The Times Australia
News From Asia

.

Hong Kong Baptist University joint research reveals that gut microbial enzymes reactivate triclosan which induces colitis

HONG KONG SAR - Media OutReach - 3 May 2022 - A Hong Kong Baptist University (HKBU) collaborative research study has revealed that certain gut microbial enzymes mediate the reactivation of triclosan (TCS) from its inactive glucuronide metabolite.

TCS is an antimicrobial agent commonly used in a wide range of consumer products, and it is associated with the development of colitis.

Professor Cai Zongwei, Chair Professor of the Department of Chemistry and Director of the State Key Laboratory of Environmental and Biological Analysis at HKBU, points out that according to the research results specific gut microbial enzymes drive the conversion of TCS metabolites to TCS which increases the chance of developing colitis.
Professor Cai Zongwei, Chair Professor of the Department of Chemistry and Director of the State Key Laboratory of Environmental and Biological Analysis at HKBU, points out that according to the research results specific gut microbial enzymes drive the conversion of TCS metabolites to TCS which increases the chance of developing colitis.

The research results have been published in Nature Communications, an international scientific journal.

Mechanism of TCS exposure leading to colitis previously unclear

TCS is widely used as an antimicrobial agent in consumer products such as toothpaste, mouthwash, hand sanitisers, cosmetics and toys. It is a major environmental contaminant, and it has been shown that TCS exposure increases the risk of colitis.

Once TCS enters the human body, it is rapidly metabolised to form the biologically inactive metabolite TCS-glucuronide (TCS-G), which is easily eliminated from the body. Due to this characteristic, the mechanism of how environmental exposure to TCS leads to gut toxicity in the human body has previously remained unclear.

To answer this question, a research team co-led by Professor Cai Zongwei, Chair Professor of the Department of Chemistry and Director of the State Key Laboratory of Environmental and Biological Analysis at HKBU; Professor Matthew R Redinbo from the University of North Carolina at Chapel Hill; and Professor Zhang Guodong from the University of Massachusetts Amherst conducted a research study based on the hypothesis that certain gut microbial enzymes act on TCS-G in the gut, leading to the reactivation of TCS and the subsequent development of colitis.

TCS concentration uniquely high in the gut

To begin with, the research team sought to determine whether the gut has a different TCS metabolic profile compared to other body tissues. A group of mice were fed food that contained TCS. After four weeks, it was found that the biologically inactive TCS-G was dominant in their liver, bile, heart and small intestine, while the colitis-inducing TCS was dominant in the gut (cecum and colon). The results showed that the gut has a uniquely high concentration of TCS compared to other body tissues.

The research team then analysed the relationship between TCS-containing products and the concentration of TCS in the human body. In a group of human subjects who used TCS-containing personal care products for four months, both TCS and TCS-G were detected in their stool and urine samples, with TCS being dominant in stool and TCS-G being dominant in urine. However, TCS and TCS-G were not detected in the control group who used TCS-free personal care products. The results showed that the use of TCS-containing products leads to a high level of TCS, specifically in the human gut.

Gut microbiota significant in TCS-G conversion

The question remains why the human gut has a uniquely high TCS concentration. To answer this, the research team put forth the hypothesis that gut microbiota participate in the conversion of TCS-G to TCS, leading to the accumulation of TCS in the gut.

To test this hypothesis, the researchers observed that in an in vitro setting, cultured gut bacteria from both mice and humans were able to catalyse the conversion of TCS-G to TCS. To investigate whether the same phenomenon appears in an in vivo setting, the research team found that the inhibition of gut bacteria from mice by applying an antibiotic treatment almost reduced the concentration of TCS in their guts by half, and it increased the concentration of TCS-G by six-fold. The results affirmed that gut microbiota play a significant role in the conversion of TCS-G to TCS in the gut.

Specific enzymes catalyse TCS-G conversion

To investigate the mechanism by which gut microbiota catalyse TCS-G conversion, the research team focused on the intestinal β-glucuronidase (GUS) enzymes produced by gut bacteria in both mice and humans, because they have been shown to catalyse a wide range of metabolite conversions. Using a series of screening techniques, two types of GUS, namely "Loop 1" and "flavin mononucleotide (FMN)-binding" GUSs, were found to be most effective at converting TCS-G to TCS in vitro.

