Dissolvable sodium alginate-based antibacterial wound dressing patches: Design, characterization, and in vitro biological studies.

The treatment of infected wounds in patients with highly sensitive skin is challenging. Some of the available wound dressings cause further skin tear and bleeding upon removal thereby hindering the healing process. In this study, dissolvable antibacterial wound dressing patches loaded with cephalexin monohydrate were prepared from different amounts of sodium alginate (SA) and carboxymethyl cellulose (CMC) by the solvent casting evaporation technique. The patches displayed good tensile strength (3.83-13.83 MPa), appropriate thickness (0.09 to 0.31 mm) and good flexibility (74-98 %) suitable for the skin. The patches displayed good biodegradability and low moisture uptake suitable to prevent microbial invasion on the wound dressings upon storage. The release profile of the drug from the patches was sustained in the range of 47-80 % for 48 h, revealing their capability to inhibit bacterial infection. The biological assay showed that the patches did not induce cytotoxic effects on HaCaT cells, revealing good biocompatibility. The antimicrobial effect of the patches on the different strains of bacteria used in the study was significant. The cell migration (66.7-74.3 %) to the scratched gap was promising revealing the patches' capability to promote wound closure. The results obtained show that the wound dressings are potential materials for the treatment of infected wounds.

Alginate-gum acacia based sponges as potential wound dressings for exuding and bleeding wounds.

The improper management of wound exudates can expose the wound to bacterial invasion, skin maceration etc. thereby resulting in prolonged wound healing. Biopolymers are characterized by hydrophilic functional groups which when employed for the development of wound dressings promote the wound dressings capability to absorb a high amount of wound exudates. Alginate-gum acacia sponges were prepared from a combination of biopolymers such as sodium alginate and gum acacia in varying amounts with carbopol via crosslinking with 1 and 2% CaCl2. The prepared sponges were loaded with a combination of ampicillin and norfloxacin. In vitro antibacterial analysis revealed that the antibacterial activity of the loaded antibiotics was retained and the sponges were effective against gram-positive and gram-negative bacteria. The sponges displayed rapid and high absorption capability in the range of 1022-2419% at pH 5.5 simulating wound exudates, and 2268-5042% at pH 7.4 simulating blood within a period of 1-3 h. Furthermore, the whole blood clotting studies further revealed low absorbance values when compared to the control revealing the good clotting capability of the sponges. The unique features of the sponges revealed their potential application for the management of infected, high exuding and bleeding wounds.

Secondary metabolites from Tetracera potatoria stem bark with anti-mycobacterial activity.

ETHNOPHARMACOLOGICAL RELEVANCE: Tetracera potatoria Afzel. Exg. Don (Dilleniaceae) is a medicinal plant used traditionally in Africa for the treatment of tuberculosis related ailments and respiratory infections. The antibacterial activity of the medium polar extracts of T. potatoria leaves and stem bark was recently reported against Mycobacterium smegmatis (MIC 25µg/mL) and M. aurum (65µg/mL), two fast-growing Mycobacterium strains used as model micro-organisms for the more pathogenic strain Mycobacterium tuberculosis (Fomogne-Fodjo et al., 2014). The aim of this study was consequently to isolate the compounds possibly contributing to this activity, and which may therefore be promising precursors to be used for the development of novel anti-TB drugs. MATERIALS AND METHODS: T. potatoria medium polar extract [MeOH/DCM (1:1, v/v)] was fractionated sequentially with petroleum ether to which EtOAC and MeOH were gradually added to increase the polarity. The examination of T. potatoria extract and its fractions was guided by bioassays for anti-mycobacterial activity against M. smegmatis (ATCC 23246) and M. aurum (NCTC 10437) using the minimum inhibitory concentration (MIC) method. All the isolated compounds were structurally elucidated using spectroscopic techniques and evaluated for their anti-mycobacterial activity. RESULTS: Two novel secondary metabolites (1, 2) named tetraceranoate and N-hydroxy imidate-tetracerane, together with five known compounds [ß-stigmasterol (3), stigmast-5-en-3ß-yl acetate (4), betulinic acid (5), betulin (6) and lupeol (7)] were isolated and identified. Tetraceranoate exhibited the best activity against M. smegmatis with a minimum inhibitory concentration (MIC) of 7.8µg/mL, while ß-stigmasterol, betulinic acid and betulin showed appreciable anti-mycobacterial activity against both strains (MIC 15µg/mL). CONCLUSION: Seven compounds were isolated from the medium polar extract [MeOH/DCM (1:1, v/v)] of T. potatoria stem bark. Only tetraceranoate one of the isolated compounds showed antibacterial activity against M. smegmatis having efficacy as high as rifampicin (one of a three drug regimen recommended in the initial phase short-course anti-tuberculosis therapy). Thus, tetraceranoate might be an interesting target for systematic testing of anti-TB treatment and management. This research supports the use of T. potatoria in African traditional medicine for the treatment of tuberculosis related symptoms.

Antibacterial activities of plants from Central Africa used traditionally by the Bakola pygmies for treating respiratory and tuberculosis-related symptoms.

ETHNOPHARMACOLOGICAL RELEVANCE: The antibacterial activities of 18 plants from 10 different families were investigated for their antimicrobial efficacy, based on the traditional uses of these species by Bakola pygmies living in Central Africa, especially along the Ngoyang area in Cameroon for the treatment of respiratory and tuberculosis-related symptoms. The aim of the study is to test the antimicrobial efficacy of these plants against some pathogens associated with respiratory disease and to determine if there is any validation for the traditional use against Mycobacterium species. MATERIALS AND METHODS: Medium polar extracts were prepared in MeOH/DCM (1:1, v/v) from the plant parts of each species used traditionally and were assayed against pathogens associated with respiratory tract ailments [Staphylococcus aureus (ATCC 25923), Klebsiella pneumoniae (ATCC 13883) and Morexella cattarhalis (ATCC 14468)] using the minimum inhibitory concentration (MIC) method. Two additional faster growing Mycobacterium strains [Mycobacterium smegmatis (ATCC 23246) and Mycobacterium aurum (NCTC 10437)] were included in the assay as predictive test organisms for the more pathogenic strain Mycobacterium tuberculosis. RESULTS: Some plant species, such as Alchornea floribunda, Musanga cecropioides (both leaves and stem bark), Tetracera potatoria and Xylopia aethiopica (stem bark), were effective in inhibiting Morexella cattarhalis, having MIC values between 65 and 250 µg/mL. Some noteworthy antimycobacterial inhibition (MIC≤200 µg/mL and as low as MIC 6.5 µg/mL) for 54% of the extracts were observed. CONCLUSION: While moderate activity was shown for pathogens causing respiratory tract infections, these plant species seems to be selectively targeting Mycobacteria spp. suggesting that the traditional use for treating tuberculosis related symptoms may be indeed be accurate.