부산대학교 도서관

In our screening project on immunomodulatory constituents of fungi, two Trichocomaceae Fungi, Emericella aurantio-brunnea (Ea) and Eupenicillium crustaceum (Ec) showed immunosuppressive activity against proliferation of mouse splenic lymphocytes stimulated with Con A and LPS. Activity-guided fractionation of the AcOEt extract of Ea afforded two known fungal sesterterpenes, variecolin (1) and variecolactone (2), two new variecolin congeners named variecoacetals A(3) and B(4), and a new eremophilane-type sesquiterpenetriol diester (5) as the immunosuppressive features of Ea. The absolute configuration of 1, which was previously not determined, was decided to be (2S,3S,6R,10S,11R,14S,15R,16S) from the NMR spectral data of a derivative of 1 (7). Absolute configurations of other variecolin congeners 2-4 and variecolol (6) were also estimated from biosynthetic consideration. Fractionation of the AcOEt extract of Ec carried out in the same way as described for that of Ea gave two new meroterpenoids tentatively named EC-A (9)and -B(10) as the immunosuppressive features of Ec. Compound 9 which was chemically connected with a known fungal meroterpenoid ester macrophorin D(11) afforded (R)-mevalonolactone (12) on reduction with LiEt_3BH, indicating that the absolute configuration at position 3" in the 3-hydroxy-3-methylglutaryl (HMG) ester moiety of 9 was (S). This fact also exhibited that the absolute configuration at position 3" in the HMG ester moiety of 11 which was strangely decided to be (R) formerly should be revised to be (S).