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.

Antiproliferative Activities of Diterpenes from Leaves of Isodon trichocarpus against Cancer Stem Cells.

Two new diterpenes named trichoterpene I (1) and trichoterpene II (2) were isolated from the extract from the leaves of Isodon trichocarpus together with 19 known diterpenes. Their chemical structures were elucidated on the basis of chemical and physicochemical properties. Among them, oridonin (3), effusanin A (4), and lasiokaurin (9) with the α,ß-unsaturated carbonyl moiety showed antiproliferative activities against breast cancer MDA-MB-231 and human astrocytoma U-251 MG cells [i.e., non-cancer stem cells (non-CSCs)] and their cancer stem cells (CSCs) isolated by sphere formation. In particular, compound 4 (IC50 = 0.51 µM) showed a higher antiproliferative activity against MDA-MB-231 CSCs than against MDA-MB-231 non-CSCs. The antiproliferative activity toward CSCs of compound 4 was equal to adriamycin (positive control, IC50 = 0.60 µM).

Construction of sulfur-containing compounds with anti-cancer stem cell activity using thioacrolein derived from garlic based on nature-inspired scaffolds.

Sulfur-containing compounds, such as cyclic compounds with a vinyl sulfane structure, exhibit a wide range of biological activities including anticancer activity. Therefore, the development of efficient strategies to synthesize such compounds is a remarkable achievement. We have developed a unique approach for the rapid and modular preparation of nature-inspired cyclic and acyclic sulfur-containing compounds using thioacrolein, a naturally occurring chemically unstable intermediate. We constructed thiopyranone derivatives through the regioselective sequential double Diels-Alder reaction of thioacrolein produced by allicin, a major component in garlic, and two molecules of silyl enol ether as the diene partner. The cytotoxicity toward cancer stem cells of the thiopyranones was equal to or higher than that of (Z)-ajoene (positive control) derived from garlic, and the thiopyranones had higher chemical stability than (Z)-ajoene.

Anti-inflammatory effect of isopimarane diterpenoids from Kaempferia galanga.

Two new isopimarane diterpenes, 1α-hydroxy-14α-methoxyisopimara-8(9),15-diene (7) and 1α,14α-dihydroxyisopimara-8(9),15-diene (9) and eight known isopimarane diterpenes including (-)-sandaracopimaradiene (1), 6ß-acetoxysandaracopimaradiene-9α-ol (2), sandaracopimaradiene-7ß,9α-diol (3), sandaracopimaradiene-1α,9α-diol (4), 6ß-acetoxysandaracopimaradiene-9α-ol-1-one (5), 6ß-acetoxysandaracopimaradiene-1α,9α-diol (6), 6ß,14α-dihydroxyisopimara-8(9),15-diene (8), and 6ß,14ß-dihydroxyisopimara-8(9),15-diene (10) were isolated from hexane fraction of Kaempferia galanga ethanol extract. Compounds 5, 6, 8, and 9 exerted the good anti-inflammatory effect on lipopolysaccharide-stimulated nitric oxide production from RAW264.7 cells with IC50 of 11.2, 7.7, 14.3, and 12.1 µM, respectively. These four compounds inhibited nitric oxide synthase (iNOS) mRNA expression. Compounds 5 and 6 also suppressed cyclooxygenase 2 (COX-2) mRNA expression; in addition, compound 6 had mild inhibitory effect on TNF-α mRNA. Among these compounds, 5 dramatically inhibited iNOS and COX-2 mRNA expression. The influential structures were proposed to be oxygen substitute at C-1, C-6, and α-OH at C-14.

Asymmetric Nitrogen-Containing Dimer from Aerial Parts of Mercurialis leiocarpa and Its Synthesis by Mimicking Generation Process through Radical Intermediates.

An asymmetric nitrogen-containing dimer, leiocarpanine A, was isolated from the aerial part of Mercurialis leiocarpa as a new compound. The new generation process of leiocarpanine A was estimated and a concise synthesis of leiocarpanine A could be detailed based on mimicking the generation process through the radical intermediates. In general, a lot of reaction step and organic reagents are required for the synthesis of asymmetric nitrogen-containing dimers. However, our new synthesis method enables a concise synthesis of asymmetric nitrogen-containing dimers through radical intermediates by only liquid-separation. This synthetic method provides a rapid and concise pathway to construct a library of nitrogen-containing dimers that might be useful for drug discovery. In addition, it is useful to elucidate the generation process of leiocarpanine A.

Biofunctional Effects of Thiohemiaminal-Type Dimeric Sesquiterpene Alkaloids from Nuphar Plants.

