Part F | 32.3
770 Part F Marine Derived Metabolites
off the shores of Thailand [32.98]. The structure and
absolute configuration of pre-aurantiamine (60) was
established based on extensive 1-D and 2-D nuclear
magnetic resonance (NMR) and X-ray crystallographic
analysis.
Carneamides A–C (61–63), prenylated indole diketopiperazines, and carnequinazolines A–C (64–66),
quinazoline-type alkaloids, were reported as new natural products from the marine-derived fungus Aspergillus carneus KMM 4638 isolated from the marine
brown alga Laminaria sachalinensis [32.99]. Structurally, carneamides A–C (61–63) represented the first
prenylated indole alkaloid possessing a 2,2-dimethyl2,8-dihydropyrano[3,2-f]indole ring system, and in particular 62 and 63 featured a rare indoloazocine tricyclic subunit. However, carnequinazolines A–C (64–
66) were identified as quinazoline alkaloids with additional oxidation and alkylation patters, whereas 64 and
65 are aryl C-glycosides containing glucopyranoside
units of
4 C 1 conformation [32.99].
Recently, a diketopiperazine dimer possessing a rare
N-1 to C-6 linkage was purified from the culture extract of the fungus Aspergillus taichungensis derived
from the mangrove plant Acrostichum aureum and it
was trivially named aspergilazine A (67) [32.100]. The
chemical structure and absolute configuration of aspergilazine A was established based on spectroscopic
evaluation and on Marfey’s method. In the antiviral activity assay, 67 revealed only weak activity against the
influenza A (H 1 N 1 / virus [32.100].
32.3.3 Polyketides
Three new ˛-pyrone metabolites, curvulapyrone (68,
Fig. 32.7), curvulalide (69), and the curvulalic acid
(70), were identified as new compounds together with
six further metabolites from the sea fan-derived fungus Curvularia sp. PSU-F22 [32.101]. In the antimicrobial activity assay against Staphylococcus aureus,
MRSA, and Microsporum gypseum, none of the isolated compounds revealed activity at concentrations up
to 200 g mL
1 [32.101].
Nidurufin (71), a new cell cycle inhibitor, was
isolated from the marine sediment-derived fungus Penicillium flavidorsum SHK1-27 [32.102]. In the in vitro
cytotoxicity assay, 71 exhibited significant antiproliferative activity against the K562 cell line (IC 50 D
12:6 M) by inducing cell cycle arrest at G 2 /M
transition [32.102].
Trichodermaquinone (72) and trichodermaxanthone
(73) were isolated from the marine-derived fungus
Trichoderma aureoviride PSU-F95 isolated from the
gorgonian sea fan Annella sp. [32.103]. In the antimicrobial assay, neither 72 nor 73 exhibited activity
against MRSA [32.103].
A new aflatoxin, aflatoxin B 2b (74), was isolated
together with six known compounds from the marine fungus Aspergillus flavus 092 008 derived from
the mangrove plant Hibiscus tiliaceus [32.104]. Aflatoxin B 2b revealed significant antimicrobial activity
against Escherichia coli, Bacillus subtilis, and Enterobacter aerogenes, with MIC values of 22:5, 1:7, and
1:1 M, respectively [32.104]. In addition, 74 showed
cytotoxic activity against A549, K562, and L-02 cell
lines, with IC 50 values of 8:1, 2:0, and 4:2 M, respectively [32.104]. The results disclosed that hydration
and hydrogenation of the
8 -double bond significantly
reduce the cytotoxicity of aflatoxins, while the esterification at C-8 increases the cytotoxicity [32.104].
Marilones A–C (75–77), three new phthalide
derivatives, were isolated together with the known
compound silvaticol (78) from the biomalt culture
of Stachylidium sp., a marine fungus derived from
the sponge Callyspongia sp. cf. C. flammea [32.105].
Marilones A (75) and B (76) featured an unusual
skeleton, suggesting unique fungal biosynthetic reactions. Among the isolated compounds, marilone A (75)
revealed antiplasmodial activity against Plasmodium
berghei liver stages with an IC 50 of 12:1 M, whereas
marilone B (76) showed selective antagonistic activity
towards the serotonin receptor 5-HT 2B with a K i value
of 7:7 M [32.105].
Aspergilones A (79) and B (80), two novel benzylazaphilone derivatives with an unprecedented skeleton,
were isolated from the culture broth of the marinederived fungus Aspergillus sp. obtained from the gorgonian Dichotella gemmacea [32.106]. Structurally,
aspergilone B (80) represents a symmetrical dimer of
79 with a characteristic methylene bridge. The absolute and relative configurations of aspergilones A and
B were established based on X-ray crystallography and
NMR spectral analysis. Interestingly, only the monomer
aspergilone A (79) exhibited in vitro selective cytotoxicity toward HL-60, MCF-7, and A-549 cell lines
with IC 50 values of 8:3, 72:5, and 95:85 M, respectively [32.106]. Moreover, 79 also exhibited potent antifouling activity against the larval settlement of the barnacle Balanus amphitrite at EC 50 of 20 M [32.106].
