Terminalin from African Mango (Irvingia gabonensis) Stimulates Glucose Uptake through Inhibition of Protein Tyrosine Phosphatases.

Protein tyrosine phosphatases (PTPs), along with protein tyrosine kinases, control signaling pathways involved in cell growth, metabolism, differentiation, proliferation, and survival. Several PTPs, such as PTPN1, PTPN2, PTPN9, PTPN11, PTPRS, and DUSP9, disrupt insulin signaling and trigger type 2 diabetes, indicating that PTPs are promising drug targets for the treatment or prevention of type 2 diabetes. As part of an ongoing study on the discovery of pharmacologically active bioactive natural products, we conducted a phytochemical investigation of African mango (Irvingia gabonensis) using liquid chromatography-mass spectrometry (LC/MS)-based analysis, which led to the isolation of terminalin as a major component from the extract of the seeds of I. gabonensis. The structure of terminalin was characterized by spectroscopic methods, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high-resolution (HR) electrospray ionization (ESI) mass spectroscopy. Moreover, terminalin was evaluated for its antidiabetic property; terminalin inhibited the catalytic activity of PTPN1, PTPN9, PTPN11, and PTPRS in vitro and led to a significant increase in glucose uptake in differentiated C2C12 muscle cells, indicating that terminalin exhibits antidiabetic effect through the PTP inhibitory mechanism. These findings suggest that terminalin derived from African mango could be used as a functional food ingredient or pharmaceutical supplement for the prevention of type 2 diabetes.

Bioactivity-based analysis and chemical characterization of cytotoxic compounds from a poisonous mushroom, Amanita spissacea, in human lung cancer cells in vitro.

As part of our systematic study on Korean toxic mushrooms, bioactivity-guided fractionation of the MeOH extract of Amanita spissacea (Amanitaceae) fruiting bodies and chemical investigation of its cytotoxic fractions led to the isolation of (9E)-8-oxo-9-octadecenoic acid (1), (10E)-9-oxo-10-octadecenoic acid (2), (9E)-8-oxo-9-octadecenoate methyl ester (3), (9Z)-9-octadecenoate-(2'S)-2',3'-dihydroxypropyl ester (4), (9Z)-9-octadecenoic acid (5), and palmitic acid (6). The structures of the isolates were elucidated by NMR spectroscopic analysis and LC/MS analysis. Among the isolated compounds, compounds 1 and 2 exhibited the most potent cytotoxic activity in all human lung cancer cell lines examined, with IC50 values ranging from 255.7 to 321.0 µM and 250.2 to 322.5 µM, respectively. The cytotoxicity of these compounds was also found to be mediated by apoptosis associated with caspase-3 activation. These findings provide experimental evidence suggesting the potential of A. spissacea as a promising natural source for the discovery of novel anticancer drug candidates.

Discovery of Dihydrophaseic Acid Glucosides from the Florets of Carthamus tinctorius.

Carthamus tinctorius L. (Compositae; safflower or Hong Hua) has been used in Korean traditional medicine for maintaining the homeostasis of body circulation. Phytochemical investigation was performed on the florets of C. tinctorius by liquid chromatography-mass spectrometry (LC/MS), which afforded two dihydrophaseic acid glucosides (1 and 2). Isolated compounds were structurally confirmed using a combination of spectroscopic methods including 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectroscopy. Their absolute configurations were established by quantum chemical electronic circular dichroism calculations and enzymatic hydrolysis. The anti-adipogenesis activity of the isolated compounds was evaluated using 3T3-L1 preadipocytes. Treatment with the dihydrophaseic acid glucoside (1) during adipocyte differentiation prevented the accumulation of lipid droplets and reduced the expression of adipogenic genes, Fabp4 and Adipsin. However, compound 2 did not affect adipogenesis. Our study yielded a dihydrophaseic acid glucoside derived from C. tinctorius, which has potential advantages for treating obesity.

Megastigmane Derivatives from the Cladodes of Opuntia humifusa and Their Nitric Oxide Inhibitory Activities in Macrophages.

Opuntia humifusa, known as the eastern prickly pear cactus and locally called "Cheonnyuncho" in Korea, is cultivated widely on Jeju Island, Korea. Phytochemical analysis of the methanolic extract of the cladodes of O. humifusa, for which previous research is relatively limited, was performed under the guidance of LC/MS-based analysis. As a result, one new megastigmane (1) and four new megastigmane glucosides (2-5) were isolated along with 18 known compounds (6-23). The structures of the new compounds were established by 1D and 2D NMR and HRESIMS, and their absolute configurations were established by chemical reactions, quantum chemical electronic circular dichroism calculations, and DP4+ analysis using the gauge-including atomic orbital NMR chemical shift calculations as well as the application of Snatzke's method. The isolated compounds (1-23) were tested for NO production inhibition in lipopolysaccharide (LPS)-induced RAW 264.7 cells to investigate their anti-inflammatory effects. Compounds 10 and 11 exhibited significant inhibitory effects on LPS-induced NO production in a dose-dependent manner. The potential mechanistic pathway of 10 and 11 was also investigated using Western blotting, indicating that compounds 10 and 11 inhibit NO through iNOS expression.

Withaninsams A and B: Phenylpropanoid Esters from the Roots of Indian Ginseng (Withania somnifera).

