Investigation on effectiveness of traditional Chinese topical antimicrobial uses of Ginkgo Biloba Open Access

Huang, Xinyi (2016)

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Ginkgo biloba, originated from China, has been spread as an ornamental tree around the world. Its seeds have been regarded as snacks and food materials in Asia since pre-modern time, while its leaf extracts became a source of rising pharmaceutical commerce related to brain health in the last century. Besides studies about the neuro-protective effects of Ginkgo, its antibacterial activities have gained more attention from researchers in the past decades, but its leaves were the main focus. However, 500 years ago, the traditional Chinese Material Medica, Ben cao gang mu, had already recorded prescriptions involving Ginkgo seeds to treat infectious skin diseases. Therefore, we are interested in whether different Ginkgo tree parts, leaves, seeds and branches, have antibacterial activities, especially against skin pathogens. In this study, Ginkgo plant materials were separated by part into leaves, branches, seed kernel, seedcoats and immature seeds. Extraction methods included ethanol (80%) maceration, water decoction and sonication, and oil infusion. Those extraction methods were selected based on the prescriptions of Ginkgo's topical uses in traditional Chinese remedies. Skin pathogenic bacteria studied included Staphylococcus aureus, Klebsiella pneumoniae, Propionibacterium acnes and Acinetobacter baumannii. Known chemicals present in Ginkgo plant (terpene lactones, flavonoids and ginkgotoxin) were also tested individually against the pathogens. Out of the 27 extracts, 17 demonstrated growth inhibition to at least one skin pathogen. Ginkgo extracts were more effective against Gram-positive bacteria. The flavonoids tested demonstrated activity against S. aureus; however, the other chosen chemical standards did not demonstrate any activity. Ethanolic extracts were most effective compared to extracts produced by other methods. In summary, we demonstrate here that other Ginkgo parts, especially seeds, may have some antibacterial activity meriting further study. Importantly, this study demonstrated efficacy of this TCM use of Ginkgo biloba.

Table of Contents





CHAPTER 1 - Introduction. 1

CHAPTER 2 - Background

2.1 Antibiotic resistance. 4

2.2 Ginkgo biloba. 6

2.3 Compendium of Materia Medica, "Ben cao gang mu". 9

2.4 What are known. 11

CHAPTER 3 - Materials and Methods

3.1 Historical text review. 16

3.2 Collection and extraction. 21

3.3 Microbiological assay. 25

3.4 Cytotoxicity assay. 27

CHAPTER 4 - Results

4.1 Extraction outcomes. 29

4.2 Antibacterial activities--MIC results. 32

4.3 LDH cytotoxicity results. 39

CHAPTER 5 - Discussion. 41



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