The effect of environmental conditions on the antibacterial properties of Calendula officinalis

Abstract: A health practitioner is concerned about the quality of the medication prescribed as it must remain unaltered throughout the treatment period. Calendula officinalis is a well-researched herb, known for its antimicrobial efficacy and was therefore used in this study to establish whether its antibacterial properties changed when exposed to different environmental conditions. An herbal extract and a homeopathic mother tincture were used in this study. Although both samples were prepared from Calendula officinalis, they were extracted differently. The stock samples and dilutions of the samples were exposed to different environmental conditions (Control – UJ Dispensary, Direct Sunlight, Kitchen Scenario, Office Scenario and Decreased Temperature) and the antibacterial properties were evaluated with the Kirkby Bauer Disc Diffusion Method and the broth dilution minimum inhibitory concentration test. Some samples were also separated and analysed with Gas Chromatography Mass Spectrometry. Statistical analysis of the Kirkby Bauer Disc Diffusion results was done and compared accordingly with the Mann Whitney U-Test and the kurtosis and skewness values. A comparison of the results for the broth dilution minimum inhibitory concentration test and the Gas Chromatography Mass Spectrometry was also done and reported on. The test results showed that the samples exposed to the different environmental conditions changed in their activity as well as their composition. The testing on the diluted samples were halted due to the inconsistency of the results and a suggestion was made to allow further research on this topic. Amber glass bottles showed overall better protection against environmental conditions than blue glass bottles. The samples in the control environment, the UJ Dispensary, with temperature constant at an average of 21ºC and with minimal exposure to sunlight, external lighting and electromagnetic waves and radiation showed stability and would be proposed as the best storage environment for herbal extracts and homeopathic mother tinctures