Protection of oligonucleotides against enzymatic degradation by pegylated and nonpegylated branched polyethyleneimine

Among the cationic polymers, polyethyleneimine (PEI) is a promising candidate for delivery of oligodeoxynucleotides (ODNs). In this study, we wondered whether pegylation of PEI influences the complexation with ODNs. We especially aimed to investigate whether ODNs are differently protected against enzymatic degradation in PEI and polyethylene glycol-polyethyleneimine (PEG-PEI) polyplexes. Using fluorescence resonance energy transfer combined with fluorescence correlation spectroscopy, we found that PEI/ODN polyplexes remain to protect the ODNs they carry over a prolonged period of time while in PEG-PEI/ODN polyplexes the degradation of the ODNs slowly proceeds. We attribute this to the fact that PEI seems to compact the ODNs more firmly in the polyplexes' core than PEG-PEI, which apparently also results in a better protection against enzymatic degradation. These observations may also influence the efficiency of PEI-based ODN delivery in vivo, where pegylation is an attractive strategy to enhance the stability of the polyplexes in the blood stream.     

Structures of poly(dA-dT, ip5dU) containing various small amounts of the antiherpetic 5-isopropyl-2'-deoxyuridine.

Three different concentrations of the antiherpetic agent 5-isopropyl-2'-deoxyuridine (ip5dU) were introduced into the synthetic DNA poly(dA-dT) to analyze resulting copolymers by electron microscopy, UV absorption and CD spectroscopy. The poly(dA-dT, ip5dU) containing 1.3 and 4.3% ip5dU did not much differ from the parent poly(dA-dT) but poly (dA-dT, ip5dU) with 7.1% ip5dU behaved in an unusual way. Results are explained by the notion that if bulky isopropyls occur sufficiently close to each other then stable hairpins protruding from the double helix are formed, presumably to accommodate the ip5dU-s into the loops.     

Multispectroscopic studies on the molecular interactions between bovine γ-globulin and borohydride-capped silver nanoparticles

Interactions between bovine γ-globulin (BGG) and borohydride-capped silver nanoparticles (BAgNPs) were studied using dynamic light scattering (DLS) and spectroscopic techniques such as UV–vis spectroscopy, fluorescence, and circular dichroism. The results were compared with earlier reported interactions between γ-globulin and citrate-coated AgNPs (CAgNPs). BAgNPs were synthesized and characterized. Irrespective of the coating on AgNPs, nanoparticles had formed ground-state complexes with the protein. CAgNPs, as well as BAgNPs had caused static quenching of tryptophan (Trp) fluorescence of the protein. The change in the capping agent from citrate to borohydride weakened the binding of nanoparticles with the protein. But the same change in capping agent had increased the fluorescence quenching efficiency of AgNPs. Hydrogen bonding and van der Waals interactions were involved in BGG–BAgNPs complex similar to the CAgNPs complex with γ-globulin. Polarity of the Trp microenvironment in BGG was not altered using BAgNPs as opposed to CAgNPs, as supported using synchronous and three-dimensional fluorescence. Resonance light scattering experiments also suggested nano-bio conjugation. Far-UV and near-UV circular dichroism (CD) spectra respectively pointed towards changes in the secondary and tertiary structure of BGG by BAgNPs, which was not observed for CAgNPs.     

Enantioselective cytotoxicity of ZnS:Mn quantum dots in A549 cells

Chirality strongly influences many biological properties of materials, such as cell accumulation, enzymatic activity, and toxicity. In the past decade, it has been shown that quantum dots (QDs), fluorescent semiconductor nanoparticles with unique optical properties, can demonstrate optical activity due to chiral ligands bound on their surface. Optically active QDs could find potential applications in biomedical research, therapy, and diagnostics. Consequently, it is very important to investigate the interaction of QDs capped with chiral ligands with living cells. The aim of our study was to investigate the influence of the induced chirality of Mn‐doped ZnS QDs on the viability of A549 cells. These QDs were stabilized with D‐ and L‐cysteine using a ligand exchange technique. The optical properties of QDs were studied using UV–Vis, photoluminescence (PL), and circular dichroism (CD) spectroscopy. The cytotoxicity of QDs was investigated by high content screening analysis. It was found that QDs stabilized by opposite ligand enantiomers, had identical PL and UV–Vis spectra and mirror‐imaged CD spectra, but displayed different cytotoxicity: QDs capped with D‐cysteine had greater cytotoxicity than L‐cysteine capped QDs.     

