Preparation Of Tea Polyphenols-Cadmium Complex And Its Effect On Acne

Acne has a high incidence and recurrence rate.After infection,the face is prone to redness,swelling,acne and may leave scarring,which seriously affects the physical and mental health of patients.Tea polyphenols-metal complexes as a class of natural and safe compounds with strong antibacterial activity against a variety of pathogenic bacteria.Therefore,it is feasible and necessary to study the preparation of tea polyphenols-metal complexes and to investigate their effects on acne prevention and treatment.In this paper,the antibacterial activity,structure,antibacterial mechanism and stability of TP-Cd and the preparation of antibacterial gel were studied,and the specific results are briefly described as follows.1.Study on the antibacterial activity of TP-Cd.Eleven metal complexes were prepared from commercially available TP to compare their antibacterial activity against S.aureus,and five complexes with strong antibacterial activity,including TP-Cd,TP-Cu,TP-Zn,TP-Pb and TP-Mn,were screened.Comparing the antibacterial activity of five tea polyphenols-metal complexes against acne-inducing bacteria,the results showed that TP-Cd increased the antibacterial activity against P.acnes by 1-4 times,against S.aureus by 2-4 times,and against S.epidermidis by 0.5-10 times compared with other complexes,indicating that TP-Cd has strong antibacterial activity against all three acne-inducing bacteria and can inhibit the growth of the bacteria.2.Preparation and structural study of TP-Cd.The results of the preparation study showed that the best preparation process for TP-Cd was as follows:TP was mixed with Cd²⁺at a molar ratio of 1:1,p H was adjusted to 6.5,and the highest precipitation rate of TP was 93.91%when the reaction was carried out at 30℃for 30 min.TP-Cd was prepared and structurally characterized by this process.UV spectral analysis revealed that the characteristic absorption peak of TP at 270 nm was blue-shifted to 268 nm.FT-IR analysis revealed a weakening of the hydroxyl absorption peak of TP in the range 3500-3100 cm^-1and the disappearance of the absorption peak at 1700 cm^-1.SEM revealed a clustered,irregular spherical structure of TP-Cd,and energy surface scanning detected elemental Cd on the surface of TP-Cd.TGA showed that the thermal stability of TP-Cd was better than that of TP in the range of 0-800℃.It indicates that TP has successfully complexed with Cd²⁺and the complex has better stability.3.Study on the antibacterial mechanism of TP-Cd.Studying the effects of TP-Cd on the growth curve,cell membrane permeability,integrity,energy metabolic processes and cell membrane morphology of acne-causing bacteria,it was found that TP-Cd led to an increase in the electrical conductivity of bacterial fluids and a large amount of intracellular efflux of nucleic acids,proteins and enzymes through disrupting the permeability and integrity of the cell membrane,then TP-Cd further inhibited intracellularβ-galactosidase,AKP and ATPase activities in the cells,leading to a decrease in ATP content and affecting basal and energy metabolism of bacteria.SEM revealed that TP-Cd disrupted the morphological structure of cell membranes,confirming the above results,indicating that TP-Cd inhibits the growth and reproduction of bacteria by disrupting the morphological structure of cell membranes and affecting the metabolic processes of intracellular substances.4.The stability study of TP-Cd.The effects of temperature,light,time and p H on the stability of TP-Cd were investigated,and the results showed that increasing temperature,light treatment,prolonging time and increasing p H decreased the stability of the complex,indicating that TP-Cd is suitable for short-term storage at low temperature,protected from light and neutral or slightly alkaline environment.5.A preliminary investigation of TP-Cd gel preparation.By evaluating the gloss,uniformity and spreadability of the gel,the optimal formulation composition of TP-Cd gel was obtained as:1.0%of TP-Cd,2%of gelling agent,6%of humectant,2%of solubilizer,0.1%of preservative and 1%of permeation promoter;the comprehensive performance of the gel was better when the p H is adjusted to 8.0.The gel prepared from this formulation showed 2-3 times higher inhibition of the three acne-inducing bacteria compared to adapalene gel and tretinoin ointment.In summary,TP-Cd has strong antibacterial activity which has the potential and space to be utilized as an acne inhibitor;the development of TP-Cd antibacterial gel can not only provide a theoretical basis for the development and utilization of safe and efficient new antibacterial drugs,but also provide a new idea for the comprehensive utilization of tea resources.