Cytotoxic and Antimicrobial Constituents of the Bark of Diospyros maritima Collected in Two Geographical Locations in Indonesia

Abstract

Bioactivity-directed fractionation of extracts of two Diospyros maritima bark samples from Indonesia,one collected at sea level in a beach forest in Java and the other collected at a slight elevation away from the sea shore on the island of Lombok, yielded a diverse set of secondary metabolites. The naphthoquinone plumbagin (1), although found in extracts of both specimens, constituted a much larger percentage of the former sample, which also yielded a series of plumbagin dimers, maritinone (2), chitranone (3), and zeylanone (4). The latter sample yielded a new naphthoquinone derivative, (4S)-shinanolone (5), and a new natural product coumarin, 7,8-dimethoxy-6-hydroxycoumarin (6), along with three other analogues of plumbagin, 2-methoxy-7-methyljuglone (7), 3-methoxy-7-methyljuglone (8), and 7-methyljuglone (9). The structures of compounds 5 and 6 were elaborated by physical, spectral, and chemical methods. All of the isolates were evaluated in both cytotoxicity and antimicrobial assays, and structure-activity relationships of these naphthoquinones are proposed. Plumbagin (1) and maritinone (2) were evaluated also for in vivo antitumor activity in the hollow fiber assay, but both were found to be inactive.

Studies on the Constituents of Juglans Species. I. Structural Determination of (4S)- and (4R)-4-Hydroxy-.ALPHA.-tetralone Derivatives from the Fruit of Juglans mandshurica MAXIM. var. sieboldiana MAKINO

“…On the other hand, the sign of the weakly negative [2a: De Ϫ0.8 at 341 nm)] and positive [2b: De Ϫ0.8 at 340 nm)] Cotton effects (n→p*) could be interpreted under the assumption that the half-chair form of the cyclohexenone ring is a more stable conformation than the sofa form in the molecular arrangement. 18) From the above CD effects, the absolute configuration at C-4 of 2a and 2b was assigned as S and R, and this conclusion is in agreement with the sign of the optical rotations 2,[4][5][6][7][8][9][10][11][12][13] (Fig. 2).…”

“…The extract was chromatographed on a silica gel column using an n-hexane-AcOEt gradient, and the eluate was separated into thirteen fractions (frs. [1][2][3][4][5][6][7][8][9][10][11][12][13] …”

“…From their sign of the optical rotations 2,4-13) and comparison of the circular dichroism (CD) data ( Fig. 1) with those of 4S-and 4R-configured isosclerone 4,13) and analogous compounds, 9,12,14) the absolute configurations at C-4 in 1a and 1b were determined to be S and R, respectively. This deduction was further supported by application of the exciton chirality method (see Experimental).…”

Lanostane-Type Triterpenoids from Diospyros discolor

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Plants in the Diospyros genus (Ebenacea) are well documented as a rich sources of naphthoquinones and triterpenes, which have been found to exhibit ichthyotoxic, 1,2) antimicrobial, [2][3][4] and antitumor activities. 4,5) Thirteen species of this genus are indigenous to Taiwan.

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“…4,5) Thirteen species of this genus are indigenous to Taiwan. Several species, including fruits of D. discolor WILLD., 6) leaves of D. kaki THUNB., 7) barks and stems of D. eriantha CHAMP., 8,9) stems of D. morrisiana HANCE., [10][11][12] fruits of D. ferrea, 13) and bark, root, fruits, leaves, and twigs of D. maritima BLUME.…”