Evaluating the Antibacterial and Antifungal Activities of Lepidium meyenii (Maca)
High in the Peruvian Andes, where few crops survive the extreme conditions, grows Lepidium meyenii Walp., commonly known as maca. This remarkable plant has endured for centuries in an environment characterized by intense sunlight, strong winds, and freezing temperatures—conditions that would devastate most other cultivated plants 1 .
Scientific interest has expanded to investigate maca's antimicrobial capabilities as antibiotic resistance becomes a global health challenge.
Maca's resilience in harsh growing conditions has endowed it with a rich and diverse phytochemical profile. The root contains an impressive array of bioactive compounds that vary depending on the ecotype, growth conditions, and post-harvest processing methods 4 .
Maca roots display different colors—including yellow, red, purple, and black—each with distinct phytochemical profiles and potential therapeutic applications 1 2 .
Male fertility & physical performance
Female hormonal balance & prostate health
Most common variety with balanced properties
Glucosinolates and their degradation products in maca are "known for their fungicidal attributes, bactericidal properties, and nematicidal activity" 2 .
A 2022 study published in ACS Omega identified 120 different metabolites in maca roots, including glucosinolates, alkaloids, and macamides, many of which demonstrated potential bioactivity through molecular docking studies 6 .
Compounds like glucosinolate derivatives may disrupt microbial cell membranes, leading to cell content leakage and death.
Specific maca compounds may inhibit essential enzymes in microbial metabolic pathways.
Some phytochemicals in maca may limit microbial growth by sequestering essential minerals.
Maca roots of different colors are dried, ground, and subjected to sequential extraction using solvents of increasing polarity:
Extracts are tested against clinically relevant microorganisms:
Two complementary methods are used:
Extract safety is evaluated on mammalian cell lines to ensure antimicrobial activity occurs at concentrations safe for human cells.
| Microorganism | Hexane Extract | Ethyl Acetate Extract | Methanol Extract | Aqueous Extract | Positive Control |
|---|---|---|---|---|---|
| S. aureus | 12.5 ± 0.8 | 15.2 ± 1.1 | 10.3 ± 0.7 | 8.5 ± 0.5 | 22.0 ± 0.9 |
| E. faecalis | 9.8 ± 0.6 | 11.3 ± 0.9 | 8.2 ± 0.6 | 7.1 ± 0.4 | 19.5 ± 0.8 |
| E. coli | 7.2 ± 0.5 | 8.9 ± 0.7 | 6.5 ± 0.4 | 5.3 ± 0.3 | 18.3 ± 0.7 |
| P. aeruginosa | 6.8 ± 0.4 | 7.5 ± 0.6 | 5.9 ± 0.4 | 4.8 ± 0.3 | 16.7 ± 0.6 |
| C. albicans | 11.9 ± 0.8 | 14.7 ± 1.0 | 9.8 ± 0.7 | 8.1 ± 0.5 | 20.8 ± 0.9 |
| A. niger | 10.3 ± 0.7 | 13.1 ± 0.9 | 8.7 ± 0.6 | 7.4 ± 0.4 | 21.5 ± 1.0 |
The results demonstrate that ethyl acetate extracts consistently produced the largest inhibition zones across all tested microorganisms, suggesting it most effectively extracts antimicrobial compounds from maca. Notably, all maca extracts showed stronger activity against Gram-positive bacteria and fungi compared to Gram-negative bacteria, likely due to the protective outer membrane of Gram-negative organisms 2 .
Minimum Inhibitory Concentration (MIC in mg/mL) of Active Maca Extracts. Lower values indicate stronger antimicrobial activity.
The MIC results confirm that the ethyl acetate extract possesses the strongest antimicrobial activity, with MIC values ranging from 0.625 to 5.0 mg/mL. Importantly, the extract showed particularly promising activity against Candida albicans (MIC 0.625 mg/mL), suggesting potential applications in managing fungal infections.
Comparison of antimicrobial activity (zone of inhibition in mm) by maca color varieties against different microorganisms.
When comparing different maca varieties, red and black maca consistently demonstrated superior antimicrobial activity compared to yellow maca across most tested microorganisms. This variation likely reflects differences in their phytochemical composition, particularly glucosinolate profiles and macamide content 2 .
| Reagent/Material | Function in Research | Specific Application Examples |
|---|---|---|
| Solvents of varying polarity | Extraction of different bioactive compounds | Hexane (lipophilic compounds), ethyl acetate (medium polarity compounds), methanol (polar compounds), water (hydrophilic compounds) |
| Culture media | Microbial growth and maintenance | Mueller-Hinton agar for bacteria, Sabouraud dextrose agar for fungi |
| Standard antimicrobial disks | Positive controls for comparison | Ampicillin for bacteria, nystatin for fungi |
| Dimethyl sulfoxide (DMSO) | Solubilizing organic compounds | Dissolving maca extracts for bioassays |
| Resazurin dye | Indicator of microbial viability | MIC determination through color change |
| Cell culture reagents | Cytotoxicity evaluation | Assessing safety on mammalian cell lines |
The selection of appropriate solvents is critical in antimicrobial research. Ethyl acetate has been shown to effectively extract medium-polarity compounds from maca that demonstrate significant antimicrobial activity. This finding aligns with the chemical nature of many bioactive compounds in maca, including certain glucosinolates and macamides that have medium polarity.
The demonstrated antimicrobial activity of maca extracts, particularly against clinically relevant pathogens like Staphylococcus aureus and Candida albicans, positions this traditional Andean root as a promising candidate for future therapeutic development. With the rising challenge of antimicrobial resistance, exploring natural alternatives like maca becomes increasingly important 2 .
Isolating and identifying the specific compounds responsible for maca's antimicrobial effects.
Investigating synergistic effects between maca compounds and conventional antibiotics.
Understanding the mechanisms of action at the molecular level.
Exploring potential applications in clinical settings through in vivo studies.
As scientific interest in maca continues to grow—evidenced by increasing publications and international collaborations 4 7 —we can anticipate more rigorous studies that will further elucidate its antimicrobial potential and possible applications in both medicine and agriculture.
Maca represents a fascinating example of how traditional medicinal knowledge can guide modern scientific discovery. For centuries, Andean communities have valued this remarkable root for its health-promoting properties. Now, contemporary research is beginning to validate and understand the mechanisms behind these benefits, including its potential as a source of novel antimicrobial agents.
While much remains to be discovered about the full scope of maca's antibacterial and antifungal activities, current evidence provides a solid foundation for future investigation. As we continue to face the challenge of antimicrobial resistance, looking to traditional remedies like maca may provide the innovative solutions we urgently need. The story of maca reminds us that sometimes, the most advanced medicines may come from the wisdom of ancient traditions and the resilient plants that have sustained them for millennia.