Bioactive flavones of Sida cordifolia

Two new flavones: 5,7-dihydroxy-3-isoprenyl flavone (1) and 5-hydroxy-3-isoprenyl flavone (2), along with two known compounds β-sitosterol and stigmasterol have been isolated from the chloroform extract of Sida cordifolia. Their structures were established on the basis of spectroscopic analysis. Flavones were tested for their analgesic and anti-inflammatory activity.     

A flavonoid with cytotoxic activity and other constituents from Centaurea africana

A new acylated flavonoid glucoside named algerianin 1 and a new as natural product, 4′-methyl gossypetin 2, together with 10 known compounds, isovanillic acid ethyl ester, β-sitosterol, β-sitosterol 3-O-glucoside, a mixture of α and β-amyrin, 3′-hydroxyflindulatin, chrysoeriol, jaceidin, corniculatusin and centaurein were isolated from the ethanolic extract of the flowering and aerial parts of Centaurea africana Lamk var. africana (Bonnet) M., an endemic species to Algeria and Tunisia collected from El-Kala in the eastern Algeria. The structures were established by chemical and spectral analysis, mainly HREIMS, ESIMS, UV and NMR experiments (GOESY, COSY, ROESY, HSQC and HMBC). Algerianin showed cytotoxicity against the human myeloid leukaemia cell line HL-60.     

Phytochemistry and antiglycation activity of Aloe sinkatana Reynolds

A new anthraquinone along with 10 known compounds were isolated from the leaves of Aloe sinkatana Reynolds (Aloaceae), and their structures were elucidated as the new compound 2,8-dihydroxy-6-(hydroxymethyl)-1-methoxyanthracene-9,10-dione (1) and the known compounds Aloe-emodin (2), feralolide (3), 1-hydroxy-5-methoxy-3-methyl-9,10 dihydroanthracene 9,10-dione (4), β-sitosterol (5), β-sitosterol with glycosidic bond (6), microdontin (7), homoaloins A (8) and B (9) and aloins A (10) and B (11). Characterization of compounds 1–9 was based on spectral analyses and comparison with reported data, particularly the new compound 1 was identified by 1D- and 2D NMR, mass spectroscopic and X-ray crystallography analyses. Antiglycation activity of the extracts and isolated compounds were carried out using the hemoglobin-δ-gluconolactone and glucose–bovine serum albumin assays. The results obtained showed that MeOH and EtOAc extracts as well as compound 1 showed an inhibitory effect on early stage protein glycation. Compound 1 also showed significant inhibitory effects against glucose-induced advanced glycation end-products.     

Studies on the Chemical Constituents of the Leaves of WTBX]Pseudotaxus chienii (Cheng) Cheng

Fourteen compounds were isolated from the leaves of Pseudotaxus chienii (Cheng) Cheng which is uniquely indigenous to China, and their structures were identified mainly by spectrum analyses. Among them, 13 known compounds were determined as: 2-guaiacylpropane-1, 3-diol (1), vanillic acid (2), 3-methoxy-4-hydroxy cinnamic acid (3). 3. 5-dimethoxy-phenol (4), taxicatin (5), 5-oxymaltol (6), quercetin-3-rhamnoside (7), (±)-catechin (8), ecdysterone (9), β-sitosterol (10), D-glucose (11), (±)-10-nonacosanol (12) and octacosanoic acid (13). All these compounds butβ-sitosterol were isolated from this plant for the first time. Compounds 1 and 6 have never been reported in plant kingdom. Another compound was tentatively established as a new compound, named pseudotaxlactone (14).     

Phenolic acid glycosides from Parmentiera cereifera Seem. (Candle tree)

Two new phenolic acid glycosides, parmentins A (1) and B (2) were isolated from the methanolic extract of the leaves and stems of candle tree (Parmentiera cereifera Seem). These compounds were accompanied by a mixture of β-sitosterol and stigmasterol (3), β-sitosterol glucoside (4), isovanillic acid (5), vanillic acid (6), and p-hydroxybenzoic acid (7). The structures of the isolated compounds were determined on the basis of physical and spectroscopic analyses, including 1D and 2D NMR (¹H, ¹³C, COSY, HSQC and HMBC) and mass spectrometry (HR-ESI-MS).     

