Bioactivity-guided isolation of cytotoxic triterpenoids from the trunk of Berberis koreana

A bioassay-guided fractionation and chemical investigation of the trunk of Berberis koreana resulted in the isolation and characterization of two new triterpenoids, 23-trans-p-coumaroyloxy-2α,3α-dihydroxyolean-12-en-28-oic acid (1), and 23-cis-p-coumaroyloxy-2α,3α-dihydroxyolean-12-en-28-oic acid (2), along with seven known triterpenoids (3–9). The structures of the new compounds were determined on the basis of spectroscopic analyses including 2D NMR. The cytotoxic activities of the triterpenes (1–9) were evaluated by determining their inhibitory effects on human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15) using the SRB assay. Compounds 5 and 6 showed potent cytotoxicity against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines (IC₅₀ (5): 4.37, 7.04, 9.72, and 5.83 μM, and IC₅₀ (6): 5.57, 7.84, 13.29, and 5.61 μM, respectively).     

Bioactivity-guided isolation of cytotoxic constituents of Brucea javanica collected in Vietnam

Five new triterpenoids (1–5), together with two known quassinoids, bruceantin (6) and bruceine A (7), and a known flavonolignan, (?)-hydnocarpin (8), were isolated from the chloroform-soluble subfraction of a methanol extract of the combined twigs, leaves, and inflorescence of Brucea javanica collected in Vietnam. The structures of the new compounds 1–5 were established on the basis of spectroscopic methods. All isolates were evaluated for cytotoxicity against a small panel of human cancer cell lines. Quassinoids 6 and 7 were found to be highly active against these cell lines. (?)-Hydnocarpin (8) showed a potentiating effect when combined with both 6 and 7, during cytotoxicity testing using the MCF-7 human breast cancer cell line.     

Bioactivity-guided isolation of cytotoxic constituents from stem–bark of Premna tomentosa

A bioassay-guided fractionation and chemical investigation of the stem bark of Premna tomentosa resulted in the isolation and characterization of four new icetexane diterpenes (1–4), along with the known compounds coniferaldehyde (5), syringaldehyde (6), lupeol (7), betulin (8), and 2-(4-methoxyphenyl)-2-butanone (9). Their structures were established on the basis of extensive spectroscopic (IR, MS, 2D NMR) data analysis and by comparison with the spectroscopic data reported in the literature. The new compounds exhibited diverse functionalities on a common icetexane diterpene skeleton. In addition, cytotoxic activities of the icetexanes (1–3) were evaluated by determining their inhibitory effects on the human cancer cell lines (MCF-7, HT-29, Hep-G2, A-431, and A-549). Compounds 1 and 3 showed selective inhibitory activity against MCF-7 (15.96 μg/mL and 15.84 μg/mL) and HT-29 cell lines (16.21 μg/mL and 14.57 μg/mL), respectively.     

Bioactivity-guided isolation of antiproliferative compounds from Centaurea carduiformis DC

In this study, antiproliferative activity of methanol extract of Centaura carduiformis DC. subsp. carduiformis var. carduiformis DC (CC) was examined against Vero, HeLa and C6 cell lines in 1000 and 500 μg/mL concentrations using the BrdU ELISA assay. The CC root (CCR) has the most effective antiproliferative activity. The root extract was fractionated using various solvent and determined antiproliferative activities. Two new and two known flavonoids were isolated from CC roots. The isolated known compound of 7-O-β-d-glucopyranosyl-4′-methylapigenin and new compound of 7-O-β-d-6″-O-glucopyranosyl-6″-O-β-d-furanosylpinocembrin were isolated from the ethyl acetate fractions. However, wogonin and new compound of N-(pentyloxy(m-tolyl)methyl)acetamideisowogonin were obtained from chloroform fractions. The chemical structures of pure compounds were elucidated with different chemical and spectroscopic methods (IR, ¹H NMR, ¹³C NMR, HETCOR, COSY, GC-MS, etc.) and their antiproliferative activities were determined against Vero, HeLa and C6 cell lines. The IC₅₀ results showed that the compound 4 has the highest activity against Vero (250 μg/mL) and HeLa (735 μg/mL) cell lines than isolated other compounds from determined values.     

