With the long-term support provided by the Ministry of Science and Technology and the National Taiwan Ocean University (NTOU), a team led by Prof. Chih-Ching Huang at NTOU developed a novel solid-state synthesis process to regulate the degree of polymerization and carbonization of natural molecules from Chinese herbs to enhance their biological activity. In collaboration with Prof. Han-Jia Lin from NTOU they synthesized polyamine-based bioactive carbon, which exhibits broad-spectrum and highly effective antibacterial activity against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enteritidis. The minimal inhibitory concentration value of the bioactive carbon is much lower (~25 000-fold) than that of its precursor, indicating their promising antibacterial characteristics. In addition to their action against nonmulti-drug-resistant bacteria, the inhibition of the growth of multi-drug resistant bacteria such as Methicillin-resistant Staphylococcus aureus (MRSA) is over 99%. The bioactive carbon with high biocompatibility is employed in wound dressing for the treatment of bacterial infection. In vivo MRSA-infected wound healing in rats further showed that the treatment with bioactive carbon resulted in faster healing, better epithelialization, and efficient production of collagen fibers compared to untreated wounds.
In collaboration with Prof. Jui-Yang Lai from Chang Gung University, those polyamine-based bio-carbons were further applied for the treatment of bacterial keratitis (BK). The general treatment of BK is mainly by antibiotic sulfamethoxazole-containing eye drops. However, the use of eye drops to topically deliver therapeutics is fairly common, but poor corneal penetration and low tissue bioavailability associated with various static and dynamic ocular barriers limit their practical usage. Moreover, BK is often caused as a result of multidrug-resistant bacterial infections, which are unresponsive to broad-spectrum antibiotic treatment. Topical ocular administration of polyamine-based bioactive carbon can induce the opening of the tight junction of corneal epithelial cells, thereby leading to great antibacterial treatment of S. aureus-induced BK. The research indicates that the bio-carbons are a promising antibacterial candidate for clinical applications in treating eye- and wound-related bacterial infections.
Recently, an integrated team formed by Prof. Huang, Prof. Shiow-Yi Chen at NTOU, and Prof. Robert Y.L. Wang from Chang Gung University further developed a turmeric bio-carbon for the treatment of a high-risk infection of enterovirus 71 (EV71), which is notorious for causing epidemics of hand-foot-and-mouth disease and severe fatal neurological or cardiac complications in young children. Compared with the relatively hydrophobic turmeric precursor, the water solubility of turmeric bio-carbon is much higher (>100-fold), and it possesses far superior antiviral capabilities (>1000-fold) and high biocompatibility. In in vivo infectious model of newborn mice, turmeric bio-carbon significantly decreased mortality and provided excellent protection against virus-induced hind-limb paralysis challenged with a lethal dose of EV71. More recently, their study also found that bioactivated carbons from various natural herbs possess different viral inhibition activities.
A series of research results from Prof. Huang have been published in the leading journals such as Advanced Healthcare Materials, ACS Nano, and Small. In these studies, a novel concept of bioactive carbon from simple heat-treatment of natural herbs was proposed. By transformation of the herbaceous natural materials into activated carbons, the antibacterial and antiviral biological activities can be greatly enhanced, as well as their anti-oxidation and anti-inflammatory activities. These bioactive carbons are believed to open up a new field in the development of herbal medicine. In the future, the bioactive carbon not only be applied as antibacterial and antiviral agents but also have great potential for prevention and treatment of cancer and cardiovascular diseases.
Dr. Ting-Yang Kuo
Department of Natural Sciences and Sustainable Development,
Ministry of Science and Technology