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.     

Two New Phenol Derivatives from the Cold Seep-Derived Fungus Aspergillus insuetus SD-512

Two new phenol derivatives, namely insphenol A ( 1 ) and acetylpeniciphenol ( 2 ), along with seven known analogs ( 3 – 9 ), were isolated from the deep-sea cold seep-derived fungus, Aspergillus insuetus SD-512. The structures of 1 and 2 were established by extensive interpretation of NMR and mass spectroscopic data. The absolute configuration of 1 was determined by the combination of coupling constant analysis and acid hydrolysis. Among the isolated compounds, insphenol A ( 1 ) represents the first example of isopentenyl phenol derivative with a unique 1-glycosylation from the species Aspergillus insuetus. The isolated new compounds were evaluated for antibacterial activities against six human or aquatic pathogens, while compound 2 exhibited inhibitory effect against Edwardsiella tarda, Vibrio alginolyticus, and V. vulnificus, with MIC values of 4, 8, and 8 μg/mL, respectively.     

Aspergetherins A-D,New Chlorinated Biphenyls with anti-MRSA Activity from the Marine Sponge Symbiotic Fungus Aspergillus terreus 164018

Aspergetherins A-D ( 1 – 4 ), four new chlorinated biphenyls, were isolated from the rice fermentation of a marine sponge symbiotic fungus Aspergillus terreus 164018, along with seven known biphenyl derivatives ( 5 – 11 ). The structures of four new compounds were determined by a comprehensive analysis of the spectroscopic data, including HR-ESI-MS and 2D NMR data. All 11 isolates were evaluated for their anti-bacterial activity against two strains of methicillin-resistant Staphylococcus aureus (MRSA). Among them, compounds 1 , 3 , 8 and 10 showed anti-MRSA activity with MIC values of 1.0–128 μg/mL. Preliminary structure-activity relationship analysis unveiled that both chlorinated substitution and esterification of 2-carboxylic acid could impact the antibacterial activity of biphenyls.     

Oplopane Sesquiterpenes from Ligularia knorringiana and Their Anti‐Complementary Activity

Three new oplopane sesquiterpenes, knorringianalarins D – F ( 1 – 3 , respectively), and five known analogues ( 4 – 8 , respectively), were isolated from the roots and rhizomes of Ligularia knorringiana. The structures of three new compounds were identified as 4‐acetoxy‐11α,12‐epoxy‐2β‐hydroxy‐3β‐(2‐methylbutyryloxy)‐9α‐(4‐methylsenecioyloxy)oplop‐10(14)‐ene ( 1 ), 3β,4‐diacetoxy‐9α‐(4‐acetoxy‐4‐methylsenecioyloxy)‐11α,12‐epoxy‐8α‐(2‐methylbutyryloxy)oplop‐10(14)‐ene ( 2 ), and (1R,5R,6R,7R,9R)‐5,9,11‐trihydroxy‐4,15‐dinoroplop‐10(14)‐en‐3‐one ( 3 ) based on spectroscopic methods including 1D‐ and 2D‐NMR, mass spectrometry, and CD spectroscopy techniques. All compounds were evaluated for their anti‐complementary activity on the classical pathway of the complement system in vitro. Among which, three oplopane sesquiterpenes ( 3 , 7 , and 8 ) exhibited better anti‐complementary effects with CH₅₀ values ranging from 0.33 to 0.89 mm , which are plausible candidates for developing potent anti‐complementary agents.     

