Displaying publications 1 - 20 of 112 in total

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  1. Enantioselective dihydroxylation of xanthorrhizol from Curcuma xanthorrhiza via biotransformation using Aspergillus Niger
    Aminudin NI, Abdul Aziz AA, Zainal Abidin ZA, Susanti D, Taher M
    Nat Prod Res, 2024 May;38(9):1583-1590.
    PMID: 36577029 DOI: 10.1080/14786419.2022.2161543
    Biotransformation is acknowledged as one of the green chemistry methods to synthesis various analogues for further valorization of natural product compounds chemistry and bioactivities. It has huge advantage over chemical synthesis due to its cost-efficiency and higher selectivity. In this work, a xanthorrhizol derivatives, namely (7 R,10S)-10,11-dihydro-10,11-dihydroxyxanthorrhizol was produced in 60% yield from the biotransformation process utilizing A. niger. The structure of the compound was established by extensive spectroscopic methods and comparison with literature data. This biotransformation successfully afforded enantioselective dihydroxylation reaction via green chemistry route. This is the first report on both biotransformation of xanthorrhizol and utilization of A. niger as its biocatalyst.
    Matched MeSH terms: Stereoisomerism
  2. Primitive homochiral polyester formation driven by tartaric acid and calcium availability
    Chen C, Yi R, Igisu M, Afrin R, Sithamparam M, Chandru K, et al.
    Proc Natl Acad Sci U S A, 2025 Mar 25;122(12):e2419554122.
    PMID: 40117315 DOI: 10.1073/pnas.2419554122
    α-hydroxy acids (αHAs), simple and prebiotically plausible organic monomers, were likely present in various environments on and off Earth and could have played a role in directing the emergence of the first homochiral living systems. Some αHAs, which could have been of varying chirality, can undergo dehydration polymerization into polyesters, which could assemble into membraneless microdroplets upon rehydration; understanding these processes is critical for unraveling how simple prebiotic molecules transitioned into more complex systems capable of supporting selective chemical reactions, a key step toward the origin of life. Here, we focused on tartaric acid (TA), a prebiotically relevant αHA with multiple chiral forms, to probe plausible mechanisms by which primitive αHA and polyester-based systems could have participated in selective homochiral polymer synthesis. Enantiopure solutions of d-TA or l-TA polymerize efficiently via dehydration, while racemic dl-TA polymerization is inhibited due to stereochemical incompatibility. We found that Ca2+ ions influence this process in two significant ways: 1) regulating TA monomer availability through selective crystallization, removing equal amounts of both enantiomers in racemic proportion and thereby enriching the enantiomeric excess of the remaining nonracemic TA solution; and 2) modulating polymerization by suppressing enantiopure TA polymerization while enabling dl-TA polymerization. These findings suggest that the differential availability of simple inorganic ions, such as Ca2+, could have indirectly mediated the selection of simple organic chiral monomers and the emergence of homochirality in primitive protocell-forming polymers, offering a pathway from nonliving to living matter in early Earth environments.
    Matched MeSH terms: Stereoisomerism
  3. Synthesis and applications of ionic liquids for chromatographic analysis
    Waheed A, Akram S, Butt FW, Liaqat Z, Siddique M, Anwar F, et al.
    J Chromatogr A, 2025 Jan 04;1739:465503.
    PMID: 39566285 DOI: 10.1016/j.chroma.2024.465503
    Ionic liquids (ILs) have emerged as more desirable liquids than conventional solvents for chemistry, material science, engineering and environmental science. The scientific literature reveals an exponential increase in the number of research projects aimed at exploring the chromatographic features of ionic liquids. The review provides sound scientific data to examine the structural characteristics of ionic liquids that make them ideal for use in chromatography. This contribution is distinctive since it integrates the synthesis, benefits, drawbacks, and possible uses of ionic liquids in several chromatographic separation processes. Keeping the cation the same, the introduction of different anions is also possible, and this strategy leads to the synthesis of a series of different ionic liquids with varying properties. A detailed probe is given on the influence of ionic liquid structure and properties on their chromatographic behavior, both as stationary phase and mobile phase and/or mobile phase additives. Ionic liquid based immobilized stationary phases and their analyte retention mechanisms (hydrogen bonding, electrostatic forces of attraction, π-π stacking, ion exchange, and hydrophilic interactions, etc.) are critically discussed. Finally, a thorough analysis of the literature suggests that IL-based stationary phases may undergo multi-mode and more flexible retention mechanisms. Their dual polarity can facilitate interaction with both polar and non-polar compounds. Similarly, using IL as a mobile phase can offer more pragmatic and sustainable options for enantiomer separation.
