In vitro and in vivo Biological Evaluation of Newly Tacrine-Selegiline Hybrids as Multi-Target Inhibitors of Cholinesterases and Monoamine Oxidases for Alzheimer's Disease.

Purpose: Alzheimer's disease (AD) is the most common neurodegenerative disease, and its multifactorial nature increases the difficulty of medical research. To explore an effective treatment for AD, a series of novel tacrine-selegiline hybrids with ChEs and MAOs inhibitory activities were designed and synthesized as multifunctional drugs. Methods: All designed compounds were evaluated in vitro for their inhibition of cholinesterases (AChE/BuChE) and monoamine oxidases (MAO-A/B) along with their blood-brain barrier permeability. Then, further biological activities of the optimizing compound 7d were determined, including molecular model analysis, in vitro cytotoxicity, acute toxicity studies in vivo, and pharmacokinetic and pharmacodynamic property studies in vivo. Results: Most synthesized compounds demonstrated potent inhibitory activity against ChEs/MAOs. Particularly, compound 7d exhibited good and well-balanced activity against ChEs (hAChE: IC50 = 1.57 µM, hBuChE: IC50 = 0.43 µM) and MAOs (hMAO-A: IC50 = 2.30 µM, hMAO-B: IC50 = 4.75 µM). Molecular modeling analysis demonstrated that 7d could interact simultaneously with both the catalytic active site (CAS) and peripheral anionic site (PAS) of AChE in a mixed-type manner and also exhibits binding affinity towards BuChE and MAO-B. Additionally, 7d displayed excellent permeability of the blood-brain barrier, and under the experimental conditions, it elicited low or no toxicity toward PC12 and BV-2 cells. Furthermore, 7d was not acutely toxic in mice at doses up to 2500 mg/kg and could improve the cognitive function of mice with scopolamine-induced memory impairment. Lastly, 7d possessed well pharmacokinetic characteristics. Conclusion: In light of these results, it is clear that 7d could potentially serve as a promising multi-functional drug for the treatment of AD.

Phytochemistry and pharmacology of natural prenylated flavonoids.

Prenylated flavonoids are a special kind of flavonoid derivative possessing one or more prenyl groups in the parent nucleus of the flavonoid. The presence of the prenyl side chain enriched the structural diversity of flavonoids and increased their bioactivity and bioavailability. Prenylated flavonoids show a wide range of biological activities, such as anti-cancer, anti-inflammatory, neuroprotective, anti-diabetic, anti-obesity, cardioprotective effects, and anti-osteoclastogenic activities. In recent years, many compounds with significant activity have been discovered with the continuous excavation of the medicinal value of prenylated flavonoids, and have attracted the extensive attention of pharmacologists. This review summarizes recent progress on research into natural active prenylated flavonoids to promote new discoveries of their medicinal value.

Cucurbitane-type triterpenoids from the fruits of Citrullus colocynthis.

A phytochemical investigation of the fruits of Citrullus colocynthis resulted in the isolation of 21 structurally diverse cucurbitane triterpenoids, including 9 previously undescribed ones, colocynins A-I (1-9). Their absolute configurations were elucidated by means of quantum chemical electronic circular dichroism (ECD) calculations, CD exciton chirality method, and single-crystal X-ray crystallography. Colocynins A-C (1-3) represent the first examples of nonanorcucurbitane-type triterpenoids. An anti-acetylcholinesterase activity assay showed that 6, 10, 13, 18, and 20 exhibited inhibitory activities, with IC50 values ranging from 5.0 to 21.7 µM. In addition, 18 and 21 showed significant cytotoxicity against PACA, A431, and HepG2 cells, with IC50 values ranging from 0.042 to 0.60 and 3.6-14.4 µM, respectively.

Cytotoxic phenyl polyketides from Hypericum curvisepalum N. Robson.

