Two new abietane diterpenes huperphlegmarins A and B from Huperzia phlegmaria

Phlecarinatones H-N: Abietane-type diterpenoids from Phlegmariurus carinatus with proliferative inhibitory effect on U251 glioblastoma cells

Thirteen abietane-type diterpenoids, including seven previously undescribed compounds and six known analogs, were isolated from the root and aerial parts of Phlegmariurus carinatus. Their structures were elucidated by comprehensive spectroscopic data analysis (UV, IR, NMR, and HRESIMS) and quantum chemical calculations (calculated ECD or 13C NMR). Notably, these compounds exhibited high structural diversity. Compounds 1-8 possessed six distinct fused ring systems. Phlecarinatones I (2) and J (3) were identified as rare 6,7-seco-abietane diterpenoids featuring a five-membered lactone ring B. Compounds (1-12) were evaluated for their anti-proliferative activities in the U251 cell line. In particular, phlecarinatone I (2) exhibited potential inhibitory effects on U251 cell proliferation, with an IC50 value of 13.88 ± 1.82 μM. To elucidate the underlying molecular mechanism, p53 signal pathway was enriched from our RNA-seq data. Further investigations using western blot and immunofluorescence assays confirmed that p53 expression was up-regulated in a concentration-independent manner. Additionally, molecular docking studies suggested 2 likely binds to the MDM2-p53 binding region. Finally, an shRNA-mediated MDM2 knockdown experiment provided definitive evidence that 2 acts as a potent inhibitor of glioma proliferation, operating via the modulation of the MDM2-p53 pathway. These findings suggest that 2 might be a valuable of lead compound with anti-proliferative activity.

Abietane diterpenoids from Phlegmariurus carinatus and their cytotoxic activities

Two new abietane diterpenoids (1 and 2) and two known analogs (3 and 4) were isolated from the whole plants of Phlegmariurus carinatus. Their structures were determined by comprehensive spectroscopic methods (UV, IR, NMR, and HRESIMS). Moreover, all compounds were evaluated for their cytotoxic activities against U251 glioblastoma cells. Notably, compounds 1-4 exhibited potential cytotoxic activities with IC50 values ranging from 19.81 to 81.49 μM. In addition, their stabilities were checked by HPLC in the preservation conditions and in the cell lines medium. The result showed that they were relatively stable in the preservation conditions, except for 3, but that they were decomposed in the incubation process. Finally, the most possible structures of impurities i1, i3 and i4 were deduced by spectroscopic methods (UV, HRESIMS and MS/MS). This work provides potential insights for the development of abietane diterpenoids as candidate drugs for the treatment of glioma.

Lycopodiaceae herb from Vietnam as a promising medicinal source of natural hupezine and novel huperzine-producing endophytic fungi

OBJECTIVES

(1) To evaluate the potential of producing huperzine (Hup) and anticholinesterase (AChE) activities of nine native Lycopodiaceae species collected in Vietnam; (2) Isolation, identification and characterization of a novel fungus producing both HupA and HupB isolated from Lycopodium casuarinoides Spring.

RESULTS

All methanolic extracts of nine plants showed AChE inhibition from 8.55 to 71.81%. Of note, Huperzia serrata (Thunb.) Trevis, L. casuarinoides, Lycopodium clavatum L., Phlegmariurus squarrosus (G. Forst.), and P. phlegmaria (L.) T. Sen & U. Sen were shown to biosynthesize both HupA and HupB by high-performance liquid chromatography (HPLC). Plants H. serrata, L. casuarinoides and L. clavatum showed the most potent AchE IC50 inhibition. HupA and HupB concentrations from six plants were greater than those of previously reported Lycopodiaceae species. Sixty-four endophytic fungi were isolated from tissue of natural L. casuarinoides and then screened for HupA- and HupB-production by HPLC. Out of 64 fungal strains, only TTD2-2.7 extract could produce both HupA and HupB with the yields of 0.034 and 0.028 µg gdcw-1, respectively. Moreover, TTD2-2.7 extract also had inhibitory effects on AChE with the IC50 of 129.76 ± 4.13 µg ml-1, which was lower than the extract of host plant L. casuarinoides (94.03 ± 4.13 µg ml-1). The fungus was identified as Aspergillus sp. TTD2-2.7 by morphological characteristics and Internal Transcribed Spacer sequence analysis.

CONCLUSIONS

These are the first reports of (1) two species L. clavatum and L. casuarinoides producing both HupA and HupB, and (2) L. casuarinoides as novel sources of Hup-producing endophytic fungi as well as (3) fungus Aspergillus as a novel HupA- and HupB-producing endophyte isolated from L. casuarinoides.

Photocatalytic Tandem Radical Cyclization Enables Expeditious Total Synthesis of Epoxyhinokiol Analogues for Anticancer Activity Evaluation

A photocatalytic radical cascade with an unusual endo-trig cyclization was developed, which enables the efficient assembly of divergent tricyclic diterpenoid frameworks. The first total synthesis of abietane 10-epi-epoxyhinoliol was thus achieved in six steps by a subsequent reductive coupling of i-PrBr under photoredox/nickel dual catalysis. Inhibitory tests of chiral 10-epi-epoxyhinoliol and its analogues in 4T1 cancer cells demonstrated the critical role of the C12 hydroxyl group, leading to a discovery of the simplified analogue with better activity.

