# Impact of Scutellonema curcumae sp. n. (Nematoda: Hoplolaimidae) on the Phytochemical Profile and Biological Activities of Turmeric (Curcuma longa L.)

## TL;DR

A new nematode species harms turmeric by reducing its curcuminoid content and medicinal properties, highlighting the need for nematode control in agriculture.

## Contribution

First report of a Scutellonema species affecting turmeric and its impact on phytochemical and therapeutic profiles.

## Key findings

- High nematode infestation reduces total curcuminoid content in turmeric.
- Lower nematode density increases bisdemethoxycurcumin levels by up to 250%.
- Reduced infestation enhances antioxidant and cytotoxic activities of turmeric rhizomes.

## Abstract

A new spiral nematode species, Scutellonema curcumae sp. n., was identified from the rhizosphere of turmeric (Curcuma longa L.) in the Western Highlands of Vietnam. Integrative taxonomical analysis, combining detailed morphology and molecular characterization (ITS, 28S D2–D3 rDNA, and COI mtDNA), confirmed its distinctiveness. Scutellonema curcumae sp. n. is characterized by a unique combination of a spiral body, a hemispherical lip region with four annuli, a robust stylet, and a rounded tail with a prominent scutellum, forming a highly divergent lineage within the genus. Beyond its description, this study reveals a significant inverse correlation between nematode population density and the phytochemical quality of the host. High infestation levels were associated with a marked decline in total curcuminoid content. Notably, lower nematode density favored a specific shift in the curcuminoid profile, with bisdemethoxycurcumin levels increasing by up to 250%. These phytochemical alterations directly influenced the therapeutic potential of the rhizomes: lower infestation levels resulted in significantly enhanced antioxidant capacity (lower SC50 values) and cytotoxic activity (lower IC50 against HepG2 and A549 cell lines). This work represents the first report of a Scutellonema species associated with turmeric in Vietnam and underscores its detrimental impact on the medicinal and nutraceutical value of the crop. Our findings suggest that effective nematode management is crucial not only for yield protection but as a strategic intervention in precision agriculture to optimize the secondary metabolite profiles of medicinal plants.