J. Pharm. Pharmacogn. Res., vol. 14, no. 1, Article ID 2279, Jan-Feb 2026.
DOI: https://doi.org/10.56499/jppres_14.1.2279Original Article
LC-MS/MS profiling, total phenolic and flavonoid contents, and antibacterial activity of Allium cepa L. peel extract against Staphylococcus epidermidis
[Perfil LC-MS/MS, contenido total de fenólicos y flavonoides y actividad antibacteriana del extracto de cáscara de Allium cepa L. contra Staphylococcus epidermidis]
Karnelasatri1*, Candra Yulius Tahya2, Shellina1, Sri Wahyu Ningsih Munthe1, Riskianto3, Andriyani4, Marcelia Sugata5
1Department of Pharmacy Diploma Program, Faculty of Health Sciences, Universitas Pelita Harapan, Tangerang, Indonesia.
2 Department of Medical Laboratory Technology Diploma Program, Faculty of Health Sciences, Universitas Pelita Harapan, Tangerang, Indonesia.
3Department of Pharmacist Professional Study Program, Faculty of Health Sciences, Universitas Pelita Harapan, Tangerang, Indonesia.
4Department of Pharmacy, Faculty of Health Sciences, Universitas Pelita Harapan, Tangerang, Indonesia.
5Department of Biology, Faculty of Health Sciences, Universitas Pelita Harapan, Tangerang, Indonesia.
*E-mail: karnelasatri@uph.edu
Abstract
Context: Allium cepa L. (shallot) peel contains secondary metabolites, including alkaloids and flavonoids, with potential antibacterial activity against Staphylococcus epidermidis.
Aims: To examine the antibacterial activity and minimum inhibitory concentration (MIC) of A. cepa peel extract against S. epidermidis, quantify its total phenolics and flavonoids content, and identify its active compounds using LC-MS/MS.
Methods: Extraction was conducted using ethyl acetate and n-hexane. Antibacterial activity was assessed by the disc diffusion method with clindamycin as a positive control. MIC was determined by macrodilution and analysed using a UV-Vis spectrophotometer. Total phenolics and flavonoids were measured using colorimetric assays, and LC-MS/MS performed compound profiling.
Results: The ethyl acetate extract inhibited S. epidermidis with zones of 10.27–16.04 mm (n = 4); concentrations of 200,000–500,000 μg/mL were intermediate, and lower doses were resistant. Although inhibition was lower than that of the positive control (clindamycin, 21.64 mm), the MIC was 2,500 μg/mL (n = 3). The n-hexane extract remained inactive across all concentrations. The extract contained 30.75 ± 1.56 mgGAE/G of phenolics and 22.44 ± 1.05 mgQE/G of flavonoids. LC-MS/MS identified rhamnetin (RT 16.26 min), nobiletin (RT 16.67 min), and casticin (RT 15.77) as dominant flavonoids likely responsible for the antibacterial activity.
Conclusions: Rhamnetin, nobiletin, and castisin were identified as candidate antibacterial compounds in the ethyl acetate extract of A. cepa peel.
Keywords: Allium cepa; antibacterial; flavonoids; phenolics; Staphylococcus epidermidis.
Resumen
Contexto: La cáscara de Allium cepa L. (chalota) contiene metabolitos secundarios, incluidos alcaloides y flavonoides, con potencial de actividad antibacteriana frente a Staphylococcus epidermidis.
Objetivos: Examinar la actividad antibacteriana y la concentración mínima inhibitoria (CMI) del extracto de cáscara de A. cepa contra S. epidermidis; cuantificar su contenido total de fenólicos y flavonoides e identificar sus compuestos activos mediante LC-MS/MS.
Métodos: La extracción se realizó con acetato de etilo y n-hexano. La actividad antibacteriana se evaluó mediante el método de difusión en disco con clindamicina como control positivo. La CMI se determinó por macrodilución y se analizó en un espectrofotómetro UV-Vis. Los fenólicos y flavonoides totales se midieron mediante ensayos colorimétricos y el perfil de compuestos se midió mediante LC-MS/MS.
Resultados: El extracto de acetato de etilo inhibió S. epidermidis con zonas de 10,27–16,04 mm (n = 4); las concentraciones de 200.000–500.000 μg/mL fueron intermedias, y las dosis más bajas fueron resistentes. Aunque la inhibición fue menor que la del control positivo (clindamicina, 21,64 mm), la CMI fue de 2.500 μg/mL (n = 3). El extracto de n-hexano permaneció inactivo en todas las concentraciones. El extracto contenía 30,75 ± 1,56 mg GAE/G de fenólicos y 22,44 ± 1,05 mg QE/G de flavonoides. La LC-MS/MS identificó ramnetina (RT 16,26 min), nobiletina (RT 16,67 min) y casticina (RT 15,77 min) como flavonoides dominantes, probablemente responsables de la actividad antibacteriana.
Conclusiones: La ramnetina, la nobiletina y la castisina se identificaron como compuestos antibacterianos candidatos en el extracto de acetato de etilo de la cáscara de A. cepa.
Palabras Clave: Allium cepa; antibacteriano; fenólicos; flavonoides; S. epidermidis.
Citation Format: Karnelasatri, Tahya CY, Shellina, Munthe SWNM, Riskianto, Andriyani, Sugata M (2026) LC-MS/MS profiling, total phenolic and flavonoid contents, and antibacterial activity of Allium cepa L. peel extract against Staphylococcus epidermidis. J Pharm Pharmacogn Res 14(1): 2279. https://doi.org/10.56499/jppres_14.1.2279
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