5. ANTIBIOSIS AND ANTIBIOTICS
327
Substitution on carbon number:
2'
3'
4'
5'
6'
—
C 5 H n
COOH
OH
—
—
CH 3
COOH
OH
CH 2 OH
—
COOH
—
OCH 3
CH 3
—
1
HOHC—0—CO—
OH
CHOH
—
1
H 3 C—C=CH—CH 3 CI
OCH 3
CH 3
—
1
H 3 C—C=CH—CH 3 CI
OH
CH 3
—
1
H 3 C—C=CH—CH 3 CI
OH
CH 3
These experiments have established the acetate origin of the anthraquinones studied. By analogy, it can be surmised that a similar biosynthesis occurs in the case of endocrocin (CXLVI), from the lichen Nephromopsis endocrocea, and its decarboxylated analog, emodin, from
Cortinarius sanguineus and Chaetomium affine. Whether they are formed
from the coupling of 3,5-dihydroxyphthalic acid and 6-methylsalicylic
acid, or from a straight-chain polyketomethylene precursor, remains to be
known. They are closely related to the plant antibiotic rhein or cassic
acid from Cassia reticulata.
The structure of javanicin (CXLVII), from Fusarium javanicum and
F. solani (the latter also producing fusarubin or oxyjavanicin, CXLVIII),
Javanicin
(CXLVII)
Fusarubin (oxyjavanicin)
(CXLVIII)