Structure elucidation of a new bicoumarin derivative from the leaves of Dysoxylum parasiticum (Osbeck) Kosterm

Paraxylines A-G: Highly oxygenated preurianin-type limonoids with immunomodulatory TLR4 and cytotoxic activities from the stem bark of Dysoxylum parasiticum

Seven previously undescribed preurianin-type limonoids, namely paraxylines A-G, and three known analogs were isolated from stem bark of Dysoxylum parasiticum. The structures, including absolute configurations, were established through spectroscopic analyses, quantum chemical calculations using the density functional theory method, as well as the DP4+ algorithm. Paraxylines A-G were identified as the first preurianin-type with full substitution at C, D-rings, leading to the highly oxygenated seco-limonoids skeleton. The secreted alkaline phosphate assay against an engineered human and murine TLR4 of HEK-Blue cells was performed to evaluate the immune regulating effects. Among them, paraxyline B was found to be a remarkable TLR4 agonist whereas two analogs (toonapubesins A and B) were found to antagonise lipopolysaccharide stimulation of the TLR4 pathway. Paraxylines A and C-E acted either as agonists or antagonists depending on the origin of the TLR4 receptor (human or mouse). The effect of these selected compounds on the expression of pro-inflammatory cytokines TNF-α, IL-1α, IL-1β, and IL-6 of the NF-κB signaling pathway were examined in macrophage cell lines, revealing dose-dependent effects. Additionally, paraxylines A, C, D, and G also presented modest cytotoxic activity against MCF-7 and HeLa cell lines with IC50 values ranging from 23.1 to 43.5 μM.

Dysoticans F–H: three unprecedented dimeric cadinanes from Dysoxylum parasiticum (Osbeck) Kosterm. stem bark†

An asymmetrical true-dimeric cadinane via ketonic bridge [C-15/C-3′], dysotican F (1), two symmetrical pseudo-cadinane dimers through an O-ether linkage [C-3/C-3′], dysoticans G (2) and H (3), as well as three known sesquiterpenoids 4–6 were obtained from the stem bark of Dysoxylum parasiticum (Osbeck) Kosterm. (Meliaceae). Their structures were determined by spectroscopic and quantum chemical calculations of ¹³C NMR shifts using a GIAO method and electronic circular dichroism (ECD) using a TDDFT method. A possible biogenetic pathway for 1–3 beginning from the known compounds (i–ii) was proposed. Cytotoxic evaluation showed that 2 as a new lead compound is the most potent against the MCF-7 and HeLa cell lines with IC₅₀ values of 12.07 ± 0.17 μM and 9.29 ± 0.33 μM, while 1 has moderate inhibition with IC₅₀ values of 31.59 ± 0.34 μM and 27.93 ± 0.25 μM. Furthermore, 3 is a selective inhibitor against the HeLa cell growth with an IC₅₀ value of 39.72 ± 0.18 μM. A brief structure–activity relationship analysis of all isolated compounds 1–6 was also provided, including comparison with the coexisting molecules in the previous report.

Dysoxylum parasiticum's stem bark produces an asymmetrical and two symmetrical dimers (1–3), dysoticans F–H, with a novel cadinene dimer skeleton.

Sesquiterpenoids and sesquiterpenoid dimers from the stem bark of Dysoxylum parasiticum (osbeck) kosterm

Two undescribed sesquiterpenoids, namely dysoticans A and B, and three undescribed sesquiterpenoid dimers, namely dysoticans C-E, together with six analogs, were isolated from the stem bark of Dysoxylum parasiticum (Osbeck) Kosterm. (Meliaceae), growing in West Java, Indonesia. Their structures were elucidated based on extensive spectroscopic analysis and theoretical simulations of ECD spectra and ¹³C NMR shifts. Dysoticans A and B possessed undescribed cadinanes with minor modifications, while C and D featured unprecedented pseudo-sesquiterpenoid dimers through O-ether linkages of cadinanes and guaianes, respectively. Dysotican E was also characterized as the true-sesquiterpenoid dimer featuring eudesmane-germacrene hybrid framework from the Meliaceae family. Furthermore, A-C and E showed moderate activities against the human breast cancer MCF-7 and cervical cancer HeLa cell lines with IC₅₀ values ranging from 22.15 to 45.14 μM. D selectively exhibited significant cytotoxicity against the HeLa cell line with an IC₅₀ value of 13.00 ± 0.13 μM.