Chemical constituents from Potentilla fragarioides L

Phytochemical investigation on Potentilla fragarioides L. has led to the identification of twelve compounds including β-sitosterol (1), β-daucosterol (2), ursolic acid (3), pomolic acid (4), swinhoeic acid (5), (1-p-hydroxy-cis-cinnamoyl)cinnamic acid (6), trans-caffeoylisocitric acid (7), trans-caffeic acid (8), quercetin (9), quercetin-3-O-β-D-glucuronide (10), (+)-catechin (11) and 3-O-methylellagic acid-4′-O-ɑ-L-rhamnopyranoside (12). Among them, compounds 4–7 were first identified from the genus Potentilla. And the other compounds except compounds 8 and 11 were found in Potentilla fragarioides for the first time. Chemotaxonomic significance of these compounds was discussed.     

Chemical composition of Xylopia nitida: Diterpenes and alkaloids

From the roots of Xylopia nitida, were obtained a new natural diterpene, the ent-kaur-16-en-18,19-diol and a new aporphine alkaloid, the 5,6,6a,7-tetrahydro-1-methoxy-(6aS)-4H-benzo[de][1,3]benzodioxolo [5,6-g]quinoline. Some known compounds were also isolated, ent-trachylobane, ent-trachyloban-18,19-diol, ent-trachyloban-18-oic acid, ent-trachyloban-19-oic acid, (−)-xylopine, 1-O-ethyl-β-D-glucopyranose and a mixture of β-sitosterol and stigmasterol. This is the first phytochemical study about X. nitida. In this paper chemotaxonomic significance of these compounds is discussed.     

大果大戟的化学成分

从大果大戟的根部首次分离得到11个化合物。利用波谱方法鉴定为β-香树素(1),β-香树素乙酸酯(2),3β-乙酰化羽扇豆烯醇(3),baccatin(4),2个caffeic mters(5a,5b),棕榈酸-1-甘油酯(6),棕榈酸(7),东莨菪内酯(8),β-谷甾醇(9)和胡萝卜甙(10)。其中5a,5b是第一次在大戟属中得到;并对5a,5b的碳谱和氢谱数据进行了全归属。     

A new tropane alkaloid and other constituents of Erythroxylum rimosum (Erythroxylaceae)

A new tropane alkaloid, named the 7β-acetoxy-3β,6β-dibenzoyloxytropane (1), was isolated from a methanol extract of Erythroxylum rimosum O.E. Schulz leaves. Other known compounds were detected, including quercetin, kaempferol-3-O-α-l-arabinofuranoside, (+)-catechin, epicatechin, quercetin-3-O-α-arabinofuranoside, quercetin-3-O-α-arabinopyranoside, quercetin-3-O-β-arabinopyranoside, quercetin-3-β-glucopyranoside, kaempferol, quercetin-3-O-β-galactopyranoside, β-sitosterol, α-amyrin, β-amyrin, and the ester derivatives of these two amyrins. Compound 1 exhibited weak inhibition of acetylcholinesterase. Structural identification was performed using IR, ESIHRMS and one- and two-dimensional NMR data analyses and confirmed by comparison with literature data.     

α-Glucosidase inhibitory constituents from Chrozophora plicata

Five new secondary metabolites have been isolated from Chrozophora plicata including an acacetin derivative (1), three pyrrole alkaloids plicatanins A–C (2–4, resp.) and the bilactone plicatanone (5). Together with these compounds, the known compounds, β-sitosterol (6), methyl p-coumarate (7), 4-hydroxyphenylacetic acid (8), succinic acid (9), speranberculatine A (10), β-sitosterol-3-O-β-d-glucopyranoside (11) and apigenin-5-O-β-d-glucopyranoside (12) have also been isolated. The structures of isolates 1–12 were established by 1D (¹H, ¹³C) and 2D NMR (HMQC, HMBC, COSY) spectroscopy and mass spectrometry (EIMS, HREIMS, FABMS, HRFABMS). The structure of plicatanin A (3) was further confirmed through single crystal X-ray technique. Compounds 1–12 were evaluated for their inhibitory activity against the enzyme yeast α-glucosidase. The compound 4 was found to be most potent with IC₅₀ value 27.8 μM.     