The research team then applied a GUS inhibitor, a drug that inhibits the function of Loop 1 and FMN-binding GUSs, to TCS-exposed and TCS-free mice. It was found that the GUS inhibitor could curb the conversion of TCS-G to TCS by the GUS enzymes. Colitis in TCS-exposed mice was also relieved after the application of the GUS inhibitor. The results support the notion that specific microbial GUS enzymes drive the conversion of TCS-G to TCS, and as a result, the chance of developing colitis is increased.

More stringent TCS controls needed

Professor Cai said: "Our research results clearly defined the mechanism by which gut microbiota are involved in the metabolism and toxicology of TCS, and the study offers a way to prevent the development of colitis following environmental exposure to chemicals.

"Regulatory bodies should consider imposing more stringent controls on the use of TCS. Although the US Food and Drug Administration (FDA) banned the marketing of TCS in over-the-counter antiseptic products in 2016, the chemical remains approved for use in a wide range of products. Transparency on TCS ingredients in product labelling and illustrations should also be improved so that consumers can be aware of the potential risks and make informed choices."

#HongKongBaptistUniversity #HKBU

Times Magazine

Headless CMS in Digital Twins and 3D Product Experiences

Image by freepik As the metaverse becomes more advanced and accessible, it's clear that multiple sectors will use digital twins and 3D product experiences to visualize, connect, and streamline efforts better. A digital twin is a virtual replica of ...

The Decline of Hyper-Casual: How Mid-Core Mobile Games Took Over in 2025

In recent years, the mobile gaming landscape has undergone a significant transformation, with mid-core mobile games emerging as the dominant force in app stores by 2025. This shift is underpinned by changing user habits and evolving monetization tr...

Understanding ITIL 4 and PRINCE2 Project Management Synergy

Key Highlights ITIL 4 focuses on IT service management, emphasising continual improvement and value creation through modern digital transformation approaches. PRINCE2 project management supports systematic planning and execution of projects wit...

What AI Adoption Means for the Future of Workplace Risk Management

Image by freepik As industrial operations become more complex and fast-paced, the risks faced by workers and employers alike continue to grow. Traditional safety models—reliant on manual oversight, reactive investigations, and standardised checklist...

From Beach Bops to Alpine Anthems: Your Sonos Survival Guide for a Long Weekend Escape

Alright, fellow adventurers and relaxation enthusiasts! So, you've packed your bags, charged your devices, and mentally prepared for that glorious King's Birthday long weekend. But hold on, are you really ready? Because a true long weekend warrior kn...

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Times Features

Exploring the Curriculum at a Modern Junior School in Melbourne

Key Highlights The curriculum at junior schools emphasises whole-person development, catering to children’s physical, emotional, and intellectual needs. It ensures early year...

Distressed by all the bad news? Here’s how to stay informed but still look after yourself

If you’re feeling like the news is particularly bad at the moment, you’re not alone. But many of us can’t look away – and don’t want to. Engaging with news can help us make ...

The Role of Your GP in Creating a Chronic Disease Management Plan That Works

Living with a long-term condition, whether that is diabetes, asthma, arthritis or heart disease, means making hundreds of small decisions every day. You plan your diet against m...

Troubleshooting Flickering Lights: A Comprehensive Guide for Homeowners

Image by rawpixel.com on Freepik Effectively addressing flickering lights in your home is more than just a matter of convenience; it's a pivotal aspect of both home safety and en...

My shins hurt after running. Could it be shin splints?

If you’ve started running for the first time, started again after a break, or your workout is more intense, you might have felt it. A dull, nagging ache down your shins after...

Metal Roof Replacement Cost Per Square Metre in 2025: A Comprehensive Guide for Australian Homeowners

In recent years, the trend of installing metal roofs has surged across Australia. With their reputation for being both robust and visually appealing, it's easy to understand thei...