Abstract:

Bacteria are found nearly everywhere on earth, and are the largest population in human skin microbiome. Due to the considerable negative effects of the conventional cosmetic preservatives, their long-term use is likely to disrupt the balance of skin bacterial population, then cause skin disorders or diseases. As natural preservatives, the antibacterial components in plants can reduce or eliminate the negative effects brought by conventional cosmetic preservatives. This paper introduced the mechanisms and the targets of antibacterial plant extracts, and summarized the different kinds of antibacterial components in plants, including phenolics, terpenes, alkaloids, flavones, phenylpropanoids, quinones and essential oils. The antibacterial components cause cell death, mainly by inhibiting the activities of peptidoglycan synthases, which leads to inhibit bacterial cell wall formation, destruct the cell membrane structure or modify cell membrane permeability, resulting in the leakage of intracellular components. The antibacterial effects of phenolics and alkaloids are mainly through inhibiting cell protein synthesis, the nucleic acid synthesis, DNA helicases and DNA topoisomerases, or basal metabolism and energy metabolism. Phenylpropanoids can inhibit bacterial growth by inhibiting DNA topoisomerases or cell membrane proton pumps. Some antibacterial components from plants also can inhibit bacterial biofilm formation. This paper has reviewed different kinds of antibacterial components from plants, with the aim to provide information for a better application of plant extracts in cosmetics.

Key words: plant extracts, cosmetics, antibacterial activities