This site requires JavaScript to be enable.

Elucidation of the Month

The efficiency of ACD/Structure Elucidator has been confirmed over the years by solving a great number of real world problems (almost 1000) related mainly to the structure determination of new natural products. Over 120 examples are presented in this Elucidation of the Month blog.

Wheldone

Oberlies and co-workers isolated a new natural product, Wheldone (molecular formula C₂₅H₃₄O₆). Its structure was elucidated by one- and two-dimensional NMR and mass spectrometry. We used data from this article to challenge Structure Elucidator Suite.

Setosol

Okeke et al. reported the isolation of a novel catechol, Setosol (molecular formula C₁₅H₁₆O₅). They acknowledged that this structure was unique amongst natural products, and such a ring system also appeared to be unknown amongst synthetic compounds. Considering the unusual properties of the structure, Bates et al. performed its verification and subsequent structure revision. Structure Elucidator Suite confirmed the structure revision through a comparison of NMR spectra of Setosol with those corresponding to the structure.

Two Polyenol Natural Products (Adenosine and Uridine)

In a 2023 article published in Eur. J. Org. Chem, the incorrect structures of two natural products and their subsequent reassignment was discussed. Here we discuss how Structure Elucidator Suite was used to verify these structures.

Boerelasin B

The structure of Boerelasin B (molecular formula C₂₉H₃₅NO₄) was determined from 1D and 2D NMR spectra as well as by comparison of the spectroscopic data with those of a known similar structure isolated from the same fungus. The NMR data obtained were used by us for challenging Structure Elucidator Suite.

Boerelasin B

Norflavicansone

The structure elucidation of norflavicansone, a proton-deficient metabolite, was carried out using CASE and DFT calculations with Structure Elucidator Suite.

Norflavicansone

Hectoramide B

The 1H NMR spectrum of Hectoramide B (molecular formula C₃₄H₅₀N₄O₇) was remarkably similar to that of the previously determined structure of hectoramide A. This posed a difficult structure elucidation, but by introducing minor structural constraints into Structure Elucidator Suite, this challenging problem was solved in a few minutes (in this case using the IR spectrum).

Hectoramide B

Janthinolide A

The structure of janthinolide A was established using MS spectrometry in combination with 1D and 2D NMR data (molecular formula C₂₃H₃₂N₂O₇), however it was later amended with the use of Structure Elucidator Suite combined with DFT based NMR chemical shift prediction.

Salvicatone A

The authors identified the structure of Salvicatone A in two stages, the second step being the use of Structure Elucidator Suite to validate the proposed structure.

Pseudochelin A

Sonnenschein et al. investigated the fungus Pseudoalteromonas piscicida S2040 to yield pseudochelin A – a new siderophore containing a 4,5-dihydroimidazole moiety. This challenging structure containing eight heteroatoms (three atoms of nitrogen and fife atoms of oxygen) was elucidated by Structure Elucidator fully automatically in 1.5 seconds.

Nordine

Sesquiterpenoids are a class of compounds known to have complex structures, and due to the wide variability of these compounds, it is often challenging to determine the exact structure. Here we discuss the incorrect determination of the structure of Nordine, and later correction; as well as the elucidation of the correct structure using CASE.

Aspergillamide C

Xiao-Wei and coworkers identified a new aspergillamide C (molecular formula C₂₈H₃₄N₄O₄). To elucidate the structure of this compound, 1D NMR, HSQC, HMBC, COSY and NOESY data were entered into Structure Elucidator Suite.

Aspochalasin H1

The structure of aspochalasin H1 (molecular formula C₂₄H₃₅NO₅) was elucidated using 1D and 2D NMR, high-resolution electrospray ionization mass spectroscopy, and comparisons with the reported literature. The CASE-based structure elucidation was carried out by Structure Elucidator Suite in half a minute.

Plebeianiol A

Many corrections of erroneous structures published in the literature have been made with the help of Structure Elucidator Suite. In this example, we were interested to know what the result of using Structure Elucidator for the revision of the plebeianiol A structure would be if the NMR data presented in the work of Liang and collaborators were used.

Saccharobisindole

Analysis of the chemical components of the marine bacterium Saccharomonospora sp. CNQ-490 carried out by Fenical and coworkers yielded three novel compounds, including saccharobisindole (molecular formula C₂₆H₂₈N₂O₃). Its chemical structure was elucidated by the interpretation of 1D, 2D NMR (HSQC, HMBC and COSY), and high-resolution mass spectrometry (HR-MS) data.

Rumphellol A

Sung et al. isolated two new caryophyllene-type sesquiterpenoids, rumphellol A and B, from the Rumphella antipathies gorgorian coral. These compounds contain a 9-membered ring fused with a cyclobutane ring, which is rarely observed in natural products. We used ACD/Structure Elucidator to confirm the structure of rumphellol A (molecular formula C₁₅H₂₄O₂).

Trichopsistide A

Using the traditional method of structure elucidation based on analysis of HSQC, HMBC and COSY data, the authors deduced a large part of the molecular structure, but the lack of carbons bearing hydrogen atoms prevented them to assemble the full structure. To alleviate this problem, ACD/Structure Elucidator was utilized in Trichopsistide A, molecular formula C₂₃H₂₉NO₅.

