Flavonoids and stilbenoids from Derris eriocarpa

One new resveratrol analogue, 1-(3′,4′,5′-trimethoxyphenyl)-2-methoxy-2-(4″-methoxyphenyl)-ethane-1-ol (1), and two new prenylisoflavones, 4′-hydroxy-5,7-dimethoxy-6-(3-methyl-2-butenyl)-isoflavone (2), and derrubon 5-methyl ether (3), together with 17 known compounds including one new natural product, 5,7-dihydroxy-3-[4′-O-(3-methyl-2-butenyl)-phenyl]-isoflavone (4), were isolated from the stems of ethnomedicinal plant Derris eriocarpa How. (Leguminosae). Their structures were elucidated based on chemical evidence and spectroscopic techniques including two-dimensional NMR methods. All compounds are reported from this species for the first time. Antimicrobial activities of the new compounds were evaluated. Compound 2 exhibited good inhibitory activities against Candida guilliermondii, C. albicans and Microsporium gypseum with the minimal inhibitory concentration (MIC) values of 12.5 μg/ml.     

Coumarinoids from the fruits of Micromelum falcatum

Four new compounds, microminutin B (1), microminutin C (2), micromarinate (3), and secomicromelin (4) as well as 17 known compounds were isolated from the fruits of Micromelum falcatum. All compounds were evaluated for antifungal activity against Pythium insidiosum using disc diffusion assay. P. insidiosum is a fungus-like microorganism for which antifungal agents now available are not effective. The results show that four compounds including secomicromelin (4), 7-methoxy-8-(4′-methyl-3′-furanyl)coumarin (10), micromarin B (17), and isomicromelin (19) could inhibit the mycelia growth of P. insidiosum.     

Three new phenolic compounds from the roots of Glycyrrhiza yunnanensis

Three new phenolic compounds (1–3), together with 16 known compounds (4–19), were isolated from the roots of Glycyrrhiza yunnanensis Cheng f. et L. K. Dai. On the basis of 1D and 2D NMR, HR-ESI-MS, and circular dichroism (CD) spectroscopic analysis, structures of the new compounds were elucidated as 2-(2′-methoxy-4′-hydroxy)-aryl-3-methy-6-hydroxy-benzofuran (1), (2S)-6,7-(2,2-dimethyldihydropyrano)-8-prenyl-4′-hydroxyflavanone (2), and 6-prenyl-7,3′,4′-trihydroxyflavone (3). Compounds 1, 3, 5, 12, 14, 15 and 16 showed antioxidant activity by an ABTS-based assay.     

Chemical constituents of Aloe barbadensis Miller and their inhibitory effects on phosphodiesterase-4D

Aloe barbadensis Mill has been used as food and medicine for a long time. In order to investigate the chemical constituents of A. barbadensis and their inhibitory activities towards phosphodiesterase-4D (PDE4D), 70% methanol extract of the dried A. barbadensis powder was employed. Phytochemical investigation has led to the isolation of three new chromones, 5-(hydroxymethyl)-7-methoxy-2-methylchromone (4), 5-((4E)-2′-oxo-pentenyl)-2-hydroxymethylchromone (6), and 7-hydroxy-5-(hydroxymethyl)-2-methylchromone (7), together with eighteen known compounds. Their chemical structures were determined based on spectroscopic methods including UV, IR, 1D and 2D NMR, and HRMS spectrometry. In addition, their inhibition against PDE4D was evaluated using tritium-labeled adenosine 3′,5′-cyclic monophosphate (³H-cAMP) as the substrate. Inhibition was calculated by the variation of radioactivity after the reaction, and compounds 1–4, 10, and 21 exhibited certain inhibitory activities towards PDE4D, which can provide an explanation why A. barbadensis can serve as anti-inflammatory agents.     

