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Extraction, Chemical Composition, and Antifungal Activity of Essential Oil of Bitter Almond

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ABSTRACT

The essential oil from the powder residual of dried bitter almond, a novel and environmentally-friendly fungicide, was successfully extracted in a 0.7% yield by hydro-distillation under optimized conditions. The chemical composition of bitter almond essential oil (BAEO) was analyzed by gas chromatography–mass spectrometry (GC–MS). Twenty-one different components representing 99.90% of the total essential oil were identified, of which benzaldehyde (62.52%), benzoic acid (14.80%), and hexadecane (3.97%) were the most abundant components. Furthermore, the in vitro and in vivo antifungal activities of BAEO against common plant pathogenic fungi were evaluated by the mycelium linear growth rate method and pot test, respectively. It was documented that 1 mg/mL of BAEO could variously inhibit all tested pathogenic fungi with the inhibition rates of 44.8%~100%. Among the tested 19 strains of fungi, the median effective concentration (EC50) values of BAEO against Alternaria brassicae and Alternaria solani were only 50.2 and 103.2 μg/mL, respectively, which were higher than those of other fungi. The in vivo antifungal activity of BAEO against Gloeosporium orbiculare was much higher than Blumeria graminis. The protective efficacy for the former was up to 98.07% at 10 mg/mL and the treatment efficacy was 93.41% at 12 mg/mL. The above results indicated that BAEO has the great potential to be developed as a botanical and agricultural fungicide.

No MeSH data available.


Hydrolysis of amygdalin.
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ijms-17-01421-f001: Hydrolysis of amygdalin.

Mentions: After removing the fatty oil from the dried powder of bitter almond via the heating-crushing method, BAEO was extracted in a 0.7% yield from the left press cake by the hydro-distillation method using a special apparatus designed by our group. The optimized extracting process was accomplished as follows: firstly, the powder residual (100 mg) was soaked in 500 mL of weak acid water (pH = 5) at 40 °C for 1 h, so that the main bioactive substance, amygdalin, could be totally hydrolyzed to give glucose and benzaldehyde meanwhile releasing the poisonous constituent, hydrogen cyanide (HCN) (Figure 1). The resulting suspension was then vigorously stirred and distilled for 1 h, and the yellowish BAEO accumulated at the bottom of the handmade apparatus, which was designed to extract volatile oil. After the water–oil mixture had been standing in a separatory funnel for 30 min, crude BAEO was separated from the lower organic layer, and dried with anhydrous sodium sulfate. Finally, BAEO was achieved in a 0.7% yield.


Extraction, Chemical Composition, and Antifungal Activity of Essential Oil of Bitter Almond
Hydrolysis of amygdalin.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037700&req=5

ijms-17-01421-f001: Hydrolysis of amygdalin.
Mentions: After removing the fatty oil from the dried powder of bitter almond via the heating-crushing method, BAEO was extracted in a 0.7% yield from the left press cake by the hydro-distillation method using a special apparatus designed by our group. The optimized extracting process was accomplished as follows: firstly, the powder residual (100 mg) was soaked in 500 mL of weak acid water (pH = 5) at 40 °C for 1 h, so that the main bioactive substance, amygdalin, could be totally hydrolyzed to give glucose and benzaldehyde meanwhile releasing the poisonous constituent, hydrogen cyanide (HCN) (Figure 1). The resulting suspension was then vigorously stirred and distilled for 1 h, and the yellowish BAEO accumulated at the bottom of the handmade apparatus, which was designed to extract volatile oil. After the water–oil mixture had been standing in a separatory funnel for 30 min, crude BAEO was separated from the lower organic layer, and dried with anhydrous sodium sulfate. Finally, BAEO was achieved in a 0.7% yield.

View Article: PubMed Central - PubMed

ABSTRACT

The essential oil from the powder residual of dried bitter almond, a novel and environmentally-friendly fungicide, was successfully extracted in a 0.7% yield by hydro-distillation under optimized conditions. The chemical composition of bitter almond essential oil (BAEO) was analyzed by gas chromatography–mass spectrometry (GC–MS). Twenty-one different components representing 99.90% of the total essential oil were identified, of which benzaldehyde (62.52%), benzoic acid (14.80%), and hexadecane (3.97%) were the most abundant components. Furthermore, the in vitro and in vivo antifungal activities of BAEO against common plant pathogenic fungi were evaluated by the mycelium linear growth rate method and pot test, respectively. It was documented that 1 mg/mL of BAEO could variously inhibit all tested pathogenic fungi with the inhibition rates of 44.8%~100%. Among the tested 19 strains of fungi, the median effective concentration (EC50) values of BAEO against Alternaria brassicae and Alternaria solani were only 50.2 and 103.2 μg/mL, respectively, which were higher than those of other fungi. The in vivo antifungal activity of BAEO against Gloeosporium orbiculare was much higher than Blumeria graminis. The protective efficacy for the former was up to 98.07% at 10 mg/mL and the treatment efficacy was 93.41% at 12 mg/mL. The above results indicated that BAEO has the great potential to be developed as a botanical and agricultural fungicide.

No MeSH data available.