Flavonoids of Calligonum polygonoides and their cytotoxicity

Context Calligonum polygonoides L. subsp. comosum L’ Hér. (Polygonaceae), locally known as “arta”, is a slow-growing small leafless desert shrub.

Objective Isolation, structure elucidation and evaluation of cytotoxic activity of flavonoids from C. polygonoides aerial parts.

Materials and methods Flavonoids in the hydroalcoholic extract of the of C. polygonoides were isolated and purified using column chromatography and preparative HPLC. The structures of the isolated flavonoids were elucidated on the basis of spectroscopic data including 2D NMR techniques. The cytotoxic activity of the isolated flavonoids (6.25, 25, 50 and 100?μg/mL) was evaluated against liver HepG2 and breast MCF-7 cancer cell lines using sulphorhodamine-B assay.

Results A new flavonoid, kaempferol-3-O-β-D-(6″-n-butyl glucuronide) (1), and 13 known flavonoids, quercetin 3-O-β-D-(6″-n-butyl glucuronide) (2), kaempferol-3-O-β-D-(6″-methyl glucuronide) (3), quercetin-3-O-β-D-(6″-methyl glucuronide) (4), quercetin-3-O-glucuronide (5), kaempferol-3-O-glucuronide (6), quercetin-3-O-α-rhamnopyranoside (7), astragalin (8), quercetin-3-O-glucopyranoside (9), taxifolin (10), (+)-catechin (11), dehydrodicatechin A (12), quercetin (13), and kaempferol (14), were isolated from the aerial parts of C. polygonoides. Quercetin showed significant cytotoxic activity against HepG2 and MCF-7 cell lines with IC₅₀ values of 4.88 and 0.87?μg/mL, respectively. Structure–activity relationships were analyzed by comparing IC₅₀ values of several pairs of flavonoids differing in one structural element.

Discussion and conclusion The activity against breast cancer cell lines decreased by glycosylation at C-3. The presence of 2,3-double bond in ring C, carbonyl group at C-4 and 3’,4’-dihydroxy substituents in ring B are essential structural requirements for the cytotoxic activity against breast cancer cells.     

Bioactive non-sterol triterpenoid from Streblus asper: microwave-assisted extraction,HPTLC profiling,computational studies and neuro-pharmacological evaluation in BALB/c mice

Context: In folk medicine, the stem bark of Streblus asper Lour. (Moraceae) has been reported to possess anticonvulsant activity. However, no systematic/scientific validation is available.

Objective This study explores the constituents in the stem bark, their biosassy-guided isolation and their efficacy in neuro-pharmacological disorders, for validating the traditional claims.

Materials and methods: Microwave-assisted extraction (MAE) technique was employed to obtain the crude extract. The n-hexane, dichloromethane and aqueous fractions were prepared and phytoconstituents were ascertained by phytochemical tests. The isolated compound, betulin, was characterized by different physicochemical and spectral methods, including HPTLC. Finally, neuro-pharmacological evaluations were conducted at 100, 200, 400?mg/kg b.w., p.o. (25, 50, 100?mg/kg b.w. for betulin) doses in BALB/c mice.

Results: The n-hexane fraction (400?mg/kg), and isolated compound betulin (100?mg/kg), showed maximum anticonvulsant activity in maximal electroshock (87.84% and 85.14% seizure inhibition), and isoniazid induced convulsion models (88.85% and 83.18% seizure inhibition), respectively. A dose-dependent attenuation of epileptic seizures was observed, probably through GABArgic mechanism of anticonvulsant action. Moreover, the antidepressant study was also conducted using behavioural models and the results expound that n-hexane and dichloromethane fractions (400?mg/kg) significantly reduced the duration of immobility, as compared to the control.

Discussion and conclusion: This study reports some novel aspects like applying an environmentally benign/green approach of MAE, neuro-pharmacological screening and use of docking studies, for the first time, on the plant S. asper. The findings present a rational explanation for its use in traditional medicine, for the management of neuro-pharmacological disorders.     

Screening of antidepressant activity and estimation of quercetin from Coccinia indica using TLC densitometry

Abstract

Context: Coccinia indica Naud (Cucurbitaceae) has been traditionally used for the treatment of depression but these claims have not been validated.

Objectives: The objective of this study is to investigate antidepressant activity of various extracts and fractions of C. indica aerial parts, and to estimate content of quercetin in the plant using TLC densitometry.

