Bioactive Components from Ampelopsis japonica with Antioxidant, Anti-α-Glucosidase, and Antiacetylcholinesterase Activities.

The dried root of Ampelopsis japonica (Thunb.) Makino (A. japonica.) is a traditional medicine used to treat fever, pain, and wound healing. It exhibits anti-inflammatory, antitumor, antityrosinase, and antimelanogenic activities. In this paper, we used different solvent extracts from the root of A. japonica to determine their antioxidant activity. Acetone extract showed relatively strong antioxidant properties by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH), superoxide radical scavenging activity, and ferric reducing antioxidant power (FRAP) assays. In addition, these extracts also showed significant α-glucosidase and acetylcholinesterase (AChE) inhibitory activities. Acetone extract significantly inhibited α-glucosidase with an IC50 value of 8.30 ± 0.78 µg/mL, and ethanol extract remarkably inhibited AChE with an IC50 value of 37.08 ± 7.67 µg/mL. Using HPLC analysis and comparison with the chemical composition of various solvent extracts, we isolated seven active compounds and assessed their antioxidant, anti-α-glucosidase, and anti-AChE activities. Catechin (1), gallic acid (2), kaempferol (3), quercetin (4), resveratrol (6), and epicatechin (7) were the main antioxidant components in the root of A. japonica. According to the results of DPPH, ABTS, and superoxide radical scavenging assays, these isolates showed stronger antioxidant capacity than butylated hydroxytoluene (BHT). Moreover, 1, 3, 4, euscaphic acid (5), 6, and 7 also expressed stronger anti-α-glucosidase activity than the positive control acarbose, and all the isolated compounds had a good inhibitory effect on AChE. Molecular docking models and hydrophilic interactive modes for AChE assays suggest that 1 and 5 exhibit unique anti-AChE potency. This study indicates that A. japonica and its active extracts and components may be a promising source of natural antioxidants, α-glucosidase, and AChE inhibitors.

Antioxidant and Anti-α-Glucosidase Activities of Various Solvent Extracts and Major Bioactive Components from the Fruits of Crataegus pinnatifida.

Crataegus pinnatifida is used to treat various diseases, including indigestion, congestive heart failure, hypertension, atherosclerosis, and myocardial dysfunction. We evaluated antioxidant and anti-α-glucosidase activities of various solvent extracts and major bioactive components from the fruit of C. pinnatifida. Ethyl acetate extracts showed potent antioxidant activities with IC50 values of 23.26 ± 1.97 and 50.73 ± 8.03 µg/mL, respectively, in DPPH and ABTS radical scavenging assays. Acetone extract exhibited significant anti-α-glucosidase activity with IC50 values of 42.35 ± 2.48 µg/mL. HPLC analysis was used to examine and compare the content of active components in various solvent extracts. We isolated four active compounds and evaluated their antioxidant and anti-α-glucosidase properties. Among the isolated compounds, chlorogenic acid and hyperoside showed potential antioxidant activities in ABTS and superoxide radical scavenging assays. Moreover, hyperoside also displayed stronger anti-α-glucosidase activity than other isolates. The molecular docking model and the hydrophilic interactive mode of anti-α-glucosidase assay revealed that hyperoside might have a higher antagonistic effect than positive control acarbose. The present study suggests that C. pinnatifida and its active extracts and components are worth further investigation and might be expectantly developed as the candidates for the treatment or prevention of oxidative stress-related diseases and hyperglycemia.

Comparison of Various Solvent Extracts and Major Bioactive Components from Portulaca oleracea for Antioxidant, Anti-Tyrosinase, and Anti-α-Glucosidase Activities.

