Glycosides fromGrewia damineandFilicium decipiens

Flavonoids and other phenolics from Camellia nitidissima chi flowers

From Camellia nitidissima Chi flowers four undescribed flavonoids, nitidissimol A, nitidissimol B, sexangularetin 3-O-(6''-trans-p-coumarolyglucopyranoside) and sexangularetin 3-O-(2''-trans-p-coumarolyglucopyranoside) (1-4), and two previously unreported phenolics, nitidissimol C, D (9, 10), were isolated first time along with ten known compounds, kaempferol 3-O-(6''-O-trans-p-coumaroyl)-β-D- glucopyranoside (5), kaempferol-3-O-rhamnoside (6), Quercetin-3'-O-β-D-glucoside (7), kaempferol-7-O-β-D-glucoside (8), erythro-guaiacylglycerol-O-4'-coniferyl ether (11), threo-guaiacylglycerol-O-4'-coniferyl ether (12), protocatechuic acid (13), 1,2-Diethoxybenzene (14), ethyl shikimate (15), 2,4,6-trihydroxybenzoic acid 4-O-allopyranoside (16). The structures of the isolated compounds were elucidated by spectroscopic analysis of 1 D- and 2 D-NMR and MS data. Moreover, all isolated compounds (1-16) were tested for the antibacterial activity against Xanthomonas oryzae pv. oryzae and their quorum sensing inhibitory activity in Pseudomonas aeruginosa PAO1. However, no one showed signifcant inhibition of X. oryzae pv. oryzae (MIC₉₀ > 0.1 mg/mL), nor did they significantly inhibit the pyocyanin synthesis, which is controlled by quorum sensing in PAO1.

In Vitro and in Silico Analysis of Phytochemicals From Fallopia dentatoalata as Dual Functional Cholinesterase Inhibitors for the Treatment of Alzheimer’s Disease

Current studies have found that butyrylcholinesterase (BuChE) replaces the biological function of acetylcholinesterase (AChE) in the late stage of Alzheimer’s disease. Species in the genus of Fallopia, rich in polyphenols with diverse chemical structures and significant biological activities, are considered as an important resource for screening natural products to against AD. In this study, thirty-four compounds (1–34) were isolated from Fallopia dentatoalata (Fr. Schm.) Holub, and their inhibitory effects against AChE and BuChE were assessed. Compounds of the phenylpropanoid sucrose ester class emerged as the most promising members of the group, with 31–33 displaying moderate AChE inhibition (IC50 values ranging from 30.6 ± 4.7 to 56.0 ± 2.4 µM) and 30–34 showing potential inhibitory effects against BuChE (IC50 values ranging from 2.7 ± 1.7 to 17.1 ± 3.4 µM). Tacrine was used as a positive control (IC50: 126.7 ± 1.1 in AChE and 5.5 ± 1.7 nM in BuChE). Kinetic analysis highlighted compounds 31 and 32 as non-competitive inhibitors of AChE with Ki values of ∼30.0 and ∼34.4 µM, whilst 30–34 were revealed to competitively inhibit BuChE with Ki values ranging from ∼1.8 to ∼17.5 µM. Molecular binding studies demonstrated that 30–34 bound to the catalytic sites of BuChE with negative binding energies. The strong agreement between both in vitro and in silico studies highlights the phenylpropanoid sucrose esters 30–34 as promising candidates for use in future anti-cholinesterase therapeutics against Alzheimer’s disease.

Antiallergic Properties of Biflavonoids Isolated from the Flowers of Mesua ferrea Linn

The methanolic extract from the flowers of Mesua ferrea Linn. (Calophyllaceae) showed significant hyaluronidase inhibitory activity. Following a bioassay-guided separation of the extract, two biflavonoids, viz., mesuaferrone-A (1) and mesuaferrone-B (2), were isolated, along with ten flavonoids (3–12), two xanthones (13 and 14), three triterpenes (15–17), a phenylpropanoid (18), and five aromatics (19–24). Among the isolates, 1 and 2 (IC50 = 51.1 µM and 54.7 µM, respectively) exhibited hyaluronidase inhibitory activity equivalent to that of the commercially available antiallergic agents disodium cromoglycate (64.8 μM) and ketotifen fumarate (76.5 μM). These biflavonoids (1 and 2) are 8-8″ linked dimers that are composed of naringenin (1a) or apigenin (3), with their corresponding monomers lacking inhibitory activity (IC50 > 300 μM). In addition, 1 and 2 (IC50 = 49.4 µM and 49.2 µM, respectively) inhibited the release of β-hexosaminidase, which is a marker of antigen-IgE-mediated degranulation, in rat basophilic leukemia (RBL-2H3) cells. These inhibitory activities were more potent than those of the antiallergic agents tranilast and ketotifen fumarate (IC50 = 282 μM and 158 μM, respectively), as well as one of the corresponding monomers (1a; IC50 > 100 μM). Nonetheless, these effects were weaker than those of the other monomer (3; IC50 = 6.1 μM).

