Records of Natural Products Articles

The MeOH extract of the aerial parts of Artemisia asiatica significantly inhibited the xanthine oxidase (XO) induced uric acid production. Flavonoids were isolated from the active extract and identified as eupatilin (1), hispidulin (2), jaceosidin (3), cirsilineol (4), 5,7,4’,5’-tetrahydroxy-6,3’-dimethoxyflavone (5), 6-methoxytricin (6) and chrysosplenetin (7). With the exception of cirsilineol and chrysoplenetin, all these flavonoids exerted marked XO-inhibitory effects, with IC 50 values in the range 1.33−6.13 µM. The degree of XO inhibition by 1-3, 5 and 6 suggests the importance of the free OH group on C-7. Evaluation of the isolated compounds 1-7 for their free radical scavenging activity in DPPH tests, revealed the substantial antioxidant activity of 5,7,4’,5’-tetrahydroxy-6,3’-dimethoxy-flavone (5), which contains ortho-dihydroxy and 5-hydroxy groups. In summary, the flavonoid-containing MeOH extract of A. asiatica exhibits dual action, inhibiting XO (1-3, 5, 6) and resulting in a reduced generation of reactive oxygen species, and additionally scavenging free radicals (5).

Fr om the stem barks of Jacaranda mimosifolia benzoic acid (1), 1-naphthaleneacetic acid, 5-carboxy-1,2,3,4,4a,7,8,8a-octahydro-1,2,4a-trimethyl-[1S-(1α,2β,4aβ,8aα)] (2), betulinic acid (3), lupeol (4) and ursolic acid (5) were isolated. Similarly, lapachol (6), dehydro-α-lapachone (7), 2- acetylfuro-1, 4-naphthoquinone (8), p-coumaric acid (9), caffeic acid (10), nonacosanoic acid, 2-(4-hydroxyphenyl)ethyl ester (11), β-sitosterol (12), kigelinol (13), oleanolic acid (14), β-friedelinol (15), pomolic acid (16), and kojic acid (17) were isolated from the stem barks of Kigelia africana . All the isolated compounds were characterized by using spectroscopic methods especially 1D and 2D NMR and ESI mass spectrometry and comparison with literature data. To the best of our knowledge, compounds 1, 2, 3 and 5, and compounds 11, 14, 15 and 16 were isolated for the first time from Jacaranda mimosifolia and Kigelia africana, respectively. All these compounds were screened for anticandidal activity by agar diffusion method and microbroth dilution technique on four Candida albicans strains (ATCC L26, ATCC12C, ATCCP37039, and ATCCP37037). Among them, compounds 9, 10, and 17 exhibited the highest anticandidal activity that varied between the microbial species (MIC= 0.01 ± 0.00 − 0.03 ± 0.00 mg/mL) on C. albicans ATCC L26, ATCCP37037, ATCCP37039 and ATCC12C strains. Compound 17 was likely the most active against the four Candida albicans strains (MIC= 0.01 ± 0.00 − 0.02 ± 0.00 mg/mL).

The dichloromethane and ethyl acetate extracts from the bark of Garcinia hombroniana yielded lupeol (1), lupeol acetate (2), 3β-acetoxy- lup-12,20(29)-diene (3), β-sitosterol (4), 22-dehydroclerosterol (5), mangiferolic acid (6), ursolic acid (7), betulin (8), betulinic acid (9), 1,3,6-trihydroxy-7-methoxy-2,8-(3-methyl-2-butenyl)xanthone (10), leucodin (11), p-hydroxycinnamate (12), p-hydroxybenzoic acid (13) and stearic acid (14). Compounds 10,12 and 13 exhibited significant antioxidant activities by DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid) and FRAP (ferric ion reducing antioxidant power) assays. Antibacterial studies showed strong inhibitory effects for compound 11 while other compounds (1-9and 14) were either inactive or moderately active for the bacterial strains investigated. This study presents the first report on the isolation and biological activities of the chemical constituents from the bark of G. hombroniana. The compounds 3, 5-12 and 14 are reported for the first time from this source.

