Plantainoside B in Bacopa monniera Binds to Aß Aggregates Attenuating Neuronal Damage and Memory Deficits Induced by Aß.

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by dementia. The most characteristic pathological changes in AD brain include extracellular amyloid-ß (Aß) accumulation and neuronal loss. Particularly, cholinergic neurons in the nucleus basalis of Meynert are some of the first neuronal groups to degenerate; accumulating evidence suggests that Aß oligomers are the primary form of neurotoxicity. Bacopa monniera is a traditional Indian memory enhancer whose extract has shown neuroprotective and Aß-reducing effects. In this study, we explored the low molecular weight compounds from B. monniera extracts with an affinity to Aß aggregates, including its oligomers, using Aß oligomer-conjugated beads and identified plantainoside B. Plantainoside B exhibited evident neuroprotective effects by preventing Aß attachment on the cell surface of human induced pluripotent stem cell (hiPSC)-derived cholinergic neurons. Moreover, it attenuated memory impairment in mice that received intrahippocampal Aß injections. Furthermore, radioisotope experiments revealed that plantainoside B has affinity to Aß aggregates including its oligomers and brain tissue from a mouse model of Aß pathology. In addition, plantainoside B could delay the Aß aggregation rate. Accordingly, plantainoside B may exert neuroprotective effects by binding to Aß oligomers, thus interrupting the binding of Aß oligomers to the cell surface. This suggests its potential application as a theranostics in AD, simultaneously diagnostic and therapeutic drugs.

Structures of Aromatic Glycosides from the Seeds of Cassia auriculata.

A new benzocoumarin glycoside, cassiaglycoside I (1), a new naphthol glycoside, cassiaglycoside II (2), a new chromon glycoside, cassiaglycoside III (3), a new phenylethyl glycoside, cassiaglycoside IV (4), were isolated from the seeds of Cassia auriculata, together with seven known constituents. The chemical structures of four new constituents were characterized on the basis of chemical and physicochemical evidence.

Inhibitors of melanogenesis in B16 melanoma 4A5 cells from flower buds of Lawsonia inermis (Henna).

The methanolic extract of Lawsonia inermis L. (henna) showed significant inhibitory activity toward melanogenesis in B16 melanoma 4A5 cells. Among the constituents isolated from the methanolic extract, luteolin, quercetin, and (±)-eriodictyol showed stronger inhibitory activity than the reference compound, arbutin. Several structure-activity relationships of the flavonoids were suggested, and OGlc

Chemical structures and hepatoprotective effects of constituents from Cassia auriculata leaves.

An 80% aqueous acetone extract of Cassia auriculata leaves was found to show a protective effect on D-galactosamine-induced cytotoxicity in primary cultured mouse hepatocytes. From the 80% aqueous acetone extract, we isolated a new benzocoumarin glycoside, avaraoside I (1), and a new flavanol dimer, avaraol I (2), together with 29 known constituents. The structures of the new compounds were elucidated on the basis of chemical and physicochemical evidence. In addition, three isolated compounds, pseudosemiglabrin (15, 0.0011%), (2S)-7,4'-dihydroxyflavan(4ß→8)-catechin (22, 0.00075%), and (2S)-7,4'-dihydroxyflavan(4ß→8)-gallocatechin (23, 0.092%), displayed hepatoprotective effects equivalent to that of the hepatoprotective agent, silybin.

Alkaloids from Sri Lankan curry-leaf (Murraya koenigii) display melanogenesis inhibitory activity: structures of karapinchamines A and B.

A methanolic extract and its ethyl acetate-soluble fraction from Sri Lankan curry-leaf, the leaves of Murraya koenigii, inhibited melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. Two new carbazole alkaloids, karapinchamines A and B, were isolated from the ethyl acetate-soluble fraction together with 12 known carbazole alkaloids. The structures of karapinchamines A and B were determined by physicochemical analyses. The principal alkaloid constituents were found to display potent melanogenesis inhibitory activity. The structural requirements of the carbazole alkaloids for melanogenesis inhibitory activity were discussed.

Alkaloid constituents from flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) with melanogenesis inhibitory activity in B16 melanoma cells.