Synthesis,Antimicrobial Activities,and Molecular Docking Studies of Dihydrotriazine Derivatives Bearing a Quinoline Moiety

In this article, three series of dihydrotriazine derivatives bearing a quinoline moiety ( 5a , 5b , 8a – 8c , and 9a – 9m ) have been designed, synthesized, and evaluated as antibacterial agents. Compounds 8a – 8c were found to be the most potent of all of the compounds tested with an MIC value of 1 μg/mL against several Gram‐positive (S. aureus 4220 and MRSA CCARM 3506) and Gram‐negative (E. coli 1924) strains of bacteria. In addition, 3‐[4‐amino‐6‐(phenethylamino)‐2,5‐dihydro‐1,3,5‐triazin‐2‐yl)‐6‐[(3‐chlorobenzyl)oxy]quinolin‐2‐ol ( 8a ) showed potent inhibitory activity (MIC=2 μg/mL) against Pseudomonas aeruginosa 2742, indicating that its antibacterial spectrum is similar to those of the positive controls gatifloxacin and moxifloxacin. Structure‐activity relationships (SAR) analyses and docking studies implicated the dihydrotriazine group in increasing the antimicrobial potency of the quinoline compounds. In vitro enzyme study implied that compound 8a also displayed DHFR inhibition.     

Antibacterial Diphenyl Ether,Benzophenone and Xanthone Derivatives from Aspergillus flavipes

The extract of the strain Aspergillus flavipes DL‐11 exerted antibacterial activities against six Gram‐positive bacteria. During the following bioassay‐guided separation, ten diphenyl ethers ( 1 – 10 ), two benzophenones ( 11 – 12 ), together with two xanthones ( 13 – 14 ) were isolated. Among them, 4′‐chloroasterric acid ( 1 ) was a new chlorinated diphenyl ether. Their structures were elucidated by extensive spectroscopic data analysis, including IR, HR‐ESI‐MS, NMR experiments, and by comparison with the literature data. All compounds showed moderate to strong antibacterial effects on different Gram‐positive bacteria with MIC values that ranged from 3.13 to 50 μg/mL, but none of the compounds exhibited activity against Gram‐negative bacteria Vibrio parahaemolyticus ATCC17802 (MIC>100 μg/mL). In particular, the MICs of some compounds are at the level of positive control.     

Antibacterial Δ1‐3‐Ketosteroids from the South China Sea Gorgonian Coral Subergorgia rubra

Three new Δ¹‐3‐ketosteroids characterized with a 9‐OH, subergosterones A–C ( 1 – 3 ), together with five known analogs 4 – 8 , were obtained from the gorgonian coral Subergorgia rubra collected from the South China Sea. The structures of 1 – 3 , including their absolute configurations, were determined by comprehensive spectroscopic methods and electronic circular dichroism (ECD) experiments. Compounds 2 and 3 exhibited inhibitory antibacterial activities against Bacillus cereus with MIC values of 1.56 μM .     

Six New Pentacyclic Triterpenoids from the Fruit of Camptotheca acuminata

Six new pentacyclic triterpenoids were isolated from the fruit of Camptotheca acuminata. The chemical structures of the new compounds were elucidated by extensive spectroscopic analysis including HR‐ESI‐MS, IR, UV, 1D‐ and 2D‐NMR. Moreover, the antibacterial activities of compounds 1 , 2 , 4 , 5 , and 6 were evaluated against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Dickeya zeae. All these tested compounds showed moderate antibacterial activity against Bacillus subtilis and Dickeya zeae.     

Antimicrobial Compounds from Drypetes staudtii

Antimicrobial‐directed phytochemical investigation of the MeOH extract of Drypetes staudtii afforded two new compounds, 4,5‐(methylenedioxy)‐o‐coumaroylputrescine ( 1 ), 4,5‐(methylenedioxy)‐o‐coumaroyl‐4′‐N‐methylputrescine ( 2 ), along with seven known natural products 4α‐hydroxyeremophila‐1,9‐diene‐3,8‐dione ( 3 ), drypemolundein B ( 4 ), friedelan‐3β‐ol ( 5 ), erythrodiol ( 6 ), ursolic acid ( 7 ), p‐coumaric acid ( 8 ), and β‐sitosterol ( 9 ). Structures of compounds 1 – 9 were elucidated with the aid of extensive NMR and mass spectral studies. All of the isolates exhibited antibacterial activity against Gram‐positive and Gram‐negative bacteria with minimum inhibitory concentration (MIC) in the range of 8 – 128 μg/ml. Compounds 1 – 2 were also moderately active against Candida albicans with an MIC value of 32 μg/ml.     