8-9′ linked neolignans with cytotoxicity from Alpinia conchigera

Five new 8-9′ linked neolignans conchigeranals A–E (1–5), together with three known compounds galanganal (6), galanganols A (7) and B (8), were isolated from the whole plant of Alpinia conchigera. Their structures were established by spectroscopic analysis, including 2D-NMR spectroscopic techniques. Cytotoxicities of compounds 1–8 were tested against two cancer cell lines A549 and Hela. Results showed that 4, 5, 7 and 8 exhibited cytotoxicity against A549 with the IC₅₀ values of 12.36, 9.72, 10.26, 13.05 μg/ml, respectively, and 1–8 against Hela with the IC₅₀ values from 1.53 to 5.29 μg/ml.     

Rigenolide A,a new secoiridoid glucoside with a cyclobutane skeleton,and three new acylated secoiridoid glucosides from Gentiana rigescens Franch

Rigenolide A (1), a new secoiridoid glucoside with a cyclobutane skeleton and three new acylated secoiridoid glucosides, 2′-(2,3-dihydroxybenzoyl)-gentiopicroside (2), 2′-(2,3-dihydroxybenzoyl)-swertiamarin (3), 3′-(2,3-dihydroxybenzoyl)-sweroside (4), along with two noriridoids (7 and 8) and two known secoiridoid glucosides (5 and 6), were isolated from Gentiana rigescens Franch. The structures of new compounds were elucidated by extensive spectroscopic analyses. The isolated compounds were evaluated for DPPH free-radical scavenging activity.     

New constituents of Terminalia alata

The roots of Terminalia alata yielded a new terpene glycoside, 2α, 3β, 19α-trihydroxy-olean-12-en-28-oic acid methylester 3β-O-rutinoside (1), a new flavanone, 8-methyl-5,7,2′, 4′-tetramethoxy-flavanone (2) and a new chalchone glycoside, 2-O-β-glucosyloxy-4,6,2′,4′-tetramethoxychalchone (3).     

A new antifungal coumarin from Clausena excavata

A new γ-lactone coumarin, named as excavarin-A, showing antifungal activity was isolated from the leaves of Clausena excavata by bioassay guided fractionation method. The structure was elucidated by spectroscopic data analysis and identified as 7((2E)-4(4,5-dihydro-3-methylene-2-oxo-5-furanyl)-3-methylbut-2-enyloxy) coumarin. Minimum inhibitory concentration (MIC) was determined against fifteen fungal strains pathogenic against plants and human. The least MIC was recorded against the human pathogen, Candida tropicalis and the plant pathogens Rhizoctonia solani and Sclerotinia sclerotiorum. Antifungal activities against the human pathogens, Aspergillus fumigatus and Mucor circinelloides and plant pathogens, Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Fusarium oxysporum and Rhizopus stolonifer were stronger than that of the standard antimicrobials.     

The antifungal constituents from the seeds of Itoa orientalis

Three new phenolic constituents, itolide A (1), itolide B (2), itoside P (3), and 1D-3-deoxy-3-hydroxymethyl-myo-inositol (4), which is described herein for the first time as a natural product, were isolated along with four other known compounds (5 to 8) from the methanol extract of the seeds of Itoa orientalis Hemsl by the activity-guided fractionation. Their structures were determined by spectroscopic means. Compounds 1 to 8 exhibited antifungal activities against Sclerotium rolfsii with IC₅₀ values ranging from 60.12 to 240.00 μM and against Rhizoctonia solani with IC₅₀ values ranging from 45.34 to 233.14 μM, respectively, and compounds 1, 2, 5 exhibited cytotoxic activity against Tn5B1-4 insect cell line with EC₅₀ values of 203.68, 93.41 and 40.37 μM, respectively.     

Antibacterial anthranilic acid derivatives from Geijera parviflora

Five anthranilic acid derivatives, a mixture I of three new compounds 11′-hexadecenoylanthranilic acid (1), 9′-hexadecenoylanthranilic acid (2), and 7′-hexadecenoylanthranilic acid (3), as well as a new compound 9,12,15-octadecatrienoylanthranilic acid (4) together with a new natural product, hexadecanoylanthranilic acid (5), were isolated from Geijera parviflora Lindl. (Rutaceae). Their structures were elucidated by extensive spectroscopic measurements, and the positions of the double bonds in compounds 1–3 of the mixture I were determined by tandem mass spectrometry employing ozone-induced dissociation. The mixture I and compound 5 showed good antibacterial activity against several Gram-positive strains.     