Origanum glandulosum Desf is an endemic flavoring herb widely distributed in North Africa that is commonly used in traditional medicine. This oregano species is rich in essential oils but little is known about its phenolic composition. In the present study, a crude extract of O. glandulosum was prepared in order to isolate and investigate its neuroprotective potential to inhibit β-amyloid peptide (Aβ) aggregation. The three major compounds of the extract were isolated: rosmarinic acid and two cyclolignans in Origanum genus, globoidnan A and a new derivative named globoidnan B. Rosmarinic acid and globoidnan A showed significant anti-aggregative activity against β amyloid aggregation (IC50 7.0 and 12.0 µM, respectively). In contrast, globoidnan B was found to be less active

The structure and antioxidant activity of condensed tannins isolated from Alaska Cedar inner bark have been investigated. Oligomers of flavan-3-ol were purified by column chromatography (Sephadex LH-20) and analyzed by 13CNMR and MALDI-TOF MS spectrometries. Their antioxidant activities were measured using 1,1’-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radicals scavenging, ferric reducing/antioxidant power (FRAP), and β-carotene-linoleic acid model system (β-CLAMS) assays. Results showed that the condensed tannins consents of both homogeneous and heterogeneous oligomers of procyanidins (catechin/epicatechin) and prodelphinidins (gallocatechin/ epigallocatechin) flavan-3-ol units; and oligomers from trimmers to heptamers with dominant interflavan linkages B-type as it is most common in proanthocyanidins. Condensed tannins showed significant ntioxidant activity as the median inhibition capacity IC 50 is comparable to the catechin control response. Alaska Cedar inner bark oligomers show high antioxidant capacity, evaluated by both methods based on electron transfer mechanisms and hydrogen atom transfer reactions. This bark may be considered as a new source of natural antioxidants for nutraceutical ingredients

One new oleanane-type saponin, 3-O-β-D-glucopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl hederagenin 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester (1) was isolated from the MeOH extract of whole plant parts of Cephalaria aristataC. Koch along with three known oleanane-type saponins (2-4), 3-O- α -L-rhamnopyranosyl-(1→2)- α -L-arabinopyranosyl hederagenin 28-O-( β -D-glucopyranosyl-(1→6)- β -D-glucopyranosyl) ester, 3-O- β -D-glucopyranosyl-(1→4)- β -D-xylopyranosyl-(1→3)- α -L-rhamnopyranosyl-(1→2)- α -L-arabinopyranosyl hederagenin and 3-O- α -L-rhamnopyranosyl-(1→2)- α -L-arabinopyranosyl hederagenin respectively, (5-7), oleanolic acid (5), β -amyrin (6) and 20 β -hydroxyursolic acid (7) and one sterol glucoside (8), 29-hydroxystigmast-5-en-3-O- β -D-glucopyranosyde. Their structures were established by the extensive use of 1D- and 2D-NMR experiments along with ESIMS and HRMS analysis.

 T wo new lignan glycosides named acutosides A (1) and B (2) have been isolated from the whole plant of Gentianella acute (Michx) Hulten. and t heir structures were determined as (-)-(7 R ,8S,7'E)-4-hydroxy-3, 3 '-dimethoxy-7,4'-epoxy-8, 5 '-neolign-7'-ene-9,9'-diol 9'-ethyl ether -4-O-β-D- glucopyranosid e and (-)-(7 R ,8S,7'E)-4-hydroxy-3, 3 '-dimethoxy-7,4'-epoxy-8, 5 '-neolign-7'-ene-9,9'-diol 9-ethyl ether -9 ' -O-β-D- glucopyranosid e by means of 1D-, 2D-NMR , HR -ESI -MS , CD techniques and chemical reactions. Along with the above two new compounds we got six known ones: (7R,8S)-dehydrodiconiferyl alcohol-4,9 ' -di-O-β-D- glucopyranosid e (3 ), alaschanisoside A (4 ), citrusin A (5 ) , 8,4',9'-trihydroxy-3,3'-dimethoxy-9,7'-epoxylignan 4-O- β -D- glucopyranosid e (6 ), l eptolepisol D (7 ) and acanthoside D (8 ). The cardioprotective effects of compounds 1-8 were evaluated by measuring the viability of the compounds 1-8 pretreated H9c2 cardiomyoblasts after exposure to H 2O 2-induced apoptosis, the results showed that compounds 1,3,6,8which could increase cell viability >15% at 200 μM had remarkably protective influence against H 2O 2-induced apoptosis. All the compounds were tested for cytotoxicity against two human tumor cell lines: gastric cancer SGC-7901 and breast cancer MCF-7. But they were inactive (IC 50>40 μM).

