This study investigates the phytochemical composition and biological activities of dichloromethane surface extracts from the aerial parts of Salvia karwinskii. The objective was to explore sustainable agricultural applications by evaluating the biological activity of the extract against bacterial, fungal phytopathogens and pests. Phytochemical analysis revealed the presence of three clerodane-type diterpenoids: hardwickic acid, involucratin C, and 6-hydroxyannonene. The exudate's minimum inhibitory concentrations (MICs) were assessed against two phytopathogenic bacteria using the microdilution broth method. The extract demonstrated moderate activity against Clavibacter michiganensis subsp. michiganensis (MIC: 500 μg/mL) and limited efficacy against Pectobacterium carotovorum subsp. carotovorum (MIC > 1000 μg/mL). Antifungal activity was evaluated in vitro against nine phytopathogens, compared to synthetic fungicides. The extract at 1000 μg/mL completely inhibited the mycelial growth of Phaemoniella chlamydospora, comparable to the synthetic fungicide Score® 25 EC. Additionally, significant inhibition of Pythium dissotocum (86.7%) was observed at 750 μg/mL, statistically similar to Switch® fungicide. Other notable results included 94.3% inhibition of Stemphylium sp., comparable to Ridomil Gold® WG. The extract also exhibited activity against Fusarium solani, Alternaria solani, Phoma betae, Colletotrichum lindemuthianum, and moderate inhibition of Fusarium oxysporum fsp. lactucae race 1. Interestingly, the mycelial growth of Botrytis cinerea was inhibited by 97.2% at 1000 μg/mL comparable to Switch®. Furthermore, the extract’s efficacy against gray mold disease caused by B. cinerea on tomato fruits was assessed in preventive and curative treatments. In curative trials, the exudate at concentrations as low as 100 μg/mL achieved complete decay control, comparable to peracetic acid. However, no preventive activity was observed. In addition, the bioinsecticidal potential of the extract was tested against Tuta absoluta, a major invasive pest of tomato crops. The exudate exhibited strong antifeedant and insecticidal properties, with an LC50 value of 0.410 mg/mL, outperforming the commercial insecticide Spinosad. These findings highlight the potential of S. karwinskii exudate as a sustainable source of bioactive compounds for agricultural pest and pathogen management.
Phytochemical insights and biological activity of Salvia karwinskii Benth. exudate against phytopathogens and pests
Devi P;Bisio A
2025-01-01
Abstract
This study investigates the phytochemical composition and biological activities of dichloromethane surface extracts from the aerial parts of Salvia karwinskii. The objective was to explore sustainable agricultural applications by evaluating the biological activity of the extract against bacterial, fungal phytopathogens and pests. Phytochemical analysis revealed the presence of three clerodane-type diterpenoids: hardwickic acid, involucratin C, and 6-hydroxyannonene. The exudate's minimum inhibitory concentrations (MICs) were assessed against two phytopathogenic bacteria using the microdilution broth method. The extract demonstrated moderate activity against Clavibacter michiganensis subsp. michiganensis (MIC: 500 μg/mL) and limited efficacy against Pectobacterium carotovorum subsp. carotovorum (MIC > 1000 μg/mL). Antifungal activity was evaluated in vitro against nine phytopathogens, compared to synthetic fungicides. The extract at 1000 μg/mL completely inhibited the mycelial growth of Phaemoniella chlamydospora, comparable to the synthetic fungicide Score® 25 EC. Additionally, significant inhibition of Pythium dissotocum (86.7%) was observed at 750 μg/mL, statistically similar to Switch® fungicide. Other notable results included 94.3% inhibition of Stemphylium sp., comparable to Ridomil Gold® WG. The extract also exhibited activity against Fusarium solani, Alternaria solani, Phoma betae, Colletotrichum lindemuthianum, and moderate inhibition of Fusarium oxysporum fsp. lactucae race 1. Interestingly, the mycelial growth of Botrytis cinerea was inhibited by 97.2% at 1000 μg/mL comparable to Switch®. Furthermore, the extract’s efficacy against gray mold disease caused by B. cinerea on tomato fruits was assessed in preventive and curative treatments. In curative trials, the exudate at concentrations as low as 100 μg/mL achieved complete decay control, comparable to peracetic acid. However, no preventive activity was observed. In addition, the bioinsecticidal potential of the extract was tested against Tuta absoluta, a major invasive pest of tomato crops. The exudate exhibited strong antifeedant and insecticidal properties, with an LC50 value of 0.410 mg/mL, outperforming the commercial insecticide Spinosad. These findings highlight the potential of S. karwinskii exudate as a sustainable source of bioactive compounds for agricultural pest and pathogen management.
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