Physicochemical and antimicrobial properties of microencapsulated seed extract of Acacia nilotica (Mimosaceae)

Background: Microencapsulation is an easy and inexpensive means of delivering bioactive substances and has been employed in food industries, agriculture for fertilisers, and drug stability in pharmaceuticals. 

Objective: The objective of this study was to design Acacia nilotica extract as microcapsules, evaluate its physicochemical and in vitro antimicrobial effect in selected microorganisms.

Methods: The absorption maxima and the Fourier-transform infrared spectrum of the extract were obtained. Microencapsulation was done by ionotropic gelation. The microcapsules were evaluated for particle size, swelling index, entrapment efficiency, drug release and antimicrobial activity. Data were analysed using analysis of variance and Dunnet's multiple comparison tests.

Results: The wavelength of maximum absorption for the extract was 208 nm and FTIR revealed functional groups indicating alkaloids, phenols and aromatic compounds. The particle sizes of the capsules increased with the increase in the amount of extract. Microcapsules having higher extract concentration showed lower swelling and higher entrapment efficiency. In addition, the release times (t and t ) revealed controlled release, whilst the 50 80 release kinetics followed Korsmeyer-Peppas model. The activity of the extract and its formulations appeared higher for the fungi compared to the bacteria.

Conclusion: Acacia nilotica extract was successfully formulated into microcapsules with acceptable physicochemical and antimicrobial properties.