# Secondary Metabolites and Antioxidant Activity against Moko Disease as a Defense Mechanism of Musa spp. from the Ecuadorian Coast Area

## TL;DR

This study explores how banana plants from Ecuador's coast defend against Moko disease by producing antioxidant compounds.

## Contribution

The study identifies specific secondary metabolites in Musa spp. that increase during Moko disease infection as part of the plant's defense mechanism.

## Key findings

- Diseased Musa spp. samples showed higher accumulation of antioxidant secondary metabolites than healthy ones.
- Over 40 compounds, including kaempferol and quercetin glycosides, were identified as part of the defense system against Ralstonia solanacearum.
- LC-MS and antioxidant assays confirmed increased synthesis of active compounds during Moko disease symptoms.

## Abstract

The Musa spp. represents the most commonly produced, transitioned, and consumed fruit around the globe, with several important applications in the biotechnology, pharmaceutical, and food industries. Moko disease is produced by Ralstonia solanacearum—a factor with a high impact on all crops in Ecuador, representing one of the biggest phytosanitary problems. Four of the most common varieties of Musa spp. were tested to identify the metabolic reaction of plants facing Moko disease. The phenolic and flavonoid content has been evaluated as a defense system, and the α-diphenyl-α-picrylhydrazyl free-radical-scavenging method (DPPH), free-radical-scavenging activity (ABTS), ferric-reducing antioxidant power (FRAP) assays, and liquid chromatography and mass spectrometry (LC-MS) have been adapted to analyze the active compounds with the antioxidant capacity necessary to counteract the pathogenic attack. Our results indicate that all the studied varieties of Musa spp. react in the same way, such that the diseased samples showed a higher accumulation of secondary metabolites with antioxidant capacity compared with the healthy ones, with high active compound synthesis identified during the appearance of Moko disease symptoms. More than 40 compounds and their derivatives (from kaempferol and quercetin glycosides) with protective roles demonstrate the implication of the Musa spp. defense system against R. solanacearum infection.