Photosynthetic Toxicological Effects of Organic Extracts from Zanthoxylum bungeanum Leaves on Controlling the Microcystis aeruginosa Blooms.

Abstract

In recent years, the frequent occurrence of algal blooms has posed continuous threats to aquatic ecosystems and social safety. Environmentally friendly algae-inhibiting methods utilizing allelopathic substances offer advantages such as convenient application and low costs, presenting a bright application prospect in the fields of water and ecological restoration. This study aimed to investigate the procedure for extracting total flavonoids from Zanthoxylum bungeanum leaves and assess allelopathic mechanism of Z. bungeanum leaf extracts on Microcystis aeruginosa. The optimal extraction conditions were determined as follows: solvent-to-material ratio = 10 mL/g; extraction time = 55 min; ethanol volume fraction = 80%; and ultrasonic temperature = 80 °C. Antioxidant activity tests revealed that Z. bungeanum leaf extracts exhibit superior capacity compared to Butylated hydroxytoluene (BHT) but inferior to Vitamin C (VC). Moreover, high-concentration Z. bungeanum leaf extracts can disrupt the structures of oxygen-evolving complexes at the donor sides of photosystem II (PSII) reaction center and influence energy distribution at PSII reaction centers, thereby inhibiting electron transmission activities at both donor and receptor sides of the PSII reaction center. The elucidated allelopathic mechanism of Z. bungeanum leaf extracts provides theoretical evidence for the algal-bloom control and the development of allelopathic algae-inhibiting agents, offering a reference for the further comprehensive development and utilization of Z. bungeanum.