Penicacids A–C (81–83), together with two known
analogs, namely mycophenolic acid (MPA) and 4
0 -
hydroxy-MPA, were isolated from the fungus Penicillium sp. SOF07 derived from a marine sediment col-
770 Part F Marine Derived Metabolites
off the shores of Thailand [32.98]. The structure and
absolute configuration of pre-aurantiamine (60) was
established based on extensive 1-D and 2-D nuclear
magnetic resonance (NMR) and X-ray crystallographic
analysis.
Carneamides A–C (61–63), prenylated indole diketopiperazines, and carnequinazolines A–C (64–66),
quinazoline-type alkaloids, were reported as new natural products from the marine-derived fungus Aspergillus carneus KMM 4638 isolated from the marine
brown alga Laminaria sachalinensis [32.99]. Structurally, carneamides A–C (61–63) represented the first
prenylated indole alkaloid possessing a 2,2-dimethyl2,8-dihydropyrano[3,2-f]indole ring system, and in particular 62 and 63 featured a rare indoloazocine tricyclic subunit. However, carnequinazolines A–C (64–
66) were identified as quinazoline alkaloids with additional oxidation and alkylation patters, whereas 64 and
65 are aryl C-glycosides containing glucopyranoside
units of
4 C 1 conformation [32.99].
Recently, a diketopiperazine dimer possessing a rare
N-1 to C-6 linkage was purified from the culture extract of the fungus Aspergillus taichungensis derived
from the mangrove plant Acrostichum aureum and it
was trivially named aspergilazine A (67) [32.100]. The
chemical structure and absolute configuration of aspergilazine A was established based on spectroscopic
evaluation and on Marfey’s method. In the antiviral activity assay, 67 revealed only weak activity against the
influenza A (H 1 N 1 / virus [32.100].
32.3.3 Polyketides
Three new ˛-pyrone metabolites, curvulapyrone (68,
Fig. 32.7), curvulalide (69), and the curvulalic acid
(70), were identified as new compounds together with
six further metabolites from the sea fan-derived fungus Curvularia sp. PSU-F22 [32.101]. In the antimicrobial activity assay against Staphylococcus aureus,
MRSA, and Microsporum gypseum, none of the isolated compounds revealed activity at concentrations up
to 200 g mL
1 [32.101].
Nidurufin (71), a new cell cycle inhibitor, was
isolated from the marine sediment-derived fungus Penicillium flavidorsum SHK1-27 [32.102]. In the in vitro
cytotoxicity assay, 71 exhibited significant antiproliferative activity against the K562 cell line (IC 50 D
12:6 M) by inducing cell cycle arrest at G 2 /M
transition [32.102].
Trichodermaquinone (72) and trichodermaxanthone
(73) were isolated from the marine-derived fungus
Trichoderma aureoviride PSU-F95 isolated from the
gorgonian sea fan Annella sp. [32.103]. In the antimicrobial assay, neither 72 nor 73 exhibited activity
against MRSA [32.103].
A new aflatoxin, aflatoxin B 2b (74), was isolated
together with six known compounds from the marine fungus Aspergillus flavus 092 008 derived from
the mangrove plant Hibiscus tiliaceus [32.104]. Aflatoxin B 2b revealed significant antimicrobial activity
against Escherichia coli, Bacillus subtilis, and Enterobacter aerogenes, with MIC values of 22:5, 1:7, and
1:1 M, respectively [32.104]. In addition, 74 showed
cytotoxic activity against A549, K562, and L-02 cell
lines, with IC 50 values of 8:1, 2:0, and 4:2 M, respectively [32.104]. The results disclosed that hydration
and hydrogenation of the
8 -double bond significantly
reduce the cytotoxicity of aflatoxins, while the esterification at C-8 increases the cytotoxicity [32.104].
Marilones A–C (75–77), three new phthalide
derivatives, were isolated together with the known
compound silvaticol (78) from the biomalt culture
of Stachylidium sp., a marine fungus derived from
the sponge Callyspongia sp. cf. C. flammea [32.105].
Marilones A (75) and B (76) featured an unusual
skeleton, suggesting unique fungal biosynthetic reactions. Among the isolated compounds, marilone A (75)
revealed antiplasmodial activity against Plasmodium
berghei liver stages with an IC 50 of 12:1 M, whereas
marilone B (76) showed selective antagonistic activity
towards the serotonin receptor 5-HT 2B with a K i value
of 7:7 M [32.105].
Aspergilones A (79) and B (80), two novel benzylazaphilone derivatives with an unprecedented skeleton,
were isolated from the culture broth of the marinederived fungus Aspergillus sp. obtained from the gorgonian Dichotella gemmacea [32.106]. Structurally,
aspergilone B (80) represents a symmetrical dimer of
79 with a characteristic methylene bridge. The absolute and relative configurations of aspergilones A and
B were established based on X-ray crystallography and
NMR spectral analysis. Interestingly, only the monomer
aspergilone A (79) exhibited in vitro selective cytotoxicity toward HL-60, MCF-7, and A-549 cell lines
with IC 50 values of 8:3, 72:5, and 95:85 M, respectively [32.106]. Moreover, 79 also exhibited potent antifouling activity against the larval settlement of the barnacle Balanus amphitrite at EC 50 of 20 M [32.106].
Penicacids A–C (81–83), together with two known
analogs, namely mycophenolic acid (MPA) and 4
0 -
hydroxy-MPA, were isolated from the fungus Penicillium sp. SOF07 derived from a marine sediment col-