(±)-Hypecurvone A (1) and B (2), two new undescribed phenyl polyketides, along with seven known analogues (3-9) were isolated from the whole plant of Hypericum curvisepalum. Chiral separation of 1 and 2 yielded two pairs of enantiomers 1a/1b and 2a/2b, respectively. The structures of these compounds were elucidated by extensive spectroscopic analyses and ECD spectra simulations. All isolates exhibited moderate cytotoxicity against human hepatocellular carcinoma SMMC-7721 cells, and compound 3 also showed weak cytotoxicity toward MGC-803 cells. The cytotoxicity of these compounds was found to be related to enhanced mitochondria-mediated apoptosis and inhibition of the G2/M phase of the cell cycle.

Three New Xanthones from Hypericum scabrum and Their Quorum Sensing Inhibitory Activities against Chromobacterium violaceum.

Quorum sensing (QS) plays an important role in the production of virulence factors and pathogenicity in pathogenic bacteria and is, therefore, a hopeful target to fight against bacterial infections. During our search for natural QS inhibitors, two new xanthonolignoids (1 and 2), each existing as a racemic mixture, one new simple oxygenated xanthone (7), and eight known analogs (3-6, 8-11) were isolated from Hypericum scabrum Linn. Chiral separation of 1 yielded a pair of enantiomers 1a and 1b. The structures of these compounds were elucidated by spectroscopic analysis and ECD (electrostatic circular dichroism) calculations. All isolates were evaluated for their QS inhibitory activity against Chromobacterium violaceum. Both 9 and 10 exhibited the most potent QS inhibitory effects with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 31.25 and 62.5 µM, respectively. Crystal violet staining was used to further evaluate the biofilm inhibition potential of compounds 7, 9 and 10, and the formation of biofilms increased with decreasing drug concentration in a classic dose-dependent manner. The results of a cytotoxicity assay revealed that compounds 7, 9 and 10 exhibited no cytotoxic activity on PC-12 cells at the tested concentration.

Bioactive polycyclic polyprenylated acylphloroglucinols from Hypericum scabrum.

Eighteen polycyclic polyprenylated acylphloroglucinols were isolated from the whole plant of Hypericum scabrum Linn., including six new compounds (1-6). Their structures were elucidated by comprehensive spectroscopic analyses. The evaluation of their cytotoxic activities was carried out against SMMC-7721 and MGC-803 cell lines. We found that most tested compounds exhibited moderate cytotoxic activities against SMMC-7721 cell line except for 11 and 12, while compounds 1, 5-7, 13 and 16 also showed cytotoxic activities on MGC-803 cells. Besides, Bacillus subtilis, MRSA and MDPRA were also used to test inhibitory activity of these compounds. Our results showed that only compounds 12 and 13 presented weak inhibitory activity against Bacillus subtilis, while compounds 7, 13 and 14 also inhibited MRSA weakly.

Monoterpenoid Glycosides from the Leaves of Ligustrum robustum and Their Bioactivities.

The leaves of Ligustrum robustum have been applied as Ku-Ding-Cha, a functional tea to clear heat, remove toxins, and treat obesity and diabetes, in Southwest China. The phytochemical research on the leaves of L. robustum led to the isolation and identification of eight new monoterpenoid glycosides (1-8) and three known monoterpenoid glycosides (9-11). Compounds 1-11 were tested for the inhibitory activities on fatty acid synthase (FAS), α-glucosidase, α-amylase, and the antioxidant effects. Compound 2 showed stronger FAS inhibitory activity (IC50: 2.36 ± 0.10 µM) than the positive control orlistat (IC50: 4.46 ± 0.13 µM), while compounds 1, 2, 5 and 11 displayed more potent ABTS radical scavenging activity (IC50: 6.91 ± 0.10~9.41 ± 0.22 µM) than the positive control L-(+)-ascorbic acid (IC50: 10.06 ± 0.19 µM). This study provided a theoretical basis for the leaves of L. robustum as a functional tea to treat obesity.