Bioactivity-guided isolation of antimicrobial metabolite from Xylaria sp.

Symbiotic plant-microbe metabolic interactions not only have beneficial effects on plants but also contribute to rich, unmatched and complex chemical biodiversity with biological potential. Systematic delineated bioprospecting of fungal diversity associated with Ficus pumila Linn (Moraceae) for antimicrobial metabolite revealed Xylaria sp. FPL-25(M). The present study describes bioactivity guided fractionation prioritized for antimicrobial potential. Thus, chemical investigation of culture broth of Xylaria sp. FPL-25(M) by bioactivity guided fractionation with spectroscopic techniques revealed bioactive metabolite xylobovide-9-methyl ester. The xylobovide-9-methyl ester exhibited broad-spectrum antimicrobial activity. However, Gram-positive bacteria and fungi were more susceptible than Gram-negative bacteria. The present study results represent bioassay-based screening strategy which facilitates rapid, efficient and reliable approach for endophytic strain prioritization for novel bioactive molecules.     

Bioactivity-guided isolation of antioxidant triterpenoids from Betula platyphylla var. japonica bark

The bark of Betula platyphylla var. japonica (Betulaceae) has been used to treat pneumonia, choloplania, nephritis, and chronic bronchitis. This study aimed to investigate the bioactive chemical constituents of the bark of B. platyphylla var. japonica. A bioassay-guided fractionation and chemical investigation of the bark of B. platyphylla var. japonica resulted in the isolation and identification of a new lupane-type triterpene, 27-hydroxybetunolic acid (1), along with 18 known triterpenoids (2–19). The structure of the new compound (1) was elucidated on the basis of 1D and 2D NMR spectroscopic data analysis as well as HR-ESIMS. Among the known compounds, chilianthin B (17), chilianthin C (18), and chilianthin A (19) were triterpene-lignan esters, which are rarely found in nature. Compounds 4, 6, 7, 17, 18, and 19 showed significant antioxidant activities with IC₅₀ values in the range 4.48–43.02 μM in a DPPH radical-scavenging assay. However, no compound showed significant inhibition of acetylcholine esterase (AChE). Unfortunately, the new compound (1) exhibited no significance in both biological activities. This study strongly suggests that B. platyphylla var. japonica bark is a potential source of natural antioxidants for use in pharmaceuticals and functional foods.     

Bioactivity-guided isolation of mosquitocidal constituents from the rhizomes of Plumbago capensis Thunb

A bioassay-guided fractionation and chemical examination of chloroform extract of Plumbago capensis roots resulted in isolation and characterization of two new napthaquinone derivatives (4, 8) along with six known compounds (1–3, 5–7). Their structures were determined on the basis of extensive spectroscopic (IR, MS, 1D and 2D NMR) data analysis and by comparison with the literature data. All the compounds were tested for their mosquito larvicidal activity against fourth instar larvae of Aedes aegypti, and compared with that of rotenone. Among the tested compounds, isoshinanolone (3) and plumbagin (1) showed excellent toxicity with LC₅₀ values of 1.26 and 5.43 μg/mL. New compound (8) displayed moderate toxicity against the tested mosquito species.     