Dimeric sesquiterpene thioalkaloids from the rhizomes of Nuphar pumilum exhibited immunosuppressive effects using a sheep erythrocyte plaque forming cell (PFC) assay, as well as an anti-metastasis effect, and rapid apoptosis-inducing effects in tumor cell lines. In particular, dimeric sesquiterpene thioalkaloids with a hydroxy group (6-hydroxythiobinupharidine, 6,6'-dihydroxythiobinupharidine, 6-hydroxythionuphlutine B) showed substantial effects, whereas dimeric sesquiterpene thioalkaloids lacking the hydroxy group (thiobinupharidine, thionuphlutine B, 6'-hydroxythionuphlutine B, neothiobinupharidine, thionuphlutine B ß-sulfoxide, neothiobinupharidine ß-sulfoxide) and monomeric sesquiterpene alkaloids (nupharidine, 7-epideoxynupharidine, nupharolutine) showed weak activity. In this review, we summarize our studies of the biofunctional effects of these alkaloids.

A Review of Biologically Active Natural Products from a Desert Plant Cistanche tubulosa.

An Orobanchaceae plant Cistanche tubulosa (SCHENK) WIGHT (Kanka-nikujuyou in Japanese), which is one of the authorized plant resources as Cistanches Herba in both Japanese and Chinese Pharmacopoeias, is a perennial parasitic plant growing on roots of sand-fixing plants. The stems of C. tubulosa have traditionally been used for treatment of impotence, sterility, lumbago, and body weakness as well as a promoting agent of blood circulation. In recent years, Cistanches Herba has also been widely used as a health food supplement in Japan, China, and Southeast Asian countries. Here we review our recent studies on chemical constituents from the stems of C. tubulosa as well as their bioactivities such as vasorelaxtant, hepatoprotective, and glucose tolerance improving effects.

Antiinflammation constituents from Curcuma zedoaroides.

Curcuma zedoaroides, a Zingiberaceae species, has been used for snake bite antidote and wound care in Thailand. Seven compounds were isolated from the bioactive chloroform extract consisted of one new guaiane sesquiterpene lactone, 5-epiphaeocaulisin A (4) and one new diarylheptanoid, 1,2,3,5-tetrahydroxy-1-(4-hydroxy-3-methoxyphenyl)-7-(4-hydroxyphenyl) heptane (7), together with five known guaiane-type sesquiterpene lactones including gweicurculactone (1), zedoalactone B (2), phaeocaulisin C (3), zedoalactone H (5), and zedoalactone E (6). The antiinflammation was investigated on NO and TNF-α production using RAW264.7 cells. In addition, the expressions of genes involved in inflammation including iNOS, COX-2, and TNF-α were assessed. The results found that Compounds 1-7 presented their antiinflammation against NO production. The most potential effects were demonstrated on Compounds 1 and 7 with IC50 of 27.3 and 32.6 µM, respectively. Although, Compounds 1 and 7 did not inhibit TNF-α production, their suppression on iNOS and COX-2 mRNA expression were revealed. These results support the ability of chloroform fraction, Compounds 1 and 7 on antiinflammation, whereas others exhibited moderate and mild effect.

Euphosantianane A⁻D: Antiproliferative Premyrsinane Diterpenoids from the Endemic Egyptian Plant Euphorbia Sanctae-Catharinae.

Euphorbia species are rich in diterpenes. A solvent extraction of Euphorbia sanctae-catharinae, a species indigenous to the Southern Sinai of Egypt, afforded several premyrsinane diterpenoids (1⁻4) as well as previously reported metabolites (5⁻13) that included three flavonoids. Isolated compounds were chemically characterized by spectroscopic analysis. Identified compounds were bioassayed for anti-proliferative activity in vitro against colon (Caco-2) and lung (A549) tumor cell lines. Compound 9 exhibited robust anti-proliferative activity against A549 cells (IC50 = 3.3 µM). Absolute configurations for 8 versus 9 were determined by experimental and TDDFT-calculated electronic circular dichorism (ECD) spectra.

Degranulation Inhibitors from Medicinal Plants in Antigen-Stimulated Rat Basophilic Leukemia (RBL-2H3) Cells.

Mast cells and basophils play important roles in both immediate- and late-phase reactions of type 1 allergy. Histamine, which is released from mast cells and basophils stimulated by an antigen or degranulation inducers, is usually determined as a degranulation marker in experiments on immediate allergic reactions in vitro. ß-Hexosaminidase is also stored in secretory granules of the cells and is released concomitantly with histamine when the cells are immunologically activated, and recently this enzyme activity in the medium has been used as a marker of the degranulation. In this paper, we review our studies on the search for degranulation inhibitors, such as flavonoids, stilbenes, and curcuminoids, from medicinal plants using rat basophilic leukemia (RBL-2H3) cells.

