Bioactive Sesquiterpenoids and Diterpenoids from the Liverwort Bazzania albifolia

One undescribed 6,7‐secofusicoccane‐type diterpene, albifolione ( 1 ), and one new aromadendrane‐type sesquiterpenoid ketone, methyl 2‐oxoaromadendra‐1(10),3‐dien‐12‐oate ( 2 ), along with four known compounds, δ‐cuparenol ( 3 ), fusicoauritone ( 4 ), chiloscyphenols A and B ( 5 and 6 , resp.), were isolated from the liverwort Bazzania albifolia Horik. The structures and relative configurations of 1 and 2 were established unequivocally on the basis of spectroscopic data analysis. Preliminary bioassay revealed that compound 5 showed quite strong cytotoxicity against the human tumor cell line MCF‐7, with an IC₅₀ value of 5.6 μM .     

Cyclopaldic Acid,Seiridin, and Sphaeropsidin A as Fungal Phytotoxins,and Larvicidal and Biting Deterrents against Aedes aegypti (Diptera: Culicidae): Structure?Activity Relationships

Aedes aegypti L. is the major vector of the arboviruses responsible for dengue fever, one of the most devastating human diseases. From a preliminary screening of fungal phytotoxins, cyclopaldic acid ( 1 ), seiridin ( 2 ), sphaeropsidin A ( 4 ), and papyracillic acid ( 5 ) were evaluated for their biting deterrent and larvicidal activities against Ae. aegypti L. Because compounds 1, 2, 4 , and 5 exhibited mosquito biting deterrent activities and 1 and 4 demonstrated larvicidal activities, further structure? activity relationship studies were initiated on these toxins. In biting‐deterrence bioassays, 1, 2, 4 , and 5 , 3,8‐didansylhydrazone of cyclopaldic acid, 1F , 5‐azidopentanoate of cyclopaldic acid A, 1G , the reduced derivative of cyclopaldic acid, 1 H , isoseiridin ( 3 ), 2′‐O‐acetylseiridin ( 2A ), 2′‐oxoseiridin ( 2C ), 6‐O‐acetylsphaeropsidin A ( 4A ), 8,14‐methylensphaeropsidin A methyl ester ( 4B ), and sphaeropsidin B ( 4C ) showed activities higher than the solvent control. Sphaeropsidin B ( 4C ) was the most active compound followed by 2A , while the other compounds were less active. Biting‐deterrence activity of compound 4C was statistically similar to DEET. In the larvicidal screening bioassays, only compounds 1 and 4 demonstrated larvicidal activities. Based on LD₅₀ values, compound 4 (LD₅₀ 36.8 ppm) was significantly more active than compound 1 (LD₅₀ 58.2 ppm). However, the activity of these compounds was significantly lower than permethrin.     

Microsphaerol and Seimatorone: Two New Compounds Isolated from the Endophytic Fungi,Microsphaeropsis sp. and Seimatosporium sp.

A new polychlorinated triphenyl diether named microsphaerol ( 1 ), has been isolated from the endophtic fungus Microsphaeropsis sp. An intensive phytochemical investigation of the endophytic fungus Seimatosporium sp., led to the isolation of a new naphthalene derivative named seimatorone ( 2 ) and eight known compounds, i.e., 1‐(2,6‐dihydroxyphenyl)‐3‐hydroxybutan‐1‐one ( 3 ), 1‐(2,6‐dihydroxyphenyl)butan‐1‐one ( 4 ), 1‐(2‐hydroxy‐6‐methoxyphenyl)butan‐1‐one ( 5 ), 5‐hydroxy‐2‐methyl‐4H‐chromen‐4‐one ( 6 ), 2,3‐dihydro‐5‐hydroxy‐2‐methyl‐4H‐chromen‐4‐one ( 7 ), 8‐methoxynaphthalen‐1‐ol ( 8 ), nodulisporins A and B ( 9 and 10 , resp.), and daldinol ( 11 ). The structures of 1 and 2 were elucidated by detailed spectroscopic analysis including ¹H‐ and ¹³C‐NMR, COSY, HMQC, HMBC, and HR‐EI‐MS, while the structures of the known compounds were deduced from comparison of their spectral data with those in the literature. Preliminary studies revealed that microsphaerol ( 1 ) showed good antibacterial activities against B. Megaterium and E. coli, and good antilagal and antifungal activities against C. fusca, M. violaceum, respectively. On the other hand, seimatorone ( 2 ) exhibited moderate antibacterial, antialgal, and antifungal activities.     

