Euglobal-IIIa, a novel acylphloroglucinol-sesquiterpene derivative from Eucalyptus robusta: absolute structure and cytotoxicity

In Vitro Study of Cytostatic Activity of Baicalin, Baicalein, and Chlorophyllipt on HeLa-v Cell Line

Cytostatic activity of baicalin, baicalein, and neogalenical drug Chlorophyllipt was studied in vitro on HeLa-v cells. Standard samples of Eucalimin, baicalin, and baicalein, as well as Chlorophyllipt and paclitaxel (reference drug Taxacad) were used. The cell deaths were determined by MTT assay in a Multiskan FC microplate reader with incubator. The effective inhibition concentration (IC₅₀) of the tested substances were: paclitaxel (4.0±0.4 μM)-baicalein (10.5±1.1 μM)-baicalin (16.5±1.7 μM)-sum of euglobals in Chlorophyllipt (24.1±2.5 μM). Chlorophyllipt was found to exhibit cytostatic activity. Cytostatic activity of baicalein, baicalin, and Chlorophyllipt was lower than cytostatic activity of the reference drug by 2.6, 4.1, and 6 times, respectively. The prospects of further evaluation of the synergetic effect of baicalin, baicalein, and chlorophyllipt used in combinations with different cytostatic agents for finding the most effective combination have been shown.

Eucalypglobulusals A-J, Formyl-Phloroglucinol-Terpene Meroterpenoids from Eucalyptus globulus Fruits

Ten new formyl-phloroglucinol-terpene meroterpenoids, eucalypglobulusals A-J (1-10), and ten known analogues were isolated from  Eucalyptus globulus fruits. The structures of 1-10 were determined by spectroscopic analysis, while their absolute configurations were established using calculated and experimental electronic circular dichroism (ECD) spectra. Eucalypglobulusal A was assigned as a new formyl-phloroglucinol-terpene meroterpenoid with a rearranged sesquiterpene skeleton, and an aldol condensation between C-3 and C-5 of the germacrene C moiety was proposed to be a key step in its putative biosynthetic pathway. Eucalypglobulusal F exhibited cytotoxicity against the human acute lymphoblastic cell line (CCRF-CEM) with an IC₅₀ value of 3.3 μM, while eucalypglobulusal A, eucarobustol C, macrocarpal A, macrocarpal B, and macrocarpal D exhibited DNA topoisomerase I (Top1) inhibition. The compounds eucalypglobulusal A and macrocarpal A act as Top1 catalytic inhibitors and delay Top1 poison-mediated DNA double-strand damage.

Eucalyptusdimers A-C, Dimeric Phloroglucinol-Phellandrene Meroterpenoids from Eucalyptus robusta

Eucalyptusdimers A-C, three dimeric phellandrene-derived meroterpenoids featuring an unprecedented, fused skeleton between two phellandrene and two acylphloroglucinol subunits, along with one biogenetically related intermediate, (±)-eucalyprobusone A, were isolated from the fruits of Eucalyptus robusta. Their structures and absolute configurations were elucidated using spectroscopic data, X-ray crystallography, and electronic circular dichroism analysis. The isolated meroterpenoids were evaluated for their anti-inflammatory, acetylcholinesterase inhibitory, and protein tyrosine phosphatase 1B inhibitory effects.

Eucarobustols A-I, Conjugates of Sesquiterpenoids and Acylphloroglucinols from Eucalyptus robusta

Nine new conjugates of sesquiterpenoids and acylphloroglucinols, named eucarobustols A-I (1-9), as well as 11 known analogues were isolated from the leaves of Eucalyptus robusta. The sesquiterpenoid motifs furnishing the new conjugates included four structural types of aristolane (1 and 2), guaiane (3), eudesmane (4), and aromadendrane (5-9) moieties. Compounds 1 and 2 were found to represent the first examples of conjugates of aristolane and acylphloroglucinol units. In turn, compound 3 features a new coupling model of guaiane and acylphloroglucinol via the C-4-C-7' bond. Compounds 1, 7, and 9 showed inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) with IC50 values of 1.3, 1.8, and 1.6 μM, respectively.

Cytotoxic activity of acyl phloroglucinols isolated from the leaves of Eucalyptus cinerea F. Muell. ex Benth. cultivated in Egypt

Two acyl phloroglucinol compounds namely; Sideroxylonal B (1) and Macrocarpal A (2) were isolated from the Sideroxylonal-Rich Extract (SRE) of the juvenile leaves of Eucalyptus cinerea; F. Muell. ex Benth cultivated in Egypt. Identification of the isolated compounds was established on the basis of physico-chemical properties and spectral analysis (1D & 2D NMR). The two compounds were isolated for the first time from this species. The SRE alongside with the isolated compounds were tested against three human cancer cell lines; MCF7 (breast carcinoma cell line), HEP2 (laryngeal carcinoma), CaCo (colonic adenocarcinoma) and one type of normal human cell line;10 FS (fibroblast cells). The SRE, (1), and (2) showed cytotoxic activity with IC₅₀ 13.6 ± 0.62, 7.2 ± 0.5, 14.8 ± 0.55 μg mL−1 against HEP2 respectively, 11.6 ± 0.47, 4 ± 0.36, 11.4 ± 0.45 μg mL−1 against CaCo, respectively, and 8.6 ± 0.29, 4.4 ± 0.25, and 7.8 ± 0.3 μg mL−1 against MCF7, respectively. Meanwhile, the (SRE) together with (1) and (2) exhibited low cytotoxicity against normal cell line 10 FS, with IC₅₀ 55.4 ± 1.4, 43 ± 0.8 and 50.1 ± 1.12 μg mL−1, respectively. The antiprofilerative activity of the tested compounds was evaluated. The cell cycle profile of cells treated with Sideroxylonal-B and Macrocarpal-A indicates possible S-phase specific effects.

Two new euglobals from the leaves of Eucalyptus robusta

Two new euglobals, R1 (1) and R2 (2), together with eight known euglobals (3-10) were isolated from the leaves of Eucalyptus robusta. Their structures were established by means of spectroscopic analysis and single-crystal X-ray diffraction. Euglobal R1 (1) represents a new skeleton of formyl-isovaleryl phloroglucinol-coupled β-phellandrene.