Tinopanoids K-T, clerodane diterpenoids with anti-inflammatory activity from Tinospora crispa

Acylated Iridoid glycosides with neuroprotective and α-glucosidase inhibitory activities from Buddleja lindleyana fort

Fifteen iridoid glycosides were isolated from Buddleja lindeyana, including 8 previously undescribed aucubin derivatives (buddlejaridoids A-H: 1-8), and 7 known ones (9-15). Structurally, compounds 2-7 are acylated by acetyloxy and cinnamic acid derivatives, compounds 7 and 13, 9 and 10, 11 and 12 are three pairs of trans and cis cinnamoyl aucubinglycoside esters. Compounds 1-3 and 14 were proven to have excellent antioxidant activity by ABTS, FRAP and DPPH free radical scavenging assays, compounds 3, 14 and 15 exhibited potent inhibitory activity against MAO-B with IC50 value of 12.73 ± 0.30, 16.02 ± 0.37 and 22.99 ± 0.25 μM, respectively, and the binding between MAO-B and the compounds were analyzed by molecular docking study. On a H2O2 induced PC12 oxidative damage model, compounds 1-3, 8, 14 and 15 showed great neuroprotective activity. The neuroprotective effects of the active compound 3 was further confirmed by detecting its efficacy on ROS scavenging, anti-apoptosis and anti-necrosis using appropriate fluorescent probe. Additionally, compounds 10, 14 and 15 exhibited potent α-glucosidase inhibitory activity.

Cyclic Osmate Esters from 1,2- and 1,3-Diols and α-Hydroxy Acids for X-ray Analysis

We previously demonstrated that osmium tetroxide and TMEDA generate stable crystalline adducts with alkenes that facilitate X-ray analysis and structure assignments. Alternatively, osmate esters can be prepared from diols, potassium osmate, and TMEDA·2TsOH in a nonoxidative condensation reaction. This new approach provides a convenient route to form stable, crystalline osmate(VI) esters for X-ray analysis. Because it is redox neutral, it works with a variety of diol substrates, including 1,3-diols, that cannot be prepared from alkenes. α-Hydroxy acids also form stable osmate esters in reasonable yields and readily crystallize. An alternative ligand screen was performed to assess the improved crystallinity from substituted TMEDA analogues. The enhanced crystallinity of osmate esters and the incorporation of a heavy atom make a reliable determination of structure and absolute configuration routine.

Three Undescribed Furanoditerpenoids from the Tinospora crispa that Inhibit NO Production

Phytochemical study on the methanol extract of the stems of Tinospora crispa (L.) Hook.f. & Thomson led to the isolation of thirteen compounds including three undescribed cis-clerodane-type furanoditerpenoids (1-3) and ten known ones (4-13). Their chemical structures were determined by IR, HR-ESI-MS, 1D-, and 2D-NMR spectra. Compounds 2-4, 6 and 8 inhibited moderately NO production in LPS activated RAW 264.7 cells with the IC50 values of 83.5, 57.6, 75.3, 78.1, and 74.7 μM, respectively.

Talaroterpenoids A-F: Six New Seco-Terpenoids from the Marine-Derived Fungus Talaromyces aurantiacus

Six new highly oxidized seco-terpenoids, including three 3-nor-labdane type diterpenes, talaroterpenoids A-C (1-3), and three meroterpenoids containing an orthoester group, talaroterpenoids D-F (6-8), together with five known compounds (4-5 and 9-11), were isolated from the marine-derived fungus Talaromyces aurantiacus. Their chemical structures were elucidated through 1D, 2D NMR, HRESIMS, J-based configuration analysis (JBCA), computational ECD calculations, and single-crystal X-ray diffraction analysis. Compounds 1 and 2 contain an unusual 6,20-γ-lactone-bridged scaffold. Compounds 10 and 11 presented inhibitory effects on NO release in lipopolysaccharide (LPS)-induced BV-2 cells with IC50 values of 11.47 and 11.32 μM, respectively. Talaroterpenoid C (3) showed moderate antifungal activity against A. alternata and P. theae Steyaert.