Antifungal properties of methanol extract and its active compounds from Brickellia rosmarinifolia Vent

A new isocoumarin, 7-hydroxyl-4-methyl isocoumarine (1), together with three known monoterpenes, (3R, 4R, 6S)-3, 6-dihydroxy-1-menthene (2), (+)-(1R, 3S, 4R, 6S)-6-hydroxymenthol (3) and 4-isopropyl-1-methylcyclohex-2-ene-1, 6-diol (4), was isolated from the methanol extract of Brickellia rosmarinifolia. The structures were determined by spectroscopic means. Compounds 1, 2, 3 and 4 showed antifungal activities against Colletotrichum musae and Peronophythora litchii in vitro.     

Antioxidant neolignan and phenolic glucosides from the fruit of Euterpe oleracea

Three new glucosides, namely, (–)-7R8S-7′,8′-dihydroxy-dihydrodehydroconiferyl alcohol-9-O-β-d-glucopyranoside (1), (+)-7S8R-7′,8′-dihydroxy-dihydrodehydroconiferyl alcohol-9-O-β-d-glucopyranoside (2) and 4-hydroxy-2-methoxyphenyl 1-O-[6-(hydrogen 3-hydroxy-3-methylpentanedioate)]-β-d-glucopyranoside (3), along with 6 known compounds were isolated from the fruit of Euterpe oleracea Mart. Their structures were elucidated based on spectroscopic analyses including NMR, HR-ESI-MS and CD. All the isolated compounds demonstrated significant antioxidant activity and 2 displayed moderate cytotoxicity against HL-60 cells.     

Acyl quinic acid derivatives from the stems of Erycibe obtusifolia

Eleven new acyl quinic acid derivatives, 4-O-caffeoyl-3-O-syringoylquinic acid methyl ester (1), 4-O-caffeoyl-3-O-vanilloylquinic acid (2), 4-O-caffeoyl-3-O-vanilloylquinic acid methyl ester (3), 5-O-caffeoyl-3-O-vanilloylquinic acid (4), 5-O-caffeoyl-3-O-vanilloylquinic acid methyl ester (5), 5-O-caffeoyl-3-O-sinapoylquinic acid (6), 5-O-caffeoyl-4-O-vanilloylquinic acid (7), 4-O-(7‴S, 8‴R)-glycosmisoyl-5-O-caffeoylquinic acid methyl ester (8), 4-O-(7‴S, 8‴R)-glycosmisoyl-5-O-caffeoylquinic acid (9), 3-O-(7‴S, 8‴R)-glycosmisoyl-4-O-caffeoylquinic acid (10), and 3-O-(7‴S, 8‴R)-glycosmisoyl-4-O-caffeoylquinic acid methyl ester (11), have been isolated from the stems of Erycibe obtusifolia together with eight known compounds (12–19). Their structures were elucidated on the basis of spectroscopic data analysis (UV, IR, HRESIMS, CD, and 1D and 2D NMR) and chemical evidence. In in vitro assay, compounds 7 and 16–18 exhibited significant neuroprotective effects against rotenone induced PC12 cell damage at 10 μM.     

Stereochemical determination of new cytochalasans from the plant endophytic fungus Trichoderma gamsii

Three new cytochalasans, trichalasins E (1), F (2) and H (7), together with four known analogues, trichalasin C (3), aspochalasin K (4), trichalasin G (5) and aspergillin PZ (8), were isolated from one endophytic fungus Trichoderma gamsii inhabiting in the traditional medicinal plant Panax notoginseng (BurK.) F.H. Chen. Trichalasins E (1) contains a unique hydroperoxyl group, which is the first report in all known analogues, whereas trichalasin H (7) possesses the rare 6/5/6/6/5 pentacyclic skeleton with 12-oxatricyclo [6.3.1.0^2,7] moiety as that of aspergillin PZ (8). The relative configurations of the new compounds were characterized by analysis of coupling constants and ROESY correlations, and the absolute configurations of trichalasins E (1), H (7) and aspergillin PZ (8) were determined by modified Mosher’s reaction. In addition, compounds 1–5, 7 and 8 were tested cytotoxic activities against several cancer cell lines.     

