Crystal structure of limonoid TS3, isolated from Trichilia rubescens

The title limonoid compound, C26H28O5·0.5H2O (TS3) [systematic name: (3aS,3bS,4aS,5aS,6S,7aR,8aR,8bS,11aR)-6-(furan-3-yl)-3a,5a,8b,11a-tetramethyl-3a,4a,5,5a,6,7,7a,8b,11,11a-decahydrooxireno[2′,3′:4b,5]oxireno[2′′,3′′:2′,3′]cyclopenta[1′,2′:7,8]phenanthro[10,1-bc]furan-3(3aH)-one hemihydrate], crystallizes with two independent molecules (1 and 2) in the asymmetric unit and one water molecule. TS3 is composed of three six-membered rings (A, C and D), three five-membered rings (B, E and F) and two epoxide rings. A group of five fused rings (A–E) is bonded to a furan ring (F) with a Csp3—Csp2 bond [1.500 (3) Å in molecule 1 and 1.499 (3) Å in molecule 2]. The absolute structures of the molecules in the crystal were determined by resonant scattering; Flack parameter = 0.05 (5). In the crystal, the individual molecules stack in columns along the b-axis direction. The water molecule bridges molecules 1 and 2 via Owater—H...O and C—H...Owater hydrogen bonds. Together with further C—H...O hydrogen bonds, linking molecules 1 and 2, the columns are linked to form slabs parallel to the ab plane. Within each column, molecules are also linked via C—H...π interactions involving the five-membered furan (F) rings

Rubescins I and J, further limonoid derivatives from the stem bark of <i>Trichilia rubescens</i> (Meliaceae)

<p>Two new tetranorterpenoid derivatives named rubescins I (<b>1</b>) and J (<b>2</b>), were isolated along with six known compounds including rubescin D (<b>3</b>), lichexanthone (<b>4</b>), scopoletin (<b>5</b>), scopoletin <i>O</i>-glycoside (<b>6</b>), <i>β</i>-sitosterol (<b>7</b>) and stigmasterol (<b>8</b>) from the stem bark of <i>Trichilia rubescens</i> (Meliaceae). The structures of the compounds were determined by means of MS, different NMR and by comparison with related data reported in the literature.</p

Antimycobacterial cycloartane derivatives from the roots of Trichilia welwistchii C. DC (Meliaceae).

Chemical investigation of the roots of yielded a cycloartane type terpenoid 28,29-bis-norcycloart-24-en-3 ,4 ,6 -triol ( ), isolated as pure compound for the first time, three coumarins and three sterols. New cycloartane derivatives ( ) and ( + ) were obtained by hemi-synthetic reaction of compound . The structures of – were established by spectroscopic methods including 1D and 2D-NMR analysis, HR-EIMS, chemical transformations and by comparison of these data with those of related compounds. Evaluated for their antimycobacterial potential, compound and + were determined to show significant activities against MIC values of 6.25 μg mL while compound displayed weak activity showing MIC &gt; 100 μg mL . Compounds – displayed moderate activity with MIC values range from 12.5 to 50 μg mL

The Limonoids TS3 and Rubescin E Induce Apoptosis in Human Hepatoma Cell Lines and Interfere with NF-κB Signaling.

Hepatocellular carcinoma (HCC) is extremely resistant towards pharmacological therapy. To date, the multi-kinase inhibitor Sorafenib is the only available therapeutic agent with the potential to prolong patient survival. Using the human hepatoma cell lines HepG2 and Huh7, we analyzed anti-cancer activities of 6 purified havanensin type limonoids isolated from the traditional African medicinal plant Trichilia rubescens Oliv. Our results show that two of the compounds, TR4 (TS3) and TR9 (Rubescin E) reduced hepatoma cell viability, but not primary hepatocyte viability, at TC50s of 5 to 10 μM. These were significantly lower than the TC50s for Sorafenib, the histone deacetylase inhibitor SAHA or 5-Fluoruracil. In comparison, TR3 (Rubescin D), a limonoid isolated in parallel and structurally highly similar to TR4 and TR9, did not interfere with hepatoma cell viability. Both, TR4 and TR9, but not TR3, induced apoptosis in hepatoma cells and interfered with NF-κB activation. TR4 as well as TR9 significantly supported anti-cancer activities of Sorafenib. In summary, the limonoids TR4 and TR9 exhibit anti-cancer activities and support Sorafenib effects in vitro, having the potential to support future HCC therapy

TR4 and TR9 induce apoptosis in human hepatoma cells.

<p>HepG2 cells were incubated with 5 μM TR3, TR4 or TR9 for 24 hours. As an apoptosis induction control HepG2 cells were incubated with 80 nM ActD as well as 40 ng/ml TNFα (ActD/TNFα) for 16 hours. Apoptosis was measured by Caspase-3 colorimetric assay (A) or by Western Blot analysis of Caspase-3- and PARP-cleavage (B). HepG2 cells were incubated with 5 μM TR3, TR4 or TR9 for 40 hours or with ActD/TNFα for 16 hours. Apoptotic DNA Ladder was determined by performing DNA-fragmentation analysis (C). HepG2 cells were incubated with 5 μM TR3, TR4, TR9 or with ActD/TNFα for 16 hours (D, E). FACS analysis was performed to detect apoptotic cells stained with propidium iodide (PI) and Annexin V. Representative plots are shown (D). E: Quantification of PI-positive HepG2 cells. F: HepG2 cells were incubated with 5 μM TR3, TR4 or TR9 for 6 hours. Real time RT-PCR for Bcl2 and Bcl10 expression was performed. Relative expression levels were determined using mATPsy expression as a reference. ★★ p ≤ 0.01, ★★★ p ≤ 0.001 vs DMSO controls.</p

Limonoids used in this study.

<p>Limonoids used in this study.</p

The limonoids TR4 and TR9 have strong adverse effects on human hepatoma cell viability.

<p>A: HepG2 human hepatoma cells were incubated with 25 μM of 6 different limonoids (TR3, TR4, TR8, TR9, TR11 and TR12, isolated from <i>Trichilia rubescens</i> Oliv.) for 24 hours. Cell viability was measured by MTT assay. DMSO control: 0.25%. B-D: Structures of the most powerful limonoids TR4 and TR9 as well as the structurally similar but ineffective control limonoid TR3. E: HepG2 cells were incubated with 5 μM of TR3, TR4 or TR9 for 6 to 72 hours. Cell viability was measured by MTT assay. The grey line indicates the TC50. DMSO control: 0.05%. F: Primary mouse hepatocytes (PH) isolated from male C57/Bl6 mice, as well as corresponding mouse hepatoma cells (Hepa1-6) were incubated with 10 μM TR3, TR4 or TR9 for 24 hours. Cell viability was measured by MTT assay. DMSO control: 0.1%. ★★ p ≤ 0.01, ★★★ p ≤ 0.001 vs DMSO controls.</p