Portulaca oleracea is a well-known species for traditional medicine and food homology in Taiwan. In traditional medicine, P. oleracea is also used to treat gastrointestinal disorders, liver inflammation, fever, severe inflammation, and headaches. We investigated antioxidant, anti-tyrosinase, and anti-α-glucosidase activities of various solvent extracts and major bioactive components from P. oleracea. Ethanol and acetone extracts showed potent DPPH, ABTS, and hydroxyl radical scavenging activities. Chloroform and n-hexane extracts displayed significant superoxide radical scavenging activity. Furthermore, ethyl acetate and acetone extracts of P. oleracea showed potent anti-tyrosinase and anti-α-glucosidase activities. Examined and compared to the various solvent extracts for their chemical compositions using HPLC analysis, we isolated seven major compounds and analyzed their antioxidant, anti-tyrosinase, and anti-α-glucosidase activities. Seven active compounds of P. oleracea, especially quercetin, rosmarinic acid, and kaempferol, exhibited obvious antioxidant, anti-tyrosinase, and anti-α-glucosidase activities. The molecular docking model and the hydrophilic interactive mode of tyrosinase and α-glucosidase revealed that active compounds might have a higher antagonistic effect than commonly inhibitors. Our result shows that the active solvent extracts and their components of P. oleracea have the potential as natural antioxidants, tyrosinase and α-glucosidase inhibitors. Our results suggest that the active solvent extracts of P. oleracea and their components have potential as natural antioxidants, tyrosinase and α-glucosidase inhibitors.

Lepidozenolide from the liverwort Lepidozia fauriana acts as a farnesoid X receptor agonist.

Lepidozenolide is a sesquiterpenoid isolated from the liverwort Lepidozia fauriana and its possible bioactivity is unclear. The farnesoid X receptor (FXR) is a member of nuclear receptor superfamily that has been widely targeted for developing treatments for chronic liver disease and hyperglycemia. In this study, whether lepidozenolide may act as a FXR agonist was determined. Indeed, in mammalian one-hybrid and transient transfection reporter assays, lepidozenolide transactivated FXR to modulate promoter action including GAL4, CYP7A1, and PLTP promoters in a dose-dependent manner, while it exhibited slightly less agonistic activity than chenodeoxycholic acid, an endogenous FXR agonist. Through the molecular modeling docking studies lepidozenolide was shown to bind to FXR ligand binding pocket fairly well. All these results indicate that lepidozenolide acts as a FXR agonist.

Cryptochinones from Cryptocarya chinensis act as farnesoid X receptor agonists.

Cryptochinones A-D are tetrahydroflavanones isolated from the leaves of Cryptocarya chinensis, an evergreen tree whose extracts are believed to have a variety of health benefits. The origin of their possible bioactivity is unclear. The farnesoid X receptor (FXR) is a member of nuclear receptor superfamily that has been widely targeted for developing treatments for chronic liver disease and for hyperglycemia. We studied whether cryptochinones A-D, which are structurally similar to known FXR ligands, may act at this target. Indeed, in mammalian one-hybrid and transient transfection reporter assays, cryptochinones A-D transactivated FXR to modulate promoter action including GAL4, SHP, CYP7A1, and PLTP promoters in dose-dependent manner, while they exhibited similar agonistic activity as chenodeoxycholic acid (CDCA), an endogenous FXR agonist. Through molecular modeling docking studies we evaluated their ability to bind to the FXR ligand binding pocket. Our results indicate that cryptochinones A-D can behave as FXR agonists.

Triterpenes from Alisma orientalis act as androgen receptor agonists, progesterone receptor antagonists, and glucocorticoid receptor antagonists.

Alisma orientalis, a well-known traditional medicine, exerts numerous pharmacological effects including anti-diabetes, anti-hepatitis, and anti-diuretics but its bioactivity is not fully clear. Androgen receptor (AR), progesterone receptor (PR), and glucocorticoid receptor (GR) are three members of nuclear receptor superfamily that has been widely targeted for developing treatments for essential diseases including prostate cancer and breast cancer. In this study, two triterpenes, alisol M 23-acetate and alisol A 23-acetate from Alisma orientalis were determined whether they may act as androgen receptor (AR), progesterone receptor (PR), or glucocorticoid receptor (GR) modulators. Indeed, in the transient transfection reporter assays, alisol M 23-acetate and alisol A 23-acetate transactivated AR in dose-dependent manner, while they transrepressed the transactivation effects exerted by agonist-activated PR and GR. Through molecular modeling docking studies, they were shown to respectively interact with AR, PR, or GR ligand binding pocket fairly well. All these results indicate that alisol M 23-acetate and alisol A 23-acetate from Alisma orientalis might possess therapeutic effects through their modulation of AR, PR, and GR pathways.