    Matched MeSH terms: Stereoisomerism
  4. Quantitative and Qualitative Bibliometric Scope Toward the Synthesis of Rose Oxide as a Natural Product in Perfumery
    Ziarani GM, Mohajer F, Jamali SM, Ebrahim NA
    Curr Org Synth, 2020;17(8):610-624.
    PMID: 32703138 DOI: 10.2174/1872208314666200722161044
    Rose Oxide is a monoterpene along with cyclic ether used in fragrance to produce rosy notes, in general, there are 4 stereoisomeric structures of the Rose Oxide, which the cis-configured Rose Oxide has a very unique and strong note in perfumery. In this review, several approaches were reported on account of the Rose Oxide applied in perfumery from 1864 to 2019 via quantitative and qualitative approaches.
    Matched MeSH terms: Stereoisomerism
  5. Nanoscale Chirality in Carbon Quantum Dots Enables Enantioselective Fluorescence Recognition of D-Penicillamine
    Yadegarazari R, Rezaei A, Qadir KH, Adibi H
    Luminescence, 2026 Nov;41(11).
    PMID: 42958701 DOI: 10.1002/bio.70656
    We successfully synthesized a chiral probe using a one-pot hydrothermal method involving L-/D-arginine and citric acid. The chiral carbon quantum dots (CQDs) were comprehensively characterized by various techniques such as FTIR, NMR, XPS, TEM, HRTEM, FESEM, and UV-vis. Fluorescence and circular dichroism were conducted to demonstrate that chiral ligands anchored at the nanoscale. To the best of our knowledge, this study represents the first report of arginine-derived chiral CQDs for enantioselective fluorescence recognition of D-penicillamine (D-PA). The results demonstrated an interaction between L-/D-Arg-CQDs and D-PA, evident from the significant reduction in emission intensity and quenching upon their introduction. Furthermore, experimental investigations focused on examining the enantioselective interaction behavior between D-PA and both L-Arg-CQDs and D-Arg-CQDs. It was found that both L-/D-Arg-CQDs exhibited a linear response over a concentration range of 50-10,000 nM of D-PA. Notably, the relative photoluminescence intensities of the chiral probes in relation to D-PA revealed that L-Arg-CQDs displayed a more pronounced interaction, leading to a steeper decline in emission compared to D-Arg-CQDs. In conclusion, the potential of chiral CQDs in enantioselective detection offers significant benefits for the pharmaceutical industry and related fields, where ensuring the safety and efficacy of pharmaceutical products is of utmost importance.
    Matched MeSH terms: Stereoisomerism
  6. Spectroscopic studies for the inclusion complexation of ketoprofen enantiomers with β-cyclodextrin
    Obaid A, Jamil AKM, Prabu S, Saharin SM, Mohamad S
    Spectrochim Acta A Mol Biomol Spectrosc, 2020 Nov 05;241:118674.
    PMID: 32652287 DOI: 10.1016/j.saa.2020.118674
    Inclusion complexes of R-ketoprofen and S-ketoprofen enantiomers with β-cyclodextrin (β-CD) in aqueous solution were studied using various spectroscopic techniques such as Raman, FTIR, UV and fluorescence. The different relative intensities and characteristic band shifts of the two enantiomers from Raman spectra suggests different interaction when complexed with β-CD. Raman experiments revealed a noticeable diminishing of the CC vibration and ring deformation, which indicate the embedding of ketoprofen inside the β-CD cavity. It's revealed that distinct differences between R- and S-ketoprofen in the presence of β-CD at neutral pH. The stoichiometry ratio and binding constant of the inclusion complexes were calculated using Benesi-Hildebrand plot. Both enantiomers showed stoichiometry ratio of 1:1 inclusion complex with β-CD. The binding constant of R-ketoprofen (4088 M-1) is higher than S-ketoprofen (2547 M-1). These values indicated that β-CD formed inclusion complexes more preferentially with R-ketoprofen than S-ketoprofen. Results demonstrated that β-CD can be used as a promising chiral selector for ketoprofen enantiomers.