Furaquinocin L

Tistechok et al. described the isolation, purification, and structure elucidation of a new naphthoquinone-based meroterpenoid, Furaquinocin L from Streptomyces sp. Je 1-369, which expands the structural diversity of the furaquinocin family of natural products.

Furaquanocin L Structure Elucidation

Dichocetide D

Shaker et al. recently reported the isolation of Dichocetide D from the marine fungus Dichotomomyces cejpii under oxygen stress conditions. The structure of Dichocetide D was revised by Elyashberg et al on the basis of chemical considerations and utilization of ACD/Structure Elucidator.

Piperkadsin C

Kim and coworkers isolated a new neolignan, piperkadsin C, and elucidated its structure. However, the structure was revised by the same group in their next article. Structure Elucidator Suite was used to confirm the proposed structure #2, molecular formula C₂₀H₂₀O₆.

Gancao Cyclooctenone A

The herb Radix Glycyrrhizae has been used as a traditional Chinese medicine for more than a thousand years. Zhao et al isolated a novel symmetrical cyclooctenone compound and elucidated its structure (molecular formula C₂₃H₃₄O₄).

Afzeliindanone

Okpekon et al isolated an unusual new indanone from the shrub Uvaria afzelii Scot Elliot, grown in the West African sub-region, named afzeliindanone. The molecular formula is C₁₆H₁₄O₃.

Bidysoxyletine

A new bicoumarin derivative, bidysoxyletine, (with a molecular formula of C₃₆H₄₀O₆) was isolated from the leaves of Dysoxylum parasiticum (Osbeck) Kosterm.

Dermacozine O

A series of new phenazines were isolated and their structures elucidated; one of these compounds was Dermacozine O, with a molecular formula of C₂₃H₁₅O₄N₃.

Comatulin A

The analysis of C. rotalaria extracts by UHPLC-MS in conjunction with database searching led to the isolation and structure elucidation of a series of new taurine-conjugated anthraquinones, including Comatulin A, molecular formula C₂₀H₁₉NO₁₀S.

Lobocrassin A

A rich source of cembrane-type metabolites has been found to be Lobophytum crassum, a soft coral from the family of Alcyoniidae. Among five new cembrane derivatives that were isolated is Lobocrassin A, molecular formula C₂₀H₂₉ClO₄.

Lobocrassin A

Gelstriamine A

Jin et al studied the novel analgesics used in traditional Chinese medicine and as part of this they isolated and elucidated the structure of a novel triamine monoterpene indole alkaloid, Gelstriamine A, molecular formula C₂₂H₂₇N₃O₅.

Gelstriamine A

Asperspiropene A

Asperspiropene A was first reported by He et al as the second derivative of a class of compounds containing a unique six-membered ring substructure. The molecular formula was determined from the HR-MS spectrum to be C₁₇H₂₆O₈.

Iridiod Glycoside

Iridiod Glycoside Clerodendrum (Lamiaceae) is a genus composed of 580 species. It is found in tropical and subtropical regions and…

Lyaline

30 years after the structure of lyaline was first proposed, a new spectroscopic analysis was performed using state-of-the-art techniques to reveal errors in the original analysis, and eventually, the correct structure.

Davidone F Structure Elucidation

Davidone F Sophora davidii (Franch.) belong to the family Fabaceae and are shrubs or small trees found in China. Over…

Trichilianone D Structure Elucidation

Trichilianone D Trichilia species, a genus of plants from the Meliaceae family, are found in tropical forests and are used…

Rhodimer Structure Elucidation

Rhodimer Atilaw et al [1] have been studying the roots of Tephrosia rhodesica, a member of the tropical and subtropical…

Securamine H Structure Elucidation

Securamine H Bryozoans belonging to the Flustridae family have been shown to be a rich source of structurally unique secondary…

Isatisindigoticanine I Structure Elucidation

Isatisindigoticanine I Ban Lan Gen, Isatis tinctoria L. (synonym Isatis indigotica Fort.), of the Brassicacene family, is a biennial herbaceous…

Damirine B Structure Elucidation

Damirine B The indolocarbazole family of bisindole alkaloids is a well-known class of natural products. It’s best-known member is staurosporine,…

Peyssonnoside A Structure Elucidation

Peyssonnoside A Diterpenoids and their analogues and derivatives are well known and highly varied compounds. Cyclopropane groups are also frequently…

Symmetric Helical Synthesis Product Structure Elucidation

Symmetric Helical Synthesis Product This month’s problem is again a bit different from the others. It comes from the Department…

Melohemsine J Structure Elucidation

Melohemsine J The plants of the genus Melodinus (Apocynaceae) include 53 species and several of them have been used in…

Hypocrolide A Structure Elucidation

Hypocrolide A A particular type of sesquiterpenoids are botryanes. The have the same basic skeleton of a bivyvliv nonisoprenoid system….