Esterase activity and interaction of human hemoglobin with diclofenac sodium: A spectroscopic and molecular docking study

To get an idea about the pharmacokinetics and pharmacodynamics, it is important to study the drug‐protein interaction. Therefore, herein, we studied the interaction of diclofenac sodium (DIC) with human hemoglobin. The binding study of nonsteroidal antiinflammatory drug, DIC with human hemoglobin (HHB) was done by utilizing fluorescence, UV–visible, time‐resolved fluorescence and far‐UV circular dichroism spectroscopy (CD). Various thermodynamic parameters such as enthalpy change (ΔH), entropy change (ΔS), and Gibbs free energy change (ΔG) were also calculated. CD results showed that DIC induces secondary structure change in HHB. Fluorescence resonance energy transfer was also performed. Additionally, it was also observed that DIC inhibits the esterase‐like enzymatic activity of HHB via competitive inhibition.     

Multifunctionalized CMCht/PAMAM dendrimer nanoparticles modulate the cellular uptake by astrocytes and oligodendrocytes in primary cultures of glial cells

The efficiency of the treatments involving CNS disorders is commonly diminished by the toxicity, reduced stability and lack of targeting of the administered neuroactive compounds. In this study, we have successfully multifunctionalized CMCht/PAMAM dendrimer nanoparticles by coupling the CD11b antibody and loading MP into the nanoparticles. The modification of the new antibody-conjugated nanoparticles was confirmed by S-TEM observation and (1) H NMR and FTIR spectroscopy. Cytotoxicity assays revealed that the conjugates did not affect the viability of both primary cultures of glial and microglial cells. Trace analyses of FITC-labelled nanoparticles revealed that the uptake of antibody-conjugated nanoparticles was conserved in microglial cells but significantly decreased in astrocytes and oligodendrocytes. Thus, this study demonstrates that antibody conjugation contributes to a modulation of the internalization of these nanocarriers by different cell types, which might be of relevance for specific targeting of CNS cell populations.     

Bioconjugation of papain on superparamagnetic nanoparticles decorated with carboxymethylated chitosan

Functionalized Fe3O4 nanoparticles decorated with carboxymethylated chitosan were developed and used as a novel magnetic support for the covalent conjugation of papain, one of the most important industrial proteases. The analyses of transmission electron micrographs (TEM) and X-ray diffraction (XRD) showed that the size and structure of functionalized Fe3O4 nanoparticles had no significant changes after conjugation with papain. Magnetic measurement revealed that the resultant papain-conjugated nanoparticles were superparamagnetic with a saturation magnetization of 59.3 emu/g. Analyses of Fourier transform infrared (FTIR) spectroscopy and measurement of zeta potentials confirmed the conjugation of papain with the functionalized Fe3O4 nanoparticles. Compared with the native papain, the conjugated papain was found to exhibit enhanced enzyme activity, better tolerance to the variations of medium pH and temperature, and improved storage stability as well as good reusability. Considering that the magnetic separation technique possesses the advantages of rapidity, high efficiency, cost-effectiveness, and lack of negative effect on biological activity, such a bioconjugate system may hold potential applications in food, pharmaceutical, leather, cosmetic, and textile industries.     

Near-infrared fluorescent nanoparticles as combined MR/optical imaging probes

A number of quantitative three-dimensional tomographic near-infrared fluorescence imaging techniques have recently been developed and combined with MR imaging to yield highly detailed anatomic and molecular information in living organisms (1, 2). Here we describe magnetic nanoparticle based MR contrast agents that have a near-infrared fluorescence (NIRF) that is activated by certain enzymes. The probes are prepared by conjugation of arginyl peptides to cross-linked iron oxide amine (amino-CLIO), either by a disulfide linkage or a thioether linker, followed by the attachment of the indocyanine dye Cy5.5. The NIRF of disulfide-linked conjugate was activated by DTT, while the NIRF of thioether-linked conjugate was activated by trypsin. Fluorescent quenching of the attached fluorochrome occurs in part due to the interaction with iron oxide, as evident by the activation of fluorescence with DTT when nanoparticles that have less than one dye attached per particle. With a SC injection of the probe, axillary and brachial lymph nodes were darkened on MR images and easily delineated by NIRF imaging. The probes may provide the basis for a new class of so-called smart nanoparticles, capable of pinpointing their position through their magnetic properties, while providing information on their environment by optical imaging techniques.     

