Chemical Constituents of Apios americana Tubers and Their Inhibitory Activities on Nitric Oxide Production in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages

Comparison of primary and secondary metabolites and antioxidant activities by solid-state fermentation of Apios americana Medikus with different fungi

This study compared the nutritional components, isoflavones, and antioxidant activities by solid-sate fermentation of Apios americana Medikus (AAM) with seven different fungi. The total fatty acid contents increased from 120.5 mg/100 g (unfermented AAM, UFAAM) to 242.0 to 3167.5 mg/100 g (fermented AAM, FAAM) with all fungi. In particular, the values of total fatty acids were highest (26.3-fold increase) in the FAAM with Monascus purpureus. The amount of total free amino acids increased from 591.69 mg/100 g (UFAAM) to 664.38 to 1603.07 mg/100 g after fermentation except for Monascus pilosus and Lentinula edodes. The total mineral contents increased evidently after fermentation with M. purpureus, F. velutipes, and Tricholoma matsutake (347.36 → 588.29, 576.59, and 453.32 mg/100 g, respectively). The UFAAM predominated isoflavone glycosides, whereas glycoside forms were converted into aglycone forms after fermentation by fungi. The bioconversion rates of glycoside to aglycone were excellent in the FAAM with M. pilosus, M. purpureus, F. velutipes, and T. matsutake (0.01 → 0.69, 0.50, 0.27, and 0.31 mg/g, respectively). Furthermore, the total phenolic contents, total flavonoid contents, and antioxidant activities by the abovementioned FAAM were high except for L.edodes. This FAAM can be used as a potential food and pharmaceutical materials.

Total Syntheses and Antibacterial Studies of Natural Isoflavones: Scandenone, Osajin, and 6,8-Diprenylgenistein

Isoflavones are a class of natural products that exhibit a wide range of interesting biological properties, including antioxidant, hepatoprotective, antimicrobial, and anti-inflammatory activities. Scandenone (1), osajin (2), and 6,8-diprenylgenistein (3) are natural prenylated isoflavones that share the same polyphenol framework. In this research, the key intermediate 15 was used for the synthesis of the natural isoflavones 1-3, establishing a stereoselective synthetic method for both linear and angular pyran isoflavones. The antibacterial activities of 1-3 were also evaluated, and all of them displayed good antibacterial activity against Gram-positive bacteria. Among them, 2 was the most potent one against MRSA, with a MIC value of 2 μg/mL, and the SEM assay indicated that the bacterial cell membranes of both MRSA and E. faecalis could be disrupted by 2. These findings suggest that this type of isoflavone could serve as a lead for the development of novel antibacterial agents for the treatment of Gram-positive bacterial infections.

New Sesquiterpene Glycosides from the Flowers of Aster koraiensis and Their Inhibition Activities on EGF- and TPA-Induced Cell Transformation

In total, four new eudesmane-type sesquiterpene glycosides, askoseosides A-D (1-4), and 18 known compounds (5-22) were isolated from the flowers of Aster koraiensis via chromatographic techniques. Chemical structures of the isolated compounds were identified by spectroscopic/spectrometric methods, including NMR and HRESIMS, and the absolute configuration of the new compounds (1 and 2) was performed by electronic circular dichroism (ECD) studies. Further, the anticancer activities of the isolated compounds (1-22) were evaluated using the epidermal growth factor (EGF)-induced as well as the 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced cell transformation assay. Among the 22 compounds, compounds 4, 9, 11, 13-15, 17, 18, and 22 significantly inhibited both EGF- and TPA-induced colony growth. In particular, askoseoside D (4, EGF: 57.8%; TPA: 67.1%), apigenin (9, EGF: 88.6%; TPA: 80.2%), apigenin-7-O-β-d-glucuronopyranoside (14, EGF: 79.2%; TPA: 70.7%), and 1-(3',4'-dihydroxycinnamoyl) cyclopentane-2,3-diol (22, EGF: 60.0%; TPA: 72.1%) showed higher potent activities.

