Madecassic acid from Centella asiatica targets energy in drug-resistant bacteria

Many people associate plant-based ingredients in skin care with gentle, supportive effects - the sort of substances that calm irritation or help skin recover. Yet, on occasion, the very same molecules prove to be far less straightforward.

New research has examined madecassic acid, a compound found in Centella asiatica, and reports that it can disrupt the way drug-resistant bacteria produce energy.

This reframes a familiar skin-care ingredient as something considerably more compelling: a possible lead for developing new antibacterial medicines.

It does not mean a finished antibiotic is imminent, but it does show that a widely recognised plant compound can expose an overlooked bacterial weakness - and that modest chemical adjustments might amplify that effect into something far stronger.

Inside bacteria’s energy system

Working at the inner membrane of bacteria, the compound reduced energy use and restricted growth in drug-resistant E. coli.

Tracking this activity, Dr. Mark Shepherd at the University of Kent and colleagues demonstrated that madecassic acid was obstructing a crucial element of the bacterial energy pathway.

Rather than damaging the whole cell indiscriminately, madecassic acid acted on a specific protein that bacteria depend on for energy generation, tying the slowdown in growth to that single point of attack.

By narrowing the action down to one susceptible system, the study sets up a clearer comparison between this plant-derived effect and established antibacterial strategies.

Beyond calming the skin

Well before these experiments, Centella asiatica became popular in skin care because some of its compounds were associated with wound repair and reduced irritation.

Within that mix, madecassic acid is notable as one of several pentacyclic molecules linked to healing and a quieter inflammatory response.

However, easing irritated skin and suppressing bacteria are fundamentally different tasks, which is why this result is more than a minor cosmetic aside.

It indicates that a plant compound already familiar to shoppers may also have a role that extends well beyond lotions and serums.

That idea arrives as antibiotic resistance becomes increasingly difficult to overlook. As bacteria become less responsive to standard treatments, infections that were once manageable are becoming harder to treat.

One worldwide projection suggests resistant infections could contribute to more than 39 million deaths between 2025 and 2050.

This strain has made antibiotic development seem slower, more uncertain, and more costly - particularly because many apparently promising candidates fail at late stages.

Plant-derived leads will not fix the problem by themselves, but they widen the pool of options at a time when new routes are urgently required.

Why bacteria are vulnerable

In bacteria, cytochrome bd is located in the inner membrane and helps convert oxygen use into usable cellular energy.

If that pathway is blocked, electron flow is throttled, reducing the driving force cells need to continue growing.

This family of enzymes is not found in humans, appearing instead in bacteria and some other microscopic organisms, which makes it a particularly appealing antibacterial target.

That biology helps clarify why the Kent group treated this protein as more than an academic detail within E. coli.

Tweaking the molecule matters

Using madecassic acid extracted in Vietnam as their starting material, chemists modified the molecule in three distinct ways to see whether its antibacterial behaviour could be strengthened.

All three variants still disrupted cytochrome bd, but the alterations also changed how readily each molecule could access bacterial membranes.

One bulkier version appeared, on paper, to match the target less cleanly, yet it performed better than anticipated when the team tested it in real membranes.

These discrepancies underlined that molecular design affects more than theoretical target binding, because membrane interactions matter simultaneously.

One version kills bacteria

Experiments in living bacteria revealed a striking split: the unmodified compound hindered growth but did not kill the cells. Only a single modified version succeeded in killing bacteria, and even then it required much higher amounts.

That difference shows the chemistry can be steered towards bacterial killing, but it is not yet particularly potent - still, it offers an obvious foundation for optimisation.

Part of the explanation lies in how complicated whole cells are. Predictions about target binding did not neatly mirror what intact bacteria did, because once a molecule is inside a living cell, membranes, efflux pumps, and other proteins can sequester it, divert it, or dull its impact.

The authors also highlighted earlier evidence suggesting madecassic acid may affect several systems at once, including membranes, protein production, and enzymes involved in handling DNA.

This multi-target complexity makes the compound’s effects harder to interpret, but it also gives chemists more than one direction for refinement and improvement.

Skin care meets microbiology

Alongside the antibiotic angle, the study also suggested that madecassic acid could affect bacteria that naturally live on the skin.

Because product concentrations and real-world skin exposure are very different, creams that include the ingredient are not functioning as covert antibiotics.

Even so, a compound intended to soothe redness could be subtly influencing surface microbes by limiting a respiratory system that some of them rely on.

For researchers, that possibility matters because it connects consumer formulations with the broader issue of maintaining microbial balance.

Refining a promising compound

Next steps will centre on improving the molecule so it binds more strongly, reaches bacteria more effectively, and reduces potential harm to human cells.

This work reflects a wider lesson from natural-product discovery: small chemical changes often decide whether an intriguing compound goes nowhere or progresses.

“Plants have been a source of natural medicines for millennia, and now contemporary research approaches can reveal the mechanisms of action,” said Dr. Shepherd.

With the mechanism clearer, Shepherd’s team has a firmer platform for turning what was previously viewed as a skin-soothing ingredient into a more precisely targeted antibacterial candidate.

Madecassic acid itself has also been recast - now defined by an identified bacterial target, an experimentally supported mechanism, and a chemical scaffold that can be edited. It is not yet a ready-to-use antibiotic, but it gives researchers a much more precise place to start.