Synergistic effect of hyperoside and amentoflavone found in cashew leaf crude extract and potassium sorbate on inhibition of food spoilage bacteria

Antimicrobial potential of cashew leaf crude extract (CLCE) and its major phenolic compounds, particularly when used in combination with potassium sorbate toward spoilage bacteria, was investigated. CLCE was extracted using an ultrasound-assisted method with 80 % ethanol. Yield, total phenolic content, and total flavonoid content in CLCE were 22.24 ± 0.76 %, 414.55 ± 14.64 mg GAE/g dry solid, and 321.70 ± 18.86 mg QE/g dry solid, respectively. CLCE had lower MIC and MBC toward Shewanella putrefaciens than Pseudomonas aeruginosa ( p < 0.05). Based on LC-QTOF-MS analysis, the main phenolics, namely amentoflavone, quercetin, kaempferol, and catechin, were found in CLCE. The major phenolic compounds, including hyperoside, amentoflavone, catechin, and kaempferol were identified by qualitative HPLC analysis. All major compounds demonstrated significant antimicrobial activity against S. putrefaciens and P. aeruginosa at lower concentrations (0.125–0.500 mg/mL) than potassium sorbate ( p < 0.05). The synergistic effect of amentoflavone and hyperoside at MIC/16 with potassium sorbate at various MICs was also studied. Amentoflavone and hyperoside showed higher inhibition against S. putrefaciens when used in conjunction with potassium sorbate at MIC/2 and MIC/4, respectively. However, potassium sorbate did not enhance inhibition against P. aeruginosa when used in combination with both compounds. Furthermore, scanning electron microscopic images revealed the deformed and perforated cells after treatment with all the compounds, and severe deformation was found when the compound mixtures were employed. Based on molecular docking, hyperoside or amentoflavone in combination with potassium sorbate interacted with the DNA's minor groove, mainly at the region rich in adenine and thymine. Therefore, active phenolic compounds worked synergistically with potassium sorbate, in which the lower amount of CLCE was required for treatment of perishable seafood. • Cashew leaf crude extract (CLCE) inhibited both S. putrefaciens and P. aeruginosa. • CLCE had hyperoside and amentoflavone as the major compounds. • Amentoflavone and hyperoside had synergism with K-sorbate against S. putrefaciens. • Bacterial cells treated with mixed compounds had the morphological changes. • DNA interacted with hyperoside and K-sorbate, mainly at A-T base pair.