Leonuketal Structure Elucidation

Leonuketal Leonurus Japonicus is a plant that is used in common traditional Chinese medicine. In fact, the aerial parts of…

Lucidumone Structure Elucidation

Lucidumone Meroterpenoids are natural products containing a terpenoid and a non-terpenoid part. There have been many classes of such compounds…

Vagiallene

E. Ioannou et al have developed an integrated metabolomic platform for the identification of known compounds and detection of new metabolites at the early stages of phytochemical analysis. Vagiallene was isolated through a series of chromatographic separations, molecular formula C₁₅H₁₅Br₂O₅.

Spiroaxillarone A

Spirobisnaphthalenes are a relatively new and rare family of secondary metabolites. Their core structure usually consists of two bicyclo[4.4.0]decane units, connected with one another through at least one spiro center. The reported compound is a novel symmetric spirobisnaphthalene with a unique structural feature. Spiroaxillarone A, molecular formula C₁₉H₁₂O₆.

Chloraserrtone A Structure Elucidation

Chloraserrtone A, a new sesquiterpenoid dimer with two lindenane-type sesquiterpenoid monomers bridged by two six-membered rings, was isolated from Chloranthus serratus by Bai et al. It represents the first lindenane-type sesquiterpenoid dimer with an extremely unique skeleton, molecular formula C₃H₃₆O₉.

Synthetic product C₁₄H₁₃N₃O Structure Elucidation

An unexpected synthetic product coming from Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) in Berlin, from the lab of Dr. Marc Nazaré. The dataset was provided to ACD/Labs as part of our Structure Elucidation Suite Challenge. The product was isolated after a reaction and it was found by HR-MS to have a molecular formula of C₁₄H₁₃N₃O.

Penerpene A Structure Elucidation

The Penicillium sp. KFS28 fungus was isolated from a bivalve mollusk, Meretrix Lusoria, from the Haikou Bay in China. The EtOAc extract of the fermentation broth was processed by the authors who isolated and identified four new paxilline-type indole-terpenoids. Compound 1 has the molecular formula C₂₈H₃₅NO₆.

Orbicularisine Structure Elucidation

Goudou at al described the isolation of a novel metabolite, orbicularisine, from the tropical bivalve Codakia orbicularis living in seagrass beds, molecular formula C₁₃H₁₀N₂O₅S.

Nicotabin A Structure Elucidation

Feng et al investigated the chemical constituents of N. tabacum leaves by a dereplication procedure, which resulted in the isolation of a novel compound, nicotabin A, molecular formula C₂₁H₂₈O₇.

Cascarinoid A Structure Elucidation

Gao et al isolated, amongst others, Cascarinoid A, the first example of a crotofolane diterpenoid alkaloid, molecular formula C₂₈H₃₁NO₅.

Dimericbiscognienyne A Structure Elucidation

Zhao and coworkers had been studying the secondary metabolites of Biscogniauxia sp. They isolated a diisoprenyl-cyclohexane-type meroterpenoid dimer with a new skeleton, Dimericbiscognienyne A (molecular formula C₃₂H₄₀O₆).

Ent-Kaurane-Type Diterpenoid Structure Elucidation

Yaouba et al reported the isolation and phytochemical investigation of the constituents of Aspilia pluriseta Schweinf and Aspilia mossambicensis. They isolated, identified and comprehensively investigated compound 1, molecular formula C₂₁H₃₀O₃.

Neosetophomone A Structure Elucidation

El-Elimat et al reported five new and one known meroterpenoids, including the discovery of a novel ioxa[4.3.3]propellane metabolite neosetophomone A that incorporates a 3-methyl-2,3-dihydrofuran bridge into a 5,6 tricyclic 2-hydroxycyclopent-2-en-1-one/tetrahydropyran ring system, molecular formula C₂₄H₃₂O₅.

Rhodomollacetal A

Zhou et al isolated three novel diterpenoids with an unprecedented 2,3:5,6-di-seco-grayanane carbon skeleton. Rhodomollacetal A was obtained as colorless prisms, molecular formula C₂₁H₃₂O₇.

Lancolide E Structure Elucidation

As a part of an ongoing research for SNTs from Schisandra micrantha, a minor SNT featuring a complex tetracyclo[5.4.0.02,4.03,7]undecane-bridged system, termed lancolide E, was isolated by Shi et al, molecular formula C₂₉H₃₂O₁₀.

Actinobenzoquinoline Structure Elucidation

The spectroscopic data presented for the structure elucidation of Actinobenzoquinoline (molecular formula C₁₉H₁₈N₂O₄) were used to challenge ACD/Structure Elucidator.

5α-Cyprinol Structure Elucidation

5α-cyprinol sulfate was isolated from a methanolic extract of fish bile (Cyprinus carpio) after separation by preparative LC. The molecular mass and the presence of a sulfate group were revealed by ESI–MS/MS in the negative mode, and the molecular formula of the compound was determined as C₂₇H₄₈O₈S.

Cycloshermilamine D Structure Elucidation

Investigation of Cystodytes resulted in the isolation of five pyridoacridines, including shermilamines D and E. The structure of another compound, cycloshermilamine D, also isolated from the same tunicate in minute amounts (0.4% of the crude extract) was determined by Koren-Goldshlager et al, molecular formula C₂₁H₁₆N₄OS.

