Microscopic view of programmed cell death in algal cells induced by linalool and a-terpineol.

Can Natural Compounds Combat Algae Blooms? Linalool and a-Terpineol as Potential Algaecides

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Samir D’Costa in Climate & Environment August 2025 • 4 min read.

"Unlocking the potential of linalool and a-terpineol to fight algal blooms through programmed cell death in algae."


Algal blooms, the rapid and excessive growth of algae in water bodies, pose a significant threat to aquatic ecosystems and human health. These blooms, often fueled by excess nutrients like nitrogen and phosphorus, can lead to oxygen depletion, toxin production, and disruption of the food chain. Finding effective and environmentally friendly ways to control algal blooms is a pressing challenge for scientists and environmental managers.

Traditional methods of algae control, such as chemical treatments, can have unintended consequences for non-target organisms and the overall health of the ecosystem. This has spurred the search for more sustainable and selective approaches, including the use of plant-derived compounds known as allelochemicals. These natural substances can inhibit or control algal growth without the harsh side effects of synthetic chemicals.

A recent study published in Ecotoxicology and Environmental Safety has investigated the potential of two such allelochemicals, linalool and a-terpineol, to combat algal blooms. These compounds, found in the extracts of Cinnamomum camphora (camphor tree), have shown promising algicidal properties. The research delves into the lethal mechanism of these compounds, focusing on their ability to induce programmed cell death (PCD) in Chlamydomonas reinhardtii, a common green alga.

How Do Linalool and a-Terpineol Trigger Programmed Cell Death in Algae?

Microscopic view of programmed cell death in algal cells induced by linalool and a-terpineol.

The study's findings reveal that both linalool and a-terpineol can effectively induce programmed cell death (PCD) in Chlamydomonas reinhardtii. PCD, also known as apoptosis, is a genetically controlled process of cellular self-destruction that plays a crucial role in the development and homeostasis of multicellular organisms. In algae, PCD can be triggered by various environmental stressors, including nutrient deprivation, oxidative stress, and exposure to toxins.

The researchers investigated several key indicators of PCD in C. reinhardtii cells treated with linalool and a-terpineol, including:

  • Increased production of reactive oxygen species (ROS): Both compounds caused a rapid increase in the production of ROS, particularly hydrogen peroxide (H2O2), within the algal cells. ROS are highly reactive molecules that can damage cellular components and trigger PCD.
  • Degradation of photosynthetic pigments: Linalool and a-terpineol led to a gradual degradation of chlorophyll and other photosynthetic pigments, impairing the algae's ability to perform photosynthesis.
  • Activation of caspase-like enzymes: The study found that both compounds activated caspase-9-like and caspase-3-like enzymes in C. reinhardtii cells. Caspases are a family of proteases that play a central role in the execution of PCD in animals. While algae do not possess true caspases, they have caspase-like enzymes that perform similar functions.
  • Changes in nuclear morphology and DNA fragmentation: Treatment with linalool and a-terpineol resulted in changes in the morphology of the algal cell nuclei, including condensation and fragmentation. The researchers also observed DNA degradation, a hallmark of PCD.
These findings suggest that linalool and a-terpineol trigger a cascade of events leading to PCD in C. reinhardtii. The initial increase in ROS production likely causes oxidative damage to cellular components, activating caspase-like enzymes and ultimately leading to DNA fragmentation and cell death. The degradation of photosynthetic pigments further contributes to the demise of the algal cells by shutting down their energy production.

Implications and Future Directions

This study provides valuable insights into the potential of linalool and a-terpineol as natural algaecides. By inducing programmed cell death in algae, these compounds offer a more targeted and environmentally friendly approach to controlling algal blooms compared to traditional chemical treatments. However, further research is needed to fully understand the ecological impacts of these compounds and to optimize their application in real-world settings. Future studies should focus on:

About this Article -

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Everything You Need To Know

1

What are algal blooms, and why should I care about them?

Algal blooms refer to the rapid and excessive growth of algae in water bodies. They are significant because they can deplete oxygen levels, produce toxins harmful to aquatic life and humans, and disrupt the food chain. These blooms are often fueled by excess nutrients like nitrogen and phosphorus, highlighting the importance of nutrient management in preventing them. If left unchecked, algal blooms can lead to severe ecological and economic consequences.

2

What are linalool and a-terpineol, and why are they being studied for algae control?

Linalool and a-terpineol are natural compounds, specifically allelochemicals, found in plants like *Cinnamomum camphora*. They are significant because they possess algicidal properties, meaning they can kill or inhibit the growth of algae. This is important in the context of controlling harmful algal blooms, as these compounds offer a potentially more environmentally friendly alternative to traditional chemical treatments. Their ability to induce programmed cell death in algae makes them particularly promising.

3

What is programmed cell death, and why is it important in controlling algae?

Programmed cell death (PCD), also known as apoptosis, is a genetically controlled process of cellular self-destruction. It is crucial because it allows for a controlled and organized way for cells to die, preventing damage to surrounding tissues. In algae, PCD can be triggered by stressors like nutrient deprivation or toxins. The induction of PCD by compounds like linalool and a-terpineol is significant because it offers a targeted approach to controlling algal blooms without harming other organisms.

4

How do linalool and a-terpineol actually kill algae cells?

Linalool and a-terpineol trigger programmed cell death in algae through a series of steps. First, they cause an increase in the production of reactive oxygen species (ROS) within the algal cells. These ROS damage cellular components, which then activates caspase-like enzymes. These enzymes lead to changes in the algal cell nuclei, including condensation and DNA fragmentation, ultimately resulting in cell death. Additionally, linalool and a-terpineol lead to the degradation of photosynthetic pigments, impairing the algae's ability to produce energy.

5

What are reactive oxygen species (ROS), and what role do they play in algae control using natural compounds?

Reactive oxygen species (ROS) are highly reactive molecules that can cause damage to cellular components, including DNA, proteins, and lipids. ROS are significant in the context of programmed cell death because they act as triggers for apoptosis. When algae are exposed to linalool and a-terpineol, there is a rapid increase in ROS production within the cells, leading to oxidative stress and the activation of caspase-like enzymes, ultimately resulting in cell death.

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