Materials and methods: Coccinia indica aerial parts were successively extracted using solvents in increasing order of polarity, namely n-hexane, chloroform, methanol, and water. Various extracts were evaluated for antidepressant activity at doses of 200 or 400?mg/kg, p.o., upon acute administration in mice using the forced swim test (FST). The bioactive extract was partitioned successively using solvents in increasing order of polarity, namely n-hexane, ethyl acetate, and n-butanol. All fractions were also screened for antidepressant activity at doses of 25 or 50?mg/kg, p.o., upon acute administration in mice.

Results: The methanol extract significantly reduced the duration of immobility in FST at dose of 400?mg/kg without affecting locomotor activity in open field test, thus, confirmed its antidepressant activity, which was statistically equivalent to the standard drug (imipramine, 15?mg/kg, i.p.). Ethyl acetate fraction (EAF) exhibited antidepressant activity at 50?mg/kg. Comparative TLC fingerprint studies confirmed the presence of quercetin in methanol extract and EAF. Quercetin was used as a chemical marker to standardize C. indica aerial parts using the validated TLC densitometric method, and the content of quercetin was found to be 0.00172% w/w.

Conclusions: The present studies scientifically validated traditional claims of C. indica for antidepressant activity.     

Schistosomicidal evaluation of flavonoids from two species of Styrax against Schistosoma mansoni adult worms

Context: Schistosomiasis is a major health problem worldwide. Thus, the search for new schistosomicidal agents from natural sources can provide prototypes for drug discovery.

Objective: The present study investigated the chemical composition of the EtOAc fractions of Styrax pohlii Pohl (Styracaceae) (EF-SP) aerial parts and S. camporum A. DC. leaves (EF-SC), as well as schistosomicidal activities against Schistosoma mansoni adult worms, which have not yet been studied.

Materials and methods: The crude ethanol extracts of S. camporum leaves and S. pohlii aerial parts (EE-SC and EE-SP) were partitioned with n-hexane, EtOAc, and n-BuOH. The EtOAc fractions were purified by preparative HPLC. The crude extracts, EtOAc fractions and pure compounds were tested against S. mansoni adult worms in vitro.

Results: The purification procedure resulted in the isolation of kaempferol-3-O-(2′′,4′′-di-O-(E)-p-coumaroyl)-β-d-glucopyranoside (1), kaempferol-3-O-(2′′,6′′-di-O-(E)-p-coumaroyl)-β-d-glucopyranoside (2), quercetin (3), and kaempferol (4). The bioassay results indicated that EE-SC, EF-SC, EF-SP, and compounds 2 and 4 are able to separate coupled S. mansoni adult worms. Additionally, EE-SC, EF-SP, and compound 4 killed the adult schistosomes in vitro at 100 µg/mL and 100 µM.

Discussion and conclusion: This is the first time that the presence of compounds 1–2 in S. pohlii and 3–4 in S. camporum has been reported. Additionally, biological results indicated that S. pohlii and S. camporum have great potential as a source of active compounds.     

Phenolic and Terpenoid Constituents from the Sri Lankan Medicinal Plant Osbeckia aspera.

Abstract

A crude aqueous acetone extract of Osbeckia aspera. Blume (Melastomataceae), a plant from Sri Lanka used traditionally to treat liver disease, was fractionated by column and preparative paper chromatography, and the fractions were analyzed by high-performance liquid chromatography (HPLC) using diode array and mass spectrometric detection. Phenolic acids (gallic, protocatechuic, and ellagic acid), flavonol glycosides [quercetin 3-O.-β-galactopyranoside, quercetin 3-O.-β-glucopyranoside, kaempferol 3-O.-β-glucopyranoside, and kaempferol 3-O.-(6″-O.-p.-coumaroyl-β-glucopyranoside) (tiliroside)] and flavonol aglycones (quercetin and kaempferol) were identified by comparison of their retention times, UV and MS spectra with those of authentic standards. Five compounds from a methanol extract were identified by NMR spectroscopy as the flavonol glycosides, quercetin 3-O.-(3″-O.-acetyl-β-galactopyranoside) and kaempferol 3-O.-[2″,6″-di-O.-(E.,E.)-p.-coumaroyl-β-glucopyranoside], and the norsesquiterpenoids 6,9-dihydroxy-4,7-megastig-madien-3-one, 9-hydroxy-4,7-megastigmadien-3-one and 9-hydroxy-4-megastigmen-3-one. A crude water extract, 50% acetone extract and fractions from this extract, a 100% methanol extract, and three of the phenolic acids in the fractions were tested for in vitro. hepatoprotective activity against bromobenzene and 2,6-dimethyl-N.-acetyl p.-quinoneimine toxicity to HepG2 liver-derived cells. The crude water extract showed protective activity against both liver toxins, whereas the fractions and compounds were more protective against 2,6-dimethyl-N.-acetyl p.-quinoneimine than bromobenzene. Of the three phenolic acids present in the extracts that were tested, gallic and protocatechuic acids were more active at protecting the liver cells from the two toxic compounds than ellagic acid.     