Oroidin Structure Elucidation

Oroidin (C₁₁H₁₀Br₂N₄O) is a highly proton-deficient bromopyrrole isolated from the sponge Agelas oroides. A CASE solution to this problem was chosen for testing the capability of DFT based NMR chemical shift prediction to distinguish the correct structure when empirical prediction methods fail to suggest the structure reliably.

Tetrabromobenzofuropyrrole Structure Elucidation

A highly brominated compound, 2,3,5,7-tetrabromobenzofuro[3,2-b]pyrrole (molecular formula C₁₀H₃Br₄NO), was extracted from a marine Protobacterium, Pseudoalteromonas sp.

Busseihydroquinone F Structure Elucidation

As part of an ongoing search for new bioactive natural products from the genus Pentas, Abdissa et al isolated three new naphthalenes from the roots of P. bussei including 2,2′-binaphthralenyl-1,1′-dione, molecular formula C₃₂H₂₈O₆.

Epoxyroussoenone Structure Elucidation

Honmura and co-workers isolated epoxyroussoenone and used calculated 13C and 1H chemical shifts, NOE data and ECD spectra analysis to define the most probable geometrical and stereoisomer, molecular formula C₁₅H₁₄O₇.

Coniothyrione Structure Elucidation

Coniothyrione is a natural product with a molecular formula of C₁₄H₉ClO₆. The ratio of the number of heavy atoms to hydrogen is 2.3 indicating an especially challenging structure elucidation.

Aquatolide

Aquatolide is a humulane-derived sesquiterpenoid lactone isolated from Asteriscus aquaticus. The structure of aquatolide (molecular formula C₁₅H₁₈O₃) contained an extremely rare ladderane substructure.

Zanthplanispine

In a search for novel anti-inflammatory bioactive drug leads from this plant, Su at al isolated from its roots a novel tetrahydrofuran lignan named zanthplanispine, molecular formula C₂₁H₂₂O₈.

Manginoid A

In the study conducted by Chen et al manginoids A−G were isolated from G. mangiferae, and their structures elucidated. Manginoid A was assigned the molecular formula C₁₇H₂₂O₅ based on its HR-ESI-MS spectrum, with a sodium adduct molecular ion peak at m/z 329.1378.

Uncarilin A

In the search for novel MT receptor agonists from natural sources, Geng at al used LC-MS to study U. rhynchophylla,, resulting in the isolation of two pairs of dimeric isoechinulin-type enantiomers, (±)-uncarilin A and (±)-uncarilin B. Here we discuss the structure elucidation of uncarilin A (molecular formula C₃₈H₄₂N₆O₄).

Matsutakone – Pleurocin A

The ethyl acetate layer of T. matsutake was fractionated and purified by repeated chromatographic methods to yield the white powder matsutakone, molecular formula C₂₈H₄₄O₄. The structure of Structure of matsutakone was elucidated from its molecular formula and 1D and 2D NMR data shown in Table 1, which were used by us for challenging ACD/Structure Elucidator.

Emodacidamide A

During screenings for new secondary metabolites from fungi originating from the South China Sea, Luo and co-workers isolated 10 anthraquinone compounds, including eight new anthraquinones regarded as emodacidamides A−H. Structures of these compounds were elucidated, and the NMR data utilized for the structure elucidation of emodacidamide A (molecular formula C₂₁H₁₉NO₈) were used by us to challenge ACD/Structure Elucidator.

Abyssomicin W

Wang et al. reported the discovery of 12 new analogs of abyssomicin as metabolites of the Streptomyces species. Amongst them Abyssomicin W (molecular formula C₂₀H₂₆O₈) has an 8/6/6/6 tetracyclic core. Spectroscopic data of this compound were used to challenge ACD/Structure Elucidator Suite.

Trichoderpyrone

Chen et al have been looking for novel secondary metabolites from Trichoderma gamsii, a plant endophytic fungus. As a result of this a new polyketide trichoderpyrone (molecular formula C₁₅H₁₇NO₅), containing a unique cyclopentenone−pyrone hybrid skeleton was isolated and its structure was determined by detailed analysis of NMR data.

Spiroschincarin A

Song et al investigated the chemical constituents of the fruit of S. incarnata. They isolated five novel spirocyclic compounds, spiroschincarins A−E, featuring a unique 1-oxaspiro[6.6]tridecane moiety. Their structures, with absolute configurations, were determined by extensive spectroscopic studies. The structure elucidation of spiroschincarin A (molecular formula C₃₁H₃₈O₁₁) from NMR data was used for challenging ACD/Structure Elucidator.

Waspergillamide A

After reverse-phase fractionation of Aspergillus sp., a new nitro depsi-tetrapeptide diketopiperazine, waspergillamide A (molecular formula C₂₀H₂₄N₄O₇), was isolated along with the known metabolites. The structure elucidation of it is described here.

Delicoferone A

Delicoferone A The fungi that colonize and reproduce in animal excrements are called Coprophilous fungi. They have specifically adapted to…

Phomopsterone A

The fungus Phomopsis sp. TJ507A was recently analyzed by Hu and co-workers. Two functionalized ergostane-type steroids, phomopsterones A and B were isolated. Phomopsterone A (molecular formula C₂₉H₄₂O₆) was chosen for challenging Structure Elucidator.

