Hupertimines A-E, Fawcettimine-Type Lycopodium Alkaloids from Huperzia serrata.

Five new fawcettimine-type Lycopodium alkaloids, hupertimines A-E (1-5), were discovered from the whole plant of Huperzia serrata, along with two known alkaloids, 8α-hydroxyphlegmariurine B (6) and 8ß-hydroxyphlegmariurine B (7). The structures of 1-7 were identified through HR-MS, IR, 1 H, 13 C, and 2D NMR, and single-crystal X-ray diffraction analysis. Structurally, compound 1 was the fourth example of Lycopodium alkaloid with an ether linkage between C-5 and C-13 and 2 was the third example of Lycopodium alkaloid with a 5/5/5/5/6 pentacyclic ring system and featuring a 1-aza-7-oxabicyclo[2.2.1]heptane unit. Compounds 1-7 were tested for their BACE1 inhibitory activity. In addition, the correct 1 H- and 13 C-NMR data for 7 were reported in current study.

Monoterpene Indole Alkaloids with Cav3.1 T-Type Calcium Channel Inhibitory Activity from Catharanthus roseus.

Catharanthus roseus is a well-known traditional herbal medicine for the treatment of cancer, hypertension, scald, and sore in China. Phytochemical investigation on the twigs and leaves of this species led to the isolation of two new monoterpene indole alkaloids, catharanosines A (1) and B (2), and six known analogues (3-8). Structures of 1 and 2 were established by 1H-, 13C- and 2D-NMR, and HREIMS data. The absolute configuration of 1 was confirmed by single-crystal X-ray diffraction analysis. Compound 2 represented an unprecedented aspidosperma-type alkaloid with a 2-piperidinyl moiety at C-10. Compounds 6-8 exhibited remarkable Cav3.1 low voltage-gated calcium channel (LVGCC) inhibitory activity with IC50 values of 11.83 ± 1.02, 14.3 ± 1.20, and 14.54 ± 0.99 µM, respectively.

Synthesis and biological evaluation of chepraecoxin A derivatives as α-glucosidase inhibitors.

The ent-kaurane diterpenoid chepraecoxin A (CA) obtained in our previous study showed a potential inhibitory activity on α-glucosidase (IC50 274.5 ± 12.5 µM). In order to figure out the structure-activity relationships (SARs), twenty-two derivatives of chepraecoxin A were synthesized by modifying the ester, allyl, double bond and carboxyl groups, and assayed for their α-glucosidase inhibitory activity. Of them, eight compounds (14-17, 19-22) significantly increased activity with IC50 values ranging from 16.1 to 71.4 µM, even higher than the positive control, acarbose (IC50 130.3 µM). Especially, compounds 17, 19 and 21 could inhibit α-glucosidase with IC50 values of 16.9 ± 3.4, 16.1 ± 1.2, and 17.1 ± 0.6 µM, 17-fold higher than CA. The most active compound 19 was proven to be a non-competitive inhibitor with a Ki value of 19.4 µM based on enzyme kinetics study. The primary SARs of CA derivatives were summarized for exploring antidiabetic candidates.

ent-Labdane and ent-kaurane diterpenoids from Chelonopsis odontochila with α-glucosidase inhibitory activity.

Eleven new ent-labdane diterpenoids, cheodontoins A-K (1-11), and thirteen known diterpenoids involving two ent-labdanes (12-13) and eleven ent-kauranes (14-24), were isolated from the active part of Chelonopsis odontochila (Lamiaceae) under the guidance of bioassay. The structures of cheodontoins A-K (1-11) were elucidated by extensive HRESIMS, 1D and 2D NMR, [α]D and ECD experiments, X-ray diffraction and quantum calculation. Interestingly, five nor-ent-labdanes (9-13) were obtained from this genus for the first time. One ent-labdane diterpenoid (12) and four ent-kaurane diterpenoids (16, 19, 23, and 24) showed α-glucosidase inhibitory activity with IC50 values of 326.5 ± 3.5, 599.1 ± 13.8, 620.1 ± 16.1, 185.0 ± 4.2, and 190.7 ± 11.6 µM, respectively. Compounds 12 and 16 were α-glucosidase mixed-type inhibitors with Ki values of 334.1 and 589.2 µM according to the enzyme kinetics using Lineweaver-Burk and Dixon plots. Docking study manifested that compounds 12 and 23 well located in the catalytic pocket of α-glucosidase by hydrophobic effects with Trp1355, Trp1369, Phe1427, Phe1559, and Phe1560 residues. This study provides new insights for the antidiabetic effects of C. odontochila with ent-labdane and ent-kaurane diterpenoids as the active constituents.

Polybenzyls from Gastrodia elata, their agonistic effects on melatonin receptors and structure-activity relationships.

