Anthraquinone Derivatives and its Antibacterial Properties from Paederia foetida Stems

Background: Paederia foetida (Rubiaceae) locally known as Chinese fever vine is a prominent plant species in the east and south Asia. The extract of Paederia foetida Linn. has been used for the treatment of gastric infections or other digestive disorders in Chinese traditional medicine. Objective: The main aim of the study was to isolate bioactive constituents of P. foetida stem through a bio-guided assay, then evaluate their antibacterial activity and compare them with standard agents. Materials and Methods: The stems of P. foetida were extracted by methanol and successively partitioned with ethyl acetate and n-butanol. The ethyl acetate layer further fractionated using column chromatography and normal phase HPLC. The chemical structures of the isolated compounds were elucidated through comparison of the 1 H and 13 C NMR and MS spectral data with the literature. The antibacterial activity of P. foetida stem was evaluated using agar well diffusion assay and resazurin based micro-dilution technique. Results: Ten compounds were isolated from the Chinese fever vine stem including four anthraquinones, morindaparvin A (1), 1,3-dihydroxy-2-methoxyanthraquinone (2), digiferrol (3), and alizarin (4); two steroids, β-sitosterol (5), and stigmastan-3-one (6); two coumarins, scopoletin (7) and fraxidin (8) and two aromatics, ferulic acid (9) and vanillic acid (10). The four anthraquinones 1-4 were isolated for the first time from Chinese fever vine stem. Compound 2 and 3 significantly inhibited Staphylococcus aureus with MIC values 18.75 and 9.37 μg/mL respectively, and streptomycin (1.8 μg/mL) was used as a positive control. Conclusion: Compound 2 and 3 can be considered as a prospective candidate for the treatment of staphylococcal bacterial infections in both human and animals.