A new active compound against kidney deficiency from the fruits of Rubus corchorifolius

Constituents of the fruits of Rubus corchorifolius were investigated. A new compound, namely rubusin A (1), along with three known compounds, was isolated and characterized. Among them, the new compound exhibited significant activity against kidney deficiency, and quercetin and kaempferol were isolated from the fruits of R. corchorifolius for the first time.     

Free radical scavengers from the aerial parts of <Emphasis Type="Italic">Euphorbia petiolata</Emphasis>

Reversed-phase preparative high-performance liquid chromatography (HPLC) of the methanol extract of the aerial parts of Euphorbia petiolata Banks & Soland, an endemic Iranian medicinal plant, yielded ten free radical scavengers including eight flavonoid glycosides myricetin 3-O-glucoside (1), kaempferol 3-O-(2-O-galloyl)-glucoside (2), myricetin 3-O-rhamnoside (3), quercetin 3-O-glucoside (4), kaempferol 3-O-glucoside (5), quercetin 3-O-rhamnoside (6), kaempferol 3-O-rhamnoside (7), and quercetin 3-O-rutinoside (10), a coumarin esculetin (8) and a phenylpropanoid 2-hydroxydihydrocinnamic acid (9). The structures of these compounds were elucidated conclusively by spectroscopic means and also by direct comparison of their spectroscopic data with respective published data. The free radical scavenging properties of these compounds were assessed by the 2,2-diphenyl-1-picrylhydrazyl assay.     

Flavonoids,cytotoxic, antioxidant and antibacterial activities of Evax pygmaea

Context: Phytochemical study and biological potential of Evax pygmaea (L.) Brot. (Asteraceae) are reported for the first time.

Objective: To identify the secondary metabolites of Evax pygmaea and to determine its antioxidant, antibacterial and cytotoxic activities.

Materials and methods: Dried aerial parts (1?kg) were macerated in 70% MeOH (5?L) during 72?h. The concentrated hydromethanolic extract was subjected to extractions with chloroform (3?×?300?mL), ethyl acetate (3?×?300?mL) and n-butanol (3?×?300?mL), successively. VLC of combined ethyl acetate (EAEP) and n-butanol (BEP) fractions was followed by column purifications. Antioxidant activity was investigated using DPPH, CUPRAC, and metal chelating, β-carotene/linoleic acid and ABTS assays. Agar method was used in the antibacterial study. Cytotoxic activity was determined by Brine shrimp lethality test in DMSO and ethanol, at varying concentrations (2, 1 and 0.2%) and (1, 0.2 and 0.1%) successively.

Results: Quercetin (1), isorhamnetin 3-O-β-d-xyloside (2), isorhamnetin 3-O-β-d-glucoside (3), quercetin 3-O-β-d-glucoside (4), quercetin 7-O-β-D-glucoside (5), patuletin 3-O-β-d-glucoside (6) were isolated from for the first time from Evax genus. The EAEP was the most active in ABTS (IC₅₀: <3.125?μg/mL) assay whereas the BEEP exhibited the highest activity in the β-carotene/linoleic acid assay (IC₅₀: <3.125?μg/mL). The EAEP and BEP exhibited good antibacterial activity (MIC: 40–80 µg/mL). The plant did not show any toxicity (LD₅₀>80 µg/mL).

Discussion and conclusions: Six flavonoids were isolated for the first time from Evax pygmaea which exhibited good antioxidant and antibacterial activities.     

Isolation of major phenolics from Launaea spinosa and their protective effect on HepG2 cells damaged with t-BHP

Context: Some Launaea species (Asteraceae) are used traditionally to treat liver oxidative stress.