Bioactive Steroid Derivatives and Butyrolactone Derivatives from a Gorgonian‐Derived Aspergillus sp. Fungus

Six steroid derivatives, 1 – 6 , and five butyrolactone derivatives, 7 – 11 , were isolated from the fermentation broth of a gorgonian‐derived Aspergillus sp. fungus. Their structures were elucidated on the basis of NMR and MS spectral data. Compound 1 is a new, highly conjugated steroid. The NMR and MS data of 7 and 8 are reported for the first time, as their structures were listed in SciFinder Scholar with no associated reference. Compounds 1, 4, 5 , and 8 – 11 inhibited the larval settlement of barnacle Balanus amphitrite with EC₅₀ values ranging from 0.63 to 18.4 μg ml^?1. Butyrolactone derivatives 7 and 8 showed pronounced antibacterial activities against Staphylococcus aureus with the same MIC values as the positive control ciprofloxacin (MIC 1.56 μM for all three compounds).     

Terpenoids from Rhizomes of Alpinia japonica Inhibiting Nitric Oxide Production

A new sesquiterpenoid, 1 , and three new diterpenoids, 3 – 5 , along with five known compounds, 2 and 6 – 9 , were isolated from rhizomes of Alpinia japonica. The structures of the new compounds were determined as (1R,4R,6S,7S,9S)‐4α‐hydroxy‐1,9‐peroxybisabola‐2,10‐diene ( 1 ), methyl (12E)‐16‐oxolabda‐8(17),12‐dien‐15‐oate ( 3 ), (12R)‐15‐ethoxy‐12‐hydroxylabda‐8(17),13(14)‐dien‐16,15‐olide ( 4 ), and methyl (11E)‐14,15,16‐trinorlabda‐8(17),11‐dien‐13‐oate ( 5 ) by means of spectroscopic data. The absolute configurations at C(4) in 1 and C(12) in 4 were deduced from the circular dichroism (CD) data of the in situ‐formed [Rh₂(CF₃COO)₄] complexes. Inhibitory effects of the isolates on NO production in lipopolysaccharide‐induced RAW264.7 macrophages were evaluated, and 2 – 4, 6 , and 7 were found to exhibit inhibitory activities with IC₅₀ values between 14.6 and 34.3 μM .     

Julichrome Monomers from Marine Gastropod Mollusk‐Associated Streptomyces and Stereochemical Revision of Julichromes Q3 ⋅ 5 and Q3 ⋅ 3

Two julichrome monomers, julichromes Q₁₁ ( 1 ) and Q₁₂ ( 2 ), along with five known julichromes (Q₁₀, Q_{3 ? 5}, Q_{3 ? 3}, Q_{6 ? 6}, Q₆, 3 – 7 ) and four known anthraquinones (chrysophanol, 4‐acetylchrysophanol, islandicin, huanglongmycin A, 8 – 11 ), were isolated from the marine gastropod mollusk Batillaria zonalis‐associated Streptomyces sampsonii SCSIO 054. This is the first report of julichromes isolated from a marine source. Extensive dissection of 1D and 2D NMR datasets combined with X‐ray crystallography enabled rigorous elucidation of the previously reported configurations of julichrome Q_{3 ? 5} ( 4 ) and related julichrome Q_{3 ? 3} ( 5 ); both of the configuration at C(9) needs to be revised. In addition, julichrome Q₁₂ ( 2 ) was found to display antibacterial activity against Micrococcus luteus and Bacillus subtilis with MICs of 2.0 and 8.0 μg mL^?1; four compounds ( 1 , 3 , 6 , 7 ) also showed inhibitory activities against an array of methicillin‐resistant Staphylococcus aureus, S. aureus and S. simulans AKA1 with MIC values ranging from 8 to 64 μg mL^?1.     

