggest the therapeutic value of the plant in diseases where inflammation is a significant factor such as TB. The addition of the crude extracts of C. triflora, P. capensis, and P. zombamontana at the tested concentrations to the cell culture medium induced apoptosis in a time- and dose-dependent manner. This interesting preliminary result generated from this study encourages further investigations of these extracts owing to the LOX-inhibitory effect, immunomodulatory, and apoptotic-inducing properties in addition to their antimycobacterial properties

Immunomodulatory and intracellular antimycobacterial activity of Oxyanthus speciosus investigated using human (U937) and mouse (RAW264.7) macrophage cell lines

Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis, remains a significant cause of death due to challenges associated with present chemotherapy. Coinfection with HIV also greatly increases the risk of latent TB infection (LTBI) progressing to active disease due to the fact that HIV suppresses the immune system, thereby allowing infected individuals to become more susceptible to TB infection. Medicinal plants are used in many parts of southern Africa to treat TB-related symptoms including chest pain and coughing. The acetone extract of Oxyanthus speciosus was screened for its immunomodulatory effect against LPS-stimulated U937 macrophage cells using a cytometric bead array (CBA) technique. Human TH1/TH2 kits consisting of a mixture of six cytokines were used for the assay and analysed using flow cytometry. The intracellular efficacy of the O. speciosus extract against Mycobacterium-infected macrophages was investigated using RAW 264.7 mouse macrophage cell line. Mouse macrophages were infected with M. fortuitum with a multiplicity of infection at 10 mycobacteria per cell. The result obtained from this study revealed that the acetone extract of O. speciosus increased the expression of IL-2 at 0.1 mg/mL while rifampicin supressed the expression of this pro-inflammatory cytokine. At the tested concentration the crude extract of O. speciosus, inhibited the stimulation of IL-4 and IL-5 while it markedly increased the expression of IL-10. The acetone extract of O. speciosus did not show cytotoxicity to RAW 264.7 macrophages at the highest tested concentration (1 mg/ml). On day 6 post-infection, the intracellular antimycobacterial activity of the acetone crude extract of O. speciosus at 1X to 4X MIC was superior to that of rifampicin, showing more than 90% reduction in colony forming units. In conclusion, the extract of O. speciosus had a mixed Th1/Th2 effect. The bactericidal activity observed was both dose and time-dependent.Poster presented at the University of Pretoria, Faculty of Veterinary Science Faculty Day, August 25, 2016, Pretoria, South Africa.ab201

Flavonoids isolated from the South African weed Chromolaena odorata (Asteraceae) have pharmacological activity against uropathogens

BACKGROUND: Urinary tract infections (UTIs) caused by opportunistic pathogens are among the leading health challenges globally. Most available treatment options are failing as a result of antibiotic resistance and adverse effects. Natural sources such as plants may serve as promising alternatives. METHODS: Compounds were isolated from the South African weed Chromolaena odorata through column chromatography. Purified compounds were tested for antimicrobial activity using the p-iodonitrotetrazolium chloride (INT) colorimetric method, against uropathogenic Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Aspergillus fumigatus and Cryptococcus neoformans. Anti-biofilm, anti-adhesion and metabolic inhibition activities were investigated against selected strains. Safety of the compounds was determined against Vero monkey kidney, C3A human liver and colon (Caco2) cells. RESULTS: Four compounds identified as pectolinaringenin (1), (±)-4′,5,7-trimethoxy flavanone (2), 5-hydroxy-3,7,4′- trimethoxyflavone (3) and 3,5,7-trihydroxy-4′-methoxyflavone) (4) were isolated. Minimum inhibitory concentration (MIC) varied between 0.016 and 0.25 mg/mL. Compounds 2 and 3 showed promising antimicrobial activity against E. coli, S. aureus, K. pneumoniae, A. fumigatus and C. neoformans with MIC between 0.016 and 0.125 mg/mL, comparable to gentamicin, ciprofloxacin and amphotericin B used as positive controls. Compounds 2 and 3 showed good anti-biofilm and metabolic inhibition activities against E. coli and S. aureus but weak anti-adhesion activity against the organisms. Low toxicity with selectivity indexes between 1 and 12.625 were recorded with the compounds, indicating that the compounds were rather toxic to the microbial strains and not to the human and animal cells. CONCLUSION: Pharmacological activities displayed by compounds 2 and 3 isolated from C. odorata and low toxicity recorded credits it as a potential lead for the development of useful prophylactic treatments and anti-infective drugs against UTIs. Although known compounds, this is the first time these compounds have been isolated from the South African weed C. odorata and tested for antimicrobial, anti-biofilm, metabolic inhibition and anti-adhesion activities.The National Research Foundation, South Africahttps://bmccomplementmedtherapies.biomedcentral.compm2020Paraclinical Science