Antiviral and cytotoxic activities of new derivatives of natural sesquiterpenes and taxol

Common occurrences of serious viral infections and a small number of available antiviral chemotherapeutics necessitate research for new, biologically active substances, which might be of use as antiviral drugs. Natural compounds, e.g., derived from plants and fungi, which show significant and various biological activities, may be a source of potential drugs. Sesquiterpenes, as well as taxol, and their derivatives, may serve as an example. The aim of the present study was to investigate the antiviral, antibacterial and cytotoxic properties of 7 new compounds: derivatives of sesquiterpenes of Lactarius mushroom origin and taxol--N-benzoylphenylisoserinates of sesquiterpenoid alcohols. The cytotoxicity of the tested compounds against Vero, RD, LLC-MK2 and A549 cell lines were assessed using the formazan method. All compounds showed a lower cytotoxicity than taxol. Their antiviral activity in vitro was evaluated by assessing the reduction of virus titre in cells subjected to the compounds in comparison to the cells, which were not subjected to them. It was found that out of 7 investigated compounds 3 exhibited antiviral activity. These compounds inhibited replication of HSV-1 virus in Vero cells. It appears therefore that further investigation of these groups of compounds and their derivatives is justified because they may constitute a potential source of chemotherapeutics.     

Bioactivity-guided isolation of the active compounds from Rosa nutkana and quantitative analysis of ascorbic acid by HPLC

Rosa nutkana Presl. (Rosaceae) is distributed abundantly throughout central and southern areas of British Columbia, Canada. Aboriginal people in the Pacific Northwest have traditionally used R. nutkana as a food, medicine, and source of cultural material. The methanolic extract of the fruits of R. nutkana was previously found to have inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA). In our study, bioactivity-guided fractionation of the methanol extract from R. nutkana led to the isolation of the following 10 compounds: (i) tormentic acid, (ii) euscaphic acid, (iii) ursolic acid, (iv) maslinic acid, (v) quercetin, (vi) catechin gallate, (vii) quercetin-3-O-glucoside, (viii) 1,2,3,4,6-penta-O-galloyl-beta-D-glucoside, (ix) L-ascorbic acid (vitamin C), and (x) 1,6-digalloyl-beta-D-glucoside. Structures were elucidated by ultraviolet, infrared, mass spectrometry, and nuclear magnetic resonance data, as well as by comparison with those of the literature. The compounds quercetin, catechin gallate, quercetin-3-O-glucoside, 1,2,3,4,6-penta-O-galloyl-beta-D-glucoside, and 1,6-digalloyl-beta-D-glucoside exhibited weak antibacterial activity against MRSA. Our research demonstrates the value of traditional knowledge held by Aboriginal people in the Pacific Northwest with respect to uses of R. nutkana. Some described uses in the ethnobotanical literature correspond to activities observed under laboratory conditions. Further work on British Columbia Rosa spp. may contribute to identifying other potential therapeutic uses.     

Bioactivity-guided isolation of anti-inflammatory triterpenoids from the sclerotia of Poria cocos using LPS-stimulated Raw264.7 cells

Poria cocos Wolf (Polyporaceae) has been used as a medicinal fungus to treat various diseases since ancient times. This study aimed to investigate the anti-inflammatory chemical constituents of the sclerotia of P. cocos. Based on bioassay-guided fractionation using lipopolysaccharide (LPS)-stimulated Raw264.7 cells, chemical investigation of the EtOH extract of the sclerotia of P. cocos resulted in the isolation and identification of eight compounds including six triterpenoids, namely poricoic acid A (1), 3-O-acetyl-16α-hydroxydehydrotrametenolic acid (2), polyporenic acid C (3), 3β-hydroxylanosta-7,9(11),24-trien-21-oic acid (4), trametenolic acid (5), and dehydroeburicoic acid (6), as well as (−)-pinoresinol (7) and protocatechualdehyde (8). The structures of the isolated compounds were determined by spectroscopic analysis, including ¹H and ¹³C NMR spectra, and LC/MS analysis. The anti-inflammatory activities of the isolates were evaluated by estimating their effect on the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) in LPS-stimulated Raw264.7 as well as on the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Compounds 1–5 inhibited NO production and iNOS expression in LPS-stimulated Raw264.7 cells. Among them, compound 1 exerted the highest anti-inhibitory activity and reduced PGE₂ levels via downregulation of COX-2 protein expression. The findings of this study provide experimental evidence that the sclerotia of P. cocos are a potential source of natural anti-inflammatory agents for use in pharmaceuticals and functional foods. Furthermore, the most active compound 1, seco-lanostane triterpenoid, could be a promising lead compound for the development of novel anti-inflammatory agents.     