Objective: The present study investigates the protective effects of isolated compounds from Launaea spinosa Sch. Bip. (Asteraceae) against oxidative stress on t-BHP-induced HepG2 cells.

Materials and methods: Major phenolic content from flowering aerial parts of L. spinosa was isolated and identified. The protective effects of isolated compounds (10 and 20?μM) against oxidative stress induced by tert-butyl hydroperoxide (t-BHP) in HepG2 cells were investigated through the measurement of aspartate aminotransferase (AST), alanine transaminase (ALT), and superoxide dismutase (SOD) levels.

Results: A new phenolic compound identified as 2,3-diferulyl R,R-(+) methyl tartrate (6), in addition to five known metabolites, esculetin (1), esculetin-7-O-d-glucoside (cichoriin) (2), fertaric acid (3), acacetin-7-O-d-glucoside (4), and acacetin-7-O-d-glucuronic acid (5), were isolated. Oxidant-induced damage by 200?μM t-BHP in HepG2 cells was inhibited by compounds 1, 4, and 5 (10 and 20?μM), or quercetin (10?μM; positive control). The protective effects of compounds 1, 4, and 5 were associated with decreasing in AST, ALT, and SOD levels. Compound 4 (20?μM) decreased the AST level from 128.5?±?13.9 to 7.9 ±1.8?U/mL. Meanwhile, compound 1 (20?μM) decreased ALT activity from 20.3?±?7.0 to 7.6?±?2.4?U/mL, while compound 5 decreased SOD levels from 41.6?±?9.0 to 28.3?±?3.4?mU/mg.

Conclusion: The major phenolic compounds isolated from L. spinosa displayed a significant cytoprotective effect against oxidative stress, leading to maintenance of the normal redox status of the cell.     

Flavonol glycosides from the aerial parts of<Emphasis Type="Italic">Aceriphyllum rossii</Emphasis> and their antioxidant activities

The methanol extract obtained from the aerial parts ofAceriphyllum rossii (Saxifragaceae) was fractionated into ethyl acetate (EtOAc),n-BuOH and H₂O layers through solvent fractionation. Repeated silica gel column chromatography of EtOAc andn-BuOH layers afforded six flavonol glycosides. They were identified as kaempferol 3-O-β-D-glucopyranoside (astragalin,1), quercetin 3-O-β-D-glucopyranoside (isoquercitrin,2), kaempferol 3-O-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside (3), quercetin 3-O-α-L-rhamnopyranosyl (1→6)-β-D-glucopyrano-side (rutin,4), kaempferol 3-O-[α-L-rhamnopyranosyl (1→4)-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside] (5) and quercetin 3-O-[α-L-rhamnopyranosyl (1→4)-α-L-rhamnopyranosyl (1→6)-β-D-glucopyranoside] (6) on the basis of several spectral data. The antioxidant activity of the six compounds was investigated using two free radicals such as the ABTS free radical and superoxide anion radical. Compound1 exhibited the highest antioxidant activity in the ABTS2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging method. 100 mg/L of compound1 was equivalent to 72.1±1.4 mg/L of vitamin C, and those of compounds3 and5 were equivalent to 62.7±0.5 mg/L and 54.3±1.3 mg/L of vitamin C, respectively. And in the superoxide anion radical scavenging method, compound5 exhibited the highest activity with an IC₅₀ value of 17.6 ± 0.3 μM. In addition, some physical and spectral data of the flavonoids were confirmed.     

Anti-inflammatory,anti-cholinergic and cytotoxic effects of Sida rhombifolia

Context: Sida (Malvaceae) has been used as a traditional remedy for the treatment of diarrhoea, malarial, gastrointestinal dysentery, fevers, asthma and inflammation.

Objectives: This study evaluates the anti-inflammatory, cytotoxic and anti-cholinergic activities of Sida rhombifolia Linn. whole plant for the first time.

Materials and methods: S. rhombifolia whole plant was extracted by n-hexane, ethyl acetate and methanol using Soxhlet apparatus. The plant extracts were evaluated for their antioxidant (DPPH, FIC and FRAP), anti-inflammatory (NO and protein denaturation inhibitions), cytotoxic (MTT) and anti-cholinesterase (AChE) properties in a range of concentrations to obtain IC₅₀ values. GC-MS analysis was carried out on the n-hexane extract.

