Chitosan nanoencapsulation of flavonoids enhances their quorum sensing and biofilm formation inhibitory activities against an E.coli Top 10 biosensor

Phytochemicals have been found to be promising alternatives to conventional antibiotic therapies for the control of bacterial infections, as they may entail less selective pressure and hence reduce the development of resistance. This study involved examining the inhibition of biofilm formation and of quorum sensing (QS), and the cytotoxicity on mammalian cells of two flavonoids, quercetin and baicalein, in free form and associated into chitosan-based nanocapsules. This was done by use of a transformed E. coli Top 10 biosensor strain, while the cytotoxicity was evaluated on MDCK-C7 cells. In free form, application both flavonoids exhibited slight inhibitory activity on the QS response and biofilm formation, a scenario that was improved positively upon encapsulation with chitosan (Mw ∼115,000 g/mol and DA ∼42%). The association efficiency of 99% (quercetin) and 87% (baicalein) was determined, and each formulation had an average diameter of 190 ± 4 and 187 ± 2 nm, and zeta (ζ) potential of +48.1 ± 2.03 and +48.4 ± 3.46 mV, respectively. Both types of systems were stable against aggregation in M9 and MEM media. The in vitro release kinetics data of both flavonoids seemed to be similar with only ∼20% released over the first 5 h, or ∼10% over the first 4 h, respectively, with subsequent sudden release increase up to ∼40% in both cases. The free phytochemicals seemed to be cytotoxic to MDCK-C7 cells at higher doses, however, upon nanoencapsulation, a cytoprotective effect was evidenced. We have gained proof-of-principle of the advantages of encapsulation of two bioactive flavonoids.

Ethnobotanical survey of traditionally used medicinal plants for infections of skin, gastrointestinal tract, urinary tract and the oral cavity in Borabu sub-county, Nyamira county, Kenya

ETHNOPHARMACOLOGICAL RELEVANCE

Different communities throughout the world have specialized and profound knowledge on the use medicinal plants for various diseases. However, the detailed information on the respective use may extinct in near future as this knowledge is passed only orally among generations in most of the communities.

AIM OF THE STUDY

The present survey aimed to document the use of medicinal plants by traditional healers from the Kisii community, Borabu sub-county in Nyamira county, Kenya, to treat infections of the urinary tract, oral cavity, gastrointestinal system and the skin and to evaluate the social context in which the healers work and practice.

MATERIALS AND METHODS

Validated questionnaires were applied to 50 traditional healers in the study region, followed by interviews and structured conversations. Information on the relevant traditionally used medicinal plants and their use were documented, including sampling and identification of voucher specimens.

RESULTS

The ethnopharmacological survey revealed 25 medicinal plant species belonging to 19 families. It got evident that most of these species will be extinct in the near future unless appropriate measures are taken, as it turned out difficult to collect some of the wild growing species. Elaeodendron buchananii Loes, Erlangea marginata S. Moore, Acacia gerrardii Benth., Balanites orbicularis Sprague, Solanum renschii Vatke and Orthosiphon hildebrandtii Vatke have not been described before for its medicinal use. Among the 25 species collected from the various regions of Borabu sub-county Urtica dioica L. was the only medicinal plant that was collected from all regions. In contrast Erythrina abyssinica and Rhus natalensis were found in only two regions of the study area.

CONCLUSION

The traditional medicinal use of the reported plants for infections should be documented and a great need of awareness from scientists and local government for improved preservation or field cultivation of some species is obvious.

Prevalence of multidrug resistant Staphylococcus aureus in milk from large- and small-scale producers in Kenya

This study evaluated the prevalence of multidrug resistant Staphylococcus aureus in Kenyan milk and investigated any differences in antimicrobial resistance between large- (>200 L/d) and small- (<50 L/d) scale producers. Susceptibility profiles for penicillin G, tetracycline, erythromycin, trimethoprim/sulfamethazine, and chloramphenicol were determined for Staph. aureus (n=402) isolated from cows with subclinical mastitis. There was a significant difference in the overall mean resistance profile between large- (7.1%) and small-scale farm (14.7%) isolates. The overall prevalence of multidrug resistance (> or =2 antibiotics) differed significantly between isolates from small farms (34.3%) and those from large farms (18.0%). Additionally, the producers were interviewed about their usage of antimicrobial drugs and their attitudes toward education in related fields. There was an evident difference between the producer types in their documentation of the use of antimicrobial drugs. Small-scale farms were less inclined to documentation, and treatment records were available from 22% of small-scale farms, compared with 73% of large-scale farms. Farmers expressed a need for more information in 5 areas, ranking preventive management highest (34.0%); followed by affordable tests to control residues in milk (22.8%); preparation of antimicrobial drugs (20.0%); public health concerns (11.2%); disposal of surplus antimicrobial drugs (7.8%); and antimicrobial drug residue persistence in milk (4.2%). It was concluded that herd size might be an indirect risk factor in the development of antimicrobial resistance in Staph. aureus within the region.