Sophaline C

Y.-B. Zhang and co-workers reported four novel matrine-based alkaloids, sophalines A-D. Their structures were elucidated using spectroscopic methods and single-crystal X-ray diffraction. We used the Spectroscopic data for Sophaline C (molecular formula C₂₁H₂₆N₂O₂) to challenge Structure Elucidator.

4-Bromobenzoic-biscognienyne A

4-Bromobenzoic-biscognienyne A (molecular formula C₂₃H₂₅O₄Br) is relatively simple but its elucidation was chosen as a demonstrated approach, using ACD/Structure Elucidator, in situations where several equiprobable user assumptions (“axioms”) should be checked to determine the right structure.

Alistonitrine A

Monoterpene Indole Alkaloids (MIAs) are found in Alstonia scholaris R. Br. (Apocynaceae) which originates in South Asia. People in the area have been using the bark and leaves as traditional medicines. Zhu and co-workers successfully isolated a new MIA, Alistonitrine A (molecular formula C₂₁H₂₅N₃O₃), which possesses an unprecedented caged monoterpene indole skeleton.

Euphorikanin A

Fei and co-workers4 isolated Euphorikanin A (molecular formula C₂₀H₂₆O₃), a structurally novel diterpenoid lactone with an unprecedented carbon skeleton featuring a unique tetradecahydrobenzo[cd]-cyclopropa[f ]azulene. Its structure was determined by spectroscopic methods and confirmed by single crystal X-ray analysis.

Ciliatonoid A

Structures of ciliatonoids A-C, complete with absolute stereochemistry, were characterized by spectroscopic data, X-ray crystallography, and electronic circular dichroism (ECD) analysis. To challenge ACD/Structure Elucidator Suite, Ciliatonoid A (molecular formula C₂₆H₃₂O₅) was used. It featured an unprecedented limonoid architecture by way of a very unique cis-fused central motif (in red).

Pepluacetal

Wan et al isolated and identified three highly modified and biogenetically related diterpenoids including Pepluacetal (molecular formula C₂₂H₃₂O₄), which has a novel unprecedented fused-ring skeleton containing cyclopentane and cyclobutane rings which rarely occur in natural compounds.

Flueggether A

H. Zhang et al observed interesting signals from very minor constituents from F. virosa in their MS analysis. A further fractionation of the fractions returned two extra new alkaloids, one of which, Flueggether A(molecular formula C₂₅H₃₀N₂O₅), is the first example of Securinega alkaloid oligomers which features an ether bond linkage.

Astellifadiene

The authors reported the production and structure characterization of the novel sesterterpene Astellifadiene. Analysis of the 1H-1H COSY, HMBC, and NOESY correlations established the planar structure as an unprecedented 6-8-6-5-membered tetracyclic ring system. The use of NMR analyses combined with the crystalline sponge method facilitated the unambiguous determination of the Astellifadiene structure (molecular formula C₂₅H₄₀).

Mannolide A

Ni et al investigated Cephalotaxus mannii Hook f. which led to the isolation of three new diterpenoids, namely, mannolides A−C, and two new Cephalotaxus troponoids. We used the example of Mannolide A (molecular formula C₂₀H₂₄O₅) to challenge our ACD/Structure Elucidator Suite software.

Sarglaperoxide A

From investigating the constituents of Sarcandra glabra, P. Wang et al isolated a pair of structurally-related terpene lactones, sarglaperoxides A and B. The original experimental data related to Sarglaperoxide A (molecular formula C₂₃H₂₈O₅) were used to challenge ACD/Structure Elucidator Suite and determine if the software could reliably elucidate this novel structure.

Teotihuacanin

Bautista et al reinvestigated the chemical composition of S. amarissima. As a result, Teotihuacanin (molecular formula C₂₀H₂₀O₆), an unusual rearranged clerodane diterpene with a new carbon skeleton containing a spiro-10/6 bicyclic system, was isolated from the leaves and flowers of Salvia amarissima.

Ruthmycin

Ruthmycin (molecular formula C₂₁H₂₂O₇) possesses an unprecedented signature C3 bridge and a corresponding fused six-member ring. In the context of known frenolicin-type scaffolds, the presence of a C-3/C-4 double bond is also unprecedented.

Flueggether A

H. Zhang et al observed interesting signals from very minor constituents from F. virosa in their MS analysis. A further fractionation of the fractions showing the interesting MS peaks returned two extra new alkaloids, one of which, Flueggether A (molecular formula C₂₅H₃₀N₂O₅) is the first example of Securinega alkaloid oligomers which features an ether bond linkage.

Callyspongiolide

Callyspongiolide Macrolides have been reported from various marine macroorganisms, but are especially prominent for marine sponges. Many macrolides display potent…

Tronoharine

Tronoharine was isolated in a small amount as a minor alkaloid from a sample of T. corymbosa and given a proposed structure. In a more recent work, it was obtained in a more significant amount, which enabled the authors to reevaluate the previously proposed structure. Structure Elucidator Suite was used to confirm the newly proposed structure of Tronoharine ((molecular formula C₂₁H₂₄N₂O₂).