Biological Evaluation of Secondary Metabolites from the Root of Machilus obovatifolia

Bioassay‐guided fractionation of the root of Machilus obovatifolia led to the isolation of four new lignans, epihenricine B ( 1 ), threo‐(7′R,8′R) and threo‐(7′S,8′S)‐methylmachilusol D ( 2 and 3 ), and isofragransol A ( 4 ), along with 23 known compounds. The compounds were obtained as isomeric mixtures (i.e., 2 / 3 and 4 / 20 , resp.). The structures were elucidated by spectral analyses. Among the isolates, 1 , licarin A ( 12 ), guaiacin ( 14 ), (±)‐syringaresinol ( 21 ), and (?)‐epicatechin ( 23 ) showed ABTS (=2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) cation radical‐scavenging activity, with SC₅₀ values of 11.7±0.5, 12.3±1.1, 11.0±0.1, 10.6±0.3, and 9.5±0.2 μM in 20 min, respectively. In addition, kachirachirol B ( 17 ) showed cytotoxicity against the NCI‐H460 cell line with an IC₅₀ value of 3.1 μg/ml.     

Two New Sesquiterpene Derivatives from the Tunisian Endemic Ferula tunetana Pom.

A new sesquiterpene ester, tunetanin A ( 1 ), a new sesquiterpene coumarin, tunetacoumarin A ( 2 ), together with eight known compounds, i.e., coladin ( 3 ), coladonin ( 4 ), isosmarcandin ( 5 ), 13‐hydroxyfeselol ( 6 ), umbelliprenin ( 7 ) propiophenone ( 8 ), β‐sitosterol ( 9 ), and stigmasterol ( 10 ), were isolated from the roots of Ferula tunetana. Their structures were elucidated on the basis of extensive spectroscopic methods, including 1D‐ and 2D‐NMR experiments and MS analysis, as well as by comparison with published data. The cytotoxicity of compounds 1 – 7 towards two human colon cancer cell lines, HT‐29 and HCT 116, was evaluated. Compounds 3, 4 , and 6 showed weak cytotoxic activities.     

Salvisertin A,a New Hexacyclic Triterpenoid,and Other Bioactive Terpenes from Salvia deserta Root

Using various chromatographic methods, a new hexacyclic triterpenoid, 2β,3β,24β‐trihydroxy‐12,13‐cyclotaraxer‐l4‐en‐28oic acid ( 1 ), together with ten known compounds, 2α,3α,23‐trihydroxyurs‐12,20(30)‐dien‐28oic acid ( 2 ), 6,7‐dehydroroyleanone ( 3 ), horminone ( 4 ), 7‐O‐methylhorminone ( 5 ), sugiol ( 6 ), demethylcryptojaponol ( 7 ), 14‐deoxycoleon U ( 8 ), 5,6‐didehydro‐7‐hydroxy‐taxodone ( 9 ), ferruginol ( 10 ), and dichroanone ( 11 ), were isolated from the roots of Salvia deserta. Their structures were identified on the basis of spectroscopic analysis and comparison with the reported data. The individual compounds ( 1 , 3  –  8 ) were screened for cytotoxic activity, using the sulforhodamine B bioassay (SRB) method. As the results, Compounds 3 , 5 , and 8 showed cytotoxic potency against A549, MDA‐MB‐231, KB, KB‐VIN, and MCF7 cell lines with IC₅₀ values ranging from 6.5 to 10.2 μm .     

Cytotoxic Grifolin Derivatives Isolated from the Wild Mushroom Boletus pseudocalopus (Basidiomycetes)

Activity‐guided purification of a MeOH extract of the Korean wild mushroom Boletus pseudocalopus afforded three new grifolin derivatives, 1 – 3 , along with four known phenolic compounds 4 – 7 . Their structures were established by a combination of ¹H‐ and ¹³C‐NMR, NOESY, and extensive two‐dimensional NMR spectroscopic experiments such as gCOSY, gHSQC, gHMBC, and ROESY. The major metabolites 4 and 5 were subjected to reduction to provide the side chain‐reduced compounds 8 and 9 for biological testing. All of the compounds except compound 6 showed anticancer activities in the range of IC₅₀ 3.5–11.0 μg/ml against human lung carcinoma A549 and mouse melanoma B16F1 cell lines. In addition, all compounds showed moderate radical‐scavenging activities determined by DPPH assay.     