Cathayanalactone G and other constituents from leaves and twigs of Callicarpa cathayana

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Thannilignan glucoside and 2-(β-glucopyranosyl)-3-isoxazolin-5-one derivative, two new compounds isolated from Terminalia bellirica

Two new compounds, thannilignan 9-O-β-glucoside (1) and 2-(β-glucopyranosyl)-3-isoxazolin-5-one derivative (2), and seven known compounds were isolated from the methanol extract of Terminalia bellirica leaves, collected in Bangladesh. The structures of the compounds were elucidated using spectroscopic analysis. Among these isolated compounds, corilagin (3) was cytotoxic against human gastric adenocarcinoma cell line AGS at an IC₅₀ of 20.8 μM, and β-D-glucopyranose 1,3,6-trigallate (4) exhibited the ability to overcome tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resistance.

Non-ephedrine constituents from the herbaceous stems of Ephedra sinica

Three new flavonoids, ephedroside A (1), ephedroside B (2), ephedroside C (3), together with fifty-four known compounds 4-57 were isolated from the EtOH extract of the herbaceous stems of Ephedra sinica. The structures of these compounds were elucidated by spectroscopic techniques, as well as by comparison with literature data. Thirty-eight of these compounds were isolated from the genus Ephedra for the first time. The antimicrobial activities of eight compounds were tested by measuring the minimum inhibitory concentrations (MIC) against bacteria (both Gram positive and Gram negative) and fungi, and were found to be in the range of 0.105-0.926 mM. Among them, compound 2 showed the best antimicrobial activity against Pseudomonas aeruginosa with MIC value of 0.105 mM.

Dihydrostilbene glycosides from Camellia sinensis var. assamica and their cytotoxic activity

Three undescribed dihydrostilbene glycosides, 3,5-dihydroxyldihydrostilbene 4'-O-[6''-O-(4'''-hydroxylbenzoyl)]-β-D-glucopyranoside (1), 3,5-dihydroxyldihydrostilbene 4'-O-(6''-O-galloyl)-β-D-glucopyranoside (2), and 3,5-dihydroxyldihydrostilbene 4'-O-[6''-O-(3''',4'''-dimethoxyl)galloyl]-β-D-glucopyranoside (3), and seven known compounds, kaempferol 3-O-β-D-glucopyranoside (4), isoquercitrin (5), kaempferol 3-O-α-L-rhamnoside (6), quercitrin (7), (6S,9R)-roseoside (8), (-)-epicatechin 3-O-gallate (9), and (-)-epigallocatechin 3-O-gallate (10) have been isolated from the methanol extract of the leaves of Camellia sinensis var. assamica (J.W.Mast.) Kitam. (synnonym of Camellia assamica (Mast.) H.T.Chang) (Theaceae). Their structures were elucidated by spectroscopic methods (1 D-, 2 D-NMR) and mass spectra. All compounds were evaluated for cytotoxic activity against human oral cancer (CAL27) and human breast cancer (MDAMB231) cell lines. Compound 10 showed significant cytotoxic activity against CAL27 and MDAMB231 cell lines with IC₅₀ values of 9.78 ± 0.25 and 3.27 ± 0.18 μM, respectively, compared to those of positive control, capecitabine (IC₅₀ values of 8.20 ± 0.75 and 5.20 ± 0.89 μM).

