New ursane triterpenoids from <Emphasis Type="Italic">Ficus pandurata</Emphasis> and their binding affinity for human cannabinoid and opioid receptors

Phytochemical investigation of Ficus pandurata Hance (Moraceae) fruits has led to the isolation of two new triterpenoids, ficupanduratin A [1β-hydroxy-3β-acetoxy-11α-methoxy-urs-12-ene] (11) and ficupanduratin B [21α-hydroxy-3β-acetoxy-11α-methoxy-urs-12-ene] (17), along with 20 known compounds: α-amyrin acetate (1), α-amyrin (2), 3β-acetoxy-20-taraxasten-22-one (3), 3β-acetoxy-11α-methoxy-olean-12-ene (4), 3β-acetoxy-11α-methoxy-12-ursene (5), 11-oxo-α-amyrin acetate (6), 11-oxo-β-amyrin acetate (7), palmitic acid (8), stigmast-4,22-diene-3,6-dione (9), stigmast-4-ene-3,6-dione (10), stigmasterol (12), β-sitosterol (13), stigmast-22-ene-3,6-dione (14), stigmastane-3,6-dione (15), 3β,21β-dihydroxy-11α-methoxy-olean-12-ene (16), 3β-hydroxy-11α-methoxyurs-12-ene (18), 6-hydroxystigmast-4,22-diene-3-one (19), 6-hydroxystigmast-4-ene-3-one (20), 11α,21α-dihydroxy-3β-acetoxy-urs-12-ene (21), and β-sitosterol-3-O-β-d-glucopyranoside (22). Compound 21 is reported for the first time from a natural source. The structures of the 20 compounds were elucidated on the basis of IR, 1D (¹H and ¹³C), 2D (¹H–¹H COSY, HSQC, HMBC and NOESY) NMR and MS spectroscopic data, in addition to comparison with literature data. The isolated compounds were evaluated for their anti-microbial, anti-malarial, anti-leishmanial, and cytotoxic activities. In addition, their radioligand displacement affinity on opioid and cannabinoid receptors was assessed. Compounds 4, 11, and 15 exhibited good affinity towards the CB2 receptor, with displacement values of 69.7, 62.5 and 86.5 %, respectively. Furthermore, the binding mode of the active compounds in the active site of the CB2 cannabinoid receptors was investigated through molecular modelling.     

Two new ursane-type triterpenoid saponins from <Emphasis Type="Italic">Elsholtzia bodinieri</Emphasis>

Two new ursane-type triterpenoid saponins, bodiniosides M (1) and N (2), along with three known saponins, oblonganosides I (3), pseudobuxussaponin B (4) and bodinioside A (5), were isolated from the aerial parts of Elsholtzia bodinieri. The structures of compounds 1 and 2 were characterized by spectroscopic data as well as acid hydrolysis and GC analysis as 3-O-β-d-xylopyranosyl-19α-hydroxy-23-acetoxy-urs-12(13)-en-28-oic acid 28-O-α-l-rhamnopyranosyl-(1-2)-β-d-glucopyranoside and 3-O-β-d-glucopyranosyl-2α,19α-dihydroxy-urs-12(13)-en-28,20β-lactone. Compounds 1 and 5 exhibited potent anti-HCV activities in vitro with a selective index of 6.53 and 4.41, respectively.     

A new indole glycoside from the seeds of <Emphasis Type="Italic">Raphanus sativus</Emphasis>

A new indole glycoside, β-d-glucopyranosyl 2-(methylthio)-1H-indole-3-carboxylate, named raphanuside A (1), as well as eight known compounds, β-d-fructofuranosyl-(2 → 1)-(6-O-sinapoyl)-α-d-glucopyranoside (2), (3-O-sinapoyl)-β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranoside (3), (3-O-sinapoyl)-β-d-fructofuranosyl-(2 → 1)-(6-O-sinapoyl)-α-d-glucopyranoside (4), (3,4-O-disinapoyl)-β-d-fructofuranosyl-(2 → 1)-(6-O-sinapoyl)-α-d-glucopyranoside (5), isorhamnetin 3,4′-di-O-β-d-glucoside (6), isorhamnetin 3-O-β-d-glucoside-7-O-α-l-rhamnoside (7), isorhamnetin 3-O-β-d-glucoside (8) and 3'-O-methyl-(?)-epicatechin 7-O-β-d-glucoside (9) were isolated from the seeds of Raphanus sativus. Furthermore, compounds 1–3 and 6–9, were isolated from this plant for the first time. The structures of compounds 1–9 were identified using 1D and 2D NMR, including ¹H–¹H COSY, HSQC, HMBC and NOESY spectroscopic analyses. The inhibitory activity of these isolated compounds against interleukin-6 (IL-6) production in TNF-α stimulated MG-63 cells was also examined.     

