# Improving the Activity of Aminophenoxazinones: Synthesis, CPC Purification, and Phytotoxicity Potential

## TL;DR

This paper describes the synthesis and purification of aminophenoxazinone derivatives that show strong phytotoxic effects, making them promising candidates for sustainable herbicides.

## Contribution

A novel purification method and structure-activity relationship analysis led to the discovery of a highly potent agrochemical lead.

## Key findings

- Compound 11 caused 89% root inhibition in Portulaca oleracea at 1000 μM.
- Compound 10 exhibited an IC50 of 4.5 μM against P. oleracea roots, much lower than natural APO.
- Centrifugal partition chromatography successfully purified APO derivatives with strong compound-solid phase interactions.

## Abstract

Aminophenoxazinones (APOs) are potent phytotoxic metabolites
and
histone deacetylase inhibitors, offering a low-resistance bioherbicide
profile. This research synthesized a library of APO derivatives with
targeted modifications to optimize physicochemical properties and
biological activity using oxidative cyclocondensation. Purification
challenges from strong compound-solid phase interactions were overcome
by using centrifugal partition chromatography (CPC). Phytotoxicity
was screened against Lolium rigidum, Portulaca oleracea, and Plantago lanceolata. While germination remained largely
unaffected, compounds 10 and 11 caused significant
root inhibition (77% and 89%, respectively for P. oleracea) at 1000 μM. Specifically, 11 reached inhibition
levels comparable to the positive control, pendimethalin (86% for P. oleracea). Following a detailed structure–activity
relationship analysis, 10 emerged as the most potent
candidate, exhibiting an IC50 of 4.5 μM against P. oleracea roots, considerably lower than that of
natural APO (332.5 μM). These findings strongly
validate this rational design and purification strategy, positioning 10 as a valuable agrochemical lead for sustainable weed management.