Beneficial effects of beta-sitosterol on glucose and lipid metabolism in L6 myotube cells are mediated by AMP-activated protein kinase

AMP-activated protein kinase (AMPK) is an energy-sensing enzyme that has been implicated as a key factor for controlling intracellular lipids and glucose metabolism. β-Sitosterol, a plant sterol known to prevent cardiovascular disease was identified from Schizonepeta tenuifolia to an AMPK activator. In L6 myotube cells, β-sitosterol significantly increased phosphorylation of the AMPKα subunit and acetyl-CoA carboxylase (ACC) with stimulating glucose uptake. In contrast, β-sitosterol treatment reduced intracellular levels of triglycerides and cholesterol in L6 cells. These effects were all reversed by pretreatment with AMPK inhibitor Compound C or LKB1 destabilizer radicicol. Similarly, β-sitosterol-induced phosphorylation of AMPK and ACC was not increased in HeLa cells lacking LKB1. These results together suggest that β-sitosterol-mediated enhancement of glucose uptake and reduction of triglycerides and cholesterol in L6 cells is predominantly accomplished by LKB1-mediated AMPK activation. Our findings further reveal a molecular mechanism underlying the beneficial effects of β-sitosterol on glucose and lipid metabolism.     

A cinnamoyl pyrrolidine amide from Piper peepuloides

Analysis of a petrol extract of the leaves of Piper peepuloides resulted in the isolation of a new cinnamoyl pyrrolidine amide characterized as Z-pyrrolidine-1-3-(6-methoxy-1,3-benzodioxol-5-yl)-1-oxo-2-propenyl along with peepuloidin, 2-methoxy-4,5-methylenedioxy-Z-cinnamoyl piperidide, β-sitosterol and β-sitosterol glucoside.     

Long chain esters of Virola species

The esters of n-fatty acids and ω-hydroxy n-fatty acids of β-sitosterol, D-glucose and ferulic acid (trans and cis) as well as β-sitosterol, fatty acids and β-sitosteryl-β-D-glucoside were isolated from three Virola species and identified by optical data and chemical reactions. A novel series of acidic esters derived from C₂₂C₂₉ ω-hydroxy fatty acids and cis- and trans-ferulic acid is reported for the first time. These compounds also occurred as the corresponding diester 1-monoglycerides whereas the ω-hydroxy acids themselves were also present as the corresponding glucosyl esters.     

Chemical constituents from Lespedeza cuneata G. Don (Leguminosae)

Phytochemical investigation of Lespedeza cuneata led to the isolation of seventeen compounds including three steroids (β-sitosterol 1, β-sitosterol-6′-linolenoyl-3-O-β-d-glucopyranoside 3, and β-sitosterol glucoside 13), nine flavonoids (quercetin 4, kaempferol 5, isovitexin 8, hirsutrin 9, nicotiflorin 10, vitexin 11, astragalin 12, trifolin 14, and isorhamnetin 17), two phenolics (benzyl-β-d-glucopyranoside 7 and homovanillyl alcohol 16), one carotenoid (loroxanthin 2), one lignin (7R,8S–dihydrodehydrodiconiferyl alcohol 15), and one hexose (pinitol 6) on the basis of their spectroscopic data. Among these compounds, 2, 3, 7, 15 and 16 were reported for the first time from the genus Lespedeza. The taxonomic significance of these isolated compounds was also summarized.     

Antimicrobial constituents of Thompson seedless raisins (Vitis vinifera) against selected oral pathogens

As a part of a project directed toward the discovery of oral antimicrobial compounds from plants, eight known compounds, oleanolic acid (1), oleanolic aldehyde (2), linoleic acid (3), linolenic acid (4), betulin (5), betulinic acid (6), 5-(hydroxymethyl)-2-furfural (7), and β-sitosterol were isolated from an hexane-soluble partition of a methanol extract of Thompson seedless raisins (Vitis vinifera). From an EtOAc-soluble partition rutin (8) and β-sitosterol glycoside were isolated. In an attempt to increase the resultant antimicrobial activity of oleanolic acid (1), a series of acylation and etherification reactions were performed on oleanolic acid to obtain derivatives 1a–1f. All the compounds isolated and the derivatives 1a–1f were evaluated for their antimicrobial activity against two oral pathogens, Streptococcus mutans and Porphyromonas gingivalis associated with caries and periodontal disease, respectively. Compounds 1, 2, 7 and 1f inhibited the growth of the test bacteria with concentrations ranging from 3.9 to 500 μg/mL. Derivative 1f showed greatly enhanced antimicrobial activity when compared with oleanolic acid (1).     

