Isolation, Identification, and Evaluation of the Antifungal and Anti-TMV Activities of Sucrose Esters from Nicotiana glutinosa

This study investigated the potential application of sucrose esters (SEs) derived from Nicotiana glutinosa for biopesticide development. SEs were extracted using solvent extraction, purified by normal-phase silica gel column chromatography, followed by identification and quantification using GC/MS analysis. The antifungal properties against phytopathogenic fungi was evaluated through the mycelial growth rate method, and the anti-tobacco mosaic virus (TMV) activity using the half-leaf lesion assay. Two distinct SE configurations were isolated and identified from N. glutinosa: SE- Ⅱ (acetylated at fructose C-3’) and SE- Ⅲ (non-acetylated at fructose C-3’). SEs contents varied significantly among tissues, with the highest levels observed in upper leaves (3.56 mg/g fresh weight) and flowers (3.21 mg/g), substantially exceeding those in middle leaves, lower leaves, and stems. The ratio of SE- Ⅱ to SE- Ⅲ in various organs decreases with the rising position on the tobacco plant. The crude SE extract, SE- Ⅱ, and SE- Ⅲ exhibited broad-spectrum antifungal activity, with notably strong inhibition observed against Botrytis cinerea. At a concentration of 20 μg/mL, three SE forms achieved inhibition rates of 57.75%, 65.58%, and 84.73%, respectively. The antifungal activity of the crude SE extract against B. cinerea was superior to the botanical fungicides eugenol and osthole. SE- Ⅱ showed comparable activity to the synthetic fungicide pyrimethanil, whereas SE- Ⅲ exhibited significantly stronger inhibitory effects than pyrimethanil. In anti-TMV assays at 200 μg/mL, inhibition rates were 36.33% (crude extract), 69.09% (SE- Ⅱ), and 64.41% (SE- Ⅲ). The antiviral activity of the crude SE extract matched that of oligosaccharins, while SE- Ⅱ and SE- Ⅲ showed efficacy comparable to that of ningnanmycin. These findings identify N. glutinosa represents a valuable source of diverse and bioactive SEs showing promising potential for the management of biofungicides against gray mold and antiviral agents for crop protection.