Structurally diverse abietane-type Diterpenoids from the aerial parts of Gaultheria leucocarpa var. yunnanensis

Abietane diterpenoids from Caryopteris incana (Thunb.) Miq. And their HIF-2α inhibitory activities in vitro

Eleven previously undescribed abietane-type diterpenoids, named caryopincanoids A-K (1-11), together with five known compounds, were isolated from the EtOH extract of the aerial parts of Caryopteris incana (Thunb.) Miq. Their structures were elucidated on the basis of comprehensive spectroscopic data, NMR calculations, and ECD calculations. The inhibitory activities of all compounds against HIF-2α gene expression in 786-O cells were tested by luciferase assay. Compounds 7, 9, 15, and 16 showed significant inhibitory effects with IC50 values ranging from 12.73 to 23.80 μM. The preliminary structure-activity relationship of these compounds was also discussed.

Three new phenolic glycosides and a new lignan glycoside from Gaultheria leucocarpa var. yunnanensis

Three new phenolic glycosides (1-3) and a new lignan glycoside (4), together with five known compounds (5-9) were isolated from the ethanol extract of the aerial part of Gaultheria leucocarpa var. yunnanensis (Franch.) T.Z.Hsu & R.C.Fang. Their structures were determined on the basis of spectroscopic techniques, experimental and calculated ECD spectra, acid hydrolysis, and enzymatic hydrolysis experiments. All the isolates were evaluated for their anti-inflammatory and antioxidant activities. Compounds 7 and 8 exhibited inhibitory effects against the LPS-induced production of NO with IC50 of 63.71 and 10.66 μM, respectively, compared to L-NMMA having an IC50 of 6.95 μM. Besides, compound 7 also represented significant DPPH radical scavenging activity with EC50 of 18.75 μM, comparable with vitamin C (EC50 = 15.77 μM).

Recent Updates on Phytoconstituent Alpha-Glucosidase Inhibitors: An Approach towards the Treatment of Type Two Diabetes

Diabetes is a common metabolic disorder marked by unusually high plasma glucose levels, which can lead to serious consequences such as retinopathy, diabetic neuropathy and cardiovascular disease. One of the most efficient ways to reduce postprandial hyperglycemia (PPHG) in diabetes mellitus, especially insulin-independent diabetes mellitus, is to lower the amount of glucose that is absorbed by inhibiting carbohydrate hydrolyzing enzymes in the digestive system, such as α-glucosidase and α-amylase. α-Glucosidase is a crucial enzyme that catalyzes the final stage of carbohydrate digestion. As a result, α-glucosidase inhibitors can slow D-glucose release from complex carbohydrates and delay glucose absorption, resulting in lower postprandial plasma glucose levels and control of PPHG. Many attempts have been made in recent years to uncover efficient α-glucosidase inhibitors from natural sources to build a physiologic functional diet or lead compound for diabetes treatment. Many phytoconstituent α-glucosidase inhibitors have been identified from plants, including alkaloids, flavonoids, anthocyanins, terpenoids, phenolic compounds, glycosides and others. The current review focuses on the most recent updates on different traditional/medicinal plant extracts and isolated compounds' biological activity that can help in the development of potent therapeutic medications with greater efficacy and safety for the treatment of type 2 diabetes or to avoid PPHG. For this purpose, we provide a summary of the latest scientific literature findings on plant extracts as well as plant-derived bioactive compounds as potential α-glucosidase inhibitors with hypoglycemic effects. Moreover, the review elucidates structural insights of the key drug target, α-glucosidase enzymes, and its interaction with different inhibitors.

Lignans and terpenoids from Gaultheria leucocarpa var. yunnanensis and their anti-inflammatory and antioxidant activities

Six new compounds, including three lignans (1a, 1b, and 2), two abietane-type diterpenoids (3 and 4), and a triterpenoid (5), together with 13 known compounds (6a, 6b, and 7-17) were isolated from the aerial parts of Gaultheria leucocarpa var. yunnanensis. Their structures were elucidated by analysis of spectroscopic data involving NMR, IR, UV, and HRESIMS. The absolute configurations of lignans were confirmed by experimental and calculated ECD spectra. The anti-inflammatory and antioxidant activities of the isolates were evaluated. Compounds 12, 13, and 15 showed inhibitory effects against the LPS-induced production of NO in BV-2 microglial cells with the IC₅₀ values of 30.50, 23.26, and 13.02 μM, respectively. In addition, compounds 2 and 7 performed moderate DPPH radical scavenging activities.