Microbial Reactions on 7α‐Hydroxyfrullanolide and Evaluation of Biotransformed Products for Antibacterial Activity

7α‐Hydroxyfrullanolide ( 1 ), a known sesquiterpenoid, was isolated from Sphaeranthus indicus using an antibacterial‐activity‐directed fractionation method. This compound had exhibited a significant antibacterial activity against Gram‐positive bacteria. Chemical and microbial reactions were performed to prepare eight different analogues of compound 1 in order to evaluate these newly synthesized compounds for antibacterial activity. These compounds were 1β,7α‐dihydroxyfrullanolide ( 2 ), 7α‐hydroxy‐1‐oxofrullanolide ( 3 ), 4,5‐dihydro‐7α‐hydroxyfrullanolide ( 4 ), 11,13‐dihydro‐7α‐hydroxyfrullanolide ( 5 ), 13‐acetyl‐7α‐hydroxyfrullanolide ( 6 ), 2α,7α‐dihydroxysphaerantholide ( 7 ), 4α,5α‐epoxy‐7α‐hydroxyfrullanolide ( 8 ), and 4β,5β‐epoxy‐7α‐hydroxyfrullanolide ( 9 ). Microbial reactions on 1 using whole‐cell cultures of Cunninghamella echinulata and Curvularia lunata yielded compounds 2 – 4 . Incubation of compound 1 with the liquid cultures of Apsergillus niger and Rhizopus circinans yielded metabolites 5 – 7 , while 8 and 9 were prepared by carrying out an epoxidation reaction on 1 using meta‐chloroperbenzoic acid (mCPBA). Structures of compounds 2 – 9 were elucidated with the aid of extensive NMR spectral studies. Compounds 2 – 4 were found to be new metabolites. Compounds 1 – 9 were evaluated for antibacterial activity and found to exhibit a wide range of bioactivities. Antibacterial‐activity data of 1 – 9 suggested that the bioactivity of 1 is largely due to the presence of C(4)?C(5), C(11)?C(13), and a γ‐lactone moiety.     

Rubipodanin B,a New Cytotoxic Cyclopeptide from Rubia podantha

Using the TLC cyclopeptide protosite detection method, a new cyclohexapeptide named rubipodanin B ( 1 ), together with 11 known Rubiaceae‐type cyclopeptides (RAs), RA‐X‐OMe ( 2 ), RA‐IV ( 3 ), RA‐XI ( 4 ), RA‐XIII‐OMe ( 5 ), rubiyunnanin C ( 6 ), RA‐I ( 7 ), RA‐III ( 8 ), RA‐V ( 9 ), RA‐VII ( 10 ), RA‐XII ( 11 ) and rubipodanin A ( 12 ), were obtained from the roots and rhizomes of Rubia podantha Diels . The structures were determined using various spectroscopic methods. Among them, 2 was firstly identified as a natural product, and 3–6 were firstly isolated from this species. Cytotoxicity and NF‐κB signaling pathway activity of 1 , 2 , 4 , 6 , 7 and 9 were evaluated. All these compounds showed cytotoxic activities against three human tumor cell lines, MDA‐MB‐231, SW620 and HepG2, with the IC₅₀ values between 0.015 and 10.27 μm , and only 7 and 9 possessed NF‐κB inhibitory activities with the IC₅₀ values of 2.42 and 0.046 μm , respectively, which demonstrated that 2‐alanine amino acid plays a key role to maintain the RAs bioactivity.     