Effect of Non-Volatile Constituents of Elsholtzia ciliata (Thunb.) Hyl. from Southern Vietnam on Reactive Oxygen Species and Nitric Oxide Release in Macrophages

The extract of Elsholtzia ciliata aerial parts was subjected to bio-guided isolation using the intercellular ROS reduction in J774A.1 macrophages to monitor the anti-oxidative activity. Fifteen compounds were isolated from the active fractions including eleven flavonoids (vitexin, pedalin, luteolin-7-O-β-d-glucopyranoside, apigenin-5-O-β-d-glucopyranoside, apigenin-7-O-β-d-glucopyranoside, chrysoeriol-7-O-β-d-glucopyranoside, 7,3'-dimethoxyluteolin-6-O-β-d-glucopyranoside, luteolin, 5,6,4'-trihydroxy-7,3'-dimethoxyflavone, 5-hydroxy-6,7-dimethoxyflavone (compound 13), 5-hydroxy-7,8-dimethoxyflavone); three hydroxycinnamic acid derivatives (caffeic acid, 4-(E)-caffeoyl-l-threonic acid, 4-O-(E)-p-coumaroyl-l-threonic acid) and one fatty acid (α-linolenic acid). The biological evaluation of these compounds (10-2.5 μm) indicated that all of them exerted good antioxidant and anti-inflammatory activities, in particular compound 13.

Phytochemical Profile and Antidepressant Effect of Ormosia henryi Prain Leaf Ethanol Extract

The Ormosia henryi Prain leaf (OHPL) is a new bioactive resource with potential antidepressant activity, but few reports have confirmed its chemical composition or antidepressant effect. To investigate the phytochemical profile of OHPL ethanol extract (OHPLE), six flavone C-glycosides and two flavone O-glycosides were purified by high-speed counter-current chromatography combined with preparative high-performance liquid chromatography (HSCCC-prep-HPLC). The eight isolated compounds were identified by NMR and MS. Forty-six flavonoids, including flavones, flavone C-glycosides, flavone O-glycosides, isoflavones, isoflavone O-glycosides, prenylflavones and polymethoxyflavones were definitively or tentatively identified from OHPLE using ultra-performance liquid chromatography/ electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS/MS) on the basis of fragment ions that are characteristic of these isolated compounds. The results of the antidepressant assay suggest that OHPLE significantly improved depression-related behaviors of chronic unpredictable mild stress (CUMS) mice. The observed changes in these mice after OHPLE treatment were an increased sucrose preference index, reduced feeding latency, prolonged tail suspension time, and upregulated expression of brain-derived neurotrophic factor (BDNF). The details of the phytochemicals and the antidepressant effect of OHPLE are reported here for the first time. This study indicates that the OHPL, enriched in flavone C-glycosides, is a new resource that might be potentially applied in the field of nutraceuticals (or functional additives) with depression-regulating functions.

Antioxidant and Antimelanogenic Activities of Compounds Isolated from the Aerial Parts of Achillea alpina L

Achillea alpina is widely distributed in Korea and is often used as a folk medicine for stomach disorders. Although a previous study isolated antioxidant compounds (flavonoid O-glucoside, sesquiterpene) from this plant, no systematic study of its chemical constituents had been reported. The present study aimed to identify the phytochemicals present in a methanol extract of A. alpina, assess their potential antioxidant activities in vitro, and determine their effects on melanogenesis in B16F10 melanoma cells. Column chromatographic separation of aqueous fractions of A. alpina led to the isolation of 17 compounds. The chemical structures of these compounds were determined using spectroscopic data from electrospray ionization-mass spectrometry and nuclear magnetic resonance. To the best of our knowledge, the present study is the first to identify compounds 2-10 and 12-17 in A. alpina. Furthermore, compound 6 possessed powerful antioxidant activity, while compound 15 suppressed intracellular tyrosinase activity and thus reduced melanogenesis in B16F10 cells. Therefore, our research suggested that these naturally occurring compounds have the potential to reduce oxidative stress and promote skin whitening. Further investigations will be required to elucidate the mechanisms underlying the antioxidant and antityrosinase activities of these compounds.

Antioxidant capacity of phenolics in Camellia nitidissima Chi flowers and their identification by HPLC Triple TOF MS/MS

Camellia nitidissima Chi (CNC) is a valuable medicinal and edible plant in China. In this study, CNC flowers were extracted with 95% ethanol, then partitioned into dichloromethane, ethyl acetate, n-butanol, and water fractions, with the antioxidant capacity of flavonoids and other phytochemicals in CNC flowers investigated for the first time. Results showed that the ethyl acetate fraction exhibited the strongest antioxidant capacity and highest total phenolic content (TPC) compared with the other fractions. Furthermore, in the ethyl acetate fraction, the 50% effective concentrations (EC₅₀) of ABTS⁺ and DPPH radical scavenging activities were 64.24 ± 1.80 and 78.80 ± 0.34 μg/mL, respectively, and the ferric reducing antioxidant power (FRAP) was 801.49 ± 2.30 μM FeSO₄ at 1,000 μg/mL. Pearson’s correlation coefficients and principal component analyses (PCA) for the TPC and antioxidant capacity of the five fractions indicated that the phenolic compounds were the major antioxidant constituents in the flowers. To exploit the antioxidants in CNC flowers, 21 phenolic compounds in the ethanolic extract fraction were identified by HPLC Triple TOF MS/MS, next, 12 flavonoids were isolated and elucidated, of which compounds 1–5 showed potent antioxidant capacity. In addition, the potential structure-activity relationship among these 12 flavonoids showed that (1) the o-catechol group in the B-ring was primarily responsible for the antioxidant capacity of flavonoids and (2) steric hindrance, produced by glycosides and other groups, could reduce the antioxidant capacity of the flavonoids.