    Matched MeSH terms: Stereoisomerism
  7. Effect of reductive alkylation of Candida rugosa lipase on its enantioselective esterification reaction
    Basri M, Th'ng BL, Razak CN, Salleh AB
    Ann N Y Acad Sci, 1998 Dec 13;864:192-7.
    PMID: 9928091
    Matched MeSH terms: Stereoisomerism
  8. L-cysteine capped silver nanoparticles as chiral recognition sensor for ketoprofen enantiomers
    Obaid A, Mohd Jamil AK, Saharin SM, Mohamad S
    Chirality, 2021 11;33(11):810-823.
    PMID: 34486177 DOI: 10.1002/chir.23354
    A simple, inexpensive but effective approach for visual chiral recognition of ketoprofen enantiomers was developed using L-cysteine capped silver nanoparticles (L-Cys-AgNPs) as a colorimetric sensor. Upon the addition of R-ketoprofen to L-Cys-AgNPs, rapid aggregation occurred, and the solution changed color from yellow to green. However, the presence of S-ketoprofen did not induce any color change. The results were characterized using UV-Vis, FESEM, FT-IR, SERS, and zeta potential measurements. The chiral assay described in this work is easily distinguished with the naked eyes or using a UV-Vis spectrometer. The sensor revealed a good linear response to ketoprofen enantiomers in the concentration range of 8.33-33.3 μM with a detection limit of 4.52 μM and relative standard deviation of 3.73%. The proposed method was utilized for the determination of ketoprofen racemic mixtures in water samples and commercial tablets. The method excels by its simplicity, low cost, and good availability of materials.
    Matched MeSH terms: Stereoisomerism
  9. Enantioselective analysis in complex matrices using capillary electrophoresis-mass spectrometry: A case study of the botanical drug Corydalis Rhizoma
    Yan B, Huang ZA, Yahaya N, Chen DDY
    J Chromatogr B Analyt Technol Biomed Life Sci, 2020 Sep 01;1152:122216.
    PMID: 32531643 DOI: 10.1016/j.jchromb.2020.122216
    Enantioselective analysis is critically important in the pharmaceutical and agricultural industries. However, most of the methods reported were developed for the analysis of pure racemates acquired from chemical synthesis or purification. Direct analysis of chiral enantiomers in complex matrices has rarely been reported. This work demonstrated capillary electrophoresis-mass spectrometry (CE-MS) for the enantioselective analysis of botanical drugs for the first time, using a widely used botanical drug, Corydalis Rhizoma, as an example. The method was used for the simultaneous enantioselective analysis of dl-tetrahydropalmatine and (RS)-tetrahydroberberine (canadine) in Corydalis Rhizoma extract. Using (2-hydroxypropyl)-β-cyclodextrin as the chiral selector, a partial filling technique was used to avoid signal suppression and contamination of the MS detector. Post column organic modifier was used to assist with ionization in the flow through microvial CE-MS interface, therefore, organic solvents was not used in the background electrolyte. The completely aqueous background electrolyte contributed to better chiral separations. The CE-MS method established here can directly determine the analytes in their complex matrix without any pre-purification steps, while also offering high sensitivity and low operational costs (including sample, chiral selector and solvent). In the method validation process, good linearity (r > 0.993), sensitivity and accuracy (recoveries within 89.1-110.0%) were demonstrated. The CE-MS technique was shown to be able to provide good selectivity for the simultaneous chiral separation of multiple pairs of enantiomers in complex matrices.
    Matched MeSH terms: Stereoisomerism
  10. Fulltext Synthesis, characterization and evaluation of antidengue activity of enantiomeric Schiff bases derived from S-substituted dithiocarbazate
    Maryam M, Tan SL, Crouse KA, Mohamed Tahir MI, Chee HY
    Turk J Chem, 2020;44(5):1395-1409.
