Chem. Pharm. Bull. 55(9) 1404—1405 (2007)

stances from plants and endophytic fungi, the ethyl acetate extract from the culture broth of the endophytic fungus Botryosphaeria mamane PSU-M76 exhibited interesting antibacterial activity against Staphylococcus aureus ATCC 25923 (SA) and methicillin-resistant S. aureus SK1 (MRSA) with MIC values of 32 and 64 mg/ml, respectively. The endophytic fungus B. mamane PSU-M76 was isolated from the leaves of Garcinia mangostana. Chemical investigation of B. mamane has never been reported. Investigation of the extract of the culture filtrate led to the isolation of one new dihydrobenzofuran derivative, botryomaman (1), along with six known compounds, 2,4-dimethoxy-6-pentylphenol (2), (R)( )-mellein (3), primin (4), cis-4-hydroxymellein (5), trans-4-hydroxymellein (6), and 4,5-dihydroxy-2-hexenoic acid (7). Their structures were assigned by spectroscopic methods and comparison of the Hand C-NMR data with those reported in literature. All compounds were tested for antibacterial activity against both strains. Botryomaman (1) was obtained as a white solid, melting at 149.6—150.0 °C with [a]D 22.2° (c 0.2, MeOH). The UV spectrum showed a maximum absorption band at lmax 300 nm. The IR spectrum exhibited absorption bands at 3392 cm 1 for a hydroxyl group and 1684 cm 1 for a carbonyl group of an a ,b unsaturated carboxylic acid. The HREI-MS showed the molecular formula C18H24O5. The HNMR spectrum displayed typical signals of two transolefinic protons of the a ,b unsaturated carboxylic acid (d 6.96, dd, J 15.5, 9.0 Hz and d 5.79, d, J 15.5 Hz), one aromatic proton (d 6.32, s), one oxymethine proton (d 4.85, dq, J 9.0, 6.5 Hz), one methine proton (d 3.90, t, J 9.0 Hz), one methoxyl group (d 3.84, s), one pentyl side chain [d 2.55 (m, 1H), 2.37 (m, 1H), 1.55 (m, 1H), 1.48 (m, 1H), 1.31 (m, 4H) and 0.87 (t, J 7.0 Hz, 3H)] and one secondary methyl group (d 1.40, d, J 6.5 Hz). The carbonyl carbon signal at d 168.8 in the C-NMR spectrum supported the presence of the a ,b unsaturated carboxylic acid. The aromatic proton at d 6.32 was assigned as H-7. Irradiation of H7 in the NOEDIFF experiment enhanced the signal intensity of the methoxyl group, thus indicating the attachment of the methoxyl group at C-6 (d 146.8). HMBC correlations of H7/C-3a (d 118.2), C-5 (d 137.9), C-6 and C-7a (d 152.3) and those of the methylene protons of the pentyl moiety (d 2.55, 2.37, H2-12)/C-3a, C-4 (d 126.2) and C-5 established the linkage of the pentyl group at C-4. In the COSY spectrum, the methine proton at d 3.90 (H-3) was coupled with the oxymethine proton at d 4.85 (H-2) and the downfield transolefinic proton (d 6.96, H-9) of the a ,b unsaturated carboxylic acid. H-2 was further coupled with the methyl protons at d 1.40 (H3-8). HMBC cross peaks of H-3/C-3a and C-7a established the linkage of the methine group carrying the 1-oxysubstituted ethyl group and trans a ,b unsaturated carboxylic acid moiety at C-3a. According to the chemical shifts of both C-2 (d 82.8) and C-7a and the molecular formula, these carbons were joined together with an ether linkage to form a dihydrobenzofuran skeleton. Since there was no other signal in the H-NMR spectrum, the substituent at C-5 must be a hydroxyl group. This hydroxycarbon resonanted at much higher field due to the resonance effect of two oxysubstituents at C-6 and C-7a. Irradiation of H-3 in the NOEDIFF experiment enhanced signal intensity of H-2, indicating their cis relationship. Therefore, botryomaman (1) was determined as a new dihydrobenzofuran derivative, possibly derived from the condensation of the demethylated 2 and 7. All isolated compounds were tested for antibacterial activitiy against SA and MRSA. Primin (4) exhibited the best activity against SA and MRSA with equal MIC values of 1404 Vol. 55, No. 9