Dysoxylum binectariferum bark as a new source of anticancer drug camptothecin: Bioactivity-guided isolation and LCMS-based quantification

Camptothecin (CPT, 1) is a potent anticancer natural product which led to the discovery of two clinically used anticancer drugs topotecan and irinotecan. These two drugs are semisynthetic analogs of CPT, and thus the commercial production of CPT as a raw material from various plant sources and tissue culture methods is highly demanding. In the present study, the Dysoxylum binectariferum bark, was identified as an alternative source of CPT, through bioassay-guided isolation. The barks showed presence of CPT (1) and its 9-methoxy analog 2, whereas CPT alkaloids were not present in seeds and leaves. This is the first report on isolation of CPT alkaloids from Meliaceae family. An efficient chromatography-free protocol for enrichment and isolation of CPT from D. binectariferum has been established, which was able to enrich CPT up to 21% in the crude extract. The LCMS (MRM)-based quantification method revealed the presence of 0.105% of CPT in dry barks of D. binectariferum. The discovery of CPT from D. binectariferum bark will certainly create a global interest in cultivation of this plant as a new crop for commercial production of CPT. Isolation of anticancer drug CPT from this plant, indicates that along with rohitukine, CPT and 9-methoxy CPT also contributes significantly to the cytotoxicity of D. binectariferum.     

Actinomycetes from Moroccan habitats: isolation and screening for cytotoxic activities

In our screening for actinomycetes showing cytotoxic activities, 8 samples were collected from various Moroccan habitats, 136 isolates were tested for their capacity to produce antibacterial compounds against gram positive bacteria. Thirty-seven strains of these isolates were active against Gram-positive bacteria. Using the following steps of primary screening: antibacterial activity, confrontation between the isolates and toxicity to Artemia salina; fifteen different isolates were used for further investigation. The aqueous extracts of Streptomyces sp. T5 and Streptomyces sp. AS8 were selected for their cytotoxic activity against Hep2, BSR and P815 cell lines, and two active compounds were observed on HPLC. The two isolates exhibited high activity against human cancer cell lines and were inactive on PBMC cell lines. Furthermore, the Streptomyces sp. T5 extract showed a proliferative activity.     

Bioactivity-guided isolation of chemical constituents against H2O2-induced neurotoxicity on PC12 from Cimicifuga dahurica (Turcz.) Maxim.

Three new compounds (1, 6, 9), with six known compounds (2–5, 7–8) were obtained from water-soluble extract of Cimicifuga dahurica (Turcz.) Maxim. by bioactivity-guided isolation. Their structures were elucidated by chemical and spectral analysis, including 1D, 2D NMR data and HRESIMS. H₂O₂-induced neurotoxicity on PC12 cells model were conducted to evaluate the neuro-protective capability of these compounds. The piscidic acid derivatives compounds 4–7 showed marked neuro-protective effect at certain concentration.     

紫穗槐的离体快速繁殖

以子叶节为外植体,建立起了紫穗槐的快速离体再生系统.经过四周的培养,在附加8mg·L-16-BA的MS培养基上能够获得再生频率为100%,平均每个外植体5.21个芽点的高效再生植株.以再生植株的茎节为外植体所进行的继代能够在相同的培养基上连续的产生新的不定芽,但芽点数要少于起始培养.经过3周的培养,有82.53%切下的再生茎段能够在含2.0mg·L-1IAA的MS培养基上生根.在所有进行分析过的再生植株中,它们的染色体数目都没有发生变异(2n=40).经过练苗以后,再生植株成功地定植于土壤当中并展示了一致的外部形态和生长特性.     