Withania somnifera (L.) Dunal (Solanaceae), known as Indian ginseng or ashwagandha, has been used in Indian Ayurveda for the treatment of a variety of disorders, such as diabetes and reproductive and nervous system disorders. It is particularly used as a general health tonic, analgesic, and sedative. As part of continuing projects to discover unique bioactive natural products from medicinal plants, phytochemical investigation of the roots of W. somnifera combined with a liquid chromatography-mass spectrometry (LC/MS)-based analysis has led to the isolation of two novel phenylpropanoid esters, Withaninsams A (1) and B (2), as an inseparable mixture, along with three known phenolic compounds (3, 4, and 6) and a pyrazole alkaloid (5). The structures of the new compounds were elucidated using a combination of spectroscopic methods, including one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HR-ESIMS). Withaninsams A (1) and B (2) are phenylpropanoid esters that contain a side chain, 4-methyl-1,4-pentanediol unit. To the best of our knowledge, the present study is the first to report on phenylpropanoid esters with 4-methyl-1,4-pentanediol unit. The anti-inflammatory activity of the isolated compounds (1-6) was evaluated by determining their inhibitory effects on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, where compound 3 inhibited LPS-induced NO production (IC50 = 33.3 µM) and TNF-α production, a pro-inflammatory cytokine (IC50 = 40.9 µM). The anti-inflammatory mechanism through the inhibition of transcriptional iNOS protein expression was confirmed by western blotting experiments for the active compound 3, which showed decreased iNOS protein expression.

(3ß,16α)-3,16-Dihydroxypregn-5-en-20-one from the Twigs of Euonymus alatus (Thunb.) Sieb. Exerts Anti-Inflammatory Effects in LPS-Stimulated RAW-264.7 Macrophages.

To discover new pharmacologically active natural products, here, we performed the phytochemical analysis of a Korean medicinal plant. Euonymus alatus (Thunb.) Sieb. is a traditional medicinal plant that has been used as a remedy for various diseases in Asian countries. In particular, the cork cambium on the twigs of E. alatus has been used to treat dysmenorrhea, tumors, diabetes, and wound. Phytochemical analysis of the methanolic extract of E. alatus twigs led to the isolation of a sterol, which was identified as (3ß,16α)-3,16-dihydroxypregn-5-en-20-one (1) by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy and high-resolution electrospray ionization mass spectrometry. The stereochemistry of 1 was established with nuclear Overhauser effect spectroscopy (NOESY) analysis and comparison of electronic circular dichroism (ECD) data. To the best of our knowledge, the isolation of compound 1 from nature is first reported here, as well as the complete and revised NMR data assignment of 1. In lipopolysaccharide (LPS)-stimulated RAW-264.7 macrophages, compound 1 significantly inhibited nitric oxide (NO) production at an IC50 value of 12.54 ± 0.05 µM as well as the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Moreover, the pre-treatment with compound 1 attenuated the LPS-induced phosphorylation of nuclear factor kappa B (NF-κB) p65 through the inhibition of the phosphorylation of IκB kinase alpha (IKKα), IKKß, and inhibitor of kappa B alpha (IκBα). Compound 1 also inhibited the LPS-induced phosphorylation of p38, c-Jun NH2-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK). Taken together, compound 1 may serve as an anti-inflammatory constituent of E. alatus twigs and its anti-inflammatory property is thought to be associated with the inhibition of NO production via suppression of iNOS and COX-2 expression through inhibition of IKKα/ß, I-κBα and NF-κB p65 activation and downregulation of p38, JNK, and ERK mitogen-activated protein kinase signal pathways in RAW 264.7 macrophages. These findings also provide experimental evidence that compound 1 identified from E. alatus twigs could be a candidate for an anti-inflammatory agent.

Chemical Composition and Antimicrobial Activity of Essential Oils from the Aerial Parts of Pinus eldarica Grown in Northwestern Iran.

Pinus eldarica (Pinaceae), an evergreen plant, is distributed across the warm and dry climates of western Asia, including Asia Minor, the Middle East, and land surrounding the Caspian Sea. Essential oils (EOs) from different aerial parts of this tree have been used in traditional medicine. We aimed to investigate the chemical profile and antimicrobial activity of the EO from P. eldarica grown in northwestern Iran. EO from the needles, bark, and pollen were extracted with boiling water using a Clevenger apparatus at yield of 0.7-1.2 cm3/100 g of dry plant material. The main chemical components of the EO from the needles were D-germacrene (18.17%), caryophyllene (15.42%), γ-terpinene (12.96%), and ß-pinene (10.62%); those from the bark were limonene (16.99%), caryophyllene oxide (13.22%), and drimenol (13.2%); and those from the pollen were α-pinene (25.64%) and limonene (19.94%). In total, 83 constituents were characterized in the EOs, using gas chromatography mass spectrometry analysis; mainly, sesquiterpene hydrocarbons in needle EO and monoterpene hydrocarbons in pollen and bark EOs. ß-Pinene, ß-myrcene, limonene, and caryophyllene were identified in the EOs from all three plant parts. The antibacterial and antifungal properties of the EOs were examined: pollen EO exhibited antibacterial activity against Escherichia coli; bark EO inhibited the growth of Candida albicans and Staphylococcus aureus; and the needle EO inhibited the growth of S. aureus. Thus, the EOs from aerial parts of P. eldarica can benefit the EO industry and antibiotic development.