Bioassay-Guided Isolation of Prenylated Xanthones and Polycyclic Acylphloroglucinols from the Leaves of Garcinia nujiangensis

Abstract

Bioassay-guided fractionation of the acetone extract of the leaves of Garcinia nujiangensis resulted in the isolation of two new prenylated xanthones, nujiangexanthones A (1) and B (2), three new polycyclic polyprenylated acylphloroglucinols, nujiangefolins A-C (3-5), and 10 known related analogues. The structures of compounds 1-5 were elucidated by interpretation of their spectroscopic data. Compounds 3 and 4 are unusual polycyclic polyprenylated acylphloroglucinols in which the enol hydroxy group forms a six-membered ring with a benzene ring carbon. The compounds isolated were evaluated for their cytotoxic effects against 11 cancer cell lines and immortalized MIHA normal liver cells, and the test substances demonstrated selectivity toward the cancer cells. Isojacareubin (6) was found to be the most potent cytotoxic compound of those tested.

Four new cytotoxic xanthones from Garcinia nujiangensis

“…Furthermore, a chelated hydroxy proton signal at  H 13.40 (1H, s, OH-1) showed a cross peak to the carbon signals at C-1 ( C 148.0) and C-2 ( C 132.8)(Figure 1). The location of the methoxy group at C-3 ( C 153 6). was confirmed in the HMBC spectrum from the correlation of the OCH 3 ( H 3.88) and C-3 ( C 153.0) signals (Figure 2).…”

“…The ten known compounds, nujiangexanthones A-B (5-6) [6], nujiangefolins A-B (7-8) [6], guttiferone F (9) [10], jacareubin (10) [11], xanthone V 1 a (11) [12], xanthone V 1 (12) [12], 6-deoxy-jacareubin (13) [13], and cudratricusxanthone E (14) A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT [14] were identified by comparison of spectroscopic data with reported values.…”

“…Previous phytochemical studies of the leaves of this plants lead to the discovery of xanthones, and polycyclic polyprenylated acylphloroglucinols, some compounds exhibit cytotoxic activities [6].…”

“…was confirmed in the HMBC spectrum from the correlation of the OCH 3 ( H 3.88) and C-3 ( C 153.0) signals (Figure 2). After comparing the 1 H and 13 C NMR data of 1 with those of known xanthones with similar structures[6], tri(3-methyl-2-butenyl)xanthone. Therefore, four hydroxy groups were located at C-1 ( C 148.0), C-3 ( C 153.0), C-5 ( C 129.9), and C-6 ( C 151.4) by analysis of the HSQC and HMBC spectra.Compound 2 was isolated as a yellow gum.…”

“…H and13 C NMR Spectroscopic Data of Compound 1-4 in DMSO-d6 a 1 H and13 CNMR was recorded at 400 and 100 Hz, respectively. b 1 H and 13 CNMR was recorded at 600 and 150 Hz, respectively.…”