Four new unusual pentacyclic triterpenoids (1-4) were isolated from the roots of Jasminum sambac (L.) Ait. Their structures were elucidated by 1D and 2D NMR analysis, single crystal X-ray diffraction and HRESIMS.

Recent years have witnessed a breakthrough in identification of a trimer-of-hairpins motif within viral envelopes that triggers a broad range of virus-host fusion. Identifying a domain capable of controlling virus-host fusion remains a challenge due to sequence diversity, heavy glycan shielding and multiple conformations. Here, we report that HR2, a prevalent heptad repeat sequence comprising an alpha-helical coil anchored in viral membranes, is an accessible site to triterpenes, a class of widely distributed natural products. Triterpenes and their derivatives inhibit the entry of Ebola, HIV, and influenza A viruses with distinct structure-activity relationships. Specifically, triterpenoid probes, upon activation by ultraviolet light, capture the viral envelope via crosslinking the HR2 coil. Profiling the Ebola HR2 sequence using amino acid substitution, surface plasmon resonance (SPR) and nuclear magnetic resonance (NMR) spectroscopy disclosed six constitutive residues that are accessible to triterpenoids, leading to wrapping of the hydrophobic helix by triterpenoids and blocking of the HR1-HR2 interaction, which is critical in the trimer-of-hairpins formation. This finding was also observed in the envelopes of HIV and influenza A viruses and might potentially extend to a broader variety of viruses. Our findings might translate into a shared mechanism that host utilize natural product triterpenoids to antagonize membrane fusion of respective viruses, complementing the current repertoire of antiviral agents.

Abstract: In the last decade, gypsogenin has widely grabbed the attention of medicinal chemists by virtue of its prominent anti-cancer potential. Despite its late identification, gypsogenin proved itself as a new an-ti-proliferative player battling for a front position among other classic pentacyclic triterpenes such as oleanolic acid, glycyrrhetinic acid, ursolic acid, betulinic acid, and celastrol. Herein, we present insights into the anti-cancer activity of gypsogenin and its semisynthetic derivatives and go further by introducing our perspective to judiciously guide the prospect rational design. The present article opens a new venue for better exploitation of gypsogenin chemical entity as a lead compound in cancer chemotherapy. To the best of our knowledge, this is the first review article exploring the anti-cancer activity of gypsogenin derivatives.

Pancreatic cancer (PC) is considered one of the most challenging and formidable malig-nancies to treat because it is usually diagnosed at terminal stage, thus it is characterized with a poor prognosis with 5% of patients living over 5 years. The late diagnosis leads to a lower suc-cess rate of resectability, hence chemotherapy or chemoradiotherapy are the only hopes for most PC patients. However, the available drug combinations for PC treatment did not provide satisfactory clinical outcomes. There is a pressing and urgent need to discover new chemothera-peutics which fight PC with tolerable side effects and less liability for resistance. Pentacyclic triterpenes (PTs) are privileged structures with a multitude of biological activities mitigating several ailments, particularly in neoplasm field. They are characterized by a high therapeutic window and their activity can be highly enhanced through structural modifications. Indeed, several parent PTs such as oleanolic acid, ursolic acid, lupeol, betulinic acid, and celastrol proved effective against different PC phenotypes inhibiting their proliferation, invasion, and metastasis mainly via KRAS modulation. Some PTs worked as adjuvant chemosensitizers in gemcitabine-resistant or TRAIL-resistant cells. Owing to their potential in PC treatment, we pre-sent this review article summarizing PC pathogenesis and the promising role of PTs in the man-agement of PC when used either solely or in combination with other chemotherapies such as gemcitabine and 5-Fluorouracil.

In recent times, a great interest has been motivated in plant-derived compounds known as phytochemicals. The pentacyclic oleanane-, ursane-, lupane-type triterpenes are phytochemicals that exert significant activities against diseases like cancer. Lung cancer is the leading cause of cancer-related death worldwide. Although chemotherapy is the treatment of choice for lung cancer, its effectiveness is hampered by the dose‐limiting toxic effects and chemoresistance. Herein, we investigated the structure-activity relationship of six pentacyclic triterpenes: oleanolic acid (OleA), ursolic acid (UrA), asiatic acid (AsA), betulinic acid (BeA), betulin (Betu), lupeol (Lupe), on NSCLC A549 cells. From our studies, we confirmed that all these triterpenes showed cytotoxicity in the mid µM range, where BeA showed the strongest effect. Then, we determined that most of these triterpenes induced S-phase and G2/M phase cycle arrest, reactive oxygen species, mitochondrial depolarization, and caspase 3 activation. For chemoresistance markers, we elucidated that most triterpenes downregulated STAT3 and PDL1 genes. In contrast, ursane-type UrA and AsA also induced DNA damage, reactive nitrogen species and autophagy. These results showed that even slight structural changes in these triterpenes can influence the cellular response and mechanistic pathways. This study opens promising perspectives for further research on the pharmaceutical role of phytochemical triterpenoids.