Results and discussion: The ethyl acetate extract exhibited the most significant antioxidant activities by scavenging DPPH radicals and ferrous ions with EC₅₀ of 380.5 and 263.4?μg/mL, respectively. In contrast, the n-hexane extract showed the strongest anti-inflammatory activity with IC₅₀ of 52.16 and 146.03?μg/mL for NO and protein denaturation inhibition assays, respectively. The same extract also revealed the strongest effects in anti-cholinesterase and cytotoxic tests at the concentration of 100?μg/mL, AChE enzyme inhibition was 58.55% and human cancer cells, SNU-1 and Hep G2 inhibition was 68.52% and 47.82%, respectively. The phytochemicals present in the n-hexane extract are palmitic acid, linoleic acid and γ-sitosterol.

Conclusions: The present study revealed that the n-hexane extract possessed relatively high pharmacological activities in anti-inflammation, cytotoxicity and anti-cholinesterase assays. Thus, further work on the detail mechanism of the bioactive phytochemicals which contribute to the biological properties are strongly recommended.     

Antimicrobial acylphloroglucinols from the leaves of Rhodomyrtus tomentosa

Phytochemical study on the leaves of Rhodomyrtus tomentosa resulted in the isolation of fourteen compounds including a new acylphloroglucinol, named tomentosone C (1), and a new flavonol glycoside, namely myricetin-3,7,3′-trimethyl ether-5′-O-β-glucopyranoside (2). Their structures were characterized by spectral data interpretation for new structures and in comparison with published data for known compounds. The antimicrobial activity evaluation revealed that 1 and the known acylphloroglucinol rhodomyrtone (3) exhibited significant antimicrobial activity with MIC 3.66 and 1.83 μg ml^?1, respectively, toward Staphylococcus aureus, responsible for the antimicrobial activity observed with the n-hexane and EtOAc-soluble fraction of the ethanol extract of R. tomentosa leaves.     

Antimicrobial effect of the extracts from Hypericum perforatum against oral bacteria and biofilm formation

Context: One traditional medicines, Hypericum perforatum L. (Hypericaceae), possesses several beneficial effects against depression, ulcers, dyspepsia, abdominal pains, burns, bacterial infections, migraine headaches, and sciatica.

Objective: The present study investigates the antimicrobial activity of the ethanol extract (HP-EtOH) of H. perforatum and its sub-extracts, namely n-hexane (HP-hexane), chloroform (HP-CHCl₃), ethyl acetate (HP-EtOAc), n-butanol (HP-n-BuOH), and water (HP-H₂O) extracts, against Streptococcus mutans, S. sobrinus, Lactobacillus plantarum, and Enterococcus faecalis.

Materials and methods: For the evaluation of the antimicrobial activity, flowering aerial parts of H. perforatum were extracted with EtOH and then this extract was fractionated to obtain five sub-extracts in different polarities. Antimicrobial activities of HP-EtOH and its sub-extracts against Streptococcus mutans, S. sobrinus, L. plantarum, and E. faecalis were assessed by using colorimetric micro-well dilution at concentration ranges of 64–0.5?μg/ml as well as resazurin microplate and modified microtiter-plate assays between the ranges of 100 and 0.78125?μg/ml.

Results: According to the results of the present study, HP-H₂O sub-extract displayed strong antibacterial activity (MIC values 8?μg/mL) against S. sobrinus and L. plantarum, and exerted moderate activity against S. mutans and E. faecalis at 32 and 16?μg/mL concentrations, respectively. Other sub-extracts also demonstrated antimicrobial activity against S. sobrinus at a concentration of 16?μg/mL. HP-EtOAc and HP-n-BuOH showed antimicrobial activity against L. plantarum and HP-EtOAc and HP-H₂O were also active against E. faecalis at the same concentrations (16?μg/mL).

Conclusion: According to the results, we suggest that H. perforatum could be employed as a natural antibacterial agent in oral care products.     

Cytotoxic withanolides from the leaves of Moroccan Withania frutescens

Abstract

Context: Withania species are a rich source of interesting phytochemical substances (withanolides) which have shown several biological properties.

Objective: To investigate the cytotoxic potential of Withania frutescens (L.) Pauquy (Solanaceae) leaf extracts and isolated active compounds against cultured tumor cell lines.

Materials and methods: The crude methanol extract of W. frutescens leaves was partitioned with dichloromethane, ethyl acetate and n-butanol. MeOH extract and its fractions were tested for their cytotoxic activity against cancer cell lines (HepG2 and HT29) using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. Bioassay-guided fractionation was performed for the active CH₂Cl₂ fraction employing column chromatography and preparative high-performance liquid chromatography. Structural elucidation of the isolated active compounds was carried out mainly by 1D and 2D NMR and mass spectrometry. The compounds were then tested for their cytotoxic activity.