Fluorescent substrates for the proteinases ADAM17, ADAM10, ADAM8, and ADAM12 useful for high-throughput inhibitor screening

In this paper we describe novel fluorescent substrates for the human ADAM family members ADAM17, ADAM10, ADAM8, and ADAM12 that have good specificity constants and are useful for high-throughput screening of inhibitors. The fluorescence resonance energy transfer substrates contain a 4-(4-dimethylaminophenylazo)benzoyl and 5-carboxyfluorescein (Dabcyl/Fam) pair and are based on known cleavage sequences in precursor tumor necrosis factor-alpha (TNF-alpha) and CD23. The precursor TNF-alpha-based substrate, Dabcyl-Leu-Ala-Gln-Ala-Homophe-Arg-Ser-Lys(Fam)-NH2, is a good substrate for all the ADAMs tested, including ADAM12 for which there is no reported fluorescent substrate. The CD23-based substrate, Dabcyl-His-Gly-Asp-Gln-Met-Ala-Gln-Lys-Ser-Lys(Fam)-NH2, is more selective, being hydrolyzed efficiently only by ADAM8 and ADAM10. The substrates were used to obtain inhibition constants for four inhibitors that are commonly used in shedding assays: TMI-1, GM6001, GW9471, and TAPI-2. The Wyeth Aerst compound, TMI-1, is a potent inhibitor against all of the ADAMs tested and is slow binding against ADAM17.     

Detection of triplet repeat sequences in the double-stranded DNA using pyrene-functionalized pyrrole-imidazole polyamides with rigid linkers

Methods for sequence-specific detection in double-stranded DNA (dsDNA) are becoming increasingly useful and important as diagnostic and imaging tools. Recently, we designed and synthesized pyrrole (Py)-imidazole (Im) polyamides possessing two pyrene moieties, 1, which showed an increased excimer emission in the presence of (CAG)(12)-containing oligodeoxynucleotides (ODN) 1 and 2. In this study, we synthesized bis-pyrenyl Py-Im polyamides with rigid linkers 2, 3, and 4 to improve their fluorescence properties. Among the conjugates, 2 showed a marked increase in excimer emission, which was dependent on the concentration of the target ODN and the number of CAG repeats in the dsDNA. Unlike conjugate 1, which has flexible linkers, the excimer emission intensity of 2 was retained at over 85%, even after 4h. Py-Im polyamides have the potential to be important diagnostic molecules for detecting genetic differences between individuals.     

Probing the Interaction of Mutiwalled Carbon Nanotubes and Catalase: Mutispectroscopic Approach

In this study, the mechanism of the interaction between multiwalled carbon nanotubes (MWCNTs) and catalase was investigated by fluorescence, UV–vis, and circular dichroism (CD) spectroscopy under physiological conditions. The fluorescence quenching mechanism of catalase by MWCNTs was shown to be a static quenching procedure and was a result of the formation of a catalase–MWCNT complex. The secondary structure and conformation of the catalase adsorbed on MWCNTs was determined by CD and UV‐vis spectroscopy, and the results indicate that the catalase in this complex is partially unfolded with its lost in α‐helical content and obtainment in β‐sheet content. Moreover, binding of MWCNTs to catalase inhibited the enzymatic activity, which may trigger some toxic effects and undesirable physiological consequences. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:493‐498, 2012;Viewthis article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21454     

The thermodynamic contribution of the 5-methyl group of thymine in the two- and three-stranded complexes formed by poly(dU) and poly(dT) with poly(dA)