Limonoids and Flavonoids from the Flowers of Azadirachta indica var. siamensis,and Their Melanogenesis‐Inhibitory and Cytotoxic Activities

A new limonoid, 7‐O‐acetyl‐7‐O‐debenzoyl‐22‐hydroxy‐21‐methoxylimocinin ( 2 ), and two new flavonoids, 3′‐(3‐hydroxy‐3‐methylbutyl)naringenin ( 7 ) and 4′‐O‐methyllespedezaflavanone C ( 9 ), along with nine known compounds, including two limonoids, 1 and 3 , and seven flavonoids, 4 – 6, 8 , and 10 – 12 , were isolated from a MeOH extract of the flowers of Azadirachta indica A.Juss. var. siamensis Valeton (Siamese neem tree; Meliaceae). The structures of new compounds were elucidated on the basis of extensive spectroscopic analysis and comparison with literature data. All of these compounds were evaluated for their melanogenesis‐inhibitory activities in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH). Compound 2 (16.9% melanin content at 30 μM ), 6‐deacetylnimbin ( 3 ; 49.6% melanin content at 100 μM ), and kaempferide ( 10 ; 41.7% melanin content at 10 μM ) exhibited inhibitory effects with no, or almost no, toxicity to the cells (81.0–111.7% cell viability). In addition, evaluation of their cytotoxic activities against HL60, A549, AZ521, and SK‐BR‐3 human cancer cell lines, isoazadironolide ( 1 ), 4′‐O‐methyl‐8‐prenylnaringenin ( 5 ), euchrestaflavanone A ( 8 ), 9 , and 3‐methoxy‐3′‐prenylnaringenin ( 12 ) revealed potent cytotoxicities against one or more cell lines with IC₅₀ values in the range of 4.5–9.9 μM .     

Secolignans with antiangiogenic activities from Peperomia dindygulensis

Two new secolignans, peperomins G and H ( 1 and 2 , resp.), were isolated from the whole plant of Peperomia dindygulensis, together with five known secolignans, peperomin A ( 3 ), peperomin E ( 4 ), peperomin B ( 5 ), 2,3‐trans‐2‐methyl‐3‐{(3‐hydroxy‐4,5‐dimethoxyphenyl)[5‐methoxy‐3,4‐(methylenedioxy)phenyl]methyl}butyrolactone ( 6 ), 2,3‐cis‐2‐(hydroxymethyl)‐3‐{bis[5‐methoxy‐3,4‐(methylenedioxy)phenyl]methyl}butyrolactone ( 7 ). Their structures and configurations were elucidated by spectroscopic methods including 2D‐NMR techniques. Antiangiogenic effects of all compounds were evaluated using human umbilical vein endothelial cells (HUVEC) proliferation and tube‐formation tests, with compounds 4 and 5 being active in the bioassay. Compounds 4 and 5 induced obvious cell toxicity to HUVEC with IC₅₀ values of 1.64±0.19 and 8.44±0.4 μM , respectively. Compounds 4 and 5 also exhibited significant HUVEC tube formation‐inhibiting activity with IC₅₀ values of 3.13±0.09 and 6.24±0.12 μM , respectively.     

Phytochemical Investigation and Cytotoxic Evaluation of the Components of the Medicinal Plant Ligularia atroviolacea

A phytochemical investigation of the roots of Ligularia atroviolacea resulted in the isolation of 24 compounds including seven new eremophilanoids named eremophila‐3,7(11),8‐triene‐12,8;14,6α‐diolide ( 1 ), 3β‐(angeloyloxy)eremophil‐7(11)‐en‐12,8β‐olid‐14‐oic acid ( 2 ), 1α‐chloro‐10β‐hydroxy‐6β‐(2‐methylpropanoyloxy)‐9‐oxo‐7,8‐furoeremophilane ( 3 ), (10βH)‐8‐oxoeremophila‐3(4),6(7)‐diene‐12,14‐dioic acid ( 4 ), (10αH)‐8‐oxoeremophila‐3(4),6(7)‐diene‐12,14‐dioic acid ( 5 ), 8β‐[eremophila‐3′,7′(11′)‐diene‐12′,8′α;14′,6′α‐diolide]eremophila‐3,7(11)‐diene‐12,8α;14,6α‐diolide ( 6 ), and ligulatrovine A ( 7 ), eleven known eremophilanoids, 8 – 18 , four steroids, one glucose derivative, and one fatty acid. The structures of these compounds were elucidated by spectroscopic methods including 2D‐NMR experiments. The structure of 3 was also established by an X‐ray diffraction study. The in vitro cytotoxicity evaluation of selected compounds was performed on seven cultured tumor cell lines, i.e., KB, BEL‐7404, A549, HL‐60, HeLa, CNE, and P‐388D1. The preliminary taxonomy of this species was also discussed, and the possible biogenesis of a dimer possessing a new noreremophilanoid type skeleton, 7 , is presented in a preliminary form.     