Meliasanines A-L, tirucallane-type triterpenoids from Melia toosendan with anti-inflammatory properties via NF-κB signaling pathway

Meliasanines A-L, twelve previously unreported tirucallane-type triterpenoids, together with fifteen known ones, have been isolated from the stem bark of Melia toosendan. Their structures and absolute configurations were determined based on HRESIMS, and NMR, combined with calculated ECD and single-crystal X-ray diffraction analyses. Subsequently, all compounds except 10 were evaluated for their inhibitory effect on the production of nitric oxide induced by lipopolysaccharide in RAW264.7 macrophage cells. The results indicated that seven compounds (1, 13, 14, 16, 20, 22, and 23) exhibited significant NO inhibitory effects, with IC50 values ranging from 1.35 to 5.93 μM, which were more effective than the positive control indomethacin (IC50 = 13.18 μM). Moreover, the corresponding results of Western blot analysis revealed that meliasanine A (1) can significantly suppress the protein expression of inducible nitric oxide synthase and cyclooxygenase 2 in a concentration-dependent manner. The mechanism study suggested that meliasanine A exerts an anti-inflammatory effect via the nuclear factor-κB signaling pathway by suppressing phosphorylation of P65 and IκBα.

Characteristic terpenylated coumarins from Ferula ferulaeoides as potential inhibitors on overactivation of microglia

A total of 37 characteristic terpenylated coumarins (1-25), including 17 undescribed compounds (1-5, 6a/6b, 7-10, 11a/11b-13a/13b), have been isolated from the root of Ferula ferulaeoides. Meanwhile, twelve pairs of enantiomers (6a/6b, 11a/11b-15a/15b, 17a/17b, 18a/18b, 20a/20b-22a/22b, and 25a/25b) were chirally purified. The structures of these new compounds were elucidated using HRESIMS, UV, NMR, and calculated 13C NMR with a custom DP4 + analysis. The absolute configurations of all the compounds were determined for the first time using electronic circular dichroism (ECD). Then, their inhibitory effects on nitric oxide (NO) production were evaluated with LPS-induced BV-2 microglia. Compared with the positive control minocycline (IC50 = 59.3 μM), ferulaferone B (2) exhibited stronger inhibitory potency with an IC50 value of 12.4 μM. The immunofluorescence investigation indicated that ferulaferone B (2) could inhibit Iba-1 expression in LPS-stimulated BV-2 microglia.

Talaroacids A-D and Talaromarane A, Diterpenoids with Anti-Inflammatory Activities from Mangrove Endophytic Fungus Talaromyces sp. JNQQJ-4

Five new diterpenes including four diterpenes with 1,2,3,4,4a,5,6,8a-octalin skeleton talaroacids A-D (1-4) and an isopimarane diterpenoid talaromarane A (5) were isolated from the mangrove endophytic fungus Talaromyces sp. JNQQJ-4. Their structures and absolute configurations were determined by analysis of high-resolution electrospray ionization mass spectroscopy (HRESIMS), 1D/2D Nuclear Magnetic Resonance (NMR) spectra, single-crystal X-ray diffraction, quantum chemical calculation, and electronic circular dichroism (ECD). Talaromarane A (5) contains a rare 2-oxabicyclo [3.2.1] octan moiety in isopimarane diterpenoids. In bioassays, compounds 1, 2, 4, and 5 displayed significant anti-inflammatory activities with the IC50 value from 4.59 to 21.60 μM.

