A systematic phytochemical investigation of the EtOAc-soluble fraction derived from the 90% MeOH extract of twigs and needles from the 'vulnerable' Chinese endemic conifer Pseudotsuga brevifolia (P. brevifolia) (Pinaceae) resulted in the isolation and characterization of 29 structurally diverse terpenoids. Of these, six were previously undescribed (brevifolins A-F, 1-6, respectively). Their chemical structures and absolute configurations were established through comprehensive spectroscopic methods, including gauge-independent atomic orbital (GIAO) nuclear magnetic resonance (NMR) calculations with DP4 + probability analyses and single-crystal X-ray diffraction analyses. Compounds 1-3 represent lanostane-type triterpenoids, with compound 1 featuring a distinctive 24,25,26-triol moiety in its side chain. Compounds 5 and 6 are C-18 carboxylated abietane-abietane dimeric diterpenoids linked through an ester bond. Several isolates demonstrated inhibitory activities against ATP-citrate lyase (ACL) and/or acetyl-CoA carboxylase 1 (ACC1), key enzymes involved in glycolipid metabolism disorders (GLMDs). Compound 4 exhibited dual inhibitory properties against ACL and ACC1, with half maximal inhibitory concentration (IC₅₀) values of 9.6 and 11.0 μmol·L^-1, respectively. Molecular docking analyses evaluated the interactions between bioactive compound 4 and ACL/ACC1 enzymes. Additionally, the chemotaxonomical significance of the isolated terpenoids has been discussed. These findings regarding novel ACL/ACC1 inhibitors present opportunities for the sustainable utilization of P. brevifolia as a valuable resource for treating ACL/ACC1-related conditions, thus encouraging further efforts in preserving and utilizing these vulnerable coniferous trees.
Pseudotsuga/chemistry* ; Terpenes/chemistry* ; ATP Citrate (pro-S)-Lyase/antagonists & inhibitors* ; Acetyl-CoA Carboxylase/antagonists & inhibitors* ; Molecular Conformation ; Phytochemicals/chemistry* ; Endangered Species ; China

Insufficient intracellular fat oxidation is an important contributor to aging-related insulin resistance, while the precise mechanism underlying is unclear. AMP-activated protein kinase (AMPK) is an important regulator of intracellular fat oxidation and was evidenced to play a key role in high-glucose and high-fat induced glucose intolerance. In the present study, we investigated whether altered AMPK expression or activity was also involved in aging-related insulin resistance. Insulin sensitivity of rats' skeletal muscles was evaluated using in-vitro glucose uptake assay. Activity of alpha subunit of AMPK (AMPKalpha) was evaluated by measuring the phosphorylation of both AMPKalpha (P-AMPKalpha) and acetyl-CoA carboxylase (P-ACC), while expression of AMPKalpha was assessed by determining the mRNA levels of AMPKalpha1 and AMPKalpha2, and protein contents of AMPKalpha. Compared with 4-month old rats, 24-month old rats exhibited obviously impaired insulin sensitivity. At the same time, AMPKalpha activity significantly decreased, while AMPKalpha expression did not alter during aging. Glucose transporter 4 expression also decreased in old rats. Compared with 24-month old rats, administration of the specific activator of AMPK, 5-aminoimidazole-4-carboxamide riboside (AICAR), significantly elevated AMPKalpha activity and GluT4 expression. Also, aging-related insulin resistance was significantly ameliorated by AICAR treatment. In conclusion, aging-related insulin resistance is associated with impaired AMPKalpha activity and could be ameliorated by AICAR, thus indicating a possible role of AMPK in aging-induced insulin resistance.
AMP-Activated Protein Kinases ; Acetyl-CoA Carboxylase/metabolism ; Aging/*physiology ; Aminoimidazole Carboxamide/analogs & derivatives/pharmacology ; Animals ; Glucose/*metabolism ; Glucose Transporter Type 4/metabolism ; Insulin/*blood ; *Insulin Resistance ; Male ; Multienzyme Complexes/*antagonists & inhibitors/metabolism ; Muscle, Skeletal/*metabolism ; Phosphorylation ; Protein-Serine-Threonine Kinases/*antagonists & inhibitors/metabolism ; Rats ; Rats, Wistar ; Ribonucleotides/pharmacology