New polyisoprenyl benzophenone derivatives and antitubercular constituents from Garcinia multiflora

Garcinia multiflora (Guttiferae) Champ. is a small evergreen tree, growing in South China, Hong Kong, and Taiwan [1]. Xanthones [2,3,4], benzophenones [5], flavonoids [6], and their derivatives are widely distributed in plants of genus Garcinia. Many of these compounds exhibit cytotoxic [2], anti-inflammatory [3], and antibacterial [4] activities. However, the chemical constituents and biological activities of this plant have never been studied. Investigation of the EtOAc-soluble fraction of the fruits of G. multiflora led to the isolation of three new polyisoprenyl benzophenone derivatives, garcimultiflorone A (1), garcimultiflorone B (2), and garcimultiflorone C (3), together with three known compounds, including a benzopyran, δ-tocotrienol (4) and two steroids, β-sitosterol (5) and stigmasteroid (6). The structures of three new polyisoprenyl benzophenone derivatives were determined through spectral analyses including extensive 2D NMR. Garcimultiflorone A (1) and garcimultiflorone C (3) are the most effective among the isolates, with MICs of 31.2 and 27.6µM, respectively, against Mycobacterium tuberculosis H₃₇Rv.

Acknowledgements: This work was supported by grant from the National Science Council of the Republic of China.

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