Anti-allergic and Cytotoxic Effects of Sesquiterpenoids and Phenylpropanoids Isolated from Magnolia biondii

Ten sesquiterpenoids (1-10) and six phenylpropanoid derivatives (11-16) were isolated from the flower buds of Magnolia biondii Pamp. Their structures were determined by 1D- and 2D-NMR spectroscopy, mass spectrometry, and optical rotation. To evaluate their anti-allergic properties, the inhibitory effect of each isolate (1-16) on interleukin-2 (IL-2) gene expression was examined in Jurkat T cells. Among the isolated compounds, three sesquiterpenoids (2, 5, and 7) and two monoterpenoids (12 and 13) strongly inhibited IL-2 production in Jurkat T cells. Four compounds, (-)-parthenolide (2), eudesm-4(15)-eno-1β,6α-diol (5), biondinin D (12), and tiliroside (16), showed cytotoxicity against Jurkat T cells. In addition, (-)-parthenolide (2) exhibited cytotoxicity against the human cervical cancer HeLa cell line, the human breast cancer MCF-7, and human promyelocytic leukemia HL-60 cell lines.

Phenylanthraquinones and flavone-C-glucosides from the disjunct Bulbinella in New Zealand

The genera Bulbine, Bulbinella and Kniphofia produce phenylanthraquinones and are mostly found in southern Africa, although a disjunct group of Bulbinella species endemic to New Zealand also contain phenylanthraquinones as reported herein. The sub-Antarctic megaherb B. rossii yielded sulphated phenylanthraquinones, including a phenylanthraquinone found to carry a sulphated glycoside substituent, 4'-O-demethylknipholone-4'-β-D-xylopyranosyl-3″-sulphate. A sensitive HPLC method was used to analyse 5 of the 6 New Zealand Bulbinella species, all of which contained phenylanthraquinones. Leaves and roots had different profiles, but species were not distinct. Roots were rich in sulphated and free phenylanthraquinones (0.27 ± 0.09% dry wt), whereas leaves typically only contained free knipholone (0.14 ± 0.01%). Localisation of phenylanthraquinones to the stele and peel was observed in roots. Two flavone-C-glucosides were found in leaves of Bulbinella.

Chemical Constituents of the Leaves of Tussilago farfara and their Aldose Reductase Inhibitory Activity

The inhibitory activity of 37 medicinal plant extracts against aldose reductase (AR) activity was evaluated. The most potent AR inhibitory activity was found in the MeOH extract of the leaves of Tussilago farfara (Compositae). Enzyme assay-guided fractionation of the extract led to the isolation of a new flavonoid glycoside, kaempferol 3- O-[3,4- O-(isopropylidene)-α-L-arabinopyranoside] (1), along with 15 known compounds (2–16), of which 3, 5, 13, 15, and 16 were isolated from T. farfara for the first time. The structures of 1–16 were elucidated based on MS and NMR data. Dicaffeoylquinic acid derivatives (7–12) showed potent AR inhibitory activity with IC50 values ranging from 0.58 to 5.38 μM, whereas flavonoid glycosides 1, 3, 5, and 6 showed weak inhibitory activity with IC50 values of 13.9, 15.1, 13.3, and 14.1 μM, respectively.