Discovery of potential components characteristic by conjugated enone from the branches and leaves of Croton lauioides with anti-neuroinflammatory activity via regulating the NF-κB pathway

In this study, the chemical composition and pharmacological activity of Croton lauioides were investigated for the first time. The bioactive and HPLC-UV guided isolation led to the discovery of twenty-three conjugated enone-type components (1-23), including nine previously unknown sesquiterpenoid derivatives (1-4, 9-10, 12-14). Notably, compounds 1 and 12 are epoxides containing an endoperoxide bridge (1) or a unique dioxaspiro core (12), respectively. Compounds 2-7 are non-benzenoid aromatics featuring a tropone function, while 9-11 possess a rare rearranged scaffold with tropone shift into benzene. Extensive characterization was performed using NMR spectra, HRESIMS data, and electronic circular dichroism (ECD) calculations. Furthermore, we evaluated the bioactivities of all isolated compounds against neuroinflammation in LPS-stimulated BV-2 microglial cells. Remarkably, most sesquiterpenoid derivatives exhibited significant NO inhibit activities, and compound 5 showed the most potent effect with an IC50 value of 0.14 ± 0.04 μM. Structure-activity relationship (SAR) analysis revealed that sesquiterpenoids modified with endocyclic enone conjugation may serve as a key pharmacophore for NO inhibition, particularly involving aromatic tropone moiety. The qPCR and Western blot results demonstrated that 5 exerted an inhibitory effect on the mRNA levels of iNOS, TNF-α and COX-2 in a time-dependent manner, as well as suppressed the protein expression of iNOS, TNF-α, COX-2. In mechanism, 5 could prevented activation of NF-κB pathway by suppressing phosphorylation of p65 and IκB-α. These findings revealed C. lauioides might be a promising resource for drug candidate development targeting neuroinflammation.

Structural Revision of Tinotufolins from Tinospora crispa Leaves Guided by Empirical Rules and DFT Calculations

Clerodane diterpenes are a class of secondary metabolites that can be classified into four types according to the configuration of the H3-19/H-10-H3-17/H3-20 fragment, i.e., trans-cis (TC), trans-trans (TT), cis-cis (CC), and cis-trans (CT). Tinotufolins A-C and E (1a-3a and 5a), isolated from the leaves of Tinospora crispa, were previously elucidated as CT-type clerodanes; however, our established 13C NMR-based empirical rules and density functional theory calculations suggested that these clerodanes belong to the CC type. Therefore, tinotufolins A-F (1-6) were reisolated from the leaves of T. crispa, along with an undescribed compound 7 and known compounds 8-11, and their structures were established by extensive spectroscopic analyses. The structures of tinotufolins A-C and E were revised to CC-type 1-3 and 5, and undescribed compound 7 was established as a CC-type clerodane. The present study demonstrates that empirical rules and calculations can efficiently identify and revise erroneous structures in clerodane diterpenes.

Clerodane diterpenoids with in-vitro anti-neuroinflammatory activity from the tuberous root of Tinospora sagittata (Menispermaceae)

Twenty-six clerodane diterpenoids have been isolated from T. sagittata, a plant species of traditional Chinese medicine Radix Tinosporae, also named as "Jin Guo Lan". Among them, there are eight previously undescribed clerodane diterpenoids (tinotanoids A-H: 1-8), and 18 known diterpenoids (9-26). The absolute configurations of compounds 1, 2, 5, 8, 13, 17 and 20 were determined by single-crystal X-ray diffraction. Compound 1 is the first example of rotameric clerodane diterpenoid with a γ-lactone ring which is constructed between C-11 and C-17; meanwhile, compounds 3 and 4 are two pairs of inseparable epimers. Compounds 2, 12 and 17 demonstrated excellent inhibitory activity on NO production against LPS-stimulated BV-2 cells with IC50 values of 9.56 ± 0.69, 9.11 ± 0.53 and 11.12 ± 0.70 μM, respectively. These activities were significantly higher than that of the positive control minocycline (IC50 = 23.57 ± 0.92 μM). Moreover, compounds 2, 12 and 17 dramatically reduced the LPS-induced upregulation of iNOS and COX-2 expression. Compounds 2 and 12 significantly inhibited the levels of pro-inflammatory cytokines TNF-α, IL-1β and IL-6 that were increased by LPS stimulation.