Four new diterpenoids from the roots of Euphorbia fischeriana

Four new diterpenoids (1,4,5,9), together with 7 known diterpenoids (2,3,6–8,10,11), were isolated from the roots to Euphorbia fischeriana. On the basis of 1D and 2D NMR, HR-ESI-MS spectroscopic analysis, structures of the new compounds were elucidated as 11β-hydroxy-8,14-epoxy-ent-abieta-13(15)-en-16,12-olide (1), 3,20-dihydroxy-ent-1(10), 15-rosadiene (4), 3,7-dihydroxy-ent-1(10), 15-rosadiene (5), ingenol 6,7-epoxy-3- tetradecanoate (9). The compounds isolated were evaluated for their cytotoxicity against four cancer cell lines (A549, BEL7402, HCT116, and MDA-MB-231). Three ingenol diterpenoids (9–11) showed significant cytotoxicity against A549 with IC₅₀ value of 3.35, 2.85, 2.88 μg/mL, respectively.     

Two new sesquiterpenes from Artemisia sieversiana

Two new sesquiterpenes, together with 32 known compounds(3–34), were isolated from Artemisia sieversiana Ehrhart ex willd. and the compounds 3–21 were isolated from this plant for the first time. The new compounds were elucidated as 2α,9α-dihydroxymuurol-3(4)-en-12-oic acid (1) and 13α-methyl-(5αH,6αH,7αH,8αH)-austricin 8-O-β-D-glucopyranoside (2), respectively. The structural identification of these compounds was mainly achieved by spectroscopic methods including 1D and 2D NMR techniques, and the structure of compound 1 was confirmed by a single crystal X-ray diffraction experiment. Compounds 1–2 were evaluated for cytotoxic activity in vitro against MCF-7, NCI-H460 and Hep-G2 cell lines, respectively.     

Polyketides with antimicrobial activity from the solid culture of an endolichenic fungus Ulocladium sp

Two new polyketides, 7-hydroxy-3, 5-dimethyl-isochromen-1-one (1) and 6-hydroxy-8-methoxy-3a-methyl-3a,9b-dihydro-3H-furo[3,2-c]isochromene-2,5-dione (2), along with eleven known compounds, 5′-methoxy-6-methyl-biphenyl-3,4,3′-triol (3), 7-hydroxy-3-(2-hydroxy-propyl)-5-methyl-isochromen-1-one (4), rubralactone (5), isoaltenuene (6), altenuene (7), dihydroaltenuenes A (8), altenusin (9), alterlactone (10), 6-O-methylnorlichexanthone (11), norlichexanthone (12), and griseoxanthone C (13) were isolated from the culture of the endolichenic fungus Ulocladium sp. Compound 2 was obtained as a racemate with an unprecedented chemical skeleton. The NMR data assignments for 3 and 4 were achieved for the first time. Compounds 1-13 were screened for their antimicrobial and radical scavenging activities. Compound 1 showed some antifungal activity against Candida albicans SC 5314 with IC₅₀ of 97.93 ± 1.12 μM. Compounds 11-13 showed strong activity against Bacillus subtilis with IC₅₀ in the range of 1-5 μM. Compound 12 significantly inhibited the growth of methicillin-resistant Staphylococcus aureus with IC₅₀ of 20.95 ± 1.56 μM. Compounds 9 and 10 showed strong radical scavenging activity in comparison with vitamin C. The plausible biosynthetic pathways for compounds 1, 2, and 4-8 were discussed.     