New Flavonol Glucuronides from the Flower Buds of Syzygium aromaticum (Clove)

Repeated chromatography of the EtOAc-soluble fraction from the 70% EtOH extract of the flower buds of Syzygium aromaticum (clove) led to the isolation and characterization of four new flavonol glucuronides, rhamnetin-3-O-β-d-glucuronide (1), rhamnazin-3-O-β-d-glucuronide (2), rhamnazin-3-O-β-d-glucuronide-6″-methyl ester (3), and rhamnocitrin-3-O-β-d-glucuronide-6″-methyl ester (4), together with 15 flavonoids (5-19) having previously known chemical structures. The structures of the new compounds 1-4 were determined by interpretation of spectroscopic data, particularly by 1D- and 2D-NMR studies. Six flavonoids (6, 7, 9, 14, 18, and 19) were isolated from the flower buds of S. aromaticum for the first time in this study. The flavonoids were examined for their cytotoxicity against human ovarian cancer cells (A2780) using MTT assays. Among the isolates, pachypodol (19) showed the most potent cytotoxicity on A2780 cells with an IC50 value of 8.02 μM.

Three new iridoids from two Viburnum species

Three new iridoids, 10-deacetyl suspensolide A aglycone (1), 7-deacetyl suspensolide A aglycone (2), and 7,10-dideacetyl suspensolide A aglycone (3), were isolated from two species of Viburnum. Their structures were elucidated on the basis of spectroscopic methods, including 1D and 2D NMR techniques. Compound 2 exhibited moderate anti-inflammatory activity against NO production in LPS-stimulated RAW 264.7 cells with IC50 of 17.2 μM.

Grewialin and optivanin new constituents from the stem bark of Grewia optiva Drummond ex Burret (Tiliaceae)

Studies on the chemical constituents from the stem bark of Grewia optiva have led to the isolation of two new compounds, grewialin (1) and optivanin (2), along with three known constituents which were hitherto unreported from this species. The structures of the new constituents have been elucidated by spectral studies including 1D and 2D NMR experiments (HSQC, HMBC, COSY, NOESY and J-resolved) as well as HR EI-MS spectroscopic data analysis, as 2S*-(3-hydroxy-4-methoxyphenyl)-3R*-methyl-2H-[1,4]-dioxin [2,3]-chromen-7(3H)-one (1); a coumarinolignan and 3-hydroxy-1-(3-hydroxy-4-methoxyphenyl) propan-1-one (2). The known compounds were identified as β-sitosterol, stigmasterol and lupeol by comparing their spectral data with those reported in the literature.

Ethnic uses, pharmacological and phytochemical profile of genus Grewia

A number of species of genus Grewia have been used as medicinal agents to treat several diseases. This review based on 45 literary sources discusses the current knowledge of traditional uses, chemistry, biological effects, and toxicity of different species of this genus. Triterpenoids, steroids, glycosides, flavones, lignans, phenolics, alkaloids, lactones, anthocyanins, flavones, and organic acids have been isolated from various species of this genus. The extracts and preparations from the various plants, which are expectantly safe, exhibited various biological effects, e.g. anti-oxidant, anti-bacterial, hepatoprotective, anti-inflammatory, anti-emetic, anti-malarial, analgesic, and anti-pyretic activities.

Antioxidant flavonol glycosides from Elaeocarpus serratus and Filicium decipiens

Chemical investigation of the leaves of Elaeocarpus serratus yielded myricitrin (1), mearnsetin 3-O-β-D-glucopyranoside (2), mearnsitrin (3), tamarixetin 3-O-α-L-rhamnopyranoside (4) and the fruits of Filicium decipiens yielded three flavonol glycosides, kaempferol 3-O-rutinoside (5), kaempferol 3-O-robinobioside (6) and trifolin (7). Compound 1 showed strong antioxidant activity against DPPH.

Aldose-reductase- and protein-glycation-inhibitory principles from the whole plant of Duchesnea chrysantha

Ellagic acid (1), 3,3'-di-O-methylellagic acid (2), 3,3',4-tri-O-methylellagic acid (3), isovitexin (4), kaempferol 3-O-beta-D-glucuronide methyl ester (5), quercetin 3-O-alpha-L-arabinopyranosyl-(1-->6)-beta-D-galactopyranoside (6), ursolic acid, pomolic acid, tormentic acid, euscaphic acid, euscaphic acid 28-O-beta-D-glucopyranoside, and maslinic acid were isolated from the AcOEt- and BuOH-soluble MeOH extract of Duchesnea chrysantha (whole plant). The isolates were subjected to in vitro bioassays to evaluate their inhibitory activity on rat-lens aldose reductase (RLAR) and formation of advanced glycation end products (AGEs). The ellagic acids and flavonoids, compounds 1-6, exhibited moderate inhibitory effects on RLAR. However, compounds 1 and 4-6 showed excellent inhibitory activities towards the formation of AGEs. This is the first report that 4 and 6 exhibit inhibitory activity towards AR and AGEs formation.