Iridoids from Pedicularis verticillata and Their Anti‐Complementary Activity

Three new iridoids named as pediverticilatasin A – C ( 1 – 3 , resp.), together with five known iridoids ( 4 – 8 , resp.) were isolated from the whole plants of Pedicularis verticillata. The structures of three new compounds were identified as (1S,7R)‐1‐ethoxy‐1,5,6,7‐tetrahydro‐7‐hydroxy‐7‐methylcyclopenta[c]pyran‐4(3H)‐one ( 1 ), (1S,4aS,7R,7aS)‐1‐ethoxy‐1,4a,5,6,7,7a‐hexahydro‐7‐hydroxy‐7‐methylcyclopenta[c]pyran‐4‐carboxylic acid ( 2 ), (1S,4aS,7R,7aS)‐1‐ethoxy‐1,4a,5,6,7,7a‐hexahydro‐7‐hydroxy‐7‐methylcyclopenta[c]pyran‐4‐carbaldehyde ( 3 ). Their structures were elucidated on the basis of spectroscopic methods and compared with the NMR spectra data in the literature. All compounds were evaluated for their anti‐complementary activity on the classical pathway of the complement system in vitro. Among which, compounds 1 , 3 , and 6 exhibited anti‐complementary effects with CH₅₀ values ranging from 0.43 to 1.72 mm , which are plausible candidates for developing potent anti‐complementary agents.     

椿根皮的化学成分及抑菌活性研究

为探寻椿根皮抑菌的物质基础，该研究采用硅胶、Sephadex LH-20等方法对椿根皮甲醇提取物进行分离和纯化，通过理化性质和波谱数据分析单体化合物的结构，并以卡那霉素为对照组采用流式细胞法测试化合物的抑菌活性。结果表明：从椿根皮中得到22个化合物，分别鉴定为pleuchiol (1)、withastramonolide (2)、7-ketositosterol (3)、白桦酯醇(4)、桦木酸甲酯(5)、1, 2, 4-trimethoxybenzene (6)、顺丁烯二酸二甲酯(7)、sonderianol (8)、dibutyl phthalate (9)、pinoresinol (10)、对羟基苯甲酸乙酯(11)、avenalumic acid methyl ester (12)、5,3′-dihydroxy-3,7,4′-trimethoxy-flavone (13)、spathulenol (14)、2-甲基-5-丙基酮-7-羟基色原酮(15)、 7,4′-dihydroxyflavone (16)、annphenone (17)、3-羟基-4-甲氧基苯甲酸(18)、5,3′...     

Synthesis and Antibacterial Activity Evaluation of Imidazole Derivatives Containing 6-Methylpyridine Moiety

A series of 2-cyclopropyl-5-(5-(6-methylpyridin-2-yl)-2-substituted-1H-imidazol-4-yl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazoles ( 15a – t and 16a – f ) were synthesized and their antibacterial activities were evaluated. More than half of the compounds showed moderate or strong antibacterial activity. Among them, compounds 15t (MIC=1–2 μg/mL) and 16d (MIC=0.5 μg/mL) showed the strongest antibacterial activities. Notably, compound 16d did not exhibit cytotoxicity in HepG2 cells and did not show hemolysis like the positive control compound Gatifloxacin. The results suggest that compound 16d should be further investigated as a candidate antibacterial agent.     

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.     

Naphthalene Derivatives and Quinones from Ventilago denticulata and Their Nitric Oxide Radical Scavenging,Antioxidant, Cytotoxic,Antibacterial, and Phosphodiesterase Inhibitory Activities