    PMID: 33488239 DOI: 10.3906/kim-2006-22
    A series of Schiff bases have been successfully synthesized through the acid-catalyzed condensation of S-substituted dithiocarbazates and three enantiomerically pure monoterpenes, (1 R )-(+)-camphor, (1 S )-(-)-camphor, (1 R )-(-)-camphorquinone, (1 S )-(+)-camphorquinone, ( R )-(-)-carvone and ( S )-(+)-carvone. Spectroscopic results revealed that the Schiff bases containing camphor or carvone likely adopted an E -configuration along the characteristic imine bond while those containing camphorquinone assumed a Z -configuration. The antidengue potential of these compounds was evaluated based on DENV 2 caused cytopathic effect (CPE) reduction-based in vitro evaluation. The compounds were validated through secondary foci forming unit reduction assay (FFURA). Compounds were also tested for their cytotoxicity against Vero cells. The compounds showed variable degrees of antiviral activity with the camphor compounds displaying the highest antidengue potential. The enantiomers of the compounds behaved almost similarly during the antiviral evaluation.
    Matched MeSH terms: Stereoisomerism
  11. 1,4-Methano-11a-methyl-4,4a,11,11a-tetrahydro-1H-benzo[b]fluoren-11-one
    Usman A, Razak IA, Chantrapromma S, Ghorai SK, Mal D, Fun HK, et al.
    Acta Crystallogr C, 2001 Sep;57(Pt 9):1118-9.
    PMID: 11588390
    The title compound, C(19)H(16)O, crystallizes with two molecules of opposite chirality in the asymmetric unit. In both molecules, the naphthalene and cyclopentanone moieties are individually planar. The two cyclopentane rings adopt envelope conformations, while the cyclohexane ring adopts a boat conformation.
    Matched MeSH terms: Stereoisomerism
  12. Total synthesis of a cuticular hydrocarbon from the cane beetle Antitrogus parvulus: confirmation of the relative stereochemistry
    Basar NB, Liu H, Negi D, Sirat HM, Morris GA, Thomas EJ
    Org Biomol Chem, 2012 Mar 7;10(9):1743-5.
    PMID: 22274635 DOI: 10.1039/c2ob06906g
    The stereoselective reaction of an allyl bromide with an aldehyde mediated by a low valency bismuth species was the key reaction in stereoselective syntheses of (4S,6R,8R,10S,16S)- and (4S,6R,8R,10S,16R)-4,6,8,10,16-pentamethyldocosanes. (13)C NMR data for these compounds confirmed that the cuticular hydrocarbon isolated from the cane beetle Antitrogus parvulus was the (4S,6R,8R,10S,16S)-stereoisomer.
    Matched MeSH terms: Stereoisomerism
  13. Fulltext Dry Thermotropic Glycolipid Self-Assembly:A Review
    Hashim R, Zahid NI, Velayutham TS, Aripin NFK, Ogawa S, Sugimura A
    J Oleo Sci, 2018 Jun 01;67(6):651-668.
    PMID: 29760332 DOI: 10.5650/jos.ess17261
    Also recognized as carbohydrate liquid crystals, glycolipids are amphiphiles whose basic unit comprises of a sugar group attached to an alkyl chain. Glycolipids are amphitropic, which means these materials form liquid crystal self-assemblies when dry (thermotropic) as well as when dissolved in solvents (lyotropic/surfactants) such as water. Many glycolipids are also naturally derived since these can be found in cell membranes. Their membrane and surfactant functions are largely understood through their lyotropic properties. While glycolipids are expected to play major roles as eco-friendly surfactants in the global surfactant market, their usefulness as thermotropic liquid crystal material is, to date, unknown, due to relatively lack of research performed and data reported in the literature. Understandably since glycolipids are hygroscopic with many hydroxy groups, removing the last trace water is very challenging. In recent time, with careful lyophilization and more consistent characterization technique, some researchers have attempted serious studies into "dry" or anhydrous glycolipids. Motivated by possible developments of novel thermotropic applications, some results from these studies also provide surprising new understanding to support conventional wisdom of the lyotropic systems. Here we review the dry state of glycosides, a family of glycolipids whose sugar headgroup is linked to the lipid chain via a glycosidic oxygen linker. The structure property relationship of both linear and anhydrous Guerbet glycosides will be examined. In particular, how the variation of sugar stereochemistry (e.g. anomer vs. epimer), the chain length and chain branching affect the formation of thermotropic liquid crystals phases, which not only located under equilibrium but also far from equilibrium conditions (glassy phase) are scrutinized. The dry glycolipid assembly has been subjected to electric and magnetic fields and the results show interesting behaviors including a possible transient current generation.
