The endophytic fungus Penicillium citrinum was isolated from a fresh stem of the Moroccan plant Ceratonia siliqua. Extracts of P. citrinum grown on rice and white bean media yielded five new compounds, namely, citriquinochroman (1), tanzawaic acids G and H (2 and 3), 6-methylcurvulinic acid (4), 8-methoxy-3,5-dimethylisoquinolin-6-ol (5), and one new natural product, 1,2,3,11b-tetrahydroquinolactacide (6), which had previously been described as a synthetic compound. In addition, 13 known compounds including seven alkaloids and six polyketides were isolated. The structures of the new compounds were unambiguously determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. Citriquinochroman (1) features a new skeleton, consisting of quinolactacide and (3S)-6-hydroxy-8-methoxy-3,5-dimethylisochroman linked by a C-C bond. 1,2,3,11b-Tetrahydroquinolactacide (6) may be a biogenetic precursor of quinolactacide. Citriquinochroman (1) showed cytotoxicity against the murine lymphoma L5178Y cell line with an IC50 value of 6.1 μM, while the other compounds were inactive (IC50 >10 μM) in this assay.

Two new hydroazulenoid (prenyl guaiane) diterpenes, dictyone acetate (2) and 3,4-epoxy 13-hydroxy pachydictyol A (4) were isolated from the petroleum ether fraction of the alcoholic extract of the brown alga, Dictyota dichotoma (Hudson) Lamouroux, which was collected from the Red Sea coasts at Hurgada, Egypt, together with three known ones, pachydictyol A (1), dictyone (3) and 11-hydroxypachydictyol A (dictyol E) (5). In addition, the steroidal compound, stigmasta-5,(E)-24(28)-dien-3-β-ol (fucosterol) (6) was also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity

New naturally occurring spirostane saponin (25S)-5β-spirostan-3β-yl-3-O-β-D-xylopyranosyl(1 → 3)-O-β-D-xylopyranosyl(1 → 4)-β-D-galactopyranoside (6) and biflavonoid glycoside myricetin-3-O-rhamnoside (C7-O-C7) myricetin-3-O-rhamnoside (4) along with a series of known compounds erythrodiol (1), 3β-O-trans-p-coumaroyl-erythrodiol (2), quercetin-3-O-α-L-rhamnoside (3) and myricetin-3-O-α-L-rhamnoside (5) were separated from the leaves of Acacia saligna (Labill.), H.L. Wendl. Compounds 1 and 2 were separated for the first time from genus Acacia. The structures of compounds 1-6 were established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with EI-MS and HR-ESI-MS. These compounds were screened for their antioxidant and cytotoxic activities against HEPG2 (liver cancer) cell line and significant results were obtained.

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