Paeoniflorin acts as a liver X receptor agonist.

Paeoniflorin is one of the active ingredients of Paeonia lactiflora Pall., a novel traditional herbal medicine exerting pharmacological effects including antihyperlipidemic, neuroprotective, and anti-hepatofibrosis effects. Liver X receptor (LXR) acts as a ligand-activated transcription factor to exhibit antihyperlipidemic and neuroprotective effects. In this study, the activity of paeoniflorin against LXR was evaluated by the mammalian one-hybrid and transient transfection reporter assays. The results showed that paeoniflorin transactivated GAL4, rat cholesterol 7 α-hydroxylase, phospholipid transfer protein, and ATP-binding cassette A1 gene promoters in dose-dependent manner. Furthermore, the docking study demonstrated that paeoniflorin resided in the LXR ligand-binding pocket in the similar manner as GSK 3987, a novel LXR agonist. These results indicated that paeoniflorin might exert pharmacological effects through LXR pathway.

Triterpenes from Alisma orientalis act as farnesoid X receptor agonists.

Alisma orientalis is a well-known traditional medicine exerting pharmacological effects including antidiabetes, antihepatitis, and antidiuretics, but the respective molecular mechanism is not completely clear. Farnesoid X receptor (FXR) is a member of nuclear receptor superfamily and viewed as one of the essential target proteins to develop antidiabetic treatments. In this study, the triterpenes, alisol M 23-acetate and alisol A 23-acetate, were isolated from A. orientalis and further evaluated for their activity against FXR. In the mammalian one-hybrid and transient transfection reporter assays, both triterpenes transactivated FXR to modulate promoter action including GAL4, SHP, CYP7A1, and PLTP promoters in dose-dependent manner, while they exhibited similar agonistic activity as chenodeoxycholic acid (CDCA), an endogenous FXR agonist. These results highly indicated that alisol M 23-acetate and alisol A 23-acetate acted as FXR agonists so A. orientalis might exert therapeutic effect including antihyperglycemic effect through FXR pathway.

Sesquiterpene lactones from Tithonia diversifolia act as peroxisome proliferator-activated receptor agonists.

Tithonia diversifolia is a well-known traditional Chinese medicine treating diabetes, hepatitis, and hepatocarcinoma but its molecular mechanism is not fully understood. Peroxisome proliferator-activated receptors (PPARs) α and γ are members of nuclear receptor superfamily. Their agonists are prescribed as antihyperlipidemic and antihyperglycemic drugs now. In this study, sesquiterpene lactones, tirotundin and tagitinin A, were isolated from T. diversifolia and evaluated for their activity against PPARs by the transient transfection reporter assay. Tirotundin and tagitinin A transactivated PPARγ dependent promoters including PPRE (PPARγ response element), SHP, and ABCA1 gene promoters in dose-dependent manner. Furthermore, the fluorescence polarization competitive binding assay showed that tirotundin (IC(50)=27 µM) and tagitinin A (IC(50)=55 µM) enhanced PPARγ transactivation activity by directly binding to PPARγ ligand binding domain. Additionally, they stimulated the transactivation of PPARα dependent SULT2A1 gene promoter by 2.3-fold of vehicle effect at 10 µM. These results highly indicated that tirotundin and tagitinin A are the active components of T. diversifolia to exert anti-diabetic effect through PPARγ pathway. Moreover, these sesquiterpene lactones behaved as PPARα/γ dual agonists so they might be useful as the potential herbal treatment for diabetes.

Sesquiterpenoids from Atractylodes macrocephala act as farnesoid X receptor and progesterone receptor modulators.