Phenylacylphenol derivatives with anti-melanogenic activity from <Emphasis Type="Italic">Stewartia pseudocamellia</Emphasis>

Three new phenylacylphenol derivatives, stewartianol (1), deoxystewartianol-4′-O-arabinoglucoside (2), and stewartianol-3-O-glucoside (3), along with nine known compounds, methylesculin (4), fraxoside (5), fraxetin (6), scopletin (7), (+)-dihydromyricetin (8), (+)-taxifolin-7-O-β-d-glucose (9), (+)-taxifolin (10), (+)-dihydrokaempferol-7-O-β-d-glucose (11), and 3-acetyl-ursolic acid (12), were isolated from the twigs of Stewartia pseudocamellia; commonly used as folk medicine in Korea. The structures of the isolated compounds were identified using spectroscopic analysis, including 1D, 2D NMR, MS and compared with published data. The compounds were tested for their anti-melanogenic activity in cultured murine B16 melanoma cells. Stewartianol (1) and stewartianol-3-O-glucoside (3) showed an inhibitory effect significantly on melanogenesis in a concentration-dependent manner.     

Two new naphthalenic lactone glycosides from <Emphasis Type="Italic">Cassia obtusifolia</Emphasis> L. seeds

Two new naphthalenic lactone glycosides, (3S)-9,10-dihydroxy-7-methoxy-3-methyl-1-oxo-3,4-dihydro-1H-benzo[g]isochromene-3-carboxylic acid 9-O-β-d-glucopyranoside (1) and (3R)-cassialactone 9-O-β-d-glucopyranoside (2) were isolated from seeds of Cassia obtusifolia Linn., along with five known compounds: (3R)-cassialactone 9-O-β-d-gentiobioside (3), emodin 1-O-β-gentiobioside (4), 1-hydroxyl-2-acetyl-3,8-dimethoxy-naphthalene 6-O-β-d-apiofuranosyl-(1?→?2)-β-d-glucopyranoside (5), rubrofusarin 6-O-β-d-gentiobioside (6), rubrofusarin 6-O-β-d-triglucoside (7). Structures of 1 and 2 were elucidated by NMR and HR-ESI-MS spectroscopic analysis. Their stereochemistry was determined by CD experiment. All compounds were tested for their ability to inhibit the formation of advanced glycation end-products in vitro. Compounds 1, 2, 3, 5, and 6 showed significant in vitro inhibitory activities (IC₅₀ values of 11.63, 23.40, 7.32, 89.03, and 38.89 µM, respectively).     

Two new phenylpropane glycosides from <Emphasis Type="Italic">Allium tuberosum</Emphasis> Rottler

A phytochemical investigation of Allium tuberosum Rottler afforded two new phenylpropane glycosides, named tuberonoid A (1) and B (2), along with four known flavonoids, kaempferol 3-O-β-sophoroside (3), 3-O-β-d-(2-O-feruloyl)-glucosyl-7,4′-di-O-β-d-glucosylkaempferol (4), 3-O-β-sophorosyl-7-O-β-d-(2-O-feruloyl)glucosyl kaempferol (5), kaempferol 3,4′-di-O-β-d-glucoside (6). The identification and structural elucidation of the new compounds were carried out based on spectral data analyses (¹H and ¹³C NMR, ¹H–¹H COSY, HMQC) and HR-MS.     

Alkyl phenols,alkenyl cyclohexenones and other phytochemical constituents from <Emphasis Type="Italic">Lannea rivae</Emphasis> (chiov) Sacleux (Anacardiaceae) and their bioactivity