Methanolic extracts from the flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) were found to show inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extracts, a new alkaloid, N-methylasimilobine N-oxide, was isolated together with eleven benzylisoquinoline alkaloids. The absolute stereostructure of the new alkaloid was determined from chemical and physicochemical evidence. Among the constituents isolated, nuciferine, N-methylasimilobine, (-)-lirinidine, and 2-hydroxy-1-methoxy-6a,7-dehydroaporphine showed potent inhibition of melanogenesis. Comparison of the inhibitory activities of synthetic related alkaloids facilitated characterization of the structure-activity relationships of aporphine- and benzylisoquinoline-type alkaloids. In addition, 3-30 µM nuciferine and N-methylasimilobine inhibited the expression of tyrosinase mRNA, 3-30 µM N-methylasimilobine inhibited the expression of TRP-1 mRNA, and 10-30 µM nuciferine inhibited the expression of TRP-2 mRNA.

Analysis of Active Compounds Using Target Protein Cofilin-Cucurbitacins in Cytotoxic Plant Bryonia cretica.

We examined a two-step target protein binding strategy that uses cofilin as the target protein to analyze the active constituents in Bryonia cretica. In the first step, we prepared the target protein, and used it to analyze the compounds binding to it in the second step. We used the methanolic extract of B. cretica as a library of possible active compounds. We conducted LC-MS analysis using information from our previous study. The peaks in the HPLC profile were identified as cucurbitacin D, isocucurbitacin D, and cucurbitacin I. As far as we know, there is no known study of the activity of isocucurbitacin D in this research field. Therefore, we examined the effects of isocucurbitacin D on cell proliferation and cofilin protein in human fibrosarcoma cell line HT1080 to confirm the effectiveness of this strategy. The cytotoxicity assay, the fibrous/globular actin ratio assay, and the immunoblotting analysis revealed that isocucurbitacin D showed a cytotoxic effect with disruption of target protein cofilin. The target protein binding strategy is a direct and straightforward method for finding new drug seeds from crude sources, such as natural plant extracts.

Cucurbitacin E as a new inhibitor of cofilin phosphorylation in human leukemia U937 cells.

Cucurbitane-type triterpenes, cucurbitacins B and E, were reported to exhibit cytotoxic effects in several cell lines mediated by JAK/STAT3 signaling. However, neither compound inhibited phosphorylation of STAT3 in human leukemia (U937) cells at low concentrations. We therefore synthesized a biotin-linked cucurbitacin E to isolate target proteins based on affinity for the molecule. As a result, cofilin, which regulates the depolymerization of actin, was isolated and suggested to be a target. Cucurbitacins E and I inhibited the phosphorylation of cofilin in a concentration-dependent manner, and their effective concentrations having the same range as the concentrations at which they had cytotoxic effects in U937 cells. In addition, the fibrous-/globular-actin ratio was decreased after treatment with cucurbitacin E in HT1080 cells. These findings suggested that the inhibition of cofilin's phosphorylation increased the severing activity of cofilin, and then the depolymerization of actin was enhanced after treatment with cucurbitacin E at lower concentrations.

Melanogenesis inhibitors from the desert plant Anastatica hierochuntica in B16 melanoma cells.

The methanolic extract from the whole plants of Anastatica hierochuntica, an Egyptian herbal medicine, was found to inhibit melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. Among the constituents isolated, anastatin A, silybin A, isosilybins A and B, eriodictyol, luteolin, kaempferol, quercetin, hierochins A and B, (2R,3S)-2,3-dihydro-2-(3,4-dimethoxyphenyl)-3-hydroxymethyl-5-(2-formylvinyl)-7-hydroxybenzofuran, (+)-dehydrodiconiferyl alcohol, (+)-balanophonin, 1-(4-hydroxy-3-methoxyphenyl)-2-{4-[(E)-3-hydroxy-1-propenyl]-2-methoxyphenoxy}-1,3-propanediol, and 3,4-dihydroxybenzaldehyde substantially inhibited melanogenesis with IC(50) values of 6.1-32 microM. With regard to the mechanism of action of silybins and isosilybins, the inhibition of tyrosinase activity suggested to be important. In addition, isosilybins A and B inhibited the mRNA expression of TRP-2, but silybins A and B oppositely enhanced the mRNA expression of tyrosinase and TRP-1 and -2 at 10 and/or 30 microM, and the inhibition of phosphorylation of extracellular signal-regulated kinases (ERK1/2) is involved in the enhanced expression of mRNA, at least in part, similar to that of PD98059.

