If you’ve ever Googled “natural remedies for anxiety,” you’ve probably stumbled across herbs with names you can’t pronounce.

Lavender.

Ashwagandha.

Passionflower.

Now add another one to the list:

Aloysia polystachya.

It’s a South American plant traditionally used as a calming tea for digestion, stress, and sleep. Researchers recently decided to see whether there might actually be science behind the folklore.

The results?

Promising—but with a giant asterisk.

Let’s explain.

Your Brain Has Two Jobs During Stress

Imagine you’re walking through the woods.

You hear rustling.

Your brain instantly asks:

Should I run?

That’s anxiety.

Later that night, if stress never seems to switch off…

Your brain starts asking a different question:

Why even bother?

That’s where depression can begin.

Although anxiety and depression are different conditions, they often share one common ingredient:

Chronic stress.

Researchers have been searching for new treatments that calm these pathways without causing heavy sedation or significant side effects.

Plants have become an increasingly popular place to look.

Meet the Plant

Aloysia polystachya grows throughout parts of South America.

Locals have used its leaves for generations as a traditional herbal remedy.

Scientists became interested because the plant contains large amounts of a natural compound called acteoside (also known as verbascoside).

Acteoside already has an impressive résumé in laboratory research.

Previous studies suggest it may:

  • Act as an antioxidant
  • Help reduce inflammation
  • Protect nerve cells
  • Support mitochondrial function (your cells’ energy factories)
  • Inhibit an enzyme called monoamine oxidase A (MAO-A), which is involved in regulating mood-related neurotransmitters like serotonin and norepinephrine

That last point caught researchers’ attention because some prescription antidepressants also target similar brain pathways.

Why Study Fish?

Believe it or not, zebrafish have become tiny celebrities in neuroscience labs.

Why?

Because many of their brain chemicals work surprisingly similarly to ours.

When zebrafish become anxious, they display predictable behaviors.

For example:

  • They avoid bright areas.
  • They freeze in place.
  • They hug the edges of their tank.
  • They make sudden, erratic swimming movements.

Researchers can measure these behaviors to test whether a substance appears calming—or stimulating.

The Experiment

Researchers exposed zebrafish to situations designed to trigger anxiety or depression-like behaviors.

Some fish received:

  • Only the stressor
  • A standard anti-anxiety or antidepressant medication
  • The Aloysia polystachya extract

The extract was given both by mouth and by immersion in water.

Then the scientists watched what happened.

The Fish Became Less Anxious

One of the tests measured whether fish would explore the bright side of a tank.

Normally, anxious fish avoid bright spaces.

They’re basically thinking:

“No thanks. I’ll stay hidden.”

Fish treated with the plant extract behaved differently.

Compared with stressed fish, they:

  • Spent more time exploring the light area
  • Froze less often
  • Swam more normally
  • Showed fewer panic-like movements
  • Were less likely to cling to the tank walls

Perhaps most interestingly, their behavior looked similar to fish treated with buspirone, a prescription anti-anxiety medication used in humans.

It Also Showed Antidepressant-Like Effects

Researchers also tested behaviors associated with depression-like states.

Stressed fish usually:

  • Stay near the bottom of the tank
  • Move less
  • Explore less
  • Freeze more often

Fish receiving the plant extract became much more active.

They:

  • Explored higher parts of the tank
  • Started swimming sooner
  • Crossed more of the tank
  • Froze less frequently

Again, their behavior resembled fish treated with fluoxetine (better known as Prozac).

So…Does This Mean It Works in Humans?

Not even close.

This is where headlines often go wrong.

These were animal experiments, not human clinical trials.

That’s an important difference.

Many substances that appear promising in mice—or fish—never become effective human medicines.

Why?

Because:

  • Human brains are much more complex.
  • Doses don’t always translate.
  • Long-term safety may differ.
  • Human anxiety and depression involve genetics, environment, trauma, relationships, sleep, hormones, and many other factors.

Animal studies are excellent for generating ideas.

They’re not proof that a treatment works in people.

Why Scientists Are Still Interested

Even with that limitation, the study matters.

Here’s why.

Researchers identified a plant containing a compound that appears to interact with brain pathways already known to influence mood.

Instead of simply saying,

“This herb seems calming,”

they can now start asking:

  • Which molecule is responsible?
  • How does it affect brain chemistry?
  • Is it safe?
  • Could it someday become a medication?

That’s how many modern drugs begin.

Not in a pharmacy.

In nature.

What About Drinking the Tea?

That’s the obvious question.

Unfortunately, this study doesn’t answer it.

The extract used in the laboratory was carefully prepared and standardized.

A homemade tea could contain very different amounts of the active compounds depending on:

  • The plant variety
  • Growing conditions
  • Harvest timing
  • Brewing method
  • Storage

In other words:

There’s no evidence that drinking this herb will treat anxiety or depression in humans.

The Bigger Picture

Mental health disorders affect hundreds of millions of people worldwide.

Current medications help many people—but not everyone.

Some cause unwanted side effects.

Others simply don’t work well enough.

That’s why scientists continue searching for new options, including compounds found in plants that have been used in traditional medicine for centuries.

Studies like this help identify promising leads.

They don’t provide clinical answers yet—but they do point researchers in new directions.

The Bottom Line

Researchers found that an extract from the South American plant Aloysia polystachya reduced anxiety-like and depression-like behaviors in zebrafish.

The plant’s primary compound, acteoside, has biological properties that make it an interesting candidate for future research, including antioxidant, anti-inflammatory, and potential mood-related effects.

But here’s the key takeaway:

This was a laboratory animal study—not a human clinical trial.

It’s an encouraging first step, not a recommendation to replace proven treatments.

For now, the research tells us something exciting:

Nature still contains compounds we haven’t fully explored.

Whether one of them becomes tomorrow’s antidepressant remains a question only future human studies can answer.

Costa de Melo N, Sánchez-Ortiz BL, Dos Santos Sampaio TI, Matias Pereira AC, Pinheiro da Silva Neto FL, Ribeiro da Silva H, Alves Soares Cruz R, Keita H, Soares Pereira AM, Tavares Carvalho JC. Anxiolytic and Antidepressant Effects of the Hydroethanolic Extract from the Leaves of Aloysia polystachya (Griseb.) Moldenke: A Study on Zebrafish (Danio rerio). Pharmaceuticals (Basel). 2019 Jul 11;12(3):106. doi: 10.3390/ph12030106. PMID: 31373315; PMCID: PMC6789669.