Cassane diterpenoid derivative induces apoptosis in IDH1 mutant glioma cells through the inhibition of glutaminase in vitro and in vivo

Synthesis of Tricyclic Pterolobirin H Analogue: Evaluation of Anticancer and Anti-Inflammatory Activities and Molecular Docking Investigations

Pterolobirin H (3), a cassane diterpene isolated from the roots of Pterolobium macropterum, exhibits important anti-inflammatory and anticancer properties. However, its relatively complex tetracyclic structure makes it difficult to obtain by chemical synthesis, thus limiting the studies of its biological activities. Therefore, we present here a short route to obtain a rational simplification of pterolobirin H (3) and some intermediates. The anti-inflammatory activity of these compounds was assayed in LPS-stimulated RAW 264.7 macrophages. All compounds showed potent inhibition of NO production, with percentages between 54 to 100% at sub-cytotoxic concentrations. The highest anti-inflammatory effect was shown for compounds 15 and 16. The simplified analog 16 revealed potential NO inhibition properties, being 2.34 higher than that of natural cassane pterolobirin H (3). On the other hand, hydroxyphenol 15 was also demonstrated to be the strongest NO inhibitor in RAW 264.7 macrophages (IC50 NO = 0.62 ± 0.21 μg/mL), with an IC50NO value 28.3 times lower than that of pterolobirin H (3). Moreover, the anticancer potential of these compounds was evaluated in three cancer cell lines: HT29 colon cancer cells, Hep-G2 hepatoma cells, and B16-F10 murine melanoma cells. Intermediate 15 was the most active against all the selected tumor cell lines. Compound 15 revealed the highest cytotoxic effect with the lowest IC50 value (IC50 = 2.45 ± 0.29 μg/mL in HT29 cells) and displayed an important apoptotic effect through an extrinsic pathway, as evidenced in the flow cytometry analysis. Furthermore, the Hoechst staining assay showed that analog 15 triggered morphological changes, including nuclear fragmentation and chromatin condensation, in treated HT29 cells. Finally, the in silico studies demonstrated that cassane analogs exhibit promising binding affinities and docking performance with iNOS and caspase 8, which confirms the obtained experimental results.

Cucurbitane triterpenoid entities derived from Hemsleya penxianensis triggered glioma cell apoptosis via ER stress and MAPK signalling cross-talk

In the present study, six new cucurbitane type compounds, including three triterpenoids hemsleyacins P-R (6-7, 13) and three cucurbitane-type triterpenoid glycosides hemsleyaosides L-N (15-17), along with seventeen known cucurbitacin analogues were separated from the root tuber of Hemsleya penxianensis and elucidated based on NMR and HRESIMS. Then, 23 analogues of three types, namely, polyhydroxy-type (I) (1-7), monohydroxy-type (II) (8-13), and glycosides-type (III) (14-23), were assessed for their antitumor activity and structure-activity relationship analysis (SAR). We determined temozolomide (TMZ)-resistant GBM cell was the most sensitive to the tested compounds, and found hemsleyaoside N (HDN) displayed the best antineoplastic potency. Furthermore, we confirmed the anti-glioma activity of HDN in patient-derived recurrent GBM strains, GBM organoid (GBO) and orthotopic nude mouse models. Investigations exploring the mechanism made clear that HDN induced synchronous activation of UPR and MAPK signaling, which triggered deadly ER stress and apoptosis. Taken together, the potent antitumor activity of HDN warrants further comprehensive evaluation as a novel anti-glioma agent.

Cassane diterpenoids from the aerial parts of Caesalpinia pulcherrima and their antibacterial and anti-glioblastoma activity

Sixteen cassane diterpenoids (CAs), including four undescribed lactam-type, four unreported lactone-type, along with eight known ones, were isolated from the aerial parts of Caesalpinia pulcherrima (L.) Sw. Their structures were characterized by comprehensive spectroscopic analyses (including NMR and HRESIMS). The absolute configuration of pulcherritam A was finally established by single-crystal X-ray diffraction with Cu Kα radiation. Notably, pulcherritam s A-D were elucidated as a group of rare CAs bearing an α, β-unsaturated γ-lactam ring rather than a typical lactone moiety. Almost all compounds were examined for their antibacterial. The results reveal that pulcherritam H exhibited significant antibacterial activities against Bacillus cereus, Staphylococcus aureus, as well as Pseudomonas syringae pv. actinidae (Psa) with the MIC from 6.25 to 12.5 μM, while pulcherritams A and C displayed potent antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA). Then, all isolates were evaluated for their anti-glioblastoma activities. Pulcherritam A and Pulcherrimin G illustrated moderate inhibitory activity against glioblastoma multiforme (GBM) U87MG cell, and the other compounds did not show obvious inhibitory activity against GBM U87MG cell. Furthermore, the preliminary structure-activity relationship and their biosynthetic pathway were also discussed.

Clavipyrrine A, a unique polycyclic nitrogenous meroterpenoid with promising anti-glioma effects isolated from the fungus Clitocybe clavipes

Clavipyrrine A (1), a novel polycyclic nitrogenous meroterpenoid with a pyrrolo[1,2-a]imidazole and a 10-membered carbocycle fused with an α,β-epoxy-γ-lactone, was isolated from Clitocybe clavipes, a basidiomycete. X-ray crystallography and spectroscopic analysis were used to fully elucidate its structure. The biosynthetic origin of the pyrrole unit in this nitrogenous meroterpenoid was identified by incorporating ¹⁵N-labeled γ-aminobutyric acid. Compound 1 displayed promising anti-glioma activities and induced glioma cell apoptosis through inhibiting the JAK/STAT3 pathway and reinforcing SOCS1/3.

Antiviral bioactivity of resveratrol against Zika virus infection in human retinal pigment epithelial cells

Resveratrol (RES) is a polyphenol with increasing interest for its inhibitory effects on a wide variety of viruses. Zika virus (ZIKV) is an arbovirus which causes a broad spectrum of ophthalmological manifestations in humans. Currently there is no certified therapy or vaccine to treat it, thus it has become a major global health threat. Retinal pigment epithelium (RPE) is highly permissive and susceptible to ZIKV. This work explored the protective effects of RES on ZIKV-infected human RPE cells. RES treatment resulted in a significant reduction of infectious viral particles in infected male ARPE-19 and female hTERT-RPE1 cells. This protection was positively influenced by the action of RES on mitochondrial dynamics. Also, docking studies predicted that RES has a high affinity for two enzymes of the rate-limiting steps of pyrimidine and purine biosynthesis and viral polymerase. This evidence suggests that RES might be a potential antiviral agent to treat ZIKV-induced ocular abnormalities.