Cuceolatins A–D: New Bioactive Diterpenoids from the Leaves of Cunninghamia lanceolata

Four new diterpenoids named cuceolatins A–D, including three labdane‐type ( 1 – 3 ) and one abietane‐type ( 4 ) as well as three known labdane analogs ( 5 – 7 ), were reported from the leaves of Cunninghamia lanceolata. Structural assignments for these compounds were conducted by analyses of spectroscopic data, and their absolute configurations were determined by time‐dependent density functional theory (TD‐DFT) based electronic circular dichroism (ECD) calculations. Among them, the abietane‐type diterpenoid (11‐hydroxy‐12‐methoxyabieta‐8,11,13‐trien‐3‐one ( 4 )) showed significant cytotoxicity against human MDA‐MB‐231, MCF‐7, and HeLa tumor cell lines with IC₅₀ measurements of 4.3, 2.8 and 4.5 μm , respectively, while the labdane‐type diterpenoids with a 4α‐carboxy group ( 1 – 3 and 5 ) exhibited moderate antibacterial activity towards Bacillus subtilis and Staphylococcus aureus with IC₅₀ values all below 25 μm .     

Two New Hydronaphthoquinones from Sinningia aggregata (Gesneriaceae) and Cytotoxic Activity of Aggregatin D

Two new hydronaphthoquinones, aggregatins E and F ( 1 and 2 , resp.) were isolated from the tubers of Sinningia aggregata (Ker‐Gawl .) Wiehler (Gesneriaceae), along with twelve known compounds aggregatin D ( 3 ), tectoquinone ( 4 ), 1‐hydroxy‐2‐methylanthraquinone ( 5 ), icosyl ferulate ( 6 ), pustuline ( 7 ), 1,6‐dihydroxy‐2‐methylanthranquinone ( 8 ), 6‐hydroxy‐2‐methylanthraquinone ( 9 ), 7‐hydroxy‐2‐methylanthraquinone ( 10 ), tyrosol ( 11 ), halleridone ( 12 ), calceolarioside B ( 13 ), and cornoside ( 14 ). All compounds were identified by analysis of spectroscopic and spectrometric data. Compounds 3, 4 , and 10 had already been reported in this species. Compounds 2 and 3 were evaluated against several tumor cell lines, but only 3 exhibited activities against UACC‐62, 786‐0 and OVCAR‐3 cell lines, with IC₅₀ values of 12.3, 12.8 and 0.3 μg/ml, respectively, without toxic effects on non‐cancer cell line HaCat (human keratinocyte).     

Diverse Secondary Metabolites Produced by Marine‐Derived Fungus Nigrospora sp. MA75 on Various Culture Media

Bioassay‐guided isolation of a fungal strain Nigrospora sp. MA75, an endophytic fungus obtained from the marine semi‐mangrove plant Pongamia pinnata, which was fermented on three different culture media, resulted in the isolation and identification of seven known compounds, 2, 3 , and 5 – 9 , from a medium containing 3.5% NaCl, while a new compound, 2,3‐didehydro‐19α‐hydroxy‐14‐epicochlioquinone B ( 10 ) was obtained from the medium containing 3.5% NaI. In addition, two new griseofulvin derivatives, 6‐O‐desmethyldechlorogriseofulvin ( 1 ) and 6′‐hydroxygriseofulvin ( 4 ), were isolated and identified from the rice solid medium. Dechlorogriseofulvin ( 2 ) and griseofulvin ( 3 ) were the major components in fermentation extracts of all these culture media, while compounds 1 and 4, 5 and 6 , and 10 were only present in the extract of respective culture medium. The structures of these compounds were elucidated by detailed spectroscopic analysis, and the absolute configuration of 1 was determined by CD measurement. Compounds 9 and 10 exhibited antibacterial activities toward five tested bacterial strains, while compounds 5, 6 , and 8 selectively inhibited MRSA, E. coli, and S. epidermidis, and compound 3 showed moderate activity against V. mali and S. solani. Moreover, compound 10 potently inhibited the growth of MCF‐7, SW1990, and SMMC7721 tumor cell lines with IC₅₀ values of 4, 5, and 7 μg/ml, respectively.     