Coumaronochromones, flavanones, and isoflavones from the twigs and leaves of Erythrina subumbrans inhibit PTP1B and nitric oxide production

A chemical investigation of the twigs and leaves of Erythrina subumbrans led to the isolation and structural elucidation of three coumaronochromones, erythrinasubumbrin A and (±)-erythrinasubumbrin B, five prenylated flavanones, (±)-erythrinasubumbrin C and erythrinasubumbrins D-F, and two prenylated isoflavones, (±)-5,4'-dihydroxy-[4,5-cis-4-ethoxy-5-hydroxy-6,6-dimethyl-4,5-dihydropyrano (2,3:7,6)]-isoflavone, in addition to 18 known analogues. Two extra cinnamylphenols previously only known as commercial synthetic products were also isolated and elucidated from a natural source for the first time, and assigned the trivial names erythrinasubumbrins G and H. Their structures were characterized by detailed analysis of spectroscopic data, including HRESIMS and 2D NMR. The absolute configurations of the previously undescribed isolates and the known coumaronochromone lupinol C were determined by specific rotation and electronic circular dichroism (ECD) data. All the isolates were evaluated for their inhibitory activities on protein tyrosine phosphatase 1 B (PTP1B) and nitric oxide (NO) production in lipopolysaccharide (LPS)-induced BV-2 microglial cells as well as their cytotoxicity against the HCT116 cell line. The pair of enantiomers, (+)-5,4'-dihydroxy-[4,5-cis-4-ethoxy-5-hydroxy-6,6-dimethyl-4,5-dihydropyrano (2,3:7,6)]-isoflavone and (-)-5,4'-dihydroxy-[4,5-cis-4-ethoxy-5-hydroxy-6,6-dimethyl-4,5-dihydropyrano (2,3:7,6)]-isoflavone, and the known compounds lupinol C, 4'-O-methyl-8-prenylnaringenin, glepidotin B, shuterin, parvisoflavones A, luteone, lupiwighteone, 2,3-dehydrokievitone, 6,8-diprenylgenistein, angustone A, and 2'-O-demethylbidwillol B exhibited different levels of PTP1B inhibitory activities with IC₅₀ values ranging from 3.21 to 19.17 μM, while erythrinasubumbrin A, (-)-erythrinasubumbrin B, (+)-5,4'-dihydroxy-[4,5-cis-4-ethoxy-5-hydroxy-6,6-dimethyl-4,5-dihydropyrano (2,3:7,6)]-isoflavone, (-)-5,4'-dihydroxy-[4,5-cis-4-ethoxy-5-hydroxy-6,6-dimethyl-4,5-dihydropyrano (2,3:7,6)]-isoflavone, and the known compounds lupinol C, 8-prenylnaringenin, macatrichocarpin A, alpinumisoflavone, and 2'-O-demethylbidwillol B substantially inhibited NO production in BV-2 microglial cells. In addition, 8-prenylnaringenin showed weak cytotoxicity with an IC₅₀ value of 9.13 μM. This is the first report of PTP1B inhibitory activity for a coumaronochromone.

Anti-neuroinflammatory 3-hydroxycoumaronochromones and isoflavanones enantiomers from the fruits of Ficus altissima Blume

A phytochemical study on the fruits of Ficus altissima Blume (lofty fig) led to the isolation and structural elucidation of three pairs of enantiomeric 3-hydroxycoumaronochromones and two pairs of enantiomeric isoflavanones, including eight undescribed compounds. Their structures were determined based on a comprehensive analysis of NMR and HR-ESI-MS spectroscopic data, calculated ¹³C NMR-DP4 plus analysis and the comparisons of experimental measurements of ECD with calculated ECD spectra by TDDFT or ECD plots in reported protocols. The inhibitory effects of the isolated enantiomers on NO production stimulated by LPS in microglial BV-2 cells were evaluated. Among them, ficusaltin D exhibited the most potent anti-neuroinflammatory activity, which inhibited the production of NO and the expression of iNOS, IL-6 and IL-1β and suppressed the NF-κB nuclear translocation in LPS-induced BV-2 cells, while its enantiomer displayed cytotoxicity.

Dalpulapans A-E from the roots of Dalbergia stipulacea

Five new compounds, dalpulapans A–E (1–5), were isolated from the hexane extract of the roots of Dalbergia stipulacea Roxb. Five new compounds, dalpulapans A–E (1–5), were isolated from the hexane extract of the roots of Dalbergia stipulacea Roxb. An evaluation of cytotoxic activity against HeLa, A549 and normal cell lines using MTT assay was performed. The results showed that R,R-velucarpin A (6) was the most active against HeLa cells with an IC₅₀ value of 10.9 ± 0.42 μM, while fortunately this compound exhibited weak cytotoxicity against normal cells (29.20 ± 1.16 μM). Structures of all isolates were identified from their 1D and 2D NMR spectroscopic data and MS analysis. Experimental and calculated ECD spectra were studied to define the absolute configurations.

Five new compounds, dalpulapans A–E (1–5), were isolated from the hexane extract of the roots of Dalbergia stipulacea Roxb.