Gastrodia elata is a famous traditional Chinese herb with medicinal and edible application. In this study, nine polybenzyls (1-9), including six new ones (2-5, 7 and 9), were isolated from the EtOAc extract of G. elata. Five compounds 1, 3, 4, 6 and 8 were found to activate melatonin receptors. Especially, compound 1 showed agonistic effects on MT1 and MT2 receptors with EC50 values of 237 and 244 µM. For better understanding their structure-activity relationships (SARs), ten polybenzyl analogs were further synthesized and assayed for their activities on melatonin receptors. Preliminary SARs study suggested that two para-hydroxy groups were the key pharmacophore for maintaining activity. Molecular docking simulations verified that compound 1 could strongly interact with MT2 receptor by bonding to Phe 118, Gly 121, His 208, Try 294 and Ala 297 residues.

PIDA/I2-Mediated α- and ß-C(sp3)-H Bond Dual Functionalization of Tertiary Amines.

The α,ß-C(sp3)-H bond dual functionalization of tertiary amines is still a challenging task for both organic and medicinal chemists. Herein a direct, mild, metal-free, and site-specific method mediated by PIDA/I2 was developed for α,ß-C(sp3)-H bond dual functionalization of tertiary amines, and this method can provide facile access to α-keto lactams or rarely studied α,α-diiodo lactams. Moreover, this method was used for the effective syntheses of three natural products [obscurumine C (13), obscurumine O (17), and strychnocarpine (18)] and direct preparation of mimics of the in vivo metabolites of two FDA-approved drugs (imatinib and donepezil) in 36-60% overall yield. The method represents a promising protocol for the late-stage α,ß-C(sp3)-H bond oxidative dual functionalization of tertiary amine-containing drugs and complex natural products.

Total Synthesis of (±)-Cermizine B.

A practical synthesis of (±)-cermizine B was achieved. The nine-step synthesis mainly comprised two uninterrupted Michael additions including a highly diastereoselective 1,4-addition of 2-picoline to methyl 4-methyl-6-oxocyclohex-1-ene-1-carboxylate, Krapcho decarboxylation, a double reductive amination that resulted in ring closure and dearomatization of pyridine in 24% overall yield.

Hypercrosslinked porous polyporphyrin by metal-free protocol: characterization, uptake performance, and heterogeneous catalysis.

Through metal-free protocol, hypercrosslinked porous polyporphyrin with permanent porosity was obatined via the Friedel-Crafts alkylation of tetracarbazolylporphyrin using formaldehyde dimethyl acetal as an external cross-linker. Its chemical structure and porosity was well characterized and confirmed. The BET specific surface area value of HCP-TCPP is 1050 m2 g-1 and related dominant pore size is centered at 0.63 nm. The adsorption amount of methanol by HCP-TCPP is high up to 800 mg g-1 (about 25.0 mmol g-1) at its saturated vapor pressure, which is higher than that of toluene (600 mg g-1, 6.5 mmol g-1). Further study indicates that polymer HCP-TCPP, possessing the high BET specific surface area and total pore volume, exhibits good hydrogen uptake of 3.44 wt % (77 K) and high carbon dioxide uptake of 41.1 wt % (298 K) at 18.0 bar. Besides, the obtained porous polymer can also be used as an effective heterogeneous catalyst for the Knoevenagel condensation between various aldehydes and malononitrile.

[Chemical Constituents of Inula japonica].

Objective: To study the chemical constituents of Inula japonica. Methods: Silica gel, Sephadex LH-20,MCI and semipreparative HPLC were used to isolate and purify the constituents of Inula japonica,and the chemical structures were elucidated by chemical properties, MS and NMR analysis. Results: 14 compounds were isolated and their structures were identified as ivangustin( 1),1-acetoxy-6α-hydroxyeriolanolide( 2), 1ß-hydroxyalantolactone( 3),tomentosin( 4),11,13-dihydroinuchinenolide B( 5), britanlin A( 6),vomifoliol( 7), 17-hydroxy-16α-ent-kauran-19-oic acid( 8), 12-hydroxygeranylgeraniol ( 9), dihydroquercetin( 10), kaempferol( 11), quercetin( 12), dihydroconiferyl alcohol( 13) and fareanol( 14). Conclusion: Compounds 5,6,9,13 and 14 are isolated from this plant for the first time.

Alisol B Alleviates Hepatocyte Lipid Accumulation and Lipotoxicity via Regulating RARα-PPARγ-CD36 Cascade and Attenuates Non-Alcoholic Steatohepatitis in Mice.

