Cytotoxic Phenanthrene, Dihydrophenanthrene, and Dihydrostilbene Derivatives and Other Aromatic Compounds from Combretum laxum

Abstract

<jats:p>The chemical investigation of the roots and stems of Combretum laxum yielded a new dihydrostilbene derivative, 4′-hydroxy-3,3′,4-trimethoxy-5-(3,4,5-trimethoxyphenoxy)-bibenzyl (1), two phenanthrenes (2–3), and three dihydrophenanthrenes (4–6), along with one lignan, three triterpenoids, one aurone, one flavone, one naphthoquinone, and two benzoic acid derivatives. Their structures were determined by 1D and 2D nuclear magnetic resonance (NMR) spectroscopic techniques and/or mass spectrometry data. The occurrence of dihydrostilbenoid, phenanthrene and dihydrophenanthrene derivatives is unprecedented in a Combretum species native to the American continent. 2,7-Dihydroxy-4,6-dimethoxyphenanthrene, 2,6-dihydroxy-4,7-dimethoxy-9,10-dihydrophenanthrene and 5-O-methyl apigenin are novel findings in the Combretaceae, as is the isolation of compounds belonging to the chemical classes of aurones and naphthoquinones, while (+)-syringaresinol is reported for the first time in the genus Combretum. Compounds 1–6 were also evaluated for their in vitro cytotoxicity against five human cancer cell lines, and radical-scavenging ability against 1,1-diphenyl-2-picryl-hydrazyl (DPPH). 6-Methoxycoelonin (4) was the most cytotoxic against melanoma cells (IC50 2.59 ± 0.11 µM), with a high selectivity index compared with its toxicity against nontumor mammalian cells (SI 25.1). Callosin (6), despite exhibiting the strongest DPPH-scavenging activity (IC50 17.7 ± 0.3 µM), proved marginally inhibitory to the five cancer cell lines tested, indicating that, at least for these cells, antioxidant potential is unrelated to antiproliferative activity.</jats:p>

Triterpene Derivatives from Garcinia oligantha and Their Anti-Cancer Activity

“…The NOESY correlations of H-3 with H-5 and H 2 -23 and H-9 with H-5 and H 3 -27 suggested their α -orientation ( Figure 3 ). After the hydrolysis of 1 , compound 1a was obtained, and its 1D NMR data and specific rotation were the same as those of arjunolic acid, which further confirmed the above conclusion [ 51 , 52 ]. Thus, the structure of 1 was determined, as shown in Figure 1 , and named 2 α ,3 β -diacetyl arjunolic acid.…”

“…The 13 C NMR spectrum ( Table 2 ) of 1 showed 34 carbon signals assigned to eight primary, ten secondary, six tertiary, and ten quaternary carbons, including two acetyl groups and the typical olefinic signals at δ C 144.0 and 122.2 for the double bond at C-12 (13) of an oleanane-type triterpene. The 1 H and 13 C NMR spectra of 1 were similar to those of arjunolic acid except for the presence of two acetyl groups instead of two hydroxy groups in arjunolic acid [ 51 ]. The HMBC spectrum showed cross-peaks from H-2 and H 3 -32 to C-31 and from H-3 and H 3 -34 to C-33, confirming two acetyl groups located at C-2 and C-3, respectively ( Figure 2 ).…”

Chemodiversity of propolis samples collected in various areas of Benin and Congo: Chromatographic profiling and chemical characterization guided by 13C NMR dereplication

“…Such derivatives have already been described by Inui et al in 2021 58 in Senegalese propolis showing significant anti‐inflammatory activity, compounds 4 , 6 , and 7 being the most active. The dihydrophenanthrene 6‐methoxycoelonin ( 3 ) has also been described displaying cytotoxic effect against five human cancer cell lines (786‐0, MCF‐7, Hep2, UACC‐62, and NCI/ADR‐RES) with remarkable activity against UACC‐62 cells (IC 50 2.59 μM) 91 . The phenanthrene 6 was also known for its moderate cytotoxic activity against KB, MCF‐7, and K562 cells and its potent inhibitory activity on CDK1/cyclin B (IC 50 0.07 μM) 92 .…”

“…The dihydrophenanthrene 6-methoxycoelonin (3) has also been described displaying cytotoxic effect against five human cancer cell lines (786-0, MCF-7, Hep2, UACC-62, and NCI/ADR-RES) with remarkable activity against UACC-62 cells (IC 50 2.59 μM). 91 The phenanthrene 6 was also known for its moderate cytotoxic activity against KB, MCF-7, and K562 cells and its potent inhibitory activity on CDK1/cyclin B (IC 50 0.07 μM). 92 Dihydrophenanthrenes from…”

Juncaceae Species as Promising Sources of Phenanthrenes: Antiproliferative Compounds from Juncus maritimus Lam

“…To date, various phenanthrene derivatives have been described from plant species belonging to the Annonaceae, Aristolochiaceae, Cannabaceae, Combretaceae, Euphorbiaceae, Dioscoreaceae, Lauraceae, Malpighiaceae, Orchidaceae, Stemonaceae, and Juncaceae families [ 1 ]. Phenanthrenes are reported to possess a wide range of biological activities including pronounced cytotoxic, antiproliferative, and apoptosis induction effects [ 2 , 3 ].…”