Results: The CH₂Cl₂ fraction was the most active against HT29 cell line. The fractionation procedure resulted in the isolation of 4β,17α,27-trihydroxy-1-oxo-22-R-witha-2,5,24-trienolide (1), 5β,6β-epoxy-4β,17α,27-trihydroxy-1-oxowitha-2,24-dienolide (2) and 2,3-dihydroxywithaferin A-3β-O-sulfate (3). The latter exhibited the strongest cytotoxic activity against HT29 cancer cell lines (IC₅₀ of 1.78?±?0.09?µM) which was comparable to that of 5-fluorouracil (5-FU) used as the positive antimitotic control.

Discussion and conclusion: Compounds 2 and 3 were isolated from W. frutescens for the first time. Data obtained suggest that the sulfated steroidal lactone (3) can be considered as a compound with potential application in the new anticancer drugs development field.     

Foetithiophenes C-F,thiophene derivatives from the roots of Ferula foetida

Abstract

Context: Ferula foetida Regel (Apiaceae) is an Iranian medicinal plant with various biological activities including antispasmodic and anthelmintic.

Objective: The sulfur compounds from the roots of F. foetida were isolated and characterized to test their cytotoxic and antimicrobial activities.

Materials and methods: The methanolic extract of the roots of F. foetida was fractionated using silica column chromatography. The components of each fraction were further purified using RP-HPLC. Their structures were elucidated by 1- and 2-D NMR spectroscopy as well as HREIMS. Their cytotoxic and antimicrobial activities were evaluated using Alamar Blue assay and broth microdilution method, respectively.

Results: Four new thiophene derivatives, namely foetithiophenes C-F (3–6), together with four known compounds, foetithiophenes A (1) and B (2), coniferaldehyde, and sinapic aldehyde, were isolated from the roots of F. foetida. Antimicrobial activities were observed in particular against the Gram-positive bacteria. The best antimicrobial activity was observed for compound 6 against B. cereus with a MIC value 50?µg/mL. The tested compounds did not show cytotoxic properties against MCF-7 and K562 cells.

Conclusion: Four new thiophene derivatives including foetithiophenes C-F (3–6) were characterized from the roots of F. foetida. Foetithiophene F (6) exhibited the most potent activity against the Gram-positive bacteria B. cereus.     

Antimicrobial activities of some Thai traditional medical longevity formulations from plants and antibacterial compounds from Ficus foveolata

Context: Medicinal plants involved in traditional Thai longevity formulations are potential sources of antimicrobial compounds.

Objective: To evaluate the antimicrobial activities of some extracts from medicinal plants used in traditional Thai longevity formulations against some oral pathogens, including Streptococcus pyogenes, Streptococcus mitis, Streptococcus mutans, and Candida albicans. An extract that possessed the strongest antimicrobial activity was fractionated to isolate and identify the active compounds.

Materials and methods: Methanol and ethyl acetate extracts of 25 medicinal plants used as Thai longevity formulations were evaluated for their antimicrobial activity using disc diffusion (5?mg/disc) and broth microdilution (1.2–2500?µg/mL) methods. The ethyl acetate extract of Ficus foveolata Wall. (Moraceae) stems that exhibited the strongest antibacterial activity was fractionated to isolate the active compounds by an antibacterial assay-guided isolation process.

Results and discussion: The ethyl acetate extract of F. foveolata showed the strongest antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 19.5–39.0 and 39.0–156.2?µg/mL, respectively. On the basis of an antibacterial assay-guided isolation, seven antibacterial compounds, including 2,6-dimethoxy-1,4-benzoquinone (1), syringaldehyde (2), sinapaldehyde (3), coniferaldehyde (4), 3β-hydroxystigmast-5-en-7-one (5), umbelliferone (6), and scopoletin (7), were purified. Among these isolated compounds, 2,6-dimethoxy-1,4-benzoquinone (1) exhibited the strongest antibacterial activities against S. pyogenes, S. mitis, and S. mutans with MIC values of 7.8, 7.8, and 15.6?µg/mL, and MBC values of 7.8, 7.8, and 31.2?µg/mL, respectively. In addition, this is the first report of these antibacterial compounds in the stems of F. foveolata.     

