The fungal strain Truncatella angustata XSB-01-43 was isolated from the finger
sponge Amphimedon sp. collected near Yongxing Island, Hainan Province. Chromatographic workup of the antioxidant extract obtained from the solid rice fermentation of T. angustata resulted in the isolation of five α-pyrone-based analogues,
angupyrones A–E (43–47) (Fig. 3), which showed moderate ARE activation in
HepG2C8 cells [29]. Fermentation in a seawater-containing liquid medium of
Epicoccum sp. JJY40, obtained from the sponge Callyspongia sp. collected offshore
at Sanya, Hainan Province, led to the isolation of a pyronepolyene C-glucoside, isoD8646-2-6 (48). Compound 48 has a unique C-3-pyranosyl 4-hydroxypyrone
O
O
HO
43 (angupyrone A)
O
O
OH
O
O
OH
O
O
OH
O
O
OH
44 (angupyrone B)
45 (angupyrone C)
46 (angupyrone D)
47 (angupyrone E)
O
HO
O
O
O
OH
HO
OH
OH
OH
48 (iso-D8646-2-6)
O
O
O
O
O
HO
51 (varioxiranol K)
O
O
O
O
O
HO
OH
52 (varioxiranol L)
O
O
OH
HO
O
O
O
O
O
O
OH
O
O
OH
53 (diasteltoxin A)
O
O
OH
HO
O
O
O
O
O
O
OH
O
O
OH
54 (diasteltoxin B)
O
O
HO
OH
O
O
O
O
O
O
O
O
OH
55 (diasteltoxin C)
OH
O
O
O
O
O
O
O
OH
R
OH
49 R = Et (asteltoxin E)
50 R = Me (asteltoxin F)
Fig. 3 Structures of α-pyrones including isocoumarins (part 2)
Secondary Metabolites from Marine-Derived Fungi from China
87