Ranunculus species suppress nitric oxide production in LPS-stimulated RAW 264.7 macrophages

Aerial parts and roots from three Ranunculus species were extracted with 70% ethanol. The phytochemical composition was investigated using GC-MS and multivariate data analysis. The total phenolic and flavonoid contents were also assessed. The in vitro inhibitory properties were evaluated as nitrite concentration in LPS-stimulated RAW 264.7 macrophage cell line. All the samples induced concentration-dependent inhibitory effects, with R. sceleratus aerial parts extract being the most interesting sample (IC50 = 22.08 ± 1.32 µg/mL), even more active than the reference compound indomethacin. A very good activity was also observed for R. sardous and R. ficaria aerial parts extracts (IC50 = 51.61 ± 3.12 µg/mL and 84.55 ± 3.40 µg/mL). A lesser but noteworthy potential was also demonstrated for the root extracts. The results suggest that Ranunculus hydroalcoholic extracts are able to inhibit nitrite accumulation and may be useful in preventing inflammatory diseases mediated by excessive production of NO.

Bioactive Diarylheptanoids from Alpinia coriandriodora

Eight new diarylheptanoids, coriandralpinins A-H (1-8), were isolated from the rhizomes of Alpinia coriandriodora, an edible plant of the ginger family. Their structures, including the absolute configurations, were established by extensive spectroscopic analysis and ECD calculations. Compounds 1-8 have a 1,5-O-bridged diarylheptanoid structure featuring polyoxygenated aryl units. When evaluated for intracellular antioxidant activity using t-BHP stressed RAW264.7 macrophages, all these compounds scavenged reactive oxygen species (ROS) in a concentration-dependent manner. Compounds 3 and 5 also showed inhibitory activity against NO release in LPS-induced RAW 264.7 cells. Six known flavonols, 7,4'-di-O-methylkaempferol, 7-O-methylquercetin, 7,4'-di-O-methylquercetin, 7,3',4'-tri-O- methylquercetin, kaempferol 3-O-β-D-(6-O-α-L-rhamnopyranosyl)glucopyranoside, and 3-O-β-D-glucopyranuronosylquercetin were also isolated and characterized from the rhizomes.

Bougainvinones NP, three new flavonoids from Bougainvillea spectabilis

In an effort to identify natural bioactive compounds, three new flavonoids (1-3) and six known compounds (4-9) were isolated from the stem bark of Bougainvillea spectabilis. The structures of these compounds were accomplished using comprehensive spectroscopic methods, including 1D and 2D NMR spectra with references to the literatures, as well as high-resolution mass spectrometric analysis. Their cytotoxicity against KB and HeLa S-3 cell lines was also evaluated.

Two new phenolic glucosides from marine-derived fungus Aspergillus sp

Two new phenolic glucosides, including a new O-glycoside (1) and a new C-glycoside (2), were isolated from a marine-derived fungus Aspergillus sp. The structures of new compounds were elucidated through interpretations of spectroscopic evidence and high-resolution electrospray ionization mass spectrometry. The hexose unit of 1 was identified as β-D-glucose by comparison with an authentic sample via HPLC after acid hydrolysis and derivatization. All compounds were evaluated for their ability to inhibit LPS-induced NO production in RAW264.7 macrophages, but none of them displayed significant activity.

Chemical Constituents from the Aerial Parts of Elsholtzia ciliata and Their Protective Activities on Glutamate-Induced HT22 Cell Death

A new phenolic glucoside, (7E,9E)-3-hydroxyavenalumic acid-3-O-[6'-O-(E)-caffeoyl]-β-d-glucopyranoside (1), and three new acetylated flavone glycosides, acacetin-7-O-[β-d-glucopyranosyl(1″″→2″)-4‴-O-acetyl-α-l-rhamnopyranosyl(1‴→6″)]-β-d-glucopyranoside (3), acacetin-7-O-[6″″-O-acetyl-β-d-glucopyranosyl(1″″→2″)-3‴-O-acetyl-α-l-rhamnopyranosyl(1‴→6″)]-β-d-glucopyranoside (5), and acacetin-7-O-[3″″,6″″-di-O-acetyl-β-d-glucopyranosyl(1″″→2″)-4‴-O-acetyl-α-l-rhamnopyranosyl(1‴→6″)]-β-d-glucopyranoside (7), as well as 34 known compounds (2, 4, 6, and 8-38) were isolated from the aerial parts of Elsholtzia ciliata. The chemical structures of the new compounds were determined by spectroscopic/spectrometric data interpretation using NMR and HRESIMS. The neuroprotective effect of the isolated compounds was evaluated by a cell viability assay on HT22 murine hippocampal neuronal cells. Among them, 23 compounds, including new substances 1 and 3, exhibited neuroprotective effects against glutamate-induced HT22 cell death. In particular, compounds 2, 16, 17, 20, 22, 28, 29, and 31 presented potent neuroprotective effects with EC₅₀ values of 1.5-8.3 μM.