Brachymeria lasus and Pachycrepoideus vindemiae: Sterol requirements during larval growth of two hymenopterous insect parasites reared in vitro on chemically defined media

Brachymeria lasus and Pachycrepoideus vindemiae failed to develop in vitro on sterol-free artificial media, and dietary acetate and squalene failed to maintain and/or support growth. The sterols, cholesterol, cholestanol, β-sitosterol, 7-dehydrocholesterol, and cholesterol linoleate were all utilized and maintained larvae of both species. Larval survival and development rate were greatest with cholesterol followed by cholestanol, β-sitosterol and 7-dehydrocholesterol. Although cholesterol linoleate maintained larvae little growth occurred and mortality was high. Cholestanol followed by β-sitosterol and 7-dehydrocholesterol displayed partial cholesterol sparing activity. Cholesterol linoleate had little effect on larval growth when fed with suboptimal levels of cholesterol or cholestanol. Both species contained 5 to 10% of the total body lipids as free sterol with traces of sterol ester. The major free sterol appears to be cholesterol.     

Anti-inflammatory effects of Leucosidea sericea (Rosaceae) and identification of the active constituents

The ‘Oldwood’ tree Leucosidea sericea is the sole representative of the genus Leucosidea and as such occupies a botanically-privileged status within the Rosaceae of southern Africa. The use of the plant in the traditional medicinal practices of some of the indigenous people of the region has been known for over a hundred years. Amongst these, its use as a vermifuge and astringent medicine, as well as anti-inflammatory agent, amongst the Basuto and Zulu tribes has been recorded. Based on these observations, the plant was here examined for the underlying phytochemical principles which might corroborate these interesting traditional uses. In the process, the known cholestane triterpenoids β-sitosterol and β-sitostenone were isolated for the first time from stems of L. sericea and identified by physical and spectroscopic techniques. These findings provide insights to the traditional usage of the plant for inflammation related ailments.     

New 19α-hydroxyursane-type triterpenes from the leaves of Meyna spinosa (= Vangueria spinosa), Rubiaceae

Two new 19α-hydroxyursane-type triterpenes, 2α,3α,19α,24,28-pentahydroxyurs-12-ene (1) and meyanthic acid, 3β-acetoxy-2β,19α,23-trihydroxyurs-12-en-28-oic acid (2) along with one new aliphatic ester, myricyl pentadecanoate (3) and five known compounds, 19α-hydroxyasiatic acid (4), oleanolic acid (5), myricyl alcohol (6), β-sitosterol (7) and its glycoside (8) were isolated from the methanolic leaf extract of Meyna spinosa Roxb. ex Link (= Vangueria spinosa Roxb., Rubiaceae). The structures of the new compounds were elucidated on the basis of extensive spectroscopic (including 2D NMR) analysis and comparison with literature. Except oleanolic acid, isolation of known compounds was reported for the first time from this plant.     

Activity of South African medicinal plants against Listeria monocytogenes biofilms,and isolation of active compounds from Acacia karroo

In South Africa, the antimicrobial activity of many indigenous plants has been investigated. In general, studies have focused on planktonic bacteria, with less attention given to bacterial biofilms. Many organisms, however, including the opportunistic pathogen Listeria monocytogenes occur more frequently as biofilms. The aim of this study was to identify and select plants that exhibit the best antilisterial activity, isolate the bioactive compounds and determine their effect on the architecture of listerial biofilms. The ethyl acetate and chloroform extracts of thirteen plants were investigated for antilisterial activity. The ethyl acetate extract of Acacia karroo and Plectranthus ecklonii showed the best antilisterial activity, exhibiting a minimum inhibitory concentration (MIC) of 3.1 mg/ml and 0.5 mg/ml, respectively. These were further selected for the identification of bioactive compounds. Column chromatographic purification of the ethyl acetate extracts of the leaves of A. karroo led to the isolation of three known pure compounds, namely epicatechin (1), β-sitosterol (2) and epigallocatechin (3). Confocal scanning laser microscopy (CSLM) showed that the biomass of the listerial biofilm was reduced when the isolated compounds were added. The aggregation of cells that were exposed to β-sitosterol and epigallocatechin was reduced from 25 μm as observed in untreated cells to < 10 μm in length.