Can Herbal Extracts be Used as Surrogates of Antibiotics
Xulan Zheng
Richmond Secondary
Floor Location : M 152 H

Super bacteria that show multiple antibiotic resistance is a global medical issue threatening human health. The common solution is to reduce the use of antibiotics and find out surrogates for antibiotics. To find out if natural herbs and plants could be used as surrogate for antibiotics, I test the antibacterial capability of the peel of pomelo fruit and the water extract of the herb medicine Prunella vulgaris. I hypothesize that pomelo skin and the dry flowers of Prunella vulgaris have antibacterial capability, because pomelo peel can protect the fruit from rotten away, and the dry flowers of Prunella vulgaris are often used to prepare herbal tea for anti-fever and detoxification.
Disk diffusion test (Kirby-Bauer’s test) was applied to test the antibacterial capability of pomelo peel juice, Prunella vulgaris water extract, as well as the positive control ampicillin and Tobramycin. The major materials used in this study include fresh pomelo, Prunella vulgaris dry flowers, liquid LB medium, solid LB medium, the bacteria strains Escherichia coli and Bacillus bacteria, ampicillin, and Tobramycin. The procedure included 3 main parts: herbal extracts preparation, LB( Lysogeny broth ) medium preparation, and bacterial culture. For the extracts preparation, it is split into two parts. The fresh pomelo peel was minced, and squeezed to produce juice, and then purified by 0.2 μm filter. In preparation of Prunella vulgaris extract, 100g of dry P. vulgaris flowers were cooked with 100 mL water, and boiled for about 30 minutes. The liquid reduced to about 25 mL and was purified by 0.2 μm filter. LB medium preparation, bacteria inoculation and the disk diffusion test (anti-bacterial test) were carried out according to the standard methods.
The radius of inhibition zone in each plate were measured and the average inhibition radius of each group (3 duplicates) was calculate. The average radius of inhibition zone in each group are listed as flowing, ampicillin is 1.08cm, pomelo peel juice is 0.37cm, Prunella vulgaris extract is 0.63cm, tobramycin is 0.37cm, and water is 0.00cm. Both pomelo peel juice and Prunella vulgaris flower extract have positive antibacterial effects to both the two strains, E.coli and B. subtilis, and the inhibition effects increase the dosage. This suggested that my hypothesis is correct. Both of the herbal extracts have positive antibacterial properties
As a result, both of my test samples have positive antibacterial results, this approve my hypothesis is correct. This indicates the traditional herbal extracts that are known to have anti-fever functions are likely to have antibacterial substances. Fruit peels and seed coat are also likely contained these substances. This experiment shows that some plant extracts are likely to be used in bacterial infections treatment. It can partly solve the problem of antibacterial resistance.
Pomelo peel juice and Prunella vulgaris flower extract can be used to treat E.coli infection. These extracts can be formulate into ointment, cream or spray that will possibly be used for bacterial infection treatments.