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

Lignan dicarboxylates and terpenoids from the flower buds of Cananga odorata and their inhibitory effects on melanogenesis.

The methanolic extract from the flower buds of Cananga odorata showed an inhibitory effect on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extract, two new lignan dicarboxylates, canangalignans I and II, three new terpenoids, canangaterpenes I, II, and III, and eight known compounds were isolated. The structures of these compounds were elucidated on the basis of chemical/physicochemical evidence. Several mono- and sesquiterpene analogues significantly inhibited melanogenesis. In particular, canangaterpene I and (3R,3aR,8aS)-3-isopropyl-8a-methyl-8-oxo-1,2,3,3a,6,7,8,8a-octahydroazulene-5-carbaldehyde exhibited a potent inhibitory effect on melanogenesis [inhibition (%): 34.7±4.2 (p<0.01), 45.5±5.7 (p<0.01) at 1 µM, respectively] without inducing cytotoxicity. Moreover, the biological effect of these compounds was much stronger than that of the reference compound, arbutin. Thus, these isolated terpenoid derivatives may be promising therapeutic agents for the treatment of several skin disorders.

Search for new type of PPARγ agonist-like anti-diabetic compounds from medicinal plants.

Potent ligands of peroxisome proliferator-activated receptor γ (PPARγ) such as thiazolidinediones (pioglitazone, troglitazone, etc.) improve insulin sensitivity by increasing the levels of adiponectin, an important adipocytokine associated with insulin sensitivity in adipose tissue. Several constituents from medicinal plants were recently reported to show PPARγ agonist-like activity in 3T3-L1 cells, but did not show agonistic activity at the receptor site different from thiazolidinediones. Our recent studies on PPARγ agonist-like constituents, such as hydrangenol and hydrangeic acid from the processed leaves of Hydrangea macrophylla var. thunbergii, piperlonguminine and retrofractamide A from the fruit of Piper chaba, and tetramethylkaempferol and pentamethylquercetin from the rhizomes of Kaempferia parviflora, are reviewed.

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.

Diarylheptanoids with inhibitory effects on melanogenesis from the rhizomes of Curcuma comosa in B16 melanoma cells.

The methanolic extract from the dried rhizomes of Curcuma comosa cultivated in Thailand was found to inhibit melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extract, three new diarylheptanoids, diarylcomosols I-III, were isolated together with 12 known diarylheptanoids. Their chemical structures were elucidated on the basis of chemical and physicochemical evidence. The diarylheptanoids inhibited melanogenesis, and several structural requirements of the active constituents for the inhibition were clarified. In particular, (3R)-1,7-bis(4-hydroxyphenyl)-(6E)-6-hepten-3-ol exhibited stronger inhibitory effect [IC50=0.36 µM] without inducing cytotoxicity. The biological effect was much stronger than that of a reference compound, arbutin [IC50=174 µM]. We conclude that diarylheptanoid analogs are promising therapeutic agents for the treatment of skin disorders.

Adipogenetic effects of retrofractamide A derivatives in 3T3-L1 cells.

In a previous study, retrofractamide A from the fruit of Piper chaba was shown to promote adipogenesis in 3T3-L1 cells. In the present study, retrofractamide A and its derivatives were synthesized, and their adipogenetic effects in 3T3-L1 cells were examined. Among the tested compounds, an amide composed of 9-(3',4'-methylenedioxyphenyl)-nona-2E,4E,8E-trienoic acid and an n-butyl or n-pentyl amine showed strongest activity. Moreover, the amide with the n-pentyl amine moiety significantly increased the uptake of 2-deoxyglucose into the cells, and also increased the mRNA levels of adiponectin, peroxisome proliferator-activated receptor γ2 (PPARγ2), glucose transporter 4 (GLUT4), fatty acid-binding protein (aP2), and CCAAT/enhancer-binding protein (C/EBP) α and ß in a similar manner as the PPARγ agonist troglitazone, although it had less agonistic activity against PPARγ.

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.

Medicinal flowers. XXXVIII. structures of acylated sucroses and inhibitory effects of constituents on aldose reducatase from the flower buds of Prunus mume.

The methanolic extract from the flower buds of Prunus mume, cultivated in Zhejiang province, China, showed an inhibitory effect on aldose reductase. From the methanolic extract, five new acylated sucroses, mumeoses F-J, were isolated together with 29 known compounds. The chemical structures of the new compounds were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effects of the isolated compounds on aldose reductase were also investigated. Acylated quinic acid analogs, which are one of the major compounds of the flower buds of P. mume, were shown to substantially inhibit aldose reductase. In particular, mumeic acid-A was found to exhibit a potent inhibitory effect [IC50=0.4 µm].