The human skin acts as a barrier, but it is constantly exposed to the environment and remains vulnerable to microbial infections. Skin infections, characterized by symptoms like pain, swelling, and redness, are commonly caused by bacteria or fungi. One prevalent bacterial skin infection is a furuncle (or boil), which develops when infection attacks hair follicles, often progressing into an abscess. The primary bacterial culprit responsible for this condition is Staphylococcus aureus, a gram-positive bacterium frequently found on human skin.
In the broader context of global health, the escalating issue of bacterial resistance demands continuous efforts to find novel antibacterial compounds. Traditionally, Indonesia’s rich biodiversity is utilized by local communities for various needs, including traditional medicine, a practice known as ethnobotany. This long history of use provides a promising avenue for research. Among the herbs frequently employed by local communities to treat skin ailments, including furuncles, are betel leaves (Piper betle) and red onions (Allium cepa). P. betle is recognized for its antibacterial, anti-inflammatory, and antioxidant properties, containing active compounds like phenolic compounds and saponins. Similarly, A. cepa is known for its antimicrobial activity due to components such as allicin and various phenolic compounds.
Given the historical and traditional application of P. betle and A. cepa in treating skin infections, this research aimed to explore the antibacterial activities of their ethanol extracts, both individually and in combination, specifically targeting S. aureus. The study sought to determine the potential synergistic effects of these natural herbs.
Methods
The study utilized the leaves of P. betle and the bulbs of A. cepa, both obtained from Surabaya, Indonesia, with S. aureus (ATCC 6538) serving as the test bacterium. The plant materials were powdered and extracted using 96% ethanol over a period of 24 hours, followed by re-extraction for four days, with the resulting filtrate concentrated via a rotary evaporator. The antibacterial efficacy of the extracts (including various combination ratios) was evaluated using a disk plate method in petri dishes. The inhibition zones were subsequently measured using a caliper, with kanamycin (100 ppm) used as a positive control, and each sample tested in three replicates.
Key Findings
The evaluation of the ethanol extracts demonstrated that all tested samples (P. betle, A. cepa, and their combinations) exhibited activity against S. aureus, showing inhibition zones similar to or greater than the positive control (kanamycin, 14.40 mm).
Key findings regarding the inhibition zone diameters (mm) are summarized below:
• P. betle extract alone (1:0 ratio): 17.70 ± 0.30 mm, exhibiting the strongest inhibitory effect.
• P. betle and A. cepa combination (1:1 ratio): 15.63 ± 0.58 mm, which was the second highest inhibition zone and considered the best combination compared to other ratios (1:2 and 2:1).
• A. cepa extract alone (0:1 ratio): 14.38 ± 0.38 mm, showing the lowest inhibition zone.
• Comparison to Control: The inhibition zone produced by the A. cepa extract (14.38 mm) was statistically similar to the inhibition zone of the positive control, kanamycin (14.40 mm).
• Classification: Based on the standard by Davis et al. (1971), all tested extracts fall into the strong antibacterial activity category (11–19 mm).
This research successfully demonstrated the robust antibacterial potential of Piper betle and Allium cepa ethanol extracts against Staphylococcus aureus, the primary cause of furuncles. The novelty of this study lies in its exploration of the potential synergistic effects of these two traditionally used plants. While the P. betle extract alone yielded the highest inhibition (17.70 mm), the 1:1 combination showed promising results (15.63 mm), confirming that the mixture improved the efficacy compared to A. cepa alone (14.38 mm).
The future implication of this research is significant, especially considering the global need for alternatives to synthetic drugs due to increasing bacterial resistance. The findings suggest that the ethanol extract of A. cepa alone holds a potency similar to that of the synthetic drug kanamycin. The strong antibacterial performance of both P. betle and A. cepa validates their long-standing use in traditional medicine for treating skin infections. These results encourage further investigation into the specific compounds responsible for this activity (such as phenolic compounds, flavonoids, and saponins) and the development of natural, ethnobotanically sourced preparations for managing S. aureus infections.
Link to the study: https://tinyurl.com/e9pk5jt2
