Aloysia polystachya

Aloysia polystachya (common names: poleo, burro herb, yerba del pollo) is a perennial aromatic shrub native to South America, belonging to the family Verbenaceae. It is closely related to lemon verbena (Aloysia citriodora) and is cultivated for its essential oil, which is rich in ®-(−)-carvone.

Composition

The essential oil of Aloysia polystachya is predominantly composed of ®-(−)-carvone, which accounts for approximately 90.2% of its composition.^[1] This monoterpenoid ketone is also the major active compound responsible for its antimicrobial properties.

Healing Properties

Antimicrobial

Natural Preservative

Essential oil derived from Aloysia polystachya leaves is a potent bactericide against Leuconostoc mesenteroides MS1, a heterofermentative lactic acid bacterium that causes spoilage of vacuum-packed Vienna sausages by producing gas and causing packaging to swell.^[1:1]

• The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Aloysia polystachya essential oil against Leuconostoc mesenteroides MS1 fall in the ranges of 0.64–1.87 mg/mL and 0.76–2.41 mg/mL, respectively.^[1:2]
• Leuconostoc mesenteroides MS1 demonstrated high sensitivity to Aloysia polystachya essential oil and to pure ®-(−)-carvone, which showed nearly identical results due to carvone comprising ~90.2% of the essential oil.^[1:3]
• 0.70 mL of Aloysia polystachya essential oil maintained viable cell counts at the initial inoculation level (10³ CFU g⁻¹) throughout 42 days of refrigerated storage in sterile sausage samples (approximately 75 times the MIC value in the food matrix).^[1:4]
• Aloysia polystachya essential oil and pure ®-(−)-carvone represent a natural alternative to conventional chemical-synthesis food preservatives for controlling spoilage bacteria in vacuum-packed meat products.^[1:5]
• A potential application lies in incorporating these antimicrobial compounds into active packaging systems (encapsulation technologies, biodegradable films, or edible coatings), enabling gradual release of active compounds throughout product shelf-life.^[1:6]

Carvone Activity

Because ®-(−)-carvone constitutes ~90.2% of Aloysia polystachya essential oil, the antimicrobial profiles of the whole essential oil and pure ®-(−)-carvone are nearly identical.^[1:7] ®-(−)-carvone has been reported to exhibit activity against both gram-positive and gram-negative bacteria.^[1:8]

Synergistic Effects

Eucalyptus cinerea, Laurus nobilis, and Citrus limon Essential Oils

In comparison studies, Aloysia polystachya essential oil and pure ®-(−)-carvone were found to be more effective antimicrobials than Citrus limon essential oil against Leuconostoc mesenteroides MS1, with similar efficacy to Eucalyptus cinerea and Laurus nobilis essential oils.^[1:9]