Mangostanaxanthones I and II,new xanthones from the pericarp of Garcinia mangostana

Two new xanthones: mangostanaxanthones I (3) and II (5) were isolated from the pericarp of Garcinia mangostana, along with four known xanthones: 9-hydroxycalabaxanthone (1), parvifolixanthone C (2), α-mangostin (4), and rubraxanthone (6). Their structures were elucidated on the basis of IR, UV, 1D, 2D NMR, and MS spectroscopic data, in addition to comparison with literature data. The isolated compounds were evaluated for their antioxidant, antimicrobial, and quorum-sensing inhibitory activities. Compounds 3 and 5 displayed promising antioxidant activity with IC₅₀ 12.07 and 14.12 μM, respectively using DPPH assay. Compounds 4–6 had weak to moderate activity against Escherichia coli and Staphylococcus aureus, while demonstrated promising action against Bacillus cereus with MICs 0.25, 1.0, and 1.0 mg/mL, respectively. The tested compounds were inactive against Candida albicans. However, they showed selective antifungal potential toward Aspergillus fumigatus. Compounds 3 and 4 possessed quorum-sensing inhibitory activity against Chromobacterium violaceum ATCC 12472.     

Caffeoylquinic acid derivatives isolated from the aerial parts of Gynura divaricata and their yeast α-glucosidase and PTP1B inhibitory activity

The phytochemical investigation of natural products of Gynura divaricata led to the isolation of eleven caffeoylquinic acid derivatives. They were characterized by spectrometric methods as 5-O-caffeoylquinic acid (1), 5-O-p-coumaroylquinic acid (2), 5-O-feruloylquinic acid (3), methyl 5-O-caffeoylquinate (4), 3,4-dicaffeoylquinic acid (5), 3,5-dicaffeoylquinic acid (6), 4,5-dicaffeoylquinic acid (7), methyl 3,4-dicaffeoylquinate (8), methyl 3,5-dicaffeoylquinate (9), methyl 4,5-dicaffeoylquinate (10) and ethyl 4,5-dicaffeoylquinate (11). The individual compounds were screened for the inhibition of yeast α-glucosidase and Protein Tyrosine Phosphatase 1B (PTP1B) using in vitro assays. Among the isolated compounds, 3,4-dicaffeoylquinic acid (5), 4,5-dicaffeoylquinic acid (7), methyl 3,4-dicaffeoylquinate (8) and methyl 4,5-dicaffeoylquinate (10) exhibited significant inhibitory activities against α-glucosidase. In addition, 5-O-p-coumaroylquinic acid (2), 3,5-dicaffeoylquinic acid (6) and 4,5-dicaffeoylquinic acid (7) had considerable inhibitory effect against PTP1B. Based on these findings, the caffeoylquinic acid derivatives were deduced to be potentially responsible for the anti-diabetic activity of G. divaricata. The preliminary structure–activity relationship study suggests that the number and positioning of caffeoyl groups in the quinic acid derivatives are important for both α-glucosidase and PTP1B inhibitory potency. Moreover, the corresponding methyl esters of some dicaffeoylquinic acids have enhanced inhibitory activity against yeast α-glucosidase.     

Bioactive phenolics from the fruits of Livistona chinensis

This study investigated the antioxidant and cytotoxic activity of the phenolics isolated from the fruits of Livistona chinensis. Four new compounds, 1-{ω-isoferul[6- (4-hydroxybutyl)pentadecanoic acid]}-glycerol (1), E-[6′-(5″-hydroxypentyl)tricosyl]-4-hydroxy-3-methoxycinnamate (2), 2-(3′-hydroxy-5′-methoxyphenyl)-3-hydroxylmethyl-7-methoxy-2,3-dihydrobenzofuran-5- carboxylic acid (3), 7-hydroxy-5,4′-dimethoxy-2-arylbenzofuran (4), together with eleven known phenolics (5-15), were isolated and identified. Among these compounds, 1-4, 5-O-caffeoylshikimic acid (5), caffeic acid (7), and 3-O-caffeoylshikimic acid (8) showed potent antioxidant activity. 1-5, and 8 showed potent antiproliferative activities with IC₅₀ values among 5-150 μM against HepG2 human liver cancer, HL-60 human myeloid leukemia, K562 human myeloid leukemia, and CNE-1 human nasopharyngeal carcinoma cell lines. On the basis of these findings, it could be proposed that the fruits of L. chinensis may serve as attractive mines of powerful anticancer and antioxidant agents for various purposes.