To assess the thermodynamic contribution of the 5-methyl group of thymine, we have studied the two-stranded helical complexes poly(dA).poly(dU) and poly(dA).poly(dT) and the three-stranded complexes--poly(dA).2poly(dU), poly(dA).poly(dT).poly(dU) and poly(dA).2poly(dT)--by differential scanning calorimetry, and uv optical melting experiments. The thermodynamic quantities associated with the 3 --> 2, 2 --> 1, and 3 --> 1 melting transitions are found to vary with salt concentration and temperature in a more complex manner than commonly believed. The transition temperatures, T(m), are generally not linear in the logarithm of concentration or activity of NaCl. The change in enthalpy and in entropy upon melting varies with salt concentration and temperature, and a change in heat capacity accompanies each transition. The poly(dA).2poly(dU) triple helix is markedly different from poly(dA).2poly(dT) in both its CD spectrum and thermodynamic behavior, while the poly(dA).poly(dT).poly(dU) triple helix resembles poly(dA).2poly(dT) in these properties. In comparing poly(dA).2poly(dT) with either the poly(dA).poly(dT).poly(dU) or the poly(dA).2poly(dU) triplexes, the substitution of thymine for uracil in the third strand results in an enhancement of stability against the 3 --> 2 dissociation of deltadeltaG degrees = -135 +/- 85 cal (mol A)(-1) at 37 degrees C. This represents a doubling of the absolute stability toward dissociation compared to the triplexes with poly(dU) as the third strand. The poly (dA).poly (dT) duplex is more stable than poly(dA).poly(dU) by deltadeltaG degrees = -350 +/- 60 cal (mol base pair)(-1) at 37 degrees C. Poly(dA).poly(dT) has 50% greater stability than poly(dA).poly(dU) as a result of the dT for dU substitution in the duplex.     

The stabilizing contribution of thymine in duplexes of (dA)24 with (dU)24, (dT)24, (dU12-dT12), (dU-dT)12, (dU2-dT2)6, or (dU3-dT3)4: nearest neighbor and next-nearest neighbor effects

Ultraviolet melting curves are used to determine the effect of the pyrimidine 5-methyl group on the stability of duplexes of (dA)(24) with (dU)(24), (dT)(24), (dU(12)-dT(12)), (dU-dT)(12), (dU(2)-dT(2))(6), and (dU(3)-dT(3))(4). Substitution of a T for a U results in an increase in stability, which is attributed to an increase in strength of dipole-induced dipole and dispersion (van der Waals) interactions. Significant additional enhancement occurs when two T residues are adjacent. A further increase in the number of adjacent T's has a relatively slight effect on T(m). The sequence effect appears to be largely attributable to an increment in dispersion forces.The CD spectra of the duplexes are all closely similar except in the region between 260 and 290 nm. A band near 272 nm associated with the presence of U in the spectrum of (dA)(24).(dU)(24) decreases in intensity when T's are incorporated in the pyrimidine strand. The band is completely replaced in the spectrum of (dA)(24).(dT)(24) with a new maximum at 282 nm and a minimum at 268 nm, both of lower magnitude. The emergence of the two new bands is correlated with the presence of adjacent T's once more, and only two adjacent T's appear necessary for a major part of the change to occur. The degree of cation release on thermal dissociation of the oligomer dimers ranges from Deltai = 0.14 to 0.16, about the same or slightly less than values reported for polynucleotide duplexes and less than predicted from theoretical calculations.     

The glycine residue in cyclic lactam analogues of galanin(1-16)-NH2 is important for stabilizing an N-terminal helix