    Matched MeSH terms: Stereoisomerism
  14. Enantioseparation of Selected Imidazole Drugs Using Dual Cyclodextrin-Modified Micellar Electrokinetic Chromatography
    Ibrahim WAW, Wahib SMA, Hermawan D, Sanagi MM
    Methods Mol Biol, 2019;1985:407-416.
    PMID: 31069749 DOI: 10.1007/978-1-4939-9438-0_24
    Particular attention has been paid to capillary electrophoresis as versatile and environmentally friendly approach for enantioseparations of a wide spectrum of compounds. Cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) is a method of choice to provide effective separation toward hydrophobic and uncharged stereoisomers. The chiral discrimination of the solutes relies upon the partitioning between a given CD in the aqueous phase and micelles formed from a surfactant. Synergistic combinations of chiral selectors, surfactant, and modifier contribute to successful enantioseparations of the enantiomers. In this chapter, an application of CD-MEKC for the enantioseparation of selected imidazole drugs employing a dual CDs system is described.
    Matched MeSH terms: Stereoisomerism
  15. Enantioseparation of ketoconazole and miconazole by capillary electrophoresis and a study on their inclusion interactions with β-cyclodextrin and derivatives
    Azhari NR, Yahaya N, Mohd Suah FBM, Prabu S, Yih Hui B, Shahriman MS, et al.
    Chirality, 2021 01;33(1):37-50.
    PMID: 33197086 DOI: 10.1002/chir.23285
    A chiral separation method coupled with capillary electrophoresis (CE) analysis for ketoconazole and miconazole enantiomers using chiral selectors such as β-cyclodextrin (β-CD) and hydroxypropyl-β-CD (HP-β-CD) was developed in this study, which included the optimisation, validation and application of the method on the antifungal cream samples. The formation of inclusion complex between the hosts (β-CD and HP-β-CD) and guests (ketoconazole and miconazole) were compared and analysed using ultraviolet-visible spectrophotometry, nuclear magnetic resonance (NMR) spectroscopy and molecular docking methods. Results from the study showed that in a concentration that ranged between 0.25 and 50 mg L-1 , the linear calibration curves of each enantiomer had a high coefficient of regression (R2 > 0.999), low limit of detection (0.075 mg L-1 ) and low limit of quantification (0.25 mg L-1 ). The relative standard deviation (RSD) of the intraday and interday analyses ranged from 0.79% to 8.01% and 3.30% to 11.43%, respectively, while the recoveries ranged from 82.0% to 105.7% (RSD < 7%, n = 3). The most probable structure of the inclusion complexes was proposed based on the findings from the molecular docking studies conducted using the PatchDock server.
    Matched MeSH terms: Stereoisomerism
  16. Enzymatic synthesis of quercetin oleate esters using Candida antarctica lipase B
    Saik AY, Lim YY, Stanslas J, Choo WS
    Biotechnol Lett, 2017 Feb;39(2):297-304.
    PMID: 27812823 DOI: 10.1007/s10529-016-2246-5
    OBJECTIVES: To investigate the lipase-catalyzed acylation of quercetin with oleic acid using Candida antarctica lipase B.

    RESULTS: Three acylated analogues were produced: quercetin 4'-oleate (C33H42O8), quercetin 3',4'-dioleate (C51H74O9) and quercetin 7,3',4'-trioleate (C69H106O10). Their identities were confirmed with UPLC-ESI-MS and (1)H NMR analyses. The effects of temperature, duration and molar ratio of substrates on the bioconversion yields varied across conditions. The regioselectivity of the acylated quercetin analogues was affected by the molar ratio of substrates. TLC showed the acylated analogues had higher lipophilicity (152% increase) compared to quercetin. Partition coefficient (log P) of quercetin 4'-oleate was higher than those of quercetin and oleic acid. Quercetin 4'-oleate was also stable over 28 days of storage.