Toxicity of Thiophenes from Echinops transiliensis (Asteraceae) against Aedes aegypti (Diptera: Culicidae) Larvae

Structure? activity relationships of nine thiophenes, 2,2′: 5′,2″‐terthiophene ( 1 ), 2‐chloro‐4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yn‐1‐yl acetate ( 2 ), 4‐(2,2′‐bithiophen‐5‐yl)but‐3‐yne‐1,2‐diyl diacetate ( 3 ), 4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yne‐1,2‐diyl diacetate ( 4 ), 4‐(2,2′‐bithiophen‐5‐yl)‐2‐hydroxybut‐3‐yn‐1‐yl acetate ( 5 ), 2‐hydroxy‐4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yn‐1‐yl acetate ( 6 ), 1‐hydroxy‐4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yn‐2‐yl acetate ( 7 ), 4‐(2,2′‐bithiophen‐5‐yl)but‐3‐yne‐1,2‐diol ( 8 ), and 4‐[5‐(penta‐1,3‐diyn‐1‐yl)thiophen‐2‐yl]but‐3‐yne‐1,2‐diol ( 9 ), isolated from the roots of Echinops transiliensis, were studied as larvicides against Aedes aegypti. Structural differences among compounds 3, 5 , and 8 consisted in differing AcO and OH groups attached to C(3″) and C(4″), and resulted in variations in efficacy. Terthiophene 1 showed the highest activity (LC₅₀, 0.16 μg/ml) among compounds 1 – 9 , followed by bithiophene compounds 3 (LC₅₀, 4.22 μg/ml), 5 (LC₅₀, 7.45 μg/ml), and 8 (LC₅₀, 9.89 μg/ml), and monothiophene compounds 9 (LC₅₀, 12.45 μg/ml), 2 (LC₅₀, 14.71 μg/ml), 4 (LC₅₀, 17.95 μg/ml), 6 (LC₅₀, 18.55 μg/ml), and 7 (LC₅₀, 19.97 μg/ml). These data indicated that A. aegypti larvicidal activities of thiophenes increase with increasing number of thiophene rings, and the most important active site in the structure of thiophenes could be the tetrahydro‐thiophene moiety. In bithiophenes, 3, 5 , and 8 , A. aegypti larvicidal activity increased with increasing number of AcO groups attached to C(3″) or C(4″), indicating that AcO groups may play an important role in the larvicidal activity.     

Daphnane‐Type Diterpenoid Glucosides and Further Constituents of Euphorbia pilosa

Phytochemical investigation of whole plants of Euphorbia pilosa led to the isolation and identification of two new daphnane‐diterpenoid glucosides, euphopilosides A and B ( 1 and 2 , resp.), and a new ent‐abietane, euphopilolide ( 3 ), together with eight known compounds. Compounds 1 and 2 are the first daphnane‐type diterpenoid glycosides. Their structures were elucidated by a combination of 1D‐ and 2D‐NMR, and MS analyses, and acid hydrolysis. Compounds 1 – 9 were evaluated for their in vitro cytotoxicities against five human tumor cell lines, HL‐60, SMMC‐7721, A‐549, MCF‐7, and SW‐480. Compound 7 showed moderate inhibitory activity against all five cell lines.     

Two New Butenolides Produced by an Actinomycete Streptomyces sp.

Two new butenolides, (4S)‐4,10‐dihydroxydodec‐2‐en‐1,4‐olide ( 1 ) and (4S)‐4,8,10‐trihydroxy‐10‐methyldodec‐2‐en‐1,4‐olide ( 2 ), together with three known compounds, MKN‐003B ( 3 ), MKN‐003C ( 4 ), and cyclo(Ala‐Leu) ( 5 ), were isolated from the culture broth of a bacterium of the genus Streptomyces derived from soil environment. The structures of these compounds were elucidated on the basis of spectroscopic analysis. The inhibitory activities of the butenolides against eight pathogenic fungi were evaluated. All of the butenolides showed moderate‐or‐weak antifungal activities in a broth microdilution assay.