Percentage Destabilization Effect of Some West African Medicinal Plants on the Outer Membrane of Various Bacteria Involved in Infectious Diarrhea.

Previous work stated that Khaya senegalensis, Anacardium ouest L., Pterocarpus erinaceus, Diospyros mespiliformis, Ocimum gratissimum, Manihot esculenta, Vernonia amygdalina Delile, and Daniellia oliveri have a great potential for the fight against infectious diarrhea. However, data on their antibacterial activity on strains of bacteria responsible for infectious diarrhea are not available. This study is aimed at elucidating the mechanism of action of the antibacterial effect of these plants on some bacterial strains responsible for diarrheal infections. The design of the study included first evaluating the degree of sensitivity of Salmonella typhimurium 14028, Escherichia coli ATCC 25922, Shigella spp., and Salmonella spp. strains to aqueous and hydroethanolic extracts of each plant, followed by the determination of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibiotic power (Pa). This screening was completed with the evaluation of the possible mode of action of the extracts by testing the membrane permeability of these bacterial strains. The data collected indicate that the bacterial strains tested were sensitive to the extracts to varying degrees, except Cassia sieberiana DC and Pseudocedrela kotschyi extracts. For the active extracts, inhibition diameters ranged from 18.33 mm to 7 mm. With the exception of Escherichia coli, all strains were sensitive to the aqueous and hydroethanolic extracts of Anacardium occidentale. MICs vary between 3.37 and 25 mg/ml. Membrane permeability test data show that all active extracts affect the bacterial strains tested by attacking the stability of their outer membrane. For all active extracts, the high percentage of membrane destabilization of the bacteria is significantly (p < 0.05) better than that of cefixime used as a reference. Thus, it appears that these extracts can destroy Gram-negative bacteria and increase the fluidity and permeability of their cytoplasmic membrane. The knowledge of the mechanism of action of these extracts is an interesting contribution to the fundamental knowledge on the alternative that medicinal plants represent to antibiotics. These extracts can be used in the management of infectious diarrhea.

Effects of Vitellaria paradoxa (C.F. Gaertn.) aqueous leaf extract administration on Salmonella typhimurium-infected rats.

BACKGROUND: The present study investigates the effects of Vitellaria paradoxa crude extract administration on Salmonella typhimurium infected Wistar rats. METHODS: Rats were infected by single dose oral administration of Salmonella typhimurium (1.5×108 CFU). Negative control groups were infected and treated orally with distilled water (vehicle), neutral control group were not infected, while the four test groups were treated up to 18 days with 55 mg/kg, 110 mg/kg, 220 mg/kg and 440 mg/kg body weight of aqueous extract of V. paradoxa respectively. The effects of this extract administration on serum markers (total protein, creatinine, transaminases, bilirubin and lipid profile) as well as acute toxicity test and phytochemical screening were also investigated. RESULTS: Following in vivo studies, aqueous extract of V. paradoxa allowed to clear salmonellosis in previously infected rats within twelve days of treatment. Infection has resulted in a significant increase of transaminases activity. Besides, significant decrease was observed in liver and kidney relative weight and their protein content. Nevertheless, administration of this plant extract at higher doses has resulted in the correction of some of these injuries. Results obtained from acute toxicity study showed that mice administered with the aqueous leaf extract exhibited a mild reaction to noise and pinch; excreted watery discharges and the LD50 value was 12.0 g/kg. In addition, the extract showed no toxic effect after 14 days. However, it may have a sedative effect or depressant effect on the central nervous system, may induce a decrease in plasma levels of algogenic substances, and may cause diarrhea at high doses. Phytochemical screening of the extract revealed the presence of flavonoids, alkaloids, tannins, phenols and polyphenols, saponins, anthocyanins, steroids and anthraquinones. CONCLUSIONS: These results support the ethnomedicinal use of V. paradoxa, and suggest that its leave can be used in the management antibacterial phytomedicine.

Seasonal Microbial Conditions of Locally Made Yoghurt (Shalom) Marketed in Some Regions of Cameroon.

The microbial conditions of locally made yoghurt (shalom) marketed in three areas of Cameroon were evaluated during the dry and rainy seasons alongside three commercial brands. A total of ninety-six samples were collected and the microbial conditions were based on total aerobic bacteria (TEB), coliforms, yeasts, and moulds counts as well as the identification of coliforms and yeasts using identification kits. Generally, there was a significant increase (p ≤ 0.05) in total aerobic and coliform counts (especially samples from Bamenda), but a decrease in yeast and mould counts of the same samples during the rainy season when compared to those obtained during the dry season. These counts were mostly greater than the recommended standards. Twenty-one Enterobacteriaceae species belonging to 15 genera were identified from 72 bacterial isolates previously considered as all coliforms. Pantoea sp. (27.77%) was highly represented, found in 41% (dry season) and 50% (rainy season) of samples. In addition, sixteen yeast species belonging to 8 genera were equally identified from 55 yeast isolates and Candida sp. (76.36%) was the most represented. This result suggests that unhygienic practices during production, ignorance, warmer weather, duration of selling, and inadequate refrigeration are the principal causes of higher levels of contamination and unsafe yoghurts.

Antioxidant and antimicrobial activities of ethyl acetate extract, fractions and compounds from stem bark of Albizia adianthifolia (Mimosoideae).

BACKGROUND: Albizia adianthifolia is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antioxidant and antimicrobial activities of ethyl acetate extract, fractions and compounds isolated from the stem bark of this plant. METHODS: The plant extract was prepared by maceration in ethyl acetate. Its fractionation was done by column chromatography and the structures of isolated compounds were elucidated using spectroscopic data in conjunction with literature data. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. Broth micro-dilution method was used for antimicrobial test. Total phenol content was determined spectrophotometrically in the extracts by using Folin-Ciocalteu method. RESULTS: The fractionation of the extract afforded two known compounds: lupeol (1) and aurantiamide acetate (2) together with two mixtures of fatty acids: oleic acid and n-hexadecanoic acid (B1); n-hexadecanoic acid, octadecanoic acid and docosanoic acid (B2). Aurantiamide acetate was the most active compound. The total phenol concentration expressed as gallic acid equivalents (GAE) was found to vary from 1.50 to 13.49 µg/ml in the extracts. The antioxidant activities were well correlated with the total phenol content (R² = 0.946 for the TEAC method and R² = 0.980 for the DPPH free-radical scavenging assay). CONCLUSIONS: Our results clearly reveal that the ethyl acetate extract from the stem bark of A. adianthifolia possesses antioxidant and antimicrobial principles. The antioxidant activity of this extract as well as that of compound 2 are being reported herein for the first time. These results provide promising baseline information for the potential use of this plant as well as compound 2 in the treatment of oxidative damage and infections associated with the studied microorganisms.