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Four new anthraquinone derivatives (1-4) and four new alterporriol-type anthranoid dimers (14-17), along with 17 analogues, were isolated from the solid rice fermentation of the fungus Stemphylium sp. 33231 obtained from the mangrove Bruguiera sexangula var. rhynchopetala collected from the South China Sea. Their structures were elucidated using comprehensive spectroscopic methods. The absolute configurations of 1, 3, and 4 were determined by single-crystal X-ray diffraction of their derivatives (1a, 3b, and 4a). The absolute configurations of the chiral 17-19 were determined by comparing their CD spectra with 21. The inhibitory activities of most of the compounds against seven terrestrial pathogenic bacteria and two cancer cell lines were evaluated.

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Xanthium sibiricum patrin ex Widder (Compositae) is an annual herb which grows all around China. Chemical investigations of its roots resulted in the identification of 15 compounds: stigmast-4-en-6β-ol-3-one (1), β-sitostenone (2), β-sitosterol (3), nonadecanoic acid (4), 5α,8α-epidioxy-22E-ergosta-6,22-dien-3β-ol (5), scopoletin (6), Jatrocin B (7), (±)syringaresinol (8), 9,9'-O-di-(E)-feruloyl-(-)-secoisolariciresinol (9), cleomiscosin A (10), cleomiscosin C (11), N-trans-feruloyl tyramine (12), daucosterol (13), 5-methyluracil (14) and uracil (15). Structures were elucidated by spectroscopic (NMR and MS) methods and confirmed by comparing with reference samples and literature data. Compounds 1-2, 4-12, 14, and 15 were isolated from this genus for the first time, while this is the first report of coumarinolignoids in the Compositae family, and coumarinoligoids could be considered as valuable chemotaxonomic markers for the plant.

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