Characterization and antimicrobial evaluation of anthraquinones and triterpenes from Rubia cordifolia

Abstract

Chemical investigation of roots of the plant, Rubia cordifolia Linn, led to the isolation of an undescribed anthraquinone, cordifoquinone R, determined as 1,2-dihydroxy-6-methoxyanthracene-9,10-dione (6) based on the 1D and 2D NMR analyses and HRESIMS. Ten other known compounds viz.1,4-dihydroxy-2-methoxyanthracene-9,10-dione (1), rubiadin (2), xanthopurpurin (3), 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone (4), alizarin (5), β-sitosterol glucoside (7), scopoletin (8), oleanolic acid, (9), pomolic acid (10), queretaroic acid (11) were also isolated. Out of these compounds, 4, 10, and 11 are first reported from this plant species. Compounds 2, 3, 6, 7, and 10 showed activity in the range of 16-32 µg/ml against S. aureus ATCC 29213.

Keywords:

• Rubia cordifolia
• Rubiaceae
• anthraquinones
• triterpenes
• antimicrobial activity

Acknowledgements

The authors are grateful to the Director, CSIR-IICT and Director, CSIR-CDRI, for providing the necessary facilities. GC and MS are thankful to UGC for fellowship, while GK thanks DST-INSPIRE for her fellowship and AcSIR, New Delhi. This manuscript bears CSIR-CDRI communication number 10570.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was financially supported by CSIR, India.