Structural characterization and immunomodulatory activity of a mannan from Helvella leucopus.

A new polysaccharide fraction HLP-1 (2.55 × 105 Da) was obtained from the fruiting bodies of Helvella leucopus. Structural characterization of HLP-1 was elucidated by infrared spectroscopy, monosaccharide composition analysis, methylation analysis, nuclear magnetic resonance spectroscopy, scanning electron microscopy and Congo red assay. HLP-1 was a mannan with a backbone of →6)-α-D-Manp(1 â†’ 4)- α-D-Manp(1 â†’6)-α-D-Manp(1 â†’ 3)-α-D-Manp(1 â†’ 4)-α-D-Manp(1 â†’ 3)-α-D-Manp(1→, which branched at the O-6 position and terminated with T-ß-D-Manp. Moreover, HLP-1 could significantly improve the proliferation and neutral red phagocytosis of RAW264.7. Besides, HLP-1 could stimulate the production of nitric oxide (NO), ROS, tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1ß) and interleukin-6 (IL-6). HLP-1 induced macrophage activation via NF-κB signal pathway. These findings indicated that HLP-1 was a potential immune enhancement agent applied in functional foods.

Anti-inflammatory effect of a polysaccharide fraction from Craterellus cornucopioides in LPS-stimulated macrophages.

Immunocytes-involved inflammation is considered to modulate the damage in various diseases. Oxidative stress is initiated by oxidative agents such as LPS and ROS, which are strongly involved in chronic inflammation. Our previous study found that a polysaccharide fraction from Craterellus cornucopioides (CCPP-1) showed good antioxidant activity. However, the anti-inflammatory effect of CCPP-1 was still elusive. The objective of this study was to evaluate the anti-inflammatory activity of CCPP-1 and its potential mechanism in LPS-stimulated RAW264.7 macrophages. The results showed that CCPP-1 could inhibit LPS-induced ROS and NO accumulation. Additionally, CCPP-1 could decrease pro-inflammatory cytokines production (TNF-α, IL-1ß, and IL-18) and inflammatory mediator (iNOS) expression, which might be associated with its capacity to inhibit NF-κB signaling pathway and NLRP3 inflammasome activation. Therefore, this study suggested that CCPP-1 had an ameliorative effect on the inflammation response and was potential to develop into functional food for treating chronic inflammation. PRACTICAL APPLICATIONS: Craterellus cornucopioides is an edible fungus widely distributed in Southwestern China. It was reported that C. cornucopioides polysaccharide (CCPP-1), as important active ingredient, showed good antioxidant activity. However, the anti-inflammatory effect was still elusive. This study showed that CCPP-1 possessed anti-inflammatory activity. The molecular mechanism might be associated with its capacity to inhibit NF-κB signaling pathway and NLRP3 inflammasome activation. Therefore, polysaccharides from C. cornucopioides have potential to develop into functional food to combat inflammatory condition and thus indirectly halt the progression of various inflammatory response-related chronic diseases.

Amicoumacins from a desert bacterium: quorum sensing inhibitor against Chromobacterium violaceum.

In our study, the anti-quorum sensing (QS) activity of fermentation broth from TRM B-02, a bacterium isolated from Taklimakan desert, was investigated using the biosensor bioassay on Chromobacterium violaceum ATCC12472. TRM B-02 was 100% similar to Bacillus subtilis subsp. Inaquosorum KCTC 13429(T) by genotypic and phenotypic analyses. Based on anti-QS activity tracking, six known amicoumacins, named as AI-77-H (1), AI-77-F (2), amicoumacin B (3), amicoumacin C (4), AI-77-C (5) and bacilosarcins D (6), were isolated and identified. Among them, compounds 1-3 exhibited a better inhibitory effect on C. violaceum ATCC12472. Further research suggested that compounds 1-3 could significantly down-regulate the expressions of violacein operon A (vioA), vioB, vioD and vioE and up-regulate vioC. Docking experiments indicated that compounds 1-3 may act as an inhibitor of violacein biosynthetic pathway competitively inhibiting the binding of flavin adenine dinucleotide (FAD) with the vioD enzyme.[Figure: see text].