Clofibrate, a peroxisome proliferator–activated receptor-alpha (PPARα) agonist, and Its molecular mechanisms of action against sodium fluoride–induced toxicity

AVAILABILITY OF DATA AND MATERIALS : Data will be made available based on request from the corresponding author.Sodium fluoride (NaF) is one of the neglected environmental pollutants. It is ubiquitously found in the soil, water, and environment. Interestingly, fluoride has been extensively utilized for prevention of dental caries and tartar formation, and may be added to mouthwash, mouth rinse, and toothpastes. This study is aimed at mitigating fluoride-induced hypertension and nephrotoxicity with clofibrate, a peroxisome proliferator–activated receptor-alpha (PPARα) agonist. For this study, forty male Wistar rats were used and randomly grouped into ten rats per group, control, sodium fluoride (NaF; 300 ppm) only, NaF plus clofibrate (250 mg/kg) and NaF plus lisinopril (10 mg/kg), respectively, for 7 days. The administration of NaF was by drinking water ad libitum, while clofibrate and lisinopril were administered by oral gavage. Administration of NaF induced hypertension, and was accompanied with exaggerated oxidative stress; depletion of antioxidant defence system; reduced nitric oxide production; increased systolic, diastolic and mean arterial pressure; activation of angiotensin-converting enzyme activity and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB); and testicular apoptosis. Treatment of rats with clofibrate reduced oxidative stress, improved antioxidant status, lowered high blood pressure through the inhibition of angiotensin-converting enzyme activity, mineralocorticoid receptor over-activation, and abrogated testicular apoptosis. Taken together, clofibrate could offer exceptional therapeutic benefit in mitigating toxicity associated with sodium fluoride.Cape Peninsula University of Technology and National Research Foundation (South Africa).https://link.springer.com/journal/12011hj2023Paraclinical Science

Immunomodulatory properties of quercetin-3-O-α-L-rhamnopyranoside from Rapanea melanophloeos against influenza a virus

Abstract Background Influenza infection is a major public health threat. The role of influenza A virus-induced inflammatory response in severe cases of this disease is widely recognized. Drug resistance and side effects of chemical treatments have been observed, resulting in increased interest in alternative use of herbal medications for prophylaxis against this infection. The South African medicinal plant, Rapanea melanophloeos (RM) (L.) Mez of the family Myrsinaceae was selected owing to its traditional use for the treatment of several diseases such as respiratory ailments and also previous preliminary studies of anti-influenza activity of its methanolic extract. The aim of this study was to investigate the immunomodulatory properties of a glycoside flavone isolated from RM against influenza A virus. Methods The non-cytotoxic concentration of the quercetin-3-O-α-L-rhamnopyranoside (Q3R) was determined by MTT assay and tested for activity against influenza A virus (IAV) in simultaneous, pre-penetration and post-penetration combination treatments over 1 h incubation on MDCK cells. The virus titer and viral load targeting NP and M2 viral genes were determined using HA and qPCR, respectively. TNF-α and IL-27 as pro- and anti-inflammatory cytokines were measured at RNA and protein levels by qPCR and ELISA, respectively. Results Quercetin-3-O-α-L-rhamnopyranoside at 150 μg/ml decreased the viral titer by 6 logs (p < 0.01) in the simultaneous procedure. The NP and M2 genes copy numbers as viral target genes, calculated based on the Ct values and standard formula, significantly decreased in simultaneous treatment (p < 0.01). The expression of cytokines was also considerably affected by the compound treatment. Conclusions This is the first report of quercetin-3-O-α-L-rhamnopyranoside from RM and its immunomodulatory properties against influenza A virus. Further research will focus on detecting the specific mechanism of virus-host interactions