Structural characterization, neuroprotective and hepatoprotective activities of flavonoids from the bulbs of Heleocharis dulcis

Chinese water chestnut, the bulb of Heleocharis dulcis, has been widely consumed as fruit or vegetable in China since ancient times. It exhibits health-promoting properties that leads to an extensive study of their active components. Successive chromatography of active fragments of H. dulcis resulted in isolation of five new chalcone-flavonone heterodimers (1-3, 6, 9), four new diverse flavonoids (4, 5, 7, 8), and sixteen known flavonoids derivatives (10-25) were elucidated on the basis of their IR, UV, NMR, MS spectrometry data analysis and references from H. dulcis for the first time. Among these isolates, compounds 4, 7, 9, 12, 13, and 17 showed moderate neuroprotective activity, which increased the cell survival rate from 49.23 ± 3.68% for the model to 67.75 ± 2.75%, 57.83 ± 2.46%, 67.98 ± 2.74%, 58.65 ± 3.43%, 56.14 ± 1.99%, and 56.70 ± 1.38% at 10 μM, respectively. Moreover, compounds 1-3, 15, 16, 18, and 20 were found to moderately improve the HepG2 cell survival rates from 39.53% (APAP, 10 mM) to 45.53-53.44%. The outcome of the study provided crucial information regarding the structural diversity and health benefits of the edible bulbs of H. dulcis.

Chemical Constituents from the Aerial Parts of Agastache rugosa and Their Inhibitory Activities on Prostaglandin E2 Production in Lipopolysaccharide-Treated RAW 264.7 Macrophages

A new flavone glucoside, acacetin-7-O-(3″-O-acetyl-6″-O-malonyl)-β-d-glucopyranoside (1), two new phenolic glucosides, (3R,7R)-tuberonic acid-12-O-[6'-O-(E)-feruloyl]-β-d-glucopyranoside (14) and salicylic acid-2-O-[6'-O-(E)-feruloyl]-β-d-glucopyranoside (15), and two new phenylpropanoid glucosides, chavicol-1-O-(6'-O-methylmalonyl)-β-d-glucopyranoside (17) and chavicol-1-O-(6'-O-acetyl)-β-d-glucopyranoside(18), as well as 26 known compounds, 2-13, 16, and 19-31, were isolated from the aerial parts of Agastache rugose. The structures of the new compounds were established by spectroscopic/spectrometric methods such as HRESIMS, NMR, and ECD. The anti-inflammatory effect of the isolated compounds was evaluated by measuring their inhibitory activities on prostaglandin E₂ (PGE₂) in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. New compounds 1, 15, 17, and 18 inhibited LPS-induced PGE₂ production with IC₅₀ values of 16.8 ± 0.8, 33.9 ± 4.8, 14.3 ± 2.1, and 48.8 ± 4.4 μM, respectively. Compounds 5, 7, 9-11, 13, 19, 20, 22, and 27-30 showed potent inhibitory activities with IC₅₀ values of 1.7-8.4 μM.

Antibacterial and Inhibitory Activities against Nitric Oxide Production of Coumaronochromones and Prenylated Isoflavones from Millettia extensa

A chemical investigation of leaf and root extracts of Millettia extensa led to the isolation and structural elucidation of four new prenylated isoflavones, millexatins G-J (1-4), and three new coumaronochromones, millexatins K-M (5-7), along with 16 known compounds. The structures of the new compounds were determined on the basis of NMR and MS data. Compound 4 is a rare isoflavone having a 2-hydroxyethyl moiety at C-8, whereas the structures of compounds 5-7 formally arise from a ring closure through HO-2' and C-2. The absolute configurations at the C-2 and C-3 positions of 5 and 6 were determined from their ECD spectra through comparison with those of previously reported compounds. Most of compounds were evaluated for their inhibitory effects against nitric oxide (NO) production on RAW264.7 macrophages and their antibacterial activities. Compounds 18 and 19 inhibited NO production with IC₅₀ values of 8.5 and 14.3 μM, respectively. Compounds 13 and 14 showed antibacterial activity against various Gram-positive bacteria with MIC values ranging from 2 to 8 μg/mL.