A new chlorine-containing iridoid glycoside from Plantago maxima.

A phytochemical investigation on the whole plant of Plantago maxima Juss. ex Jacq led to the isolation of a new and rare chlorinated iridoid glycoside named plantomoside (1), along with three known compounds, geniposidic acid (2), 10-deoxygeniposidic acid (3), and viteoid II (4). The structure of 1 was determined through 1 D and 2 D NMR spectroscopic data analysis, HR-ESI-MS, and acid hydrolysis.

Lycocasuarines I-Q, new Lycopodium alkaloids isolated from Lycopodiastrum casuarinoides.

Lycocasuarines I-Q (1-9), nine new lycodine-type Lycopodium alkaloids were isolated from the aerial parts of Lycopodiastrum casuarinoides (Spring) Holub ex R.D.Dixit. Their structures were unambiguously determined via extensive spectroscopic analyses, including HRESIMS, NMR, and electronic circular dichroism (ECD). The new alkaloids were evaluated for their in vitro inhibitory activity against acetylcholinesterase (AChE). Compounds 3, 5-8 exhibited marginal or weak activities with IC50 values ranging from 97.2 to 171.9 µM.

Lycodine-type alkaloids and their glycosides from Lycopodiastrum casuarinoides.

Thirteen previously undescribed lycodine-type Lycopodium alkaloids, namely, five alkaloids (lycocasuarines D-H) each possessing an uncommon five-membered C ring and eight Lycopodium alkaloid glycosides (casuarinosides A-H), together with a known analog, were isolated from the aerial parts of Lycopodiastrum casuarinoides (Spring) Holub ex R.D.Dixit (Lycopodiaceae). The structures of the compounds were elucidated by extensive spectroscopic analysis, single-crystal X-ray diffraction, and chemical methods. In addition, the acetylcholinesterase inhibitory activity of the isolated compounds was evaluated.

Polycyclic Polyprenylated Derivatives from Hypericum uralum: Neuroprotective Effects and Antidepressant-like Activity of Uralodin A.

The isolation of the new polycyclic polyprenylated acylphloroglucinols uraliones A-K (1-11) together with five known analogues (12-16) from a whole Hypericum uralum plant was reported. The structures of these compounds were established through spectroscopic methods, and a single-crystal X-ray diffraction analysis was used to confirm the absolute configuration of 1. The protective effects of the isolates against corticosterone-induced PC12 cell injury were assessed. Except for compound 9, all tested compounds exhibited significant protective effects against induced injury in PC12 cells. Uralodin A (14), orally administered in doses of 13 and 26 mg/kg, exhibited antidepressant-like activity in the tail suspension and forced-swimming tests in mice.

[Study on Flavonoids of Ophioglossum thermal].

Objective: To investigate the chemical components of Ophioglossum thermale,one of the original species of Chinese medicine "Yizhijian". Methods: The air-dried whole plant material of Ophioglossum thermale was extracted by thermal reflux with 95%Et OH,then separated and purified by joint utilization of various chromatography techniques including macroporous resin,silica gel,Sephadex LH-20 column chromatography and HPLC. Their structures were elucidated on the basis of spectroscopic methods. Results: Six flavonoids were isolated and identified as 3-O-methylquercetin( 1),ophioglonol( 2),3-O-methylquercetin 7-O-ß-D-glucopyranoside( 3),3-O-methylquercetin 7-O-ß-D-glucopyraosyl-4'-O-ß-D-glucopyranoside( 4),kaempferol 3-O-( 6-O-caffeoyl)-ß-D-glucopyranosyl-( 1 →2)-α-L-rhamnopyranosyl-7-O-α-L-rhamnopyranoside( 5) and quercetin 3-O-( 6-O-caffeoyl)-ß-D-glucopyranosyl( 1→2)-α-L-rhamnopyranosyl-7-O-α-L-rhamnopyranoside( 6). Conclusion: Compounds 2 ~ 6 are isolated from this plant for the first time,compounds 5 and 6are firstly isolated from Ophioglossaceae family.

