Evaluation of Alkaloids Isolated from Ruta graveolens as Photosynthesis Inhibitors.

Olívia Sampaio,Blas Lotina-Hennsen,Barbara Bellete,Lucas Vieira,Beatriz King-Diaz,Thiago Veiga,Maria Da Silva

doi:10.3390/molecules23102693

Abstract

Eight alkaloids (1–8) were isolated from Ruta graveolens, and their herbicide activities were evaluated through in vitro, semivivo, and in vivo assays. The most relevant results were observed for Compounds 5 and 6–8 at 150 μM, which decreased dry biomass by 20% and 23%, respectively. These are significant results since they presented similar values with the positive control, commercial herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Based on the performed assays, Compound 5 (graveoline) is classified as an electron-transport inhibitor during the light phase of photosynthesis, as well as a plant-growth regulator. On the other hand, Compounds 6–8 inhibited electron and energy transfers, and are also plant-growth inhibitors. These phytotoxic behaviors based on acridone and quinolone alkaloids may serve as a valuable tool in the further development of a new class of herbicides since natural products represent an interesting alternative to replace commercial herbicides, potentially due their low toxicity.

Highlights

Ruta graveolens L. (Rutaceae) is a medicinal plant whose roots and aerial parts contain more than 120 special metabolites as coumarins, flavonoids, acridones, and furoquinoline alkaloids [1,2].Many of these metabolites have attracted biological and pharmacological interest, demonstrating antifungal, phytotoxic, and antidotal activities [3,4,5,6,7,8,9]
The results found, with reaction, a increment of the step as well as a decrease in the phosphorylating and uncoupled steps, regard to electron-transport reaction, a increment of the step as well as a decrease in the indicating that (1) exhibited a dual effect by inhibiting both energy transfer and electron transport [17]
The first inhibition site (H2 O to SiMo) occurs in the enzyme where water photo-oxidation happens, and the other at DPC to DCPIPox, located at the water-splitting enzyme complex (OEC) and between the range of electron flow from P680 to QA. These results indicated that 1 inhibited PSII at the span of electron transport from H2 O to QA due the fact that SiMo accepts electrons exactly at the QA site

Summary

Introduction

(Rutaceae) is a medicinal plant whose roots and aerial parts contain more than 120 special metabolites as coumarins, flavonoids, acridones, and furoquinoline alkaloids [1,2]. Many of these metabolites have attracted biological and pharmacological interest, demonstrating antifungal, phytotoxic, and antidotal activities [3,4,5,6,7,8,9]. Light absorption by antenna molecules is followed by efficient charge separation across the membrane via photosynthetic reaction centers [14]. The antenna system absorbs and converts light into chemical energy at P680

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