Enzymes Transform Acid in Purple Coneflower Seed Sprouting

Jim Crocker
28th April, 2024

Enzymes Transform Acid in Purple Coneflower Seed Sprouting

Image Source: Natural Science News, 2024

Key Findings

  • Study at Sichuan University found how purple coneflower seeds convert chlorogenic acid during germination
  • An enzyme named CAS turns chlorogenic acid into chicoric acid, with an intermediate compound formed in between
  • This process is crucial for the seedling's growth, as too much chlorogenic acid can inhibit root development
Chlorogenic acid is a compound that most of us unknowingly consume daily, primarily through coffee. It belongs to a group of compounds known as acyl-quinic acids, which have been recognized for their potential health benefits, including anti-inflammatory and antioxidant effects[2]. In the plant world, chlorogenic acid is not just a passive compound; it plays an active role in plant growth and defense mechanisms[3]. A recent study by researchers at Sichuan University[1] has shed new light on the metabolism of chlorogenic acid, specifically during the germination process of the purple coneflower (Echinacea purpurea). The purple coneflower is known for its medicinal properties, often used in supplements to support the immune system. Interestingly, this plant accumulates large amounts of chlorogenic acid in its seeds. The Sichuan University study has discovered that during germination, a specific enzyme, a serine carboxypeptidase-like (SCPL) acyltransferase named chicoric acid synthase (CAS), converts chlorogenic acid into chicoric acid. However, this conversion doesn't happen immediately; there is a period where chlorogenic acid levels decrease before chicoric acid appears. This gap led researchers to uncover an intermediate compound, 3,5-dicaffeoylquinic acid, which is produced during this lag phase. The study went on to identify two additional enzymes, chlorogenic acid condensing enzymes (CCEs), which are responsible for creating 3,5-dicaffeoylquinic acid from chlorogenic acid. These enzymes were found to have different kinetic characteristics, which means they work at different rates and efficiencies. The presence of these enzymes and the metabolic products they create suggest that there is a finely tuned mechanism at play during the germination of Echinacea purpurea, where regulating the levels of chlorogenic acid is crucial. One might wonder why the plant needs to regulate chlorogenic acid so carefully. The study found that chlorogenic acid inhibits the elongation of the radicle (the part of a plant embryo that develops into the primary root) in a dose-dependent manner. This implies that too much chlorogenic acid could potentially hinder the growth of the seedling. Therefore, the plant's ability to metabolize chlorogenic acid through the action of SCPL acyltransferases is vital for successful germination. The researchers also highlighted that the enzymes responsible for this metabolic pathway, CCE1 and CCE2, are highly conserved among different Echinacea species. This conservation across species indicates that the metabolism of chlorogenic acid to 3,5-dicaffeoylquinic acid is a widespread strategy in Echinacea, not just limited to those species that accumulate chicoric acid. The discovery of these metabolic processes in Echinacea not only provides insights into the germination strategies of this particular plant but also contributes to the broader understanding of plant metabolism. It highlights the complex roles that compounds like chlorogenic acid play in plant development—roles that transcend the simple categorization of primary and secondary metabolites[3]. Furthermore, the study supports previous findings that the gut microbiota plays a role in the metabolism of chlorogenic acid within the human body, as these compounds can be transformed during digestion[2]. This research also emphasizes the importance of correct nomenclature and understanding of different isomers of compounds like chlorogenic acid[4]. As different isomers can have varying bioactivity and potency, clear and consistent naming is crucial for assessing their biological properties and potential health benefits. In conclusion, the work by Sichuan University expands our knowledge of plant metabolism and underscores the importance of chlorogenic acid metabolism in the germination of Echinacea purpurea. It also illustrates how plants have evolved complex biochemical pathways to manage their internal levels of certain compounds, which in turn can have implications for human health and nutrition.

BiotechBiochemPlant Science

References

Main Study

1) SCPL acyltransferases catalyze the metabolism of chlorogenic acid during purple coneflower seed germination.

Published 26th April, 2024

https://doi.org/10.1111/nph.19776

Related Studies

2) Chlorogenic acids and the acyl-quinic acids: discovery, biosynthesis, bioavailability and bioactivity.

https://doi.org/10.1039/c7np00030h

3) Plant Secondary Metabolites as Defenses, Regulators, and Primary Metabolites: The Blurred Functional Trichotomy.

https://doi.org/10.1104/pp.20.00433

4) Caffeoylquinic acids: chemistry, biosynthesis, occurrence, analytical challenges, and bioactivity.

https://doi.org/10.1111/tpj.15390


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