Two sesquiterpenoids, atractylenolide II and III, were isolated and identified from Atractylodes macrocephala (Asteraceae) to be subsequently evaluated for their activity against farnesoid X receptor (FXR) and progesterone receptor (PR) by transient transfection reporter assays. These sesquiterpenoids did not exert significant agonistic effect but antagonized the activity of chenodeoxycholic acid (CDCA), an endogenous FXR agonist, for FXR driven SHP promoter transactivation. Additionally, they transactivated CYP7A1 gene promoter activity by antagonizing FXR. Apart from acting as a FXR antagonist, atractylenolide III also showed agonistic activity against PR. All these results demonstrated that atractylenolide II and III are the active components of Atractylodes macrocephala to exert specific pharmacologic effects.

Identification of a series of tetrahydroisoquinoline derivatives as potential therapeutic agents for breast cancer.

A series of tetrahydroisoquinoline-N-phenylamide derivatives were designed, synthesized, and tested for their relative binding affinities, and antagonistic activities against estrogen receptor (ER). Compound 1f (relative binding affinity, RBA=5) showed higher binding affinity than tamoxifen (RBA=1), a potent ER antagonist and currently being used for breast cancer therapy. Compound 1f also exerted optimal antagonistic activity against ER in reporter and cell proliferation assays. Interestingly, compound 1j, which only has a minor agonistic effect against ER, acted as a progesterone receptor (PR) antagonist and exerted agonistic activity against AP-1 through ER pathway. Our results show that these new compounds can be employed as leading pharmacophore for further development of potent selective ER and/or PR modulators or antagonists.

Identification of a lead pharmacophore for the development of potent nuclear receptor modulators as anticancer and X syndrome disease therapeutic agents.

A series of tetrahydroisoquinoline-N-phenylamide derivatives were designed, synthesized, and tested for their relative binding affinity and antagonistic activity against androgen receptor (AR). Compound 1b (relative binding affinity, RBA = 6.4) and 1h (RBA = 12.6) showed higher binding affinity than flutamide (RBA = 1), a potent AR antagonist. These two compounds also exerted optimal antagonistic activity against AR in reporter assays. The derivatives were also tested for their activities against another nuclear receptor, farnesoid x receptor (FXR), with most compounds acting as weak antagonists, however, compound 1h behaved as a FXR agonist with activity slightly less than that of chenodeoxycholic acid (CDCA), a natural FXR agonist.

Structures of R- and T-state hemoglobin Bassett: elucidating the structural basis for the low oxygen affinity of a mutant hemoglobin.

The crystal structures of R- and T-state hemoglobin (Hb) Bassett have been determined to 2.15 and 1.80 A resolution, respectively. Physiologically, Hb Bassett (alphaAsp94-->Ala) is characterized by a low affinity for oxygen, a reduced Bohr effect and low cooperativity, as well as being slightly unstable (compared with normal adult hemoglobin; HbA). Comparisons between the Hb Bassett structures and previously determined R- and T-state HbA structures revealed that this mutant shares similar tertiary and quaternary structures with other Hbs. However, this analysis did identify localized structural differences between R-state Hb Bassett and R-state HbA at the alpha1beta2 (alpha2beta1) dimer interface and at the beta-cleft. Specifically, the beta-FG corner has shifted closer to the alpha-C helix in the mutant R structure. In addition, four intersubunit hydrogen bonds found at the alpha1beta2 interfaces of native R-state Hb structures are abolished or weakened and subsequently replaced by two new intersubunit hydrogen bonds in R-state Hb Bassett. Remarkably, the newly formed hydrogen bonds in the R-state mutant structure are also observed in T-state Hb structures. At the beta-cleft, betaHis46, which is known to contribute to the Bohr effect in Hb, makes a unique hydrogen-bonding interaction with betaAsn139 in the R-state Hb Bassett. Unlike the R-state mutant, the T-state Hb Bassett structure does not display any significant structural changes at both the alpha1beta2 (alpha2beta1) dimer interface and the beta-cleft. Quite significantly, the mutation has led to removal of an interdimer repulsion involving alpha1Asp94 and beta2Asp99. The R- and T-state structures of Hb Bassett suggest a stereochemical basis for the observed functional properties of this mutant.