A new abietane diterpenoid from Lycopodium complanatum

A new abietane diterpenoid, 1β, 11-epoxyabieta-12-hydroxy-8, 11, 13-triene-7-one (1), along with three known compounds (2-4), was isolated from Lycopodium complanatum. Their structures were confirmed by the analysis of 1D, 2D NMR and HRESIMS data, and comparison with previous spectral data. All compounds were tested for inhibitory activities against A549, HepG2 and MCF-7 tumor cell lines. [Figure: see text].

A new abietane diterpene tuurgan a from caryopteris mongholica

Five abietane diterpenes compounds were separated from petroleum ether extraction sites of ethanol extract of Caryopteris Mongholica, and Compound 1 was identified as a new abietane diterpenes compound by NMR and mass spectrometry, named as Tuurgan A of Caryopteris Mongholica; and Compounds 2-5 separated from Caryopteris Mongholica for the first time were identified as Ferruginol (2), Taxodione (3), Caryopterisoid Q (4), and Huperphlegmarin B (5). The anti-lung cancer activity of the Compounds 1-5 were determined, which results showed that they all had high A549 cytotoxicity.

Abietane diterpenoids from Orthosiphon wulfenioides with NLRP3 inflammasome inhibitory activity

Wulfenioidones A - K (1-11) were abietane diterpenoids with highly oxidized 6/6/6 aromatic tricyclic skeleton isolated from the whole plant of Orthosiphon wulfenioides, and their planar structures and absolute configurations were elucidated by spectroscopic data interpretation, electronic circular dichroism calculation as well as X-ray crystallography analysis. Bioactivity screening indicated that compounds 1-4, 6 and 8 exhibited lactate dehydrogenase (LDH) inhibition effect with IC₅₀ values ranging from 0.23 to 3.43 μM by preventing the mononuclear macrophage cell pyroptosis induced by double signal stimulation of LPS and nigericin. Western Blot analyses of Caspase-1 and IL-1β down-regulation exhibited that compound 1 could selectively inhibit NLRP3 inflammasome, and the cell morphological observation further supported that compound 1 prevented macrophage cell pyroptosis.

Abietane diterpenoids from Phlegmariurus carinatus and their biological activities

Five undescribed abietane diterpenoids, along with eight known analogs, were isolated from Phlegmariurus carinatus. Their structures were unambiguously elucidated by extensive analysis of spectroscopic data and comparison between the literature. The absolute configuration of phlecarinatone C was determined by evaluating ECD spectra. Four undescribed abietane diterpenoids and eight known analogs were tested for their neuroprotective and cytotoxic activities, separately. Teuvincenone C showed potential neuroprotective effect against Hemin-induced HT22 cell damage. Importantly, phlecarinatone C showed pronounced cytotoxic effect against U251 cells in vitro assays. The biological evaluation revealed that phlecarinatone C could inhibit proliferation, migration, and invasion in a concentration-dependent manner of U251 cells. Meanwhile, phlecarinatone C effectively reversed epithelial-to-mesenchymal transition (EMT) and promoted U251 cells apoptosis via a mitochondrial apoptotic pathway. Taken together, phlecarinatone C might be a valuable candidate for anti-metastatic agents against glioblastoma treatment.

Diterpenes from an Uzbek medicinal plant Perovskia scrophulariifolia: Their structures and anti-neuroinflammatory activity

Phytochemical investigation on the aerial parts of a Lamiaceous medicinal plant Perovskia scrophulariifolia collected in Uzbekistan resulted in the isolation of two new 20-norabietane diterpenes, along with thirteen known diterpenes including one 20-norabietane, eight abietanes, one 6,7-secoabietane, and three icetexanes. The structures of new 20-norabietane diterpenes, perovsfolins C (1) and D (2), were elucidated by spectroscopic analyses aided with calculations of ECD spectra. Perovsfolin C (1) is the first 20-norabietane diterpene possessing a 1,11-epoxy moiety, while perovsfolin D (2) is a 20-norabitetane diterpene with a 2-hydroxy-1,4-quinone moiety as C-ring. Anti-neuroinflammatory activity of the isolated diterpenes on microglial cells was evaluated.

Huperphlegmines A and B, two novel Lycopodium alkaloids with an unprecedented skeleton from Huperzia phlegmaria, and their acetylcholinesterase inhibitory activities

Two novel Lycopodium alkaloids, huperphlegmines A and B (1 and 2), were isolated from the aerial parts of Huperzia phlegmaria collected in Vietnam, together with the five known compounds lycophlegmariol A (3), phlegmariurine B (4), 5-hydroxymethyl-2-furaldehyde (5), rhemanone C (6), and loliolide (7). The chemical structures of the present compounds were elucidated by means of 1D and 2D NMR and HRESIMS spectroscopy, and by comparisons to the reported data in the literature. Compounds 1 and 2 showed moderate acetylcholinesterase inhibitory activities, with IC₅₀ values of 25.95 ± 0.67 and 29.14 ± 0.77 μg/mL, respectively.