# Phytotoxic Metabolites from Hyptis Species: Chemical Profiling and Bioherbicide Activity Against Amaranthus

## TL;DR

This study identifies phytotoxic compounds in Hyptis plant extracts that effectively inhibit weed seed germination and growth, comparable to commercial herbicides.

## Contribution

The study introduces a new chemical profiling approach to identify bioactive metabolites in Hyptis species with potential as natural herbicides.

## Key findings

- Hyptis crenata and Hyptis saxatilis extracts inhibited seed germination by 85–93% and suppressed weed growth comparable to commercial herbicides.
- Multivariate analysis identified 56 metabolites, with terpenoids, especially abietane-type diterpenes, strongly correlated with phytotoxicity.
- LC-MS/MS and molecular networking enabled compound annotation, revealing potential bioherbicide candidates.

## Abstract

The phytotoxic effects
of extracts from Hyptis crenata (
Hcre
), Hyptis suaveolens (
Hsua
), Hyptis saxatilis (
Hsax
), Hyptis campestris (
Hcam
), and Hyptis brevipes (
Hbre
) were evaluated against three Amaranthus weed species under controlled germination chamber
conditions. Extracts
Hcre
,
Hsua
and
Hsax
inhibited
seed germination by 85–93% relative to the control and markedly
suppressed radicle and hypocotyl growth in Amaranthus viridis and Amaranthus hybridus in Petri dish assays. At
200 ppm,
Hcre
and
Hsax
reduced radicle and hypocotyl lengths by up to 90% in both
species, comparable to the effects of commercial herbicides Sencor
and Sulfentrazone. Multivariate analyses, including PCA, PLS-DA, and
molecular networking based on LC-MS/MS data, enabled the annotation
of compounds associated with phytotoxicity. A total of 56 metabolites
were identified, including terpenoids, flavonoids, α-pyrones,
carbohydrate derivatives, and polyketides, using both an in-house
database and the GNPS platform. Terpenoids were the predominant class,
with abietane-type diterpenes as the most abundant subgroup, exhibiting
strong correlations with the observed biological activity.