New naphthalene derivatives ( 1 and 2 ) and a new isomer ( 3 ) of ventilagolin, together with known anthraquinones, chrysophanol ( 4 ), physcion or emodin 3‐methyl ether ( 5 ), and emodin ( 6 ), were isolated from vines of Ventilago denticulata. The isolated compounds exhibited cytotoxic activity with IC₅₀ values of 1.15 – 40.54 μg/ml. Compounds 1 – 3 selectively exhibited weak antibacterial activity (MIC values of 200.0 – 400.0 μg/ml), while emodin ( 6 ) displayed moderate antibacterial activity with MIC value of 25.0 μg/ml. The isolated compounds showed nitric oxide and DPPH radical scavenging activities. Compounds 1 – 3 and 6 exhibited weak xanthine oxidase inhibitory activity, while emodin ( 6 ) acted as an aromatase inhibitor with the IC₅₀ value of 10.1 μm . Compounds 1 and 2 exhibited phosphodiesterase 5 inhibitory activity with IC₅₀ values of 8.28 μm and 6.48 μm , respectively.     

Terpenes from Euphorbia antiquorum and Their in Vitro Anti‐HIV Activity

Three new compounds ( 1 – 3 ), including two euphane type triterpenes, 24,24‐dimethoxy‐25,26,27‐trinoreuphan‐3β‐ol ( 1 ) and (24S)‐24‐hydroperoxyeupha‐8,25‐dien‐3β‐ol ( 2 ), and an ent‐atisine diterpene, ent‐atisane‐3α,16α,17‐triol ( 3 ), were isolated from an acetone extract of the stems of Euphorbia antiquorum, together with eight known diterpenes ( 4 – 11 ). The structures of compounds ( 1 – 11 ) were elucidated using NMR and MS spectroscopic methods. Compound 7 showed moderate activity against HIV‐1 replication in vitro (EC₅₀ = 1.38 μm ).     

Bioactive 9,11‐Secosteroids from Gorgonian Subergorgia suberosa Collected from the South China Sea

Five new 9,11‐secosteroids 1, 2 , and 4 – 6 , and seven known analogs, 3 and 7 – 12 , with the same steroid skeleton, (5αH)‐3β,6α,11‐trihydroxy‐9,11‐secocholest‐7‐en‐9‐one, were isolated from the South China Sea gorgonian Subergorgia suberosa. Among them, 2 / 3 and 4 / 5 are C(24)‐epimeric mixtures, and 6 / 7 is an (E)/(Z) mixture of (C(24)?C(28)). Their structures and relative configurations were elucidated by using comprehensive spectroscopic methods including NOESY spectra. The absolute configuration of the steroidal nucleus was established by the modified Mosher method applied to 10 and on the basis of a common biogenesis for all of these compounds. All isolated compounds, 1 – 12 , and five synthetic acetylated derivatives, 12a – 12e , were evaluated for their cytotoxicities in vitro. Compounds 4 / 5, 11, 12 , and 12b – 12d showed cytotoxic activities against K562 cell line with the IC₅₀ values ranging from 1.09 to 8.12 μM .     

Insights into biological activity of ureidoamides with primaquine and amino acid moieties

Primaquine (PQ) ureidoamides 5a–f were screened for antimicrobial, biofilm eradication and antioxidative activities. Susceptibility of the tested microbial species towards tested compounds showed species- and compound-dependent activity. N-(diphenylmethyl)-2-[({4-[(6-methoxyquinolin-8-yl)amino]pentyl}carbamoyl)amino]-4-methylpentanamide (5a) and 2-(4-chlorophenyl)-N-(diphenylmethyl)-2-[({4-[(6-methoxyquinolin-8-yl)amino]pentyl}carbamoyl)amino]acetamide (5d) showed antibacterial activity against S. aureus strains (MIC?=?6.5?µg/ml). Further, compounds 5c and 5d had weak antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. None of the tested compounds showed a wide spectrum of antifungal activity. In contrast, most of the compounds exerted strong activity in a biofilm eradication assay against E. coli, P. aeruginosa and Candida albicans, comparable to or even higher than gentamycin, amphotericin B or parent PQ. The most active compounds were 5a and 5b. Tested compounds were inactive against biofilm formation by C. parapsylosis, Enterococcus faecalis, C. tropicalis and C. krusei. Compounds 5b–f significantly inhibited lipid peroxidation (80–99%), whereas compound 5c presented interesting LOX inhibition.