Artemisia argyi, A. feddei, A. gmelinii, A. manshurica, and A. olgensis (Asteraceae) were collected in Far East Russia. Oils were hydrodistilled and simultaneously analyzed by GC-FID and GC/MS. Main constituents were found as follows in Artemisia oils: selin-11-en-4 a -ol (18.0%), 1,8-cineole (14.2.0%), artemisia alcohol (12.9%), borneol (9.7%) in A. argyi; camphor (31.2%), 1,8-cineole (17.6%), a -thujone (5.7%) in A. feddei; longiverbenone (12.0%), isopinocamphone (8.9%), 1,8-cineole (6.7%), camphor (5.8%), trans-p-menth-2-en-1-ol (5.3%) in A. gmelinii; germacrene D (11.2%), rosifoliol (10.1%), caryophyllene oxide (6.8%), eudesma-4(15),7-dien-1 b -ol (5.6%) in A. manshurica; eudesma-4(15),7-dien-1 b -ol (6.9%), caryophyllene oxide (5.6%), guaia-6,10(14)-dien-4 b -ol (5.1%) and hexadecanoic acid (5.0%) in A. olgensis. Oils were subsequently submitted for antifungal and antimosquito evaluations. Artemisia species oils showed biting deterrent effects in Aedes aegypti and Artemisia gmelinii oil with the most active biting deterrence index values of 0.82 ± 0.1 at 10 m g/mL. Larval bioassay of A. gmelinii and A. olgensis oils showed higher larvicidal activity against Ae. aegypti larvae with LD50 values of 83.8 (72.6 – 95.7) ppm and 91.0 (73.8 – 114.5) ppm, respectively. Antifungal activity was evaluated against the strawberry anthracnose-causing fungal plant pathogens Colletotrichum acutatum, C. fragariae and C. gloeosporioides using direct overlay bioautography assay and all showed non-selective weak antifungal activity. Antioxidant evaluations of the oils were performed by using b -carotene bleaching, Trolox equivalent and DPPH tests. The tested Artemisia oils demonstrated moderate antioxidant activity.

Colon cancer is one of the most common types of cancer malignancy. Although flavonoids naturally occur as mixtures, little information is available regarding the additive or synergistic biochemical interactions between flavonoids. The objectives of this study were to examine the feasibility of combining two major structurally related flavonoids, quercetin and kaempferol, to affect the cell viability, cell cycle, and proliferation of the human colon cancer HCT-116 cell line. The combination of quercetin and kaempferol exhibited a greater cytotoxic efficacy than did either quercetin or kaempferol alone. This effect was highest and acted in a synergistic fashion in a 2-fold quercetin and 1-fold kaempferol IC50 combination, which also arrested cell growth in the G2/M phase and suppressed proliferation. Our observations support a structure-activity relationship based on the presence of 3’–OH moiety and/or 4’–OH moiety on the B-ring of flavonoids. 

Composition, antioxidant and antibacterial activities for methanol extracts, and their hexane, ethyl acetate and butanol fractions of the fresh leaf and flower of Hylotelephium spectabile x telephium were studied for the first time. The extracts contain mostly quercetin and kaempferol glycosides, as confirmed by the composition of hydrolysates whose main components were quercetin and kaempferol. Evaluations of antioxidant activity were done by the following assays: DPPH, ABTS and total reducing power assay (Fe 3+ to Fe 2+). Additionally, total flavonoid content and total phenols were determined. The antioxidant capacity of ethyl acetate flower fraction was very close or even higher than capacity of used standard antioxidants. Presented results qualify this species as a potential new source of antioxidant substances. Ethyl acetate fraction of leaf showed moderate bactericidal activity against P. aeruginosa, S. typhimurium, S. aureus, and B. subtilis.

 Four flavon glycosides, eriocitrin (1), luteolin-7-O-rutinoside (2), hesperidin (3), apigenin-7-O-rutinoside (4) and rosmarinic acid (5) were isolated from the aerial parts of Mentha dumetorum (Lamiaceae) for the first time. The structural elucidations of isolated compounds were achieved using spectral methods (1D- and 2D-NMR, and LC-TOF-HRMS).