Six novel compounds, 3-nonadec-14′-(Z)-enyl phenol (1a); 4,5-dihydroxy-4,2′-epoxy-5-[16′-Z-18′-E-heneicosenyldiene]-cyclohex-2-enone (2), 2,4,5-trihydroxy-2-[16′-Z-heneicosenyl]-cyclohexanone (3); 4S,6R-dihydroxy-6-[12′-Z-heptadecenyl]-cyclohex-2-enone (4a); 4S,6R-dihydroxy-6-[14′-Z-nonadecenyl]-cyclohex-2-enone (4b); and 1,2,4-trihydroxy-4-[16′-Z-heneicosenyl]-cyclohexane (5) were identified from the roots and stems of Lannea rivae in addition to the known cardanols, 3-heptadec-12′-Z-enyl phenol (1b), 3-pentadec-10′-Z-enyl phenol (1c) and 3-pentadecyl phenol (1d), sitosterol (6), sitosterol glucoside (7), taraxerone (8), taraxerol (9), E-lutein (10), myricetin (11), myricetin-3-O-α-rhamnopyranoside (12), myricetin-3-O-β-galactopyranoside (13) and (-)-epicatechin-3-O-gallate (14). The ketones 4a and 4b were isolated as a mixture and were qualitatively separated and identified by GCMS. Myricetin (11) and epicatechin gallate (14) displayed over 90 % DPPH radical-scavenging activity at 50 μg mL^?1, while its glycosides (12 and 13) showed percentages of over 70 % in the same assay. The same compounds 11 and 14 showed antibacterial activity similar to erythromycin and vancomycin against Gram-positive bacteria and were also active against Gram-negative bacteria, but not as much as the cefuroxime, ciprofloxacin and nalidixic acid standards. Compounds 1a–d, 4a–b and 5 were all relatively non-toxic, while 2 (the epoxy cyclohex-2-enone) and 3 (the trihydroxy cyclohexanone) showed more toxicity than the others. These two toxic compounds, 2 and 3 also showed antiplasmodial activity with IC₅₀ values between 0.48 and 2.05 μg mL^?1. The mixture of dihydroxy cyclohex-2-enones 4a and 4b, which was far less toxic than 2 and 3, also showed promising antiplasmodial activity and may be a possible lead for further investigation as an antiplasmodial drug.     

Antioxidant <Emphasis Type="Italic">C</Emphasis>-glycosylflavones of <Emphasis Type="Italic">Drymaria cordata</Emphasis> (Linn.) Willd

A new C-glycosylflavone, drymaritin E (6-C-(3-keto-β-digitoxopyranosyl)-4′-O-(β-d-glucopyranosyl)-7-methoxyl-5,4′-dihydroxylflavone) 1 was isolated from the oily upper phase (SU) of the MeOH extract from aerial parts of Drymaria cordata together with two known compounds (cassiaoccidentalin A 2 and anemonin 3) and an inseparable mixture of two known C-glycosylflavones 5,4′-dihydroxy-7-methoxyflavone-6-C-(2′′-O-α-l-rhamnopyranosyl)-β-d-glucopyranoside 4a and 5,7,3′,4′-tetrahydroxyflavone-6-C-(2′′-O-α-l-rhamnopyranosyl)-β-d-glucopyranoside 4b. The alkaline hydrolysis of 3 led to a new hemisynthetic derivative, sodium anemonate (sodium 2-((1’E) 2′-sodium-carboxylate-vinyl)-5-oxo-cyclohex-1-ene carboxylate) 3a. The chemical structures were determined by spectroscopic methods (¹H NMR, ¹³C NMR, ¹H-¹H COSY, HMBC, HSQC, and NOESY) and mass spectrometry (ESI–MS). C-glycosylflavones had significant free radical-scavenging activities on the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). However, SU and compounds 3 and 3a exhibited no activity. In particular, compound 1 exhibited a concentration-dependent radical scavenging activity on DPPH with EC₅₀ of 31.43 µg/mL.     

Degranulation inhibitors from the arils of <Emphasis Type="Italic">Myristica fragrans</Emphasis> in antigen-stimulated rat basophilic leukemia cells