Steroidal saponins from the leaves of Cordyline fruticosa (L.) A. Chev. and their cytotoxic and antimicrobial activity

Three new steroidal saponins, spirosta-5,25(27)-diene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-β-d-fucopyranoside (fruticoside H) 1, 5α-spirost-25(27)-ene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-(4-O-sulfo)-β-d-fucopyranoside (fruticoside I) 2, and (22S)-cholest-5-ene-1β,3β,16β,22-tetrol 1-O-β-galactopyranosyl-16-O-α-l-rhamnopyranoside (fruticoside J) 3, together with the known quercetin 3-O-β-d-glucopyranoside, quercetin 3-O-[6-trans-p-coumaroyl]-β-d-glucopyranoside, quercetin 3-rutinoside, apigenin 8-C-β-d-glucopyranoside and farrerol, were isolated from the leaves of Cordyline fruticosa. Their structures were elucidated by spectroscopic techniques (¹H NMR, ¹³C NMR, HSQC, ¹H–¹H COSY, HMBC, TOCSY, NOESY), mass spectrometry (HRESIMS, Tandem MS–MS), chemical methods and by comparison with published data. Compounds 1 and 2 showed moderate cytotoxic activity against MDA-MB 231 human breast adenocarcinoma cell line, HCT 116 human colon carcinoma cell line, and A375 human malignant melanoma cell line, while compound 3 was not active. Compound 2 also showed a moderate antibacterial activity against the Gram-positive Enterococcus faecalis.     

Three fragrant sesquiterpenes of agarwood

Three fragrant sesquiterpenes have been isolated as major constituents from the wood of Aquilaria malaccensis and identified as α-agarofuran, (?)-10-epi-γ-eudesmol and oxo-agarospirol.     

Labdane diterpenes from Otostegia fruticosa

The new labdane diterpenes otostegin A (2), otostegin B (6) and 15-epi-otostegin B (7) were isolated from the aerial parts of Otostegia. fruticosa, besides the previously known labdanes preleoheterin (1), leoheterin (3), leopersin C and 15-epi-leopersin C (4, 5), ballonigrin (9) and vulgarol (11), along with the iridoid glucoside 8-O-acetylharpagide (10). The structure elucidation of all the isolated compounds was based on their spectral data and chemical derivatization.     

Activity-guided isolation of cytotoxic constituents from the bark of Aglaia crassinervia collected in Indonesia

Activity-guided fractionation of a CHCl(3)-soluble partition of the MeOH extract of the bark of Aglaia crassinervia collected in Indonesia led to the isolation of three new glabretal-type triterpenoids, aglaiaglabretols A-C (1-3), as well as nine known compounds, 3-epi-cabraleahydroxylactone (4), cabraleahydroxylactone (5), rocaglaol (6), 2beta,3beta-dihydroxy-5alpha-pregn-17(20)-(E)-16-one, scopoletin, and mixtures of cabraleadiol and epicotillol and of beta-sitosterol and stigmasterol. The structures of compounds 1-3 were determined on the basis of spectroscopic and chemical methods. The structure of aglaiaglabretol A (1) was confirmed by single-crystal X-ray analysis, and the absolute stereochemistry of this isolate was established by the Mosher ester method. The cytotoxic activity of all isolates and several chemical transformation products obtained in the present study was evaluated. The known cyclopenta[b]benzofuran, rocaglaol (6), was found to be significantly active and comparable in potency to the positive controls, paclitaxel and camptothecin. Aglaiaglabretol B (2) was further tested in an in vivo hollow fiber model.     

Notonipetrone-like sesquiterpenes from Senecio Kleinia

Five new notonipetrone-like sesquiterpenes have been isolated from the roots of Senecio kleinia and their structures elucidated.