Spirochensilide A

Zhao et al isolated two novel rearranged triterpenoids from the leaves and twigs of A. chensiensis.—Spirochensilides A and B. The spectroscopic data used to elucidate the structure of Spirochensilide A (molecular formula C₃₀H₄₂O₅), a compound containing unprecedented spiro-[5,6]system, were used to challenge ACD/Structure Elucidator Suite.

Arboridinine

S.P. Wong et al investigated the alkaloid content of K. arborea Blume, and reported the isolation and structure determination of a new pentacyclic monoterpenoid indole alkaloid, Arboridinine (molecular formula C₁₉H₂₂N₂O), characterized by an unprecedented molecular skeleton.

A Heterodimer from P. kaurabassana

Two heterodimers comprising an anthraquinone moiety linked to a 3-methylbenzodihydroisocoumarin unit were isolated from P. kaurabassana tubers. The NMR spectroscopic data presented therein were used by us to challenge the ACD/Structure Elucidator system, by attempting to successfully elucidate structure 1 (molecular formula C₃₁H₂₄O₁₀).

Garcimulin A

Fan et al isolated two PPAPs, Garcimulins A and B, including a pair of enantiomers [(+)-Garcimulin A and (-)-Garcimulin A)] with the unique caged tetracyclo[5.4.1.11,5.09,13]tridecane skeleton from the leaves and twigs of G. multiflora. The spectroscopic 1D and 2D NMR data used by the authors for structure elucidation of Garcimulin A (molecular formula C₃₈H₅₀O₆) were input into ACD/Structure Elucidator Suite.

Bacillusin A

R.R. Ravu and coworkers performed work searching for new antibiotics against drug-resistant bacteria. Preliminary fractionation of the crude extracts of the B. amyloliquefaciens subsp. plantarum strain AP183 afforded activity-enriched fractions that contained an apparently unknown active compound with strong UV absorptions. A scale-up fermentation of this Bacillus strain was conducted, leading to the isolation and identification of Bacillusin A (molecular formula C₆₈H₉₂O₁₈).

Sinensilactam A

The authors’ efforts focusing on lingzhi meroterpenoids from G. sinensis led to the isolation of a meroterpenoidal hybrid metabolite, called Sinensilactam A (molecular formula C₂₀H₂₁NO₈), which contains a rare 2H-pyrrolo[2,1-b][1,3]- oxazin-6(7H)-ring system.

Laevinoid A

Wang and coworkers collected the branches and leaves of Croton laevigatus and performed an intensive chemical analysis. They isolated and elucidated structures of two diterpenoids, laevinoids A (molecular formula C₂₀H₂₂O₅) and B, which represent a new rearranged ent-clerodane scaffold with an unusual 3/5 bicyclic motif.

Virosaine

Zhao and co-workers isolated two new Securinega alkaloids (virosaines A and B) with an unprecedented skeleton and elucidated their structures. We used the spectroscopic data presented in by the authors to establish the structure of Virosaine A (molecular formula C₁₂H₁₃NO₄) which had been confirmed by X-ray diffraction.

Schiglautone A

Meng et al. investigated potentially biologically active substances from the chemical constituents of the stems of S. glaucescens. As a result, a novel triterpenoid possessing an unusual 6/7/9-fused tricyclic ring system was obtained, which was designated as Schiglautone A (molecular formula C₃₀H₄₆O₆).

Puberunine

While studying the herb Aconitum barbatum Pers. var. puberulum Ledeb., Mu et al isolated six new C18-diterpenoid alkaloids including Puberunine (molecular formula C₂₃H₃₅NO₇) that possesses an unusual rearranged 7-membered ring. This structural feature is unprecedented in the field of diterpenoid alkaloids.

Strynuxline A

Studies aimed at the discovery of trace alkaloids in S. nux-vomica led Fu and co-workers to the isolation of Strynuxlines A and B, two novel alkaloids possessing an unprecedented skeleton with a 6/5/9/6/7/6 hexacyclic ring system. Here we will describe how Strynuxlines A (molecular formula C₂₃H₂₄N₂O₅) could be identified with the assistance of a CASE-based approach using ACD/Structure Elucidator Suite.

Strophasterol A

In search for bioactive compounds from the mushroom Stropharia rugosoannulata, Wu et al discovered four novel steroids named strophasterols A, B, C, and D which contained a very unique and unprecedented carbon skeleton. Here we will describe the computerized structure determination of Strophasterol A (molecular formula C₂₈H₄₄O₄).

Acremolin

Here we describe a total synthesis of a hypothetical alternative structure and its spectroscopic confirmation, representing a huge amount of work done by the authors to disprove the original structure. We used their example to ask what solution would be obtained if the authors used ACD/Structure Elucidator Suite for processing the spectroscopic data of the unknown.