Raddeanalin,a new flavonoid glycoside from the leaves of Salix raddeana Laksh.

A new flavonoid glycoside, diosmetin 7-O-β-D-xylopyranosyl(1–6)-β-d-glucopyranoside, named raddeanalin (1), was isolated from the ethanolic extract of the leaves of Salix raddeana Laksh. together with three known compounds, kaempferol 3-O-glucoside (2), quercetin 3-O-glucoside (3) and quercetin 3-O-rutinoside (4). The structure of new compound was established by the spectral data and chemical properties.     

Chemical constituents from Sedum aizoon and their hemostatic activity

Context: Sedum aizoon L. (Crassulaceae) (SA) is widely used to treat various hemorrhages in folk medicine. However, its hemostatic constituents are not yet clear.

Objective: The chemical constituents of EtOAc fraction from SA and their hemostatic activity were investigated to provide a basis for the application in folk use.

Materials and methods: The chemical constituents were isolated from the aerial parts of SA by column chromatography and identified by IR, MS, and NMR, then tested for hemostatic activity using the capillary method and coagulation assays including blood clotting time in vivo, and prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT) in vitro at concentrations of 300.0, 100.0, and 30.0?µg/mL.

Results: Eleven compounds were identified as p-hydroxybenzoic acid (1), gallic acid (2), protocatechuic acid (3), vallinic acid (4), thymine (5), caffeic acid (6), 5,7-dihydroxy chromone (7), pyrogallol (8), quercetin (9), kaempferol (10), and luteolin (11). This is the first report of compounds 3–8 being isolated from this plant. Compounds 2 (300.0 and 100.0?µg/mL), 4 (100.0?µg/mL), and 11 (100.0 and 30.0?µg/mL) significantly reduced the clotting time (p?Discussion and conclusion: SA produced hemostatic activity possibly related to the presence of gallic acid, vallinic acid, and luteolin, which may be potent candidates of hemostatic drug.     

Antiproliferative and antimicrobial activities of alkylbenzoquinone derivatives from Ardisia kivuensis

Context: Medicinal plants are continuously screened for their pharmacological properties. Despite the diversity and the numerous phytochemicals found in Ardisia (Myrsinaceae) species, its full biological potential has not been fully explored.

Objective: Four naturally occurring alkylbenzoquinone derivatives, namely ardisiaquinone N (1), ardisiaquinone J (2), ardisiaquinone K (3) and a mixture of ardisiaquinone P (4) and K (3) from Ardisia kivuensis Taton (Myrsinaceae) were investigated in vitro for their cytotoxicity and antimicrobial activity.

Materials and methods: Minimal inhibitory concentration (MIC) was determined using the broth micro-dilution assay. Tumor cells growth inhibition was performed by sulphorhodamine B (SRB) assay while sub-diploid DNA fraction was measured by flow cytometry.

Results: Compounds 1, 2 and 3 showed significant antimicrobial activity against two Gram-positive bacteria and one fungus (with MICs varying between 3.12 and 6.25?µg/ml). The four compounds exhibited remarkable antiproliferative activity against the leukemia cell line TPH-1 with IC₅₀ inhibition values between 2 and 2.1?µg/ml. Cytotoxic activity was found to be related to apoptosis induction.

Discussion and conclusion: These findings suggest that natural compounds herein studied are interesting potential candidates for the development of new therapeutic agents, especially against leukemia and Gram-positive bacterial infections.     

Chemical constituents from the rhizome of Polygonum paleaceum and their antifungal activity

A new compounds neopaleaceolactoside (1), along with nine known compounds phyllocoumarin (2), quercetin (3), quercitrin (4), quercetin-3-methyl ether (5), vincetoxicoside B (6), isoquercitrin (7), kaempferol (8), (-)-epicatechin (9), and chlorogenic acid (10), was isolated from Polygonum paleaceum Wall. Their chemical structures were established based on one-dimensional and two-dimensional nuclear magnetic resonance techniques, mass spectrometry and by comparison with spectroscopic data reported. Some selected compounds were screened for their antifungal activity. Quercetin (3), vincetoxicoside B (6), kaempferol (8), and (-)-epicatechin (9) showed synergistic antifungal activities with the FICI values <0.5. A preliminary structure-activity relationship could be observed that free 3-OH in the structure of flavonoids was important for synergistic antifungal activity.