The neuropeptide galanin is a 29- or 30-residue peptide whose physiological functions are mediated by G-protein-coupled receptors. Galanin's agonist activity has been shown to be associated with the N-terminal sequence, galanin(1-16). Conformational investigations previously carried out on full-length galanin have, furthermore, indicated the presence of a helical conformation in the neuropeptide's N-terminal domain. Several cyclic lactam analogues of galanin(1-16)-NH2 were prepared in an attempt to stabilize an N-terminal helix in the peptide. Here we describe and compare the solution conformational properties of these analogues in the presence of SDS micelles as determined by NMR, CD, and fluorescence spectroscopy. Differences in CD spectral profiles were observed among the compounds that were studied. Both c[D4, K8]Gal(1-16)-NH2 and c[D4,K8]Gal(1-12)-NH2 adopted stable helical conformations in the micelle solution. On the basis of the analyses of their respective alpha H chemical shifts and NOE patterns, this helix was localized to the first 10 residues. The distance between the aromatic rings of Trp2 and Tyr9 in c[D4, K8]Gal(1-16)-NH2 was determined to be 10.8 +/- 3 A from fluorescence resonance energy transfer measurements. This interchromophore spacing was found to be more consistent with a helical structure than an extended one. Removal of the Gly1 residue in compounds c[D4,K8]Gal(1-16)-NH2 and c[D4, K8]Gal(1-12)-NH2 resulted in a loss of helical conformation and a concomitant reduction in binding potency at the GalR1 receptor but not at the GalR2 receptor. The nuclear Overhauser enhancements obtained for the Gly1 deficient analogues did, however, reveal the presence of nascent helical structures within the N-terminal sequence. Decreasing the ring structure size in c[D4, K8]Gal(1-16)-NH2 by replacing Lys8 with an ornithine residue or by changing the position of the single lysine residue from eight to seven was accompanied by a complete loss of helical structure and dramatically reduced receptor affinity. It is concluded from the data obtained for the series of cyclic galanin(1-16)-NH2 analogues that both the ring structure size and the presence of an N-terminal glycine residue are important for stabilizing an N-terminal helix in these compounds. However, although an N-terminal helix constitutes a predominant portion of the conformational ensemble for compounds c[D4,K8]Gal(1-16)-NH2 and c[D4, K8]Gal(1-12)-NH2, these peptides nevertheless are able to adopt other conformations in solution. Consequently, the correlation between the ability of the cyclic galanin analogues to adopt an N-terminal helix and bind to the GalR1 receptor may be considered as a working hypothesis.     

Cellular uptake of ODNs in HIV-1 human-infected cells: a role for viral particles in DNA delivery?

We have previously described how a 16 nucleotides ODN (termed 93del) is capable of inhibiting the activity of recombinant integrase in a cell-free system as well as HIV-1 replication in human-infected cells with IC(50) in the low nanomolar range. Intracellular HIV-1 replication was inhibited when the ODN was added at the onset of infection. These results raise several questions. Is a naked ODN able to enter the cell? Does the virus play a role in ODN entry? The uptake of several ODNs (93del, 60del(sc), TBA, T30923) was evaluated and then tracked by labeling the ODN with a fluorescent dye and assessing its intracellular localization by confocal microscopy. A significant level of cellular uptake of free ODN was observed in several cell lines: HeLa epithelial cells, Huh7 hepatic cells, and H9 lymphocytes, and was detected for all ODNs tested except for TBA. Striking differences were observed when naked ODNs were added to cell in the presence or absence of the virus. When HIV-1 virions were present a sharp increase in cellular fluorescence was observed. These results strongly suggest a role for HIV-1 virions in the uptake of certain ODNs.     

Conformational changes of polyomavirus major capsid protein VP1 in sodium dodecyl sulfate solution.

Conformations of polyomavirus (Py) major capsid protein VP1 were analyzed by circular dichroism (CD) and fluorescence spectroscopy in the presence of sodium dodecyl sulfate (SDS). Binding of PyVP1 to SDS induced marked conformational changes of PyVP1, which were reflected on the CD and fluorescence spectra. Abrupt changes in both optical properties occurred within the narrow ranges of SDS concentrations with the transition midpoints closely related to SDS micelle formation. Analysis of circular dichroism spectra showed that the contents of alpha-helices, beta-sheets, beta-turns and random coils in PyVP1 varied upon addition of SDS, demonstrating the exquisite sensitivity of the conformations of the protein to the environment. The interactions of PyVP1 with SDS were shown to be dependent on the ionic strength of the protein solution, suggesting that both hydrophobic and electrostatic forces contribute to the PyVP1-SDS complex formation. The SDS-induced conformational changes of PyVP1 appeared to be a two-stage process.     

Glycomimetics as decorating motifs for oligonucleotides: solid-phase synthesis, stability, and hybridization properties of carbopeptoid-oligonucleotide conjugates

The online solid-phase synthesis of oligonucleotides conjugated at the 3' end with [1-6]-linked oligosaccharide mimics having the O-glycosidic linkages replaced by amide bonds is here described. The assembly of the carbohydrate domain has been carried out by exploiting classical solid phase peptide synthetic protocols, starting from solid supports functionalized with 1-azido sugars, in association with suitably protected 1-azido uronic acids of glucose and lactose, chosen as model addition monomers. After the insertion of a flexible linker, elongation of the oligodeoxyribonucleotide (ODN) chain was performed by standard automated phosphoramidite protocols. 3'-Glycoconjugated 18-mers exhibited an increased enzymatic stability with respect to the same unmodified ODN sequence. UV thermal denaturation experiments showed that the presence of the oligosaccharide tail at the 3' end of the oligonucleotides did not negatively interfere with their duplex formation abilities.     

