The EtOAc extract of the fermentation was fractionated by repeated silica gel chromatography and Sephadex LH-20 column chromatography, as well as semi-preparative RP-HPLC, to yield the compounds19(Figure 1). endophytic fungi have been demonstrated to be a rich and reliable source of biologically active and chemically novel compounds [5]. In the past decades, our research group had been focusing on the exploration of new bioactive metabolites from mangrove endophytic fungi collected from the South China Sea [6, 7, 8, 9, 10, 11, 12, 13]. The EtOAc extract of the fermentation of a mangrove endophytic fungus, Penicilliumsp. ZJ-SY2, which was isolated from the leaves ofSonneratia apetala, has been screened to exhibit potent immunosuppressive activity and anti-inflammatory activity. Bioassay-guided fractionation from the EtOAc extract led to the isolation of two new benzophenones derivatives and seven previously reported xanthones. All of the isolated compounds (19) were evaluated for their immunosuppressive activity against concanavalin A (Con A)-induced (T cell) and lipopolysaccharide (LPS)-induced (B cell) proliferations of mouse splenic lymphocytes by the MTT method. Among them, compounds1, 3, CD180 5, and7showed potent immunosuppressive activity. Herein, details of the isolation, structural elucidation, as well as biological activity of these compounds are described. == 2 . Results and Discussion == The mangrove endophytic fungusPenicilliumsp. ZJ-SY2was cultured on solid rice medium with sea water for four weeks. The EtOAc extract from the fermentation was fractionated by repeated silica gel chromatography and Sephadex LH-20 column chromatography, as well as semi-preparative RP-HPLC, to yield the compounds19(Figure 1). The structure of two new benzophenone derivatives (12) were elucidated on the basis of MS, 1D, and 2D NMR data, and seven known xanthones were identified as conioxanthone A (3) [14], methyl 8-hydroxy-6-methyl-9-oxo-9H-xanthene-1-carboxylate (4) [15], pinselin (5) [16], sydowinin B (6) [17], sydowinin A (7) [17], remisporine B (8) [18], and epiremisporine B (9) [18], by comparison of their spectroscopic data with those reported in the literature. == Determine 1 . == Structures of compounds19. Peniphenone (1) was isolated as a yellow solid. The HRESIMS (seeFigure S1) displayed a molecular ion peak atm/z273. 0401 [M H](calcd. intended for C14H9O6, 273. 0405), implying the molecular formula C14H10O6(10 degrees of unsaturation). Its IRGI spectrum had absorption bands corresponding to hydroxyl (3354 cm1), carbonyl (1689, 1614 cm1), and aromatic groups (1601, 1500, 1452 cm1). The1H NMR (seeFigure S2) data suggesting the presence of two AMX spin systems [H7. 25 (t, J= 7. 9 Hz), 7. 49 (d, J= 7. 7 Hz), and 7. 01(d, J= 8. 1 Hz)] and [H7. 19 (t, J= 8. 2 Hz), 6. 28 (d, J= 8. 2 Hz), and 6. 28 (d, J= 8. 2 Hz)], indicated that1possessed two 1, 2, 3-trisubstituted benzene rings (Table 1). The13C (seeFigure S3) and DEPT NMR spectrum resolved the 14 sp2-hybridized carbon resonances attributed to one carbonyl function (C203. 6, C-9), one carboxyl function (C169. 7, C-11), and two aromatic rings (Table 1). The downfield-shift of carbonyl (C203. 6, C-9) indicated that1possessed a benzophenone framework. == Table 1 . == 1H and13C NMR data (Methanol-d4, 500/125 MHz, ppm, Jin Hz) of compounds1and2. Dexamethasone palmitate Extensive analysis of 2D NMR (seeFigures S4S6) exposed the structure of compound1as described below (Figure 2). The HMBC correlations from the H-2 (H7. 49) to the carbonyl carbon (C169. 7) and C-9a (C130. 4) and the H-3 (H7. 25) to C-1(C134. 9) indicated a carboxylic acid group substituted to the C-1. The hydroxyl group was located at C-4a based on the HMBC correlations from H-3 (H7. 25) to C-4a (C154. 7). NMR resonances for C-8 and C-10a (C163. 6) and for H-5 and H-7 (H6. 28) were identical and magnetically equivalent. Dexamethasone palmitate This observation is in accordance with a symmetrically substituted aromatic band possessing hydroxyl groups at C-8 as well as C-10a. Therefore Dexamethasone palmitate , compound1was identified as 2-(2, 6-dihydroxybenzoyl)-3-hydroxybenzoic acid, and named peniphenone. == Determine 2 . == Key HMBC (black arrows) and COSY (black bold lines) correlations of compounds1and2. Methyl peniphenone (2), was isolated as a yellow solid. The HRESIMS (seeFigure Dexamethasone palmitate S7) displayed a negative ion peak atm/z287. 0557 [M H](calcd. for C15H11O6, 287. 0561), corresponding to the molecular method C15H12O6. There are 10 degrees of unsaturation. The1H NMR (seeFigure S8) spectrum showed six aromatic protons containing two AMX spin systems [H7. 26 (t, J= 8. 0 Hz), 7. 46 (dd, J= 7. 8, 0. 7 Hz), and 7. 03 (d, J= 8. 1, 0. 7 Hz)] and [H7. 21 (t, J= 8. 2 Hz), 6. 28 (d, J= 8. 2 Hz), and 6. 28 (d, J= 8. 2 Hz)], indicating that2possessed two fragments of a 1, 2, 3-trisubstituted benzene ring (Table 1). The13C NMR (seeFigure S9) and DEPT spectra gave signals for 15 carbon atoms, including one ketone carbonyl (C203. 2, C-9), one ester carbonyl (C168. 4, C-11), two aromatic rings, and one methoxy (C52. 6, C-12). The spectroscopic information was quite similar to peniphenone (1), except for the presence of a methoxy group [H3. 69 (s), C52. 6]. The HMBC (seeFigure S12) correlation.