Design, synthesis and biological activity of hydroxybenzoic acid ester conjugates of phenazine-1-carboxylic acid

Abstract

We prepared 16 novel hydroxybenzoic acid ester conjugates of phenazine-1-carboxylic acid (PCA) and investigated their biological activity. Most of the synthesized conjugates displayed some level of fungicidal activities in vitro against five phytopathogenic fungi. Nine conjugates 5b, 5c, 5d, 5e, 5h, 5i, 5m, 5n and 5o (EC50 between 3.2 μg/mL and 14.1 μg/mL) were more active than PCA (EC50 18.6 μg/mL) against Rhizoctonia solani. Especially conjugate 5c showed the higher fungicidal activity against Rhizoctonia solani which is 6.5-fold than PCA. And the results of the bioassay indicated that the fungicidal activity of conjugates was associated with their LogP, and the optimal LogP values of the more potent fungicidal activities within these conjugates ranged from 4.42 to 5.08. The systemic acquired resistance induced by PCA–SA ester conjugate 5c against rice sheath blight disease in rice seedlings was evaluated. The results revealed that PCA–SA ester conjugate 5c retained the resistance induction activity of SA against rice sheath blight.Electronic supplementary materialThe online version of this article (10.1186/s13065-018-0478-2) contains supplementary material, which is available to authorized users.

The influence of steric configuration of phenazine‐1‐carboxylic acid‐amino acid conjugates on fungicidal activity and systemicity

“…The primary fungicidal activities of 10 PCA‐amino acid conjugates were evaluated using an amended agar assay described in our previously published literature . Each test compound was first dissolved within a suitable amount of acetone and diluted with water containing 0.1% Tween 80 to 2 mmol L −1 , and 1 mL of each was then added to 9 mL molten (50 °C) sterile potato dextrose agar (PDA).…”

“…The primary fungicidal activities of 10 PCA-amino acid conjugates were evaluated using an amended agar assay described in our previously published literature. 15,17 Each test compound was first dissolved within a suitable amount of acetone and diluted with water containing 0.1% Tween 80 to 2 mmol L −1 , and 1 mL of each was then added to 9 mL molten (50 ∘ C) sterile potato dextrose agar (PDA the PDA culture and PT represented colony diameter of amended agar plates. All statistical analyses were performed using DPS 7.05 software using analysis of variance at P = 0.05.…”

“…1) is an important N-containing heterocyclic secondary metabolite, with a wide range of biological activities, isolated from numerous bacterial genera, including Pseudomonas and Streptomycetes. [15][16][17] PCA has been found to be effective against several phytopathogenic fungi, and has been registered in China as the biofungicide 'Shenqinbactin' against rice sheath blight caused by Rhizoctonia solani. 18,19 The synthesis and biosynthesis of PCA and its derivatives have been widely studied and reported in the literature.…”

Systemic fungicidal activity of phenazine‐1‐carboxylic acid‐valine conjugate against tobacco sore shin and its translocation and accumulation in tobacco (Nicotiana tabacum L.)

“…[15][16][17][18][19] Recent studies have shown that it not only has wide spectrum high efficiency, and low toxicity to human and livestock, but also can be easily degraded in the natural environment and significantly improve crop yield. [20][21][22] At present, it has been registered as 'Shenqinbactin' in China as a biofungicide for the control of rice sheath blight. 23 However, the efficacy of PCA against soil borne diseases is considered low because of the lack of phloem systemicity, which seriously restricts its application to other crops.…”

Antifungal weapons of Lysobacter, a mighty biocontrol agent

“…are toxins, phenazine‐1‐carboxylate and 2,4‐diacetylphloroglucinol (Haas and Defago, 2005; Ongena and Jacques, 2008). Phenazine‐1‐carboxylate induces the production of the poisonous hydroxyl radical in fungal cells (Zhu et al ., 2018), while 2, 4‐diacetylphloroglucinol causes membrane damage (Haas and Defago, 2005). The synthesis, regulation and applications of these antifungal agents have been covered in recent reviews (Ongena and Jacques, 2008; Raaijmakers et al ., 2010; Pieterse et al ., 2014; Bilal et al ., 2017).…”