    CONCLUSIONS: Quercetin oleate esters with enhanced lipophilicity can be produced via lipase-catalyzed reaction using C. antarctica lipase B to be used in topical applications.

    Matched MeSH terms: Stereoisomerism
  17. Fulltext Chromatographic Separation of Vitamin E Enantiomers
    Fu JY, Htar TT, De Silva L, Tan DM, Chuah LH
    Molecules, 2017 Feb 04;22(2).
    PMID: 28165404 DOI: 10.3390/molecules22020233
    Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.
    Matched MeSH terms: Stereoisomerism
  18. A reevaluation of the epimeric and anomeric relationship of glucosides and galactosides in thermotropic liquid crystal self-assemblies
    Hashim R, Mirzadeh SM, Heidelberg T, Minamikawa H, Yoshiaki T, Sugimura A
    Carbohydr Res, 2011 Dec 27;346(18):2948-56.
    PMID: 22088885 DOI: 10.1016/j.carres.2011.10.032
    Anomers and epimers α- and β-gluco and -galactosides are expected to behave differently. However, recent results on a series of Guerbet glycosides have indicated similar liquid crystal clearing temperatures for pure β-glucosides and the corresponding α-galactosides. This observation has led to speculation on similarities in the self-assembly interactions between the two systems, attributed to the trans-configuration of the 4-OH group and the hydrophobic aglycon. Previous simulations on related bilayers systems support this hypothesis, by relating this clearing transition temperature to intralayer (sugar-sugar) hydrogen bonding. In order to confirm the hypothesis, the comparison was expanded to include the cis-configurated pair, that is, α-gluco/β-galactoside. A set of α-configurated Guerbet glucosides as well as octyl α-galactoside were prepared and their thermotropic phase behavior studied. The data obtained enabled a complete comparison of the isomers of interest. While the results in general are in line with a pairing of the stereo-isomers according to the indicated cis/trans-configuration, differences within the pairs can be explained based on the direction of hydrogen bonds from a simple modeling study.
    Matched MeSH terms: Stereoisomerism
  19. Fulltext Systematic comparison of sets of (13)C NMR spectra that are potentially identical. Confirmation of the configuration of a cuticular hydrocarbon from the cane beetle Antitrogus parvulus
    Basar N, Damodaran K, Liu H, Morris GA, Sirat HM, Thomas EJ, et al.
    J Org Chem, 2014 Aug 15;79(16):7477-90.
    PMID: 25019530 DOI: 10.1021/jo5012027
    A systematic process is introduced to compare (13)C NMR spectra of two (or more) candidate samples of known structure to a natural product sample of unknown structure. The process is designed for the case where the spectra involved can reasonably be expected to be very similar, perhaps even identical. It is first validated by using published (13)C NMR data sets for the natural product 4,6,8,10,16,18-hexamethyldocosane. Then the stereoselective total syntheses of two candidate isomers of the related 4,6,8,10,16-pentamethyldocosane natural product are described, and the process is applied to confidently assign the configuration of the natural product as (4S,6R,8R,10S,16S). This is accomplished even though the chemical shift differences between this isomer and its (16R)-epimer are only ±5-10 ppb (±0.005-0.01 ppm).
    Matched MeSH terms: Stereoisomerism
  20. Andransinine: an unusual case of spontaneous resolution in an indole alkaloid derivative
    Low YY, Gan CY, Kam TS
    J Nat Prod, 2014 Jun 27;77(6):1532-5.
    PMID: 24832351 DOI: 10.1021/np500289t
    Racemic andransinine (1), an indole alkaloid derivative obtained during isolation of alkaloids from Alstonia angustiloba and Kopsia pauciflora, was found to undergo spontaneous resolution when crystallized in EtOAc, forming racemic conglomerates (an equimolar mechanical mixture of enantiomerically pure individual crystals). X-ray analyses of the enantiomers (obtained from crystals from EtOAc solution and from chiral-phase HPLC) provided the absolute configuration of each enantiomer as (15R,16S,21R)-(+)-andransinine (1a or I+) and (15S,16R,21S)-(-)-andransinine (1b or I-).
    Matched MeSH terms: Stereoisomerism
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