BBB-permeable aporphine-type alkaloids in Nelumbo nucifera flowers with accelerative effects on neurite outgrowth in PC-12 cells.

Blood-brain barrier (BBB)-permeable components in the methanolic extract of Nelumbo nucifera flowers showed accelerative effects on neurite outgrowth in PC-12 cells. Among the constituents isolated from N. nucifera flowers in our previous study, aporphine-type alkaloids, lirinidine, asimilobine, N-methylasimilobine, and pronuciferine, showed accelerative effects. Lirinidine, N-methylasimilobine, and an alkaloid-rich diethyl ether fraction at low concentrations increased the expression of mRNAs coding for TrkA, Vav3, and Rac1. In addition, good permeability of asimilobine and N-methylasimilobine was confirmed using an in vitro BBB model. Asimilobine and N-methylasimilobine are considered to be suitable as seed compounds of drugs for Alzheimer's disease, because of their activity and BBB permeability.

Accelerative effects of carbazole-type alkaloids from Murraya koenigii on neurite outgrowth and their derivative's in vivo study for spatial memory.

Murraya koenigii is a medicinal plant that contains several carbazole-type alkaloids as its characteristic constituents. Blood-brain barrier permeable constituents of M. koenigii accelerated neurite outgrowth in PC-12 cells. Nine compounds were isolated from M. koenigii and their effects on neurite outgrowth were examined. Murrayamine-E (8) at 10 µM showed significant effect. Focusing on the carbazole skeleton, we synthesized derivatives to attenuate cytotoxicity. 9-Benzyl-9H-carbazol-4-ol (15) exhibited strong neurite outgrowth accelerative effect. In addition, the novel object recognition test and the Morris water maze test were performed to evaluate memory improvement of 15 in APdE9 mice. Compound 15 tended to improve spatial memory in the Morris water maze test. These results suggest that carbazole derivative 15 would be a seed compound for Alzheimer's disease drug.

Melanogenesis inhibitors from the rhizomes of Alpinia officinarum in B16 melanoma cells.

The 80% aqueous acetone extract from the rhizomes of Alpinia officinarum, a Chinese medicinal herb, were found to inhibit melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. Among the constituents isolated, four diarylheptanoids [5-hydroxy-1,7-diphenyl-3-heptanone, 7-(4('')-hydroxy-3('')-methoxyphenyl)-1-phenylhept-4-en-3-one, 5-hydroxy-7-(4('')-hydroxy-3('')-methoxyphenyl)-1-phenyl-3-heptanone, and 3,5-dihydroxy-1,7-diphenylheptane] and two flavonol constituents (kaempferide and galangin) inhibited melanogenesis with IC(50) values of 10-48microM, and several structural requirements of the active constituents for the inhibition were clarified. In addition, 7-(4('')-hydroxy-3('')-methoxyphenyl)-1-phenylhept-4-en-3-one, kaempferide, and galangin inhibited mRNA expression of tyrosinase and tyrosinase-related proteins-1 and -2, and the protein level of a microphthalmia-associated transcription factor.

Anti-proliferative effect of auriculataoside A on B16 melanoma 4A5 cells by suppression of Cdc42-Rac1-RhoA signaling protein levels.

Auriculataoside A, an anthracenone dimer glycoside isolated from Cassia auriculata seed, shows anti-proliferative effects on cell line B16 melanoma 4A5 cells with an IC50 value of 0.82 µM. However, it shows no such effect on normal human dermal fibroblast (HDF) cells. To evaluate the mode of action underlying the anti-proliferative effect of auriculataoside A on cells, we examined changes in whole protein expression after treatment with auriculataoside A and found that the expression Cdc42, RhoA, and Rac1, which are Rho family GTPases, was reduced. Auriculataoside A also arrested the cell cycle at G1 phase. These results suggest that the suppression of the above proteins induced G1 arrest. In addition, auriculataoside A also suppressed the expression of ß-catenin and c-Myc proteins. This action of auriculataoside A could be one of the mechanisms underlying its selective anti-proliferative effect on B16 melanoma cells.

