C-glycosides from the stems of Calophyllum membranaceum

Recent Advances on Natural Aryl-C-glycoside Scaffolds: Structure, Bioactivities, and Synthesis-A Comprehensive Review

Aryl-C-glycosides, of both synthetic and natural origin, are of great significance in medicinal chemistry owing to their unique structures and stability towards enzymatic and chemical hydrolysis as compared to O-glycosides. They are well-known antibiotics and potent enzyme inhibitors and possess a wide range of biological activities such as anticancer, antioxidant, antiviral, hypoglycemic effects, and so on. Currently, a number of aryl-C-glycoside drugs are on sale for the treatment of diabetes and related complications. This review summarizes the findings on aryl-C-glycoside scaffolds over the past 20 years, concerning new structures (over 200 molecules), their bioactivities-including anticancer, anti-inflammatory, antioxidant, antivirus, glycation inhibitory activities and other pharmacological effects-as well as their synthesis.

Xanthones from the stems of Calophyllum membranaceum Gardn. et Champ. and their anti-inflammatory activity

Eighteen undescribed xanthones, including six pairs of xanthone enantiomers, three xanthones, and three xanthone glycosides, together with one pair of known xanthone enantiomers and 12 known xanthones, were isolated from the stems of Calophyllum membranaceum Gardn. et Champ. Their structures were elucidated by spectroscopic analysis, and the absolute configuration of the enantiomers was determined by using experimental and calculated electronic circular dichroism data. All compounds were screened for their anti-inflammatory effects on LPS-induced BV-2 microglial cells. Among them, six compounds showed remarkable activities with IC₅₀ values of 7.8-36.0 μM.

Bioassay-guided isolation of anti-tumor polyprenylphloroglucinols from Calophyllum polyanthum and primary mechanism

Five compounds were isolated from Calophyllum polyanthum leaves (10.09 g) by bioassay-guided fractionation to evaluate their anti-tumor activity. Among these compounds, apetalic acid (1) demonstrated significant inhibitory activity against 8 types of tumor cells (MHCC97H, CNE1, CNE2, B16, LOVO, SW480, A549, 1299), especially against two colon cancer cells (LOVO, SW480). Apetalic acid could inhibit cell proliferation, migration, invasion and induce apoptosis. It could significantly up-regulate the expression levels of apoptosis-related genes (BAX, Caspase-9,) and proteins (BAX, Cleaved-caspase-9, Cleaved-caspase-3) and down-regulated the expression of inhibitor of apoptosis gene (Bcl-2) and proteins (Bcl-2, phosphorylated AKT). Possible mechanism of the antitumor activity of apetalic acid derived from Calophyllum polyanthum supports its use in the prevention and treatment of colorectal cancer.

Two New Xanthones from the Twigs of Calophyllum membranaceum and Their Anti-Inflammatory Activities in HESC Cells

Two new xanthones, calmemxanthone A (1) and calmemxanthone B (2), along with eleven known compounds were isolated from the dried twigs of Calophyllum membranaceum Gardn. et Champ. The structures of compounds 1 and 2 were established by analysis of spectra and mass spectrometry data. The absolute configuration of compound 1 was confirmed by electronic circular dichroism (ECD) spectral analysis. The anti-inflammation action of these compounds were evaluated on lipopolysaccharide (LPS)-induced inflammatory damage to human endometrial stromal cells (HESCs), and the structure-activities of 1-13 were also discussed. Compound 10 presented the anti-inflammation action with an IC₅₀ value of 20.3 μM, that might be relevant to the regulation of NF-κB signaling pathway via the suppression of TRIF, IKKα, and IκBα.

Pyranochromones with Anti-Inflammatory Activities in Arthritis from Calophyllum membranaceum

Eleven new pyranochromones, calomembranone A-K (1-11), two new pyranocoumarins, calopolyanolide E and F (12 and 13), together with six known analogues (14-19) were isolated from the leaves of Calophyllum membranaceum. Their structures and absolute configurations were elucidated by analysis of spectroscopic data, computational calculations, as well as X-ray crystallography of 4 and 9. The anti-inflammatory activities of all the isolates were evaluated by measuring their NO inhibitory effects in LPS-stimulated RAW 264.7 cells. Structure-activity relationships are also discussed. Compound 7 showed the strongest NO inhibition (IC₅₀ = 0.92 μM). Oral administration of 7 dose-dependently reduced the paw swelling and downregulated neutrophil-to-lymphocyte ratio in the carrageenan-induced acute arthritis mice model. Molecular dynamics simulation and cellular thermal shift assay results indicated that 7 participated in a robust and stable interaction with the active site of TLR4. Compound 7 also suppressed the inflammation in arthritis through the regulation of TLR4 mediated signal transduction via IKK/NF-κB signaling pathway and the consequent reduction of IL-2, IL-4, and IL-5.

Flavonoid glycosides from the fruits of Embelia ribes and their anti-oxidant and α-glucosidase inhibitory activities

Three new flavonoid glycosides, embeliaflavosides A-C (1-3), together with eight known flavonoid glycosides (4-11), were isolated from the fruits of Embelia ribes. Their structures were established based on the analyses of spectroscopic data. Compounds 1-11 were evaluated for antioxidant and α-glucosidase inhibitory activities. The results revealed that compounds 1-11 owned significant ABTS radical scavenging activity with IC₅₀ values of 2.52-9.78 µM, and DPPH scavenging activity with IC₅₀ values of 7.56-26.47 µM, respectively. However, α-glucosidase inhibition assay indicated that all the isolates were inactive.[Formula: see text].

The Genus Calophyllum: Review of Ethnomedicinal Uses, Phytochemistry and Pharmacology

The species of genus Calophyllum have been reported for several ethnomedicinal uses in the traditional systems of medicine. The scientific study of the genus Calophyllum revealed that it is a rich source of bioactive secondary metabolites. These phytochemicals have shown a wide range of biological activities. Some of these have reached to the clinical developmental stage. The Calophyllum inophyllum seed oil has been proved to be an acceptable sustainable source of biodiesel. Few species of the genus are endangered and have been included in the red list of threatened species by the IUCN Red List. Owing to the importance of the genus a review of its ethnomedicinal uses, phytochemistry, and pharmacology has been carried out. It will further help to explore the molecular mechanism of phytochemicals for health benefits.