Trigoflavidol A

Tang et al carried out a phytochemical investigation on the stems of T. flavidus collected in China. They reported the identification of five degraded diterpenoids, including the tetranorditerpenoid dimers trigoflavidols A and B. Spectroscopic data acquired for Trigoflavidol A (molecular formula C₃₅H₃₂O₁₀), possessing a rearrangement skeleton with a spiroketal core moiety, was used for challenging ACD/Structure Elucidator Suite.

Gymnopalyne A

In searching for novel antibiotics, Thongbai et al have focused on tropical basidiomycetes from Asia. The research led to the isolation of unprecedented antimicrobial metabolite Gymnopalynes A (molecular formula C₁₂H₇O₂Cl). Though the molecule is small and relatively simple, elucidation of its structure is not straightforward. With this in mind we used this problem to illustrate some nuances associated with utilization of ACD/Structure Elucidation.

Mandelalide A

Sikorska et al isolated and investigated the unusual polyketide macrolides Mandelalides A-D which were isolated from a new species of Lissoclinum ascidian. Their planar structures were elucidated from sub-milligram samples by comprehensive analysis of 1D and 2D NMR data, and supported by mass spectrometry. Here we will describe the elucidation of Mandelalide A (molecular formula C₃₃H₅₂O₁₁) using ACD/Structure Elucidator Suite.

TAEMC161 (Viridol)

This example clearly shows how an improper axiom assumption by a researcher can lead to an incorrect structure. Employing an unbiased analysis of spectral data using Structure Elucidator Suite would allow the authors to infer the correct structure (Viridol, molecular formula C₂₀H₁₈O₆) unambiguously in several seconds.

Barmumycin

Lorente and co-workers isolated two known compounds, pretomaymycin and oxotomaymycin, plus the previously unknown compound barmumycin from the culture broth of the marine actinomycete Streptomyces sp. BOSC-022A. Barmumycin (molecular formula C₁₅H₁₉NO₄)and its diacetate show antitumor activity at micromolar concentrations.

Schizocommunin

A reinvestigation of the NMR and IR results for natural schizocommunin led the researchers to propose a revised structure, quinazolinone. We suggested that if a CASE approach were used elucidate the structure when this compound was firstly isolated, the structure revision would be not necessary: for final structure confirmation X-ray crystallographic analysis would be sufficient.

Epohelmin A

This month we re-visit the example of structure revision of Epohelmin A with structure revision utilizing ACD/Structure Elucidator Suite, which demonstrates how the software allows a researcher to avoid complex multi-stage synthesis to refute a wrong proposed structure and prove the revised one.

Ascidia sydneiensis SAAF

To understand the molecular mechanism underlying the genus-specificity of ascidians’ sperm chemotaxis, Matsumori et al investigated the structure of a novel compound Ascidia-SAAF 2 (molecular formula C₂₇H₄₄O₁₀S₂Na₂), which was isolated from the eggs of the ascidian Ascidia sydneiensis. Utilizing Structure Elucidator Suite allowed the correct structure of unknown, and its configuration upon a double bond to be determined.

Phosphoiodyn A

Kim et al isolated and identified two unprecedented phosphorus-containing iodinated polyacetylenes, Phosphoiodyn A and B, from a Korean marine sponge Placospongia sp. Here we will describe the structural elucidation of Phosphoiodyn A (molecular formula C₁₆H₂₄O₄PI).

Aquatolide

Aquatolide is a humulane-derived sesquiterpenoid lactone isolated from Asteriscus aquaticus. The structure originally proposed on the basis of 1D and 2D NMR analysis contains an exceedingly rare ladderane substructure. As a result of the quantum-chemical (QM) calculations of the 13C and 1H chemical shifts and associated coupling constants for a series of possible structures, it was shown that the proposed structure was incorrect. We applied a well-established Computer Assisted Structure Elucidation (CASE) method to the problem, in order to compare results with the QM method.

Jatrophalactam

Wang and co-workers isolated Jatrophalactam (molecular formula C₂₀H₂₉NO₃), a novel diterpenoid lactam possessing an unprecedented skeleton from the roots of Jatropha curcas.

Asidia SAAF

To understand the molecular mechanism underlying the genus-specificity of sperm chemotaxis of ascidians (a type of marine invertebrate filter feeders), Matsumori et al have investigated the structure of a novel compound Ascidia-SAAF 2 (molecular formula C₂₇H₄₄O₁₀S₂Na₂) isolated from the eggs of the ascidian Ascidia sydneiensis.

Polypropionat

Marine mollusks of the genus Siphonaria, commonly known as false limpets, are shelled, air-breathing herbivores that are believed to have a marine ancestry. When disturbed, siphonariid limpets secrete a sticky white mucus rich in polypropionate secondary metabolites. Specimens were steeped in acetone, and the acetone extract was subjected to extensive chromatography to afford three new polypropionate metabolites. Spectroscopic data of Polypropionate 1 (molecular formula C₂₀H₃₂O₃) are used here to describe the structure elucidation of this compound using CASE techniques.

Geralcin A

Le Goff et al reported the structural characterization of two novel alkylhydrazides produced by the bacterial strain Streptomyces sp. LMA-545. The structures were elucidated using 1D and 2D 1H and 13C NMR spectroscopic analysis and high-resolution mass spectrometry. 1H–15N NMR experiments were required for full structural elucidation. Here we investigate the structure elucidation of Geralcin A ( molecular formula C₁₅H₂₄N₂O₅), one of the three isolated novel compounds.

