Novel carbon nanozymes with enhanced phosphatase-like catalytic activity for antimicrobial applications

In this work, Sulfur and Nitrogen co-doped carbon nanoparticles (SN-CNPs) were synthesized by hydrothermal method using dried beet powder as the carbon source. TEM and AFM images indicated that these SN-CNPs form a round-shape ball with an approximate diameter of 50 nm. The presence of Sulfur and Nitrogen in these carbon-based nanoparticles was confirmed by FTIR and XPS analyses. These SN-CNPs were found to have strong phosphatase-like enzymatic activity. The enzymatic behavior of SN-CNPs follows the Michaelis-Menten mechanism with greater v_max and much lower K_m values compared to alkaline phosphatase. Their antimicrobial properties were tested on E. coli and L. lactis, with MIC values of 63 μg mL^-1 and 250 μg mL^-1, respectively. SEM and AFM images of fixed and live E. coli cells revealed that SN-CNPs strongly interacted with the outer membranes of bacterial cells, significantly increasing the cell surface roughness. The chemical interaction between SN-CNPs and phospholipid modeled using quantum mechanical calculations further support our hypothesis that the phosphatase and antimicrobial properties of SN-CNPs are due to the thiol group on the SN-CNPs, which is a mimic of the cysteine-based protein phosphatase. The present work is the first to report carbon-based nanoparticles with strong phosphatase activity and propose a phosphatase natured antimicrobial mechanism. This novel class of carbon nanozymes has the potential to be used for effective catalytic and antibacterial applications.

Generation of particle assemblies mimicking enzymatic activity by processing of herbal food: the case of rhizoma polygonati and other natural ingredients in traditional Chinese medicine

Processed herbs have been widely used in eastern and western medicine; however, the mechanism of their medicinal effects has not yet been revealed. It is commonly believed that a central role is played by chemically active molecules produced by the herbs' metabolism. In this work, processed rhizoma polygonati (RP) and other herbal foods are shown to exhibit intrinsic phosphatase-like (PL) activity bounded with the formation of nano-size flower-shaped assembly. Via quantum mechanical calculations, an enzymatic mechanism is proposed. The enzymatic activity may be induced by the interaction between the sugar molecules distributed on the surface of the nanoassemblies and the phosphatase substrate via either a hydroxyl group or the deprotonated hydroxyl group. Meanwhile, the investigation was further extended by processing some fresh herbs and herbal food through a similar protocol, wherein other enzymatic activities (such as protease, and amylase) were observed. The PL activity exhibited by the processed natural herbs was found to be able to effectively inhibit cancer cell growth via phosphatase signaling, possibly by crosstalk with kinase signaling or DNA damage by either directly binding or unwinding of DNA, as evidenced by high-resolution atomic-force microscopy (HR-AFM). In this work, the neologism herbzyme (herb + enzyme) is proposed. This study represents the first case of scientific literature introducing this new term. Besides the well-known pharmacological properties of the natural molecules contained in herbs and herbal food, there exists an enzymatic/co-enzymatic activity attributed to the nanosized assemblies.

Abstract 4759: Nanoscale Huangjing extract from Mount Tai displays enzyme and biofuel enhancing activity: Potential in precision anti-cancer therapy

Chinese herb Huangjing has been well-known for its anti-cancer characters in xenograft models of cancers and traditional Chinese herbal classical books. However, the mechanisms are largely unknown. The processed Huangjing has the pharmacological function but fresh forms may have toxicity. Mount Tai is famous for its traditional culture and Chinese medicine resources with special environmental and nutritional potential for enrichment of herbal chemical competent. Our study aimed to test phosphatase activity of nanoparticles produced in the process of herb and to identify whether its anti-cancer properties is related to the phosphatase activity. Phosphatase has been known for its function in dephosphorylating of many drug targets therein to inhibit cancer cell growth. We recently reported engineered nanoparticles were proved to exhibit phosphatase activity and here we further demonstrated that nanoscale Huangjing herb from Mount Tai showed positive results on a few phosphatase substrates. The corresponding substrate specificity and kinetics of the reaction including the substrate concentration, pH, and temperature dependence were studied in detail. In addition, using a Biorad Biofeul kit, Huangjing was observed to catalyze p-nitrophenyl glucopyranoside to p-nitrophenol reaction. Our data suggest that Huangjing may cleave the covalent bond between beta glucose and nitrophenol suggesting the biofuel-like activity. We then performed experiments to test the effectiveness of Huangjing at nanoscale for inhibiting growth of cancer cells wherein, the growth of MDA-MB-231 and PC3 cells was greatly inhibited while normal cells are planning for comparison and investigation in mechanisms. The study has a significance in developing potential novel nanoscale drugs with phosphatase-like activity for treatment of certain cancers with combination of targeted kinase inhibitors based therapy or as a drug delivery machinery. Our preliminary results suggest a kinase synergistic based signaling. Thus, our data provided the potential concept of the combination of traditional Chinese medicine with modern chemotherapy.

Citation Format: Aigerim Kabulova, Madina Razbekova, Yingqiu Xie, Adilet Dautov, Qian Wang, Haiyan Fan. Nanoscale Huangjing extract from Mount Tai displays enzyme and biofuel enhancing activity: Potential in precision anti-cancer therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4759.