Non-alcoholic steatohepatitis (NASH) is a common chronic liver disease worldwide, with no effective therapies available. Discovering lead compounds from herb medicine might be a valuable strategy for the treatment of NASH. Here, we discovered Alisol B, a natural compound isolated from Alisma orientalis (Sam.), that attenuated hepatic steatosis, inflammation, and fibrosis in high-fat diet plus carbon tetrachloride (DIO+CCl4)-induced and choline-deficient and amino acid-defined (CDA)-diet-induced NASH mice. RNA-seq showed Alisol B significantly suppressed CD36 expression and regulated retinol metabolism in NASH mice. In mouse primary hepatocytes, Alisol B decreased palmitate-induced lipid accumulation and lipotoxicity, which were dependent on CD36 suppression. Further study revealed that Alisol B enhanced the gene expression of RARα with no direct RARα agonistic activity. The upregulation of RARα by Alisol B reduced HNF4α and PPARγ expression and further decreased CD36 expression. This effect was fully abrogated after RARα knockdown, suggesting Alisol B suppressed CD36 via regulating RARα-HNF4α-PPARγ cascade. Moreover, the hepatic gene expression of RARα was obviously decreased in murine NASH models, whereas Alisol B significantly increased RARα expression and decreased CD36 expression, along with the downregulation of HNF4α and PPARγ. Therefore, this study showed the unrecognized therapeutic effects of Alisol B against NASH with a novel mechanism by regulating RARα-PPARγ-CD36 cascade and highlighted Alisol B as a promising lead compound for the treatment of NASH.

Six New 3,5-Dimethylcoumarins from Chelonopsis praecox, Chelonopsis odontochila and Chelonopsis pseudobracteata.

Ten 3,5-dimethylcoumarins (1-6 and 8‒11) involving six new ones (1-6), together with a known 3-methylcoumarin (7), were isolated from the aerial parts of three Chelonopsis plants, C. praecox, C. odontochila, and C. pseudobracteata. The structures of the new compounds were determined by extensive HRESIMS, 1D and 2D NMR spectroscopic analyses. According to the substitution at C-5, these coumarins were classified into 5-methyl, 5-hydroxymethyl, 5-formyl, and 5-nor types. All the isolates were assayed for their inhibition on α-glucosidase, protein tyrosine phosphatase 1B, and T-cell protein tyrosine phosphatase in vitro.

Clerodane-type Diterpene Glycosides from Dicranopteris pedata.

Three new clerodane-type diterpene glycosides, (5R,6S,8R,9S,10R)-6-O-[ß-D-glucopyranosyl-(1 → 4)-α-L-rhamnopyranosyl]cleroda-3,13(16),14-diene (1), (5R,6S,8R,9S,10R,13S)-6-O-[ß-D-glucopyranosyl-(1 → 4)-α-L-rhamnopyranosyl]-2-ox-oneocleroda-3,13-dien-15-ol (2), (5R,6S,8R,9S,10R)-6-O-[ß-D-glucopyranosyl-(1 → 4)-α-L-rhamnopyranosyl]-(13E)-2-oxoneocleroda-3,14-dien-13-ol (3), together with two known compounds 4 and 5 were isolated from Dicranopteris pedata. The structures of these compounds were elucidated by detailed spectroscopic analysis, and the absolute configuration of compound 2 was determined by ECD calculations. In addition, compound 1 exhibited weak inhibitory activities against SMMC-7721, MCF-7 and SW480.

Chepraecoxins A-G, ent-Kaurane Diterpenoids with α-Glucosidase Inhibitory Activities from Chelonopsis praecox.

Our random bioassay revealed that the CHCl3 part of Chelonopsis praecox (Lamiaceae) showed significant activity against α-glucosidase with the inhibitory rate of 99.6 ± 0.4 % (330 µg/mL). Bioassay-guided isolation yielded seven new ent-kaurane diterpenoids, chepraecoxins A-G (1-7), and three known ones (8-10), driven by LC-MS analyses. The structures of chepraecoxins A-G (1-7) were elucidated by X-ray crystallographic and extensive spectroscopic analyses. Compounds 1, 6, and 10 showed obvious α-glucosidase inhibitory effects with IC50 values of 305.0, 361.0 and 174.5 µM, respectively. Enzyme kinetics study suggested that compound 1 inhibited the α-glucosidase by a noncompetitive type mechanism (Ki = 354.4 µM).

Hypophyllins A-D, Labdane-Type Diterpenoids with Vasorelaxant Activity from Hypoestes phyllostachya "Rosea".

Three rearranged labdane-type diterpenoids, hypophyllins A-C (1-3), and a caged labdane diterpenoid possessing a 8,9-dioxatricyclic[4.2.1.13,7]decane moiety, hypophyllin D (4), as well as two new biogenetically related diterpernoids, hypophyllins E (5) and F (6), were isolated from the aerial parts of Hypoestes phyllostachya "Rosea". The absolute configurations of 1-4 were determined by X-ray diffraction analysis. The plausible biogenetic pathway for 1-4 was also proposed. Compounds 4 and 5 showed potent vasorelaxant activity on endothelium-intact thoracic aorta rings precontracted with KCl.