Protuboxepin A

Lee et al have investigated the chemical constituents of the extracts obtained from cultures of the marine-derived fungus Aspergillus sp. SF-5044. This study led to the isolation of new natural products, particularly, an oxepin-containing diketopiperazine-type metabolite named Protuboxepins A (molecular formula C₂₂H₂₃N₃O₃).

Lycojaponicumin D

Previously Wang et al reported three trace Lycopodium alkaloids, lycojaponicumins A and B with a 5/5/5/5/6 pentacyclic ring system and lycojaponicumin C with a 6/5/5/6 tetracyclic ring system. The same group later described the discovery of structurally unique alkaloid, Lycojaponicumin D (molecular formula was established to be C₁₆H₂₃NO₃), with an unprecedented 5/7/6/6 tetracyclic skeleton formed by an unusual C3-C13 linkage.

Indol alkaloid

An aqueous extract of the roots of I. indigotica has been investigated by Chen and co-workers. In this work, the authors isolated and structurally characterized an indole alkaloid containing unusual dihydrothiopyran and 1,2,4-thiadiazole rings (molecular formula C₁₈H₁₇N₃O₂S₂).

Asperjinone

Liao et al isolated and elucidated the structure of a new natural product named as Asperjinone (molecular formula C₂₂H₂₀O₆). Our analysis using ACD/Structure Elucidator resulted in the revision of the structure. The story of the structure revision is described in the Journal of Natural Products.

Geranylphenazinediol

Ohlendorf and co-workers describe isolation and structure elucidation of Geranylphenazinediol (molecular formula C₂₂H₂₄N₂O₂), a phenazinediol substituted with an isoprenoid side chain. We used ACD/Structure Elucidator to elucidate structure of this new natural product using only its NMR spectroscopic data.

Aetheramide

Plaza et al [1] isolated two new unusual depsipeptides, aetheramides A and B. Here we will discuss the computer-assisted structure elucidation (CASE) of aetheramide B (molecular formula C₄₁H₅₄N₂O₉) using ACD/Structure Elucidator.

Lasionectrin

El Aouad at al isolated a new naphthopyrone (structure 1) named Lasionectrin (molecular formula C₁₉H₂₀O₆) with antiplasmodial properties from fermentation broths of a Lasionectria species. The article constitutes the first account on the isolation of a natural product from fungi of this genus.

Daphmacromine A

M. Cao and co-workers described the isolation and structure elucidation of 10 new alkaloids belonging to the Daphniphyllum alkaloids family. The spectral data presented for one of the compounds, Daphmacromine A (molecular formula C₂₅H₃₇NO₅), were used to challenge ACD/Structure Elucidator.

Lycojaponicumin

Wang et al isolated a novel alkaloid lycojaponicumin (molecular formula C₁₆H₂₁NO₄) from the alkaloidal extract in a trace amount, with a unique 5/5/5/5/6 pentacyclic ring system including two fused tetrahydroisoxazole rings. The structure was elucidated by spectroscopic methods and X-ray diffraction analysis.

Psychotripine

A recent article highlighted the isolation and structure elucidation of a new natural product Psychotripine (molecular formula C₃₃H₃₄N₆), which exhibited a complex carbon skeleton comprised of 11 rings. We attempted the Computer-Assisted Structure Elucidation (CASE) of Psychotriptine using only the original limited and incomplete NMR data gathered from the original publication

Tasiamide B

Philip Williams and co-workers isolated a new cytotoxic peptide, Tasiamide B (molecular formula C₅₀H₇₄N₈O₁₂) containing the unusual amino acid-derived residue 4-amino-3-hydroxy-5-phenylpentanoic acid. The structure of the peptide was determined through a combination of 2D NMR experiments and HPLC analysis of degradation products. The experimental data was submitted to the Structure Elucidator Challenge to determine if the software could propose the same structure.

Phoriospongin A

Robert Capon and co-workers identified two new nematocidal depsipeptides, identified as phoriospongins A (molecular formula C₅₂H₈₂N₁₁O₁₅Cl) and B. The structures of the phoriospongins were determined by detailed spectroscopic analysis and comparison with the previously reported sponge depsipeptide cyclolithistide A. The experimental data was submitted to the Structure Elucidator Challenge to determine if the software could propose the same structure.

α-botryoxanthin A

Botryococcus braunii is a colonial green microalga that is known for producing various types of hydrocarbons and other types of oils. In a 1998 publication, Okada and co-workers isolated and identified two new carotenoids in their efforts to better understand the relationship between colony color and hydrocarbon production, one of which was α-botryoxanthin A (molecular formula C₇₄H₁₁₂O₂).

Example Elucidation

For more than a decade, ACD/Structure Elucidator has been used by industry and academic experts to help solve some of the toughest structure problems. Using data from various analytical techniques (NMR, MS, UV, and IR) Structure Elucidator can propose chemical structures that are consistent with ALL available analytical data.