Comparison of lawsone contents among Lawsonia inermis plant parts and neurite outgrowth accelerators from branches.

Lawsonia inermis L. (Lythraceae) is cultivated in many countries, including Japan, China, India and Egypt. Its leaves are well known as hair dye and exhibit antibacterial, anticancer, antifungal and anticonvulsant activities. However, there are few reports on its branches. 2-Hydroxy-1,4-naphthoquinone (lawsone) is a characteristic compound in its leaves. However, it remains to be clarified whether lawsone is present in other plant parts or not. In this study, we measured lawsone contents in the extracts of L. inermis flowers, leaves and branches by HPLC with tandem mass spectrometry. The extracts of L. inermis flowers, leaves and branches contained 116.9, 486.2 and 5.4 µg/g lawsone, respectively. Lawsone content was much lower in branches than the other plant parts. Next, in order to identify the biological constituents in the branches, we isolated nine known compounds and examined their effects on neurite outgrowth in PC12 cells. Among the constituents isolated, 2-[4-(3-hydroxypropyl)-2-methoxyphenoxy]-propane-1,3-diol (1) and quercetin 7-O-ß-D-glucopyranoside (8) showed accelerative effects on neurite outgrowth in PC12 cells.

New potent accelerator of neurite outgrowth from Lawsonia inermis flower under non-fasting condition.

The methanolic extract of Lawsonia inermis L. (henna) showed accelerative effects on nerve growth factor-induced neurite outgrowth in PC12 cells under non-fasting conditions. To elucidate the active constituents responsible for the neuronal differentiation, we conducted a search of the constituents and examined their accelerative effects on neurite outgrowth in PC12 cells. We isolated a new acetophenone glycoside, inermioside A, which exerted a significant accelerative effect on neurite outgrowth. We also confirmed the activities of nine known compounds, including quercetin and lalioside. In addition, we found that quercetin, one of the active constituents, increased Vav3 mRNA expression.

Chemical structures of constituents from the whole plant of Bacopa monniera.

Two new dammarane-type triterpene oligoglycosides, bacomosaponins A and B, and three new phenylethanoid glycosides, bacomosides A, B1, and B2, were isolated from the whole plant of Bacopa monniera Wettst. The chemical structures of the new constituents were characterized on the basis of chemical and physicochemical evidence. In the present study, bacomosaponins A and B with acyl groups were obtained from the whole plant of B. monniera. This is the first report of acylated dammarane-type triterpene oligoglycosides isolated from B. monniera. In addition, dammarane-type triterpene saponins significantly inhibited the aggregation of 42-mer amyloid ß-protein.

Caffeic Acid Derivatives from Bacopa monniera Plants as Inhibitors of Pancreatic Lipase Activity and their Structural Requirements.

The methanol extract of whole Bacopa monniera plants inhibited pancreatic lipase activity in vitro. From this extract we have reported the isolation of 11 triterpene glycosides and 5 phenylethanoid- and/or phenylpropanoid- glycosides. In this paper, we describe the effects of the methanol extract and/or its constituents on pancreatic lipase activity and the isolation of an active constituent, desrhamnosyl isoacteoside. In addition, the structural requirements for its inhibitory effects were examined. We also examined the effects on the elevation of plasma triglyceride (TG) levels in olive oil loaded mice. The major active constituents, desrhamnosyl isoacteoside and plantainoside B, reduced plasma TG levels in the mice. The inhibitory effects of B. monniera and its constituents on pancreatic lipase activity and plasma TG level are reported for the first time.

Brazilian natural medicines. III. structures of triterpene oligoglycosides and lipase inhibitors from mate, leaves of ilex paraguariensis.

The methanolic extract from the leaves of Ilex paraguariensis (Aquifoliaceae) was found to show an inhibitory activity on porcine pancreatic lipase. From the methanolic extract, three new triterpene oligoglycosides, mateglycosides A, B, and C, were isolated together with 18 known compounds. The chemical structures of new oligoglycosides were elucidated on the basis of chemical and physicochemical evidence. Several constituents showed inhibitory activities on pancreatic lipase.