Four New Flavonoids with α-Glucosidase Inhibitory Activities from Morus alba var. tatarica.

Four new flavonoids, mortatarins A-D (1-4, resp.), along with eight known flavonoids (5-12) were isolated from the root bark of Morus alba var. tatarica. Their structures were established on the basis of spectroscopic data analysis, and the absolute configuration of 4 was determined by analysis of its CD spectrum. All isolates were tested for inhibitory activities against α-glucosidase. Compounds 4, 7, and 8 exhibited a significant degree of inhibition with IC50 values of 5.0 ± 0.3, 7.5 ± 0.5, and 5.9 ± 0.2 µM, respectively.

Cytotoxic polycyclic polyprenylated acylphloroglucinols from Hypericum attenuatum.

Six new polycyclic polyprenylated acylphloroglucinols, attenuatumiones A-F (1-6), together with twelve known analogs (7-18) were isolated from the whole plant of Hypericum attenuatum. Their structures were elucidated by spectroscopic methods, and the absolute configuration of C-13 in attenuatumione C (3) was deduced via the circular dichroism datum of the in situ formed [Rh2(OCOCF3)4] complexes. All isolates were evaluated for the cytotoxic activities on three human cancer cell lines. Compound 3 showed moderate cytotoxic activities with IC50 values of 10.12 and 10.56 µM against SMMC7721 and U2OS, respectively.

Geranylated 2-arylbenzofurans from Morus alba var. tatarica and their α-glucosidase and protein tyrosine phosphatase 1B inhibitory activities.

Ten new geranylated 2-arylbenzofuran derivatives, including two monoterpenoid 2-arylbenzofurans (1 and 2), two geranylated 2-arylbenzofuran enantiomers (3a and 3b), and six geranylated 2-arylbenzofurans (4-9), along with four known 2-arylbenzofurans (10-13) were isolated from the root bark of Morus alba var. tatarica. Their structures and relative configurations were established on the basis of spectroscopic data analysis. Compounds 3-7 with one asymmetric carbon at C-7″ were supposed to be enantiomeric mixtures confirmed by chiral HPLC analysis, and the absolute configurations of each enantiomer in 3-7 were determined by Rh2(OCOCF3)4-induced CD and Snatzke's method. The enantiomers with the substituting group at C-2' exhibited better resolutions on a Chiralpak AD-H column than those with the substituting group at C-4'. Compounds 1-7, 10, 11 and 13, showed α-glucosidase inhibitory activities with IC50 values of 11.9-131.9 µM, and compounds 1 and 9-13 inhibited protein tyrosine phosphatase 1B (PTP1B) with IC50 values of 7.9-38.1 µM.

Bioactive benzofuran neolignans from Aristolochia fordiana.

Six new benzofuran neolignans (1-6) were isolated from the EtOAc-soluble fraction of the aerial part of Aristolochia fordiana, together with twelve known analogues (7-18). The structures of the isolated compounds were elucidated by spectroscopic methods. All isolates were evaluated for their inhibitory effects on nitric oxide production in lipopolysaccaride-activated RAW264.7 macrophages and for their cytotoxic activities on three human cancer cell lines. Compound 2 showed significant nitric oxide production inhibitory activity with an IC50 value of 10.00 µM, while compound 16 exhibited cytotoxic activity with an IC50 value of 11.9 µM against MG-63 and compound 18 of 9.15 µM against HepG2 cell lines, respectively.