A methanol extract of mace, the aril of Myristica fragrans (Myristicaceae), was found to inhibit the release of β-hexosaminidase, a marker of antigen-IgE-stimulated degranulation in rat basophilic leukemia cells (RBL-2H3, IC₅₀ = 45.7 μg/ml). From the extract, three new 8-O-4′ type neolignans, maceneolignans I–K (1–3), were isolated, and the stereostructures of 1–3 were elucidated based on spectroscopic and chemical evidence. Among the isolates, maceneolignans A (5), D (6), and H (8), (?)-(8R)-?^8′-4-hydroxy-3,3′,5′-trimethoxy-8-O-4′-neolignan (13), (?)-(8R)-?^8′-3,4,5,3′,5′-pentamethoxy-8-O-4′-neolignan (14), (?)-erythro-(7R,8S)-?^8′-7-acetoxy-3,4-methylenedioxy-3′,5′-dimethoxy-8-O-4′-neolignan (17), (+)-licarin A (20), nectandrin B (24), verrucosin (25), and malabaricone C (29) were investigated as possible degranulation inhibitors (IC₅₀ = 20.7–63.7 μM). These inhibitory activities were more potent than those of the antiallergic agents tranilast (282 μM) and ketotifen fumalate (158 μM). Compounds 5, 25, and 29 also inhibited antigen-stimulated tumor necrosis factor-α production (IC₅₀ = 39.5–51.2 μM), an important process in the late phase of type I allergic reactions.     

Antimicrobial glycoalkaloids from the tubers of <Emphasis Type="Italic">Stephania succifera</Emphasis>

Three new glycoalkaloids, N-formyl-asimilobine-2-O-β-d-glucoside (1), (?)-1-O-β-d-glucoside-8-oxotetrahydropalmatine (2), and 1-N-monomethylcarbamate-argentinine-3-O-β-d-glucoside (3) were isolated from tubers of Stephania succifera. The structures were established based on spectroscopic analysis, and the antimicrobial activities of the three glycoalkaloids are reported.     

Chemical constituents from <Emphasis Type="Italic">Phyllanthus emblica</Emphasis> and the cytoprotective effects on H<Subscript>2</Subscript>O<Subscript>2</Subscript>-induced PC12 cell injuries

Two new compounds (1–2), including a bisabolane-type sesquiterpenoid (1), one new diphenyl ether derivative (2), together with 23 known compounds (3–25), were isolated from the fruits of Phyllanthus emblica. Their structures were elucidated by detailed spectroscopic analysis. All the isolated compounds were screened for the DPPH scavenging effects and cytoprotective effects against H₂O₂ induced PC12 cells injury. Compounds 12–15 showed significant DPPH scavenging effects with the IC₅₀ values in the range of 3.25–4.18 μM. Among these potential antioxidants, compound 14 improved the survival of PC12 cells after H₂O₂ exposure without showing any cytotoxicity at the tested concentrations.     

Chemical structures of constituents from the leaves of <Emphasis Type="Italic">Polyscias balfouriana</Emphasis>

A new pyrrolidine derivative, (5S)-hydroxyethyl 2-oxopyrrolidine-5-carboxylate (1), a new flavonol glycoside, tamaraxetin 3,7-di-O-α-l-rhamnopyranoside (2), and a new triterpene saponin, polyscioside A methyl ester (3), along with six known compounds (4–9) were isolated from the leaves of Polyscias balfouriana. Their chemical structures were elucidated on the basis of extensive spectroscopic analysis.     

Phenylpropanoid ester from <Emphasis Type="Italic">Zingiber officinale</Emphasis> and their inhibitory effects on the production of nitric oxide

A new phenylpropanoid ester mixture, (E)-geranylferulic acid (1a) and (Z)-geranylferulic acid (1b), along with 13 known compounds, [6]-gingerol (2), [8]-gingerol (3), [10]-gingerdione (4), 1-dehydro-[6]-gingerdione (5), 1-dehydro-[8]-gingerdione (6), [6]-paradol (7), [8]-paradol (8), [6]-gingeroldiacetate (9), 6-hydroxy-[6]-shogaol (10), galanolactone (11), trans-®-sesquiphellandrol (12), trans-sesquipiperitol (13), and 4α,5β-dihydroxybisabola-2,10-diene (14) were isolated from ethanol extract of Zingiber officinale. Their structures were determined based on the spectroscopic (1D, 2D-NMR and MS) and chemical evidence. All of the isolates were evaluated for their potential to inhibit LPS-induced production of nitric oxide in murine macrophage RAW264.7 cells. Compounds 1–12 were found to inhibit nitric oxide production with IC₅₀ values ranging from 5.5 to 28.5 μM.     

