Anthraquinone profile, antioxidant and antimicrobial activity of bark extracts of Rhamnus alaternus, R. fallax, R....

Area of Science:

• Phytochemistry
• Pharmacognosy
• Natural Products Chemistry

Background:

• Rhamnus species are known for their medicinal properties.
• Phenolic compounds and anthraquinones are key bioactive constituents.
• Investigation of Croatian Rhamnus species' bark for bioactive compounds is warranted.

Purpose of the Study:

• To quantify phenols and evaluate antioxidant and antimicrobial activities in four Croatian Rhamnus species.
• To identify major anthraquinones present in the bark extracts.
• To explore the correlation between phenolic content and bioactivity.

Main Methods:

• Extraction of bark from Rhamnus alaternus, R. fallax, R. intermedia, and R. pumila.
• Quantification of specific anthraquinones (chrysophanol, emodin, physcion) using chromatographic techniques.
• Assays for total phenolic and flavonoid content, antioxidant capacity, and antimicrobial activity (MICs) against selected pathogens.

Main Results:

• Chrysophanol, emodin, and physcion were identified as major anthraquinones, with varying concentrations across species.
• Rhamnus fallax and R. pumila displayed the highest antioxidant activity.
• All investigated species demonstrated antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Aspergillus niger, and Microsporum gypseum, with MICs ≤ 2.500 mg/mL.

Conclusions:

• The bark of the studied Croatian Rhamnus species is a rich source of anthraquinones and other phenols.
• These compounds possess significant multifunctional antioxidant and antimicrobial properties.
• Findings support the potential use of these Rhamnus species in traditional medicine and as a source for novel therapeutic agents.