Study On Synthesis And Bacteriostasis Performance Of Magnolol

Magnolol, the main effective component of magnolia officinalis (a traditional Chinese medicine), has wide pharmacological effect and application prospect. In the study, synthesis of magnolol was studied and its antimicrobial activity and antibacterial stability were tested. Besides, its compatibility and actual function in cosmetic products as preservative were surveyed, for reference in industrial production and application of the material.Williamson reaction was initiated between 2,2'-dihydroxybiphenyl and n-butyl bromide. The product of the reaction, sodium bromide, was involved in reaction with sodium bromate in acid medium, to generate bromine. Based on this, 5,5'-dibromo-2,2'-dibutoxybiphenyl was achieved from bromination, and was then prepared into Grignard agent. Afterwards, 5,5'-diallyl-2,2'-dibutoxybiphenyl was achieved from reaction between Grignard agent and allyl bromide. Finally, cleavage of the butyl ethers with boron tribromide produced magnolol, which was higher than 98% in purity and was 60.2% in total yield. The structures of the compounds were confirmed by UV, IR, MS, 1H NMR and 13C NMR.Diameters of inhibition zones formed by synthetic magnolol and natural magnolol on Escherichia coli, Staphylococcus aureus, Salmonella typhi, Bacillus subtilis, Sacharomyces cerevisa and Aspergillus niger were measured using the disk diffusion method. Based on this, performance comparison was carried out among magnolol, methylparaben and ethylparaben, concluding that synthetic magnolol and natural magnolol are similar, and higher than methylparaben and ethylparaben in bacteriostasis performance. As measured by means of equimultiple dilution in tubes, the minimal inhibitory concentrations of synthetic magnolol against the six cultures were 5μg/mL, 10μg/mL, 5μg/mL, 5μg/mL, 10μg/mL and 10μg/mL, respectively. Besides, influences of temperature (0~100℃), pH (3~8) and UV irradiation (6~36min) on its bacteriostasis performance were studied by means of inhibition zone. Indicated in experiment, its bacteriostasis performance is sensitive to temperature but not sensitive to pH or UV irradiation. Finally, relation between concentration/action time of magnolol and bacteriostasis rate was studied, indicating that bacteriostasis rate rises with increase in concentration and action time.In application proformance test by adding magnolol to cream, the product smelled normally and could reach the pH demanded, namely magnolol has good compatibility. Indicated in measurement of aerobic bacterial count, when magnolol was added by a percent no less than 0.125%, no bacterial colony was detected. Such effect was comparable to that of combining methylparaben, ethylparaben and Germall II, indicating that magnolol has excellent preservative performance.