In the plant extract industry, apples (Malus domestica) have been widely studied for their rich secondary metabolites such as polyphenols, flavonoids, and phenolic acids. In recent years, an increasing amount of experimental data has shown that apples and their processing by-products (such as skin and fruit residue) exhibit significant antibacterial activity both in vitro and in vivo, making them a "natural antibiotic".
1. The main antibacterial active ingredients in apples
- polyphenols
Anthocyanins, epicatechins, and quercetin have the highest content in apple peel and flesh. Research has shown that these polyphenols can damage bacterial cell membranes, inhibit enzyme activity, and thus achieve antibacterial effects.
- phenolic acid
Compounds such as chlorogenic acid and caffeic acid can form hydrogen bonds with bacterial proteins, disrupting their metabolic pathways
- organic acid
Malic acid, citric acid, etc., lower local pH and inhibit the growth of most pathogenic bacteria.
- Volatile oil
The small amount of aldehydes and ester volatile oils in apple peels exhibits inhibitory effects on Staphylococcus aureus.
2. Experimental verification - in vitro antibacterial activity
| Bacterial species | Detection method | Diameter of antibacterial zone (mm) |
| Staphylococcus aureus | Agar diffusion method | 19.25 ± 0.89 (apple peel extract) vs 20.13 ± 0.83 (ciprofloxacin) |
| Escherichia coli | Agar diffusion method | 12.3 ± 0.7 (Apple pomace ethanol extract) |
| Pseudomonas aeruginosa | Micro dilution method | MIC=0.5 mg/mL (apple polyphenols) |
| Enterococcus faecalis | Micro dilution method | MIC=0.75 mg/mL (apple peel extract) |
These data indicate that apple peel extract can almost rival the conventional antibiotic ciprofloxacin in inhibiting Staphylococcus aureus, and also has a significant inhibitory effect on gram-negative bacteria.
3. In vivo experiments and preclinical studies
3.1 Oral Health
A randomized controlled trial in Indonesia using 12.5% apple peel extract mouthwash resulted in a decrease of approximately 30% in plaque index (PLI) without any adverse reactions
3.2 Food preservation
Adding apple polyphenols to jam can inhibit common foodborne pathogens (Salmonella, Listeria) and extend shelf life by about 15 days when stored at 4 ° C for 30 days.
3.3 animal model
In a rat model of gastric mucosal inflammation, oral administration of apple polyphenol extract significantly reduced the gastric mucosal inflammation score, and serum inflammatory factors (IL-6, TNF-α) decreased by about 40%.
4. Application scenarios
| Scenario | Specific product | Feature highlights |
| Food preservation | Apple polyphenols- natural preservatives (powder/liquid) | inhibit bacterial growth, resist oxidation, and enhance sensory quality |
| Oral care | Apple peel extract- mouthwash, and toothpaste additives | inhibit dental plaque and reduce oral inflammation |
| Skin care | Apple polyphenol- facial mask, hand cream | anti-bacterial, anti-oxidation, promote skin barrier repair |
| Animal feed | Apple pomace powder (containing polyphenols) | Inhibits feed mold and enhances animal immunity |
| Medical assistance | Natural antibacterial excipient added to local ointments | Collaborate with traditional antibiotics to reduce the risk of drug resistance |
For more details about apple extract and apple polyphenol, connect with Serrisha from APPCHEM. (Email: cwj@appchem.cn; +86-138-0919-0407)
Reference
[1]Shanshan He, Gaopeng Yuan et al. "Major Latex Protein MdMLP423 Negatively Regulates Defense against Fungal Infections in Apple." International Journal of Molecular Sciences (2020). [2020-03-01]
[2]Bekämpning med "naturliga fungicider" mot lagringssjukdomar – Förstudie Protection against storage decay by natural fungicides. Ibrahim Tahir.
[3]Development of plant-based nanoemulsion and its application as a natural preservative having antioxidant and antimicrobial properties to deliver active compounds in apple juice. Kailash Barman et al. [2022-12-13]