Syntheses of arylcinnamic acids,using Alum-Cs<Subscript>2</Subscript>CO<Subscript>3</Subscript> as precursors of new 2-heterostyrylbenzimidazoles and their antimicrobial evaluation

A simple and green methodology has been developed for the syntheses of some new 2-styrylbenzimidazoles. In this method, 2-styrylbenzimidazoles 6(a–x) were synthesized by the condensation of o-phenylenediamines 4(a–c) with cinnamic acids 3(a–h) using glycerol containing boric acid (10 mol%) as the reaction medium at 180 °C about 3–5 h. The cinnamic acids 3(a–h) were obtained by the condensation between aromatic aldehydes 1(a–h), and malonic acid using a new heterogeneous catalytic system such as alum-Cs₂CO₃ in water is described. Compounds 6(a–x) were also obtained alternatively by the condensation of 2-methylbenzimidazoles 5(a-c) with 1(a-h) using the same glycerol containing boric acid (10 mol%) as reaction medium at 180 °C for 5–6 h. The catalytic systems mentioned here were found to be highly active, stable, and recyclable under reaction conditions. All the newly synthesized compounds were characterized by IR, Mass, and NMR spectral analyses. All synthesized compounds were screened for their antimicrobial activity against the clinical strains which include gram-positive bacteria (Micrococcus luteus MTCC 2470, Staphylococcus aureus MTCC 96, Staphylococcus aureus MLS-16 MTCC 2940, Bacillus subtilis MTCC 121) and gram-negative bacteria (Escherichia coli MTCC 739, Pseudomonas aeruginosa MTCC 2453, Klebsiella planticola MTCC 530, and Candida albicans MTCC 3017). The results revealed that compounds (6b, 6g, 6h, 6j, 6k, 6n, 6o, 6t) exhibited significant antibacterial activity almost equal to the standard drug, i.e., Ciprofloxacin.     

New podolactones from the seeds of <Emphasis Type="Italic">Podocarpus nagi</Emphasis> and their anti-inflammatory effect

Podolactones are a class of structural diverse diterpenoid lactones, mainly isolated from the Podocarpus species. Several bioactivities have been disclosed for podolactones, including cytotoxicity and anti-atherosclerosis. In this study, the seeds of P. nagi were isolated by comprehensive chromatographic methods to obtain three new podolatones, named nagilactone B 1-O-β-d-glucoside (1), nagilactone N3 3-O-β-d-glucoside (2), and 2-epinagilactone B (3), as well as a known compound, nagilactone B (4). Their structures were determined by analyses of NMR and HRESIMS data. Compounds 1 and 2 significantly inhibited nitric oxide (NO) production on LPS-stimulated RAW264.7 macrophages, with IC₅₀ values of 0.18?±?0.04 and 0.53?±?0.03 μM, respectively. Indomethacin (IC₅₀ 4.21?±?0.32 μM) was used as a positive control. Compound 1 suppressed the expression of inducible NO synthase (iNOS) in a concentration-dependent manner, mediating through inhibiting nuclear factor-κB (NF-κB) activity. This is the first report regarding the anti-inflammatory effect of podolactones, which could be potential anti-inflammatory agents.     

Three new <Emphasis Type="Italic">C</Emphasis>-glycosyflavones with acetyl substitutions from <Emphasis Type="Italic">Swertia mileensis</Emphasis>

Three new acetylated C-glycosylflavones, 3″,6″-di-O-acetylswertiajaponin (1), 4″,6″-di-O-acetylswertiajaponin (2), and 6″-O-acetylswertiajaponin (3), together with six known compounds were isolated from the whole herb of Swertia mileensis. Their structures were elucidated on extensive NMR experiments and mass spectrometry studies. ¹H and ¹³C NMR data exhibited doublet signals at room temperature. Variable temperature ¹H NMR experiments were carried out to investigate the presence of rotational isomerism of C-glycosylflavones. All compounds showed potential antioxidant activities against apoptosis of H₂O₂-induced human embryo liver L02 cells.     

New antimicrobial flavonoids and chalcone from <Emphasis Type="Italic">Colutea armata</Emphasis>

Colucins A (1) and B (2), new flavonoids and colucone (3), the new chalcone derivative, have been isolated from the CHCl₃-soluble fraction of the whole plant of Colutea armata along with luteolin (4), luteolin 7-O-β-D-glucoside (5), isoliquiritigenin (6), trans-caffeic acid (7) and stigmasterol (8) reported for the first time from this species. Their structures were elucidated by spectroscopic techniques including MS and 2D-NMR spectroscopy. Compounds 1 and 2 showed significant antimicrobial activity against two Gram positive and three Gram negative bacterial strains while 3 was moderately active.     

