Di(phenylpropylamino)gossypol: a derivative of the dimeric natural product gossypol.

Di(phenylpropylamino)gossypol [systematic name: 2,2'-bis{1,6-dihydroxy-5-isopropyl-8-[(3-phenylpropylamino)methylidene]naphthalen-7-one}, C48H52N2O6, was formed by reaction of the dimeric natural product gossypol with 3-phenylpropylamine. The structure of this compound has its two naphthalene ring systems oriented approximately perpendicular to each other, and the two pendant phenylpropyl groups have different conformations. One of these side groups is considerably disordered at room temperature but less so at 120 K. The enantiomeric molecules form centrosymmetric dimers that are supported by intermolecular hydrogen bonds and by hydrophobic interactions between a pair of naphthalene rings. Two additional hydrogen bonds tie the dimer pairs into layers. Unlike gossypol and many gossypol Schiff base derivatives, the title compound crystallizes without the inclusion of solvent, which appears to occur because of the size and flexibility of its phenylpropyl pendent groups.

Inhibitory effects of gossypol, gossypolone, and apogossypolone on a collection of economically important filamentous fungi.

Racemic gossypol and its related derivatives gossypolone and apogossypolone demonstrated significant growth inhibition against a diverse collection of filamentous fungi that included Aspergillus flavus, Aspergillus parasiticus, Aspergillus alliaceus, Aspergillus fumigatus, Fusarium graminearum, Fusarium moniliforme, Penicillium chrysogenum, Penicillium corylophilum, and Stachybotrys atra. The compounds were tested in a Czapek agar medium at a concentration of 100 µg/mL. Racemic gossypol and apogossypolone inhibited growth by up to 95%, whereas gossypolone effected 100% growth inhibition in all fungal isolates tested except A. flavus. Growth inhibition was variable during the observed time period for all tested fungi capable of growth in these treatment conditions. Gossypolone demonstrated significant aflatoxin biosynthesis inhibition in A. flavus AF13 (B(1), 76% inhibition). Apogossypolone was the most potent aflatoxin inhibitor, showing greater than 90% inhibition against A. flavus and greater than 65% inhibition against A. parasiticus (B(1), 67%; G(1), 68%). Gossypol was an ineffectual inhibitor of aflatoxin biosynthesis in both A. flavus and A. parasiticus. Both gossypol and apogossypolone demonstrated significant inhibition of ochratoxin A production (47%; 91%, respectively) in cultures of A. alliaceus.

6,6'-Dimethoxygossypolone.

6,6'-Dimethoxygossypolone (systematic name: 7,7'-dihydroxy-5,5'-diisopropyl-6,6'-dimethoxy-3,3'-dimethyl-1,1',4,4'-tetraoxo-2,2'-binaphthalene-8,8'-dicarbaldehyde), C(32)H(30)O(10), is a dimeric molecule formed by oxidation of 6,6'-dimethoxygossypol. When crystallized from acetone, 6,6'-dimethoxygossypolone has monoclinic (P2(1)/c) symmetry, and there are two molecules within the asymmetric unit. Of the four independent quinoid rings, three display flattened boat conformations and one displays a flattened chair/half-chair conformation. The angles between the planes of the two bridged naphthoquinone structures are fairly acute, with values of about 68 and 69°. The structure has several intramolecular O-H...O and C-H...O hydrogen bonds and several weak intermolecular C-H...O hydrogen bonds, but no intermolecular O-H...O hydrogen bonds.