Essential oils composition of the aerial parts of Artemisia nilagirica (Clarke) Pamp. var. septentrionalis Pamp. in different seasons viz. spring, summer, rainy, autumn and winter seasons under foot hills agroclimatic conditions of western Himalaya were analyzed and compared by GC–FID and GC–MS. Essential oils were mainly composed of monoterpenoids (59.0%-77.3%) and sesquiterpenoids (15.7%-31.6%). The major constituents identified were artemisia ketone (38.3%-61.2%), chrysanthenone (1.5%-7.7%), germacrene D (3.1%-6.8%), β-caryophyllene (1.9%-6.8%), germacra-4,5,10-trien-1-α-ol (1.9%-4.9%) and artemisia alcohol (1.4%-3.6%). Compositional analysis showed significant variations in the terpenoid compositions due to seasonal variations. Further, this is for the first time the seasonal variations in essential oil compositions of artemisia ketone rich chemotype of A. nilagirica var. septentrionalis is being reported from India.

Since a few decades the dengue virus became a major public health concern and no treatment is available yet. In order to propose potential antidengue compounds for chemotherapy we focused on DENV RNA polymerase (DENV-NS5 RdRp) which is specific and essential for the virus replication. Carpolepis laurifolia belongs to the Myrtaceae and is used as febrifuge in traditional kanak medicine. Leaf extract of this plant has been identified as a hit against the DENV-NS5 RdRp. Here we present a bioguided fractionation of the leaf extract of C. laurifolia which is also the first phytochemical evaluation of this plant. Five flavonoids, namely quercetin (1), 6-methyl-7-methoxyapigenin (2), avicularin (3), quercitrin (4) and hyperoside (5), together with betulinic acid (6), were isolated from the leaf extract of C. laurifolia. All isolated compounds were tested individually against the DENV-NS5 RdRp and compared with four other commercial flavonoids: isoquercitrin (7), spiraeoside (8), quercetin-3,4’-di-O-glucoside (9) and rutine (10). Compounds 3, 4, 6, 8 and 10 displayed IC 50 ranging from 1.7 to 2.1 µM, and were the most active against the DENV-NS5 RdRp.

Four limonoids, humilinolide E (1) , methyl 2-hydroxy-3 b -tigloyloxy-1-oxomeliac-8(30)-enate (2), swietenine acetate (3) and methyl angolensate (4) were isolated from the fruits of Guarea kunthiana. Compounds 1-3 are being reported for the first time in the genus Guarea, while 4 has been previously described in only one species of this genus. The isolated compounds were identified by spectral methods (1D-, 2D-NMR and EIMS).

 (–)-Fisetinidol-(4α,8)-[(–)-fisetinidol-(4α,6) ]-(+)-catechin ( 1 ), a proanthocyanidin, was isolated from the bark of Acacia leucophloea . Its structure including absolute configuration was elucidated on the basis of spectroscopic analysis and chemical correlation . The 1H NMR spectrum of this compound, exhibiting exceptional complex signals attributable to rotational isomerism, and the reported data were obtained at elevated temperature in methyl ether acetate form. This work provided the 1H and 13C NMR assignments for 1 and its rotational isomer as the free phenolic form at ambient temperature for the first time. Compound 1 showed inhibitory activity against α-glucosidase type IV from Bacillus stearothermophilus with the IC 50 value of 102.3 μM.

Bioassay-guided investigation of the branches of Cleyera japonica led to the isolation of four phenolic constituents: 3,3’-di-O-methylellagic acid (1), 3,3’-di-O-methylellagic acid 4’-O-β-D-xylofuranoside (2),  3,5,7-trihydroxychromone 3-O-α-L-arabinofuranoside (3) and aviculin (4). Their structures were elucidated on the basis of spectral studies, as well as by comparison with literature data. Tyrosinase inhibition activities were carried out for the isolated compounds using arbutin as a positive control. Among them, compound 2 was identified as a potent tyrosinase inhibitor. It inhibited mushroom tyrosinase with an IC50 value of 0.078 mM, which is about three times more active than arbutin (IC50 =0.25 mM). All of the compounds 1-4 were isolated for the first time from this plant.