Coumarins from <Emphasis Type="Italic">Angelica</Emphasis><Emphasis Type="Italic">decursiva</Emphasis> inhibit lipopolysaccharide-induced nitrite oxide production in RAW 264.7 cells

Angelica decursiva has long been used in Korean traditional medicine as an antitussive, analgesic, antipyretic, and cough remedy. In this study, the anti-inflammatory activity of 9 coumarin derivatives isolated from a 90 % methanol fraction was evaluated via inhibition of production of nitric oxide (NO) and tumor necrosis factor-α (TNF-α), as well as the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Among the tested compounds, edulisin II (1) exhibited the most potent NO production inhibitory activity, followed by decursidin (2), Pd–C-III (3), 4-hydroxy Pd–C-III (4), Pd–C-I (5), and Pd–C-II (6). In contrast, (+)-trans-decursidinol (7) did not exhibit NO suppressive effects on LPS-stimulated RAW 264.7 cells. Structure-activity relationships revealed that esterification of the hydroxyl at C-3′ or C-4′ of 7 with an angeloyl/senecioyl/acetyl group is essential for its inhibitory activity against NO production, while the number of angeloyl or senecioyl groups, and their positions greatly affect the potency of these coumarins. Coumarins 1-6 also inhibited TNF-α production and iNOS protein expression, while compounds 1-4 inhibited COX-2 protein expression in LPS-stimulated RAW 264.7 cells. These results suggest that coumarins isolated from A. decursiva might be used as potential leads for the development of therapeutic agents for inflammation-associated disorders.     

Cytotoxic constituents of <Emphasis Type="Italic">Oldenlandia umbellata</Emphasis> and isolation of a new symmetrical coumarin dimer

The study was aimed at exploring cytotoxic activity of Oldenlandia umbellata and its chemical constituents. Cell viability assay of crude methanolic extract of aerial parts of O. umbellata (HUM), its ether soluble fraction (HUM-E) and butanol soluble fraction (HUM-B) against colon cancer HT-29, lung epithelial A549 and breast adenocarcinoma MDA-MB-231 cell lines showed HUM-E to be significantly cytotoxic with IC₅₀ values of 25.7, 67.7 and 69.3 μg/mL, against HT-29, A549 and MDA-MB-231, respectively. Chemical investigation of HUM-E and HUM-B resulted in the isolation of a novel symmetrical coumarin dimer named oledicoumarin (1), together with eleven known compounds, hedyotiscone B (2), cedrelopsin (3), pheophorbide A methyl ester (4), deacetyl asperuloside (5), scandoside methyl ester (6), asperulosidic acid (7), scandoside (8), nicotinic acid (9), 6α-hydroxy geniposide (10) anthragallol 1,2-dimethyl ether (11) and anthragallol 1,3-dimethyl ether (12). All compounds were isolated for the first time from O. umbellata except anthragallols. This is the foremost report exploring the presence of coumarin derivatives in O. umbellata. Testing of cytotoxicity of isolated constituents revealed that compounds 3, 4, 11 and 12 showed significant inhibition against A549 cells with IC₅₀ values of 3.6–5.9 μg/mL. Compounds 4, 11 and 12 showed marked inhibitory effect against MDA-MB-231 cells (IC₅₀ 3.6–9.1 μg/mL). Compounds 4 (IC₅₀ 1.7 μg/mL) and 7 (IC₅₀ 6.1 μg/mL) were highly active against HT-29 cells. In summary, the less polar fraction of O. umbellata and its constituents were found to be cytotoxic.     

Microbial transformation of naringenin derivatives

Microbial transformations of (±)-7-O-prenylnaringenin (7-PN, 1) and (±)-7-O-allylnaringenin (7-AN, 2) have isolated four metabolites (3–6). Structures of these novel compounds were identified as 5,4′-dihydroxy-7-O-[(2E)-4-hydroxy-3-methyl-2-buten-1-yl]flavanone (3), 5,4′-dihydroxy-7-O-(2,3-dihdroxy-3-methylbutyl)flavanone (4), 5,4′-dihydroxy-7-O-(2,3-dihdroxypropyl)flavanone (5), and 5-O-β-D-glucopyranosyl-7-O-allyl-4′-hydroxyflavanone (6) based on spectroscopy. Compounds 1–6 were evaluated for their radical scavenging capacity using DPPH (2,2-diphenyl-1-picrylhydrazyl). The derivatives 3–6 exhibited more potent antioxidant activity than their corresponding substrates 1 and 2.