Electron transfer chemistry between DNA and DNA-binding tripeptides

A DNA system consisting of pyrene-modified oligonucleotides and nitrobenzoate (Nb)-modified DNA-binding tripeptides has been applied to study electron-transfer processes through the DNA-peptide interface. 5-(Pyren-1-yl)-2'-deoxyuridine (Py-dU) has been used as the photoinducible charge generator. Upon excitation at 350 nm, a pyrene-like excited state (Py-dU) is formed which undergoes an electron transfer yielding the charge-separated state which is the contact ion pair Py(*)(+)-dU(*)(-). The subsequent electron shift from dU(*)(-) into the base stack competes with charge recombination and can be probed chemically by trapping the electron at the 5-bromo-2'-deoxyuridine (Br-dU) group leading to strand cleavage which can be quantified by HPLC analysis. Several Nb-modified DNA-binding tripeptides influence these DNA-mediated electron-transfer processes as shown by fluorescence spectroscopy experiments. Fluorescence quenching can occur primarily through a reductive electron-transfer process in which the Nb group traps the electron thermodynamically from the contact ion pair Py(*)(+)-dU(*)(-). Moreover, our results indicate that, once the negative charge has been trapped on the peptide, oxidative processes from Py(*)(+) take place resulting in an enhanced and nonspecific strand degradation of the Py-dU-modified duplexes. The latter type of strand cleavage can be inhibited by the presence of tryptophane or tyrosine as part of the peptides. Most remarkably, DNA-binding tripeptides, which bear both the Nb and the tryptophan/tyrosine moiety, are able to trap both the negative and the positive charge from the contact ion pair Py(*)(+)-dU(*)(-).     

Interaction of a flavone loaded on surface-modified dextran-spooled superparamagnetic nanoparticles with β-cyclodextrin and DNA

Flavones are biologically active compounds obtained mainly from plant sources. Pharmaceutically important compounds can be delivered to the physiological target by loading them in carriers like cyclodextrins and magnetic nanoparticles. Herein, the binding of 6-methoxyflavone to β-cyclodextrin and DNA is studied using UV–visible absorption and fluorescence spectroscopy. The loading of 6-methoxyflavone onto a magnetic nanoparticles is employed. β-cyclodextrin encapsulates the 6-methoxyflavone to form an inclusion complex. β-cyclodextrin also used to draw forth 6-methoxyflavone loaded onto a magnetic nanoparticles. The morphology, magnetic property and the crystallite size of the nanoparticles are studied using scanning electron microscopy, vibrating sample magnetometry and X-ray diffraction techniques, respectively. The binding of the drug-loaded magnetic nanoparticles to DNA shows that the compound is accessible to DNA and available mostly on the surface of the nanoparticles despite a modified dextan polymer supposedly encapsulates the flavone.     

Amber from the Alpine Triassic of Lunz (Carnian,Austria): a classic palaeobotanical site

Amber from the Triassic (Carnian) of Lunz, a locality which has produced a rich and famous fossil flora, was analysed using UV‐B‐fluorescence, attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) and pyrolysis gas chromatography mass spectroscopy (Py‐GC‐MS). The amber is classified as a class Ib resinite based on its chemical composition, which is characterized by bicyclic products derived from a regular labdatriene structure and the absence of succinic acid. The presence of diterpenoids and absence of triterpenoids is clear evidence of a gymnosperm origin for the Lunz amber, and the prevalence of sesquiterpenoids and diterpenoids point to a conifer family as a possible botanical source. In search of amber attached to identifiable floral remains we have screened new and historical collections of the macroflora from a number of localities of the Lunz area using UV‐B, and describe a striking yellow UV‐B‐fluorescence of cuticles of pteridosperms, ginkgophytes and conifers. This varies with the diagenetic state of the sediment and may be lost altogether. Detectable amounts of fluorescent compounds were observed in gymnosperm taxa, but not in any ferns and only very weakly in horsetails. This underlines that fluorescent compounds are derived from gymnosperm plants, mostly likely arising secondarily from cyclic hydrocarbons by desaturation during diagenesis as a parallel process in amber as well as in cuticles.