Lichens as a potential natural source of bioactive compounds: a review

Biological activity of material whether known in folk medicine or observed in planned screening program has been the starting point in the drug research. The general pattern is the isolation of active principles, elucidation their structures, followed by attempts for modulation of its activity potential by chemical modification. Lichens are valuable plant resources and are used as medicine, food, fodder, perfume, spice, dyes and for miscellaneous purposes throughout the world. Lichens are well known for the diversity of secondary metabolites that they produce. Compounds isolated from various lichen species have been reported to display diverse biological activities. Here we review the medicinal efficacy of lichen substances, which intends to explore the pharmaceutical potential of lichen substances.     

Morphohistochemical analysis of secretory elements of the olfactory epithelium of marine fish

Morphohistochemical characteristics of various secretory elements of the olfactory lining have been analysed in sea fishes. In the investigation epithelium of Chondrostei and Teleostei has been used. For secrete formation, besides supporting cells, specialized secretory elements take part; among them cells of the I, II and III types can be revealed, as well as tubular and alveolar epithelial glands in some species of fishes. The secretory elements of the olfactory lining of the sea fishes produce substances of various chemical nature specific for the given type of formations and not depending on species-specific and ecological specialization. Essential species-specific differences are revealed in distribution, combinations, size and amount of the secretory elements per one unit of the olfactory lining surface. The analysis of these parameters in macro-, medio- and microsmatics, in fishes of various ecology and different systemic position, also demonstrates their differentiation.     

春大豆氮利用效率的基因型变异和性状间的相关研究

应用裂区设计3个氮处理（60,30和0公斤／公顷）3重复进行了7个春大豆基因型的试验。分别在6周和成熟时测定了生育特性,植株和经济性状及氮含量。结果表明,不同氮水平对生育特性,植株和产量性状及氮利用效率等多数参数无显著影响,而不同基因型间这些参数存在显著或极显著差异,不同测定参数间存在的显著或极显著相关表明,通过筛选可获得植株性状和氮利用效率均佳的基因型。     

A comparative analysis of data on the clastogenicity of 951 chemical substances tested in mammalian cell cultures

A literature review was conducted using original papers published during 1964-1985 on the in vitro clastogenicity of chemical substances. Results of tests on 951 chemical substances were abstracted from over 240 reports to form the database. The evaluation of these data relied on each author's original conclusion on a positive or negative outcome. Of these 951 substances, 447 (47%) were consistently positive either with or without activation; 417 (44%) were negative in the direct test but not tested with metabolic activation systems; 4 were negative but tested only with activation; and 30 (3%) were clearly negative both with and without activation. The remaining 53 substances gave variable results when tested under different experimental protocols or in different cell types, but were positive in at least one test. Although discrepant results were found associated with some cell types, the addition of metabolic activation systems tended to eliminate such variability. No one cell appeared to be superior in response to all clastogens. For screening purposes, the choice of cell may thus depend more on the general usefulness and reliability of a cell type than on a strong response to a particular chemical. However, the use of a suitable metabolic activation system does appear to be of critical importance. The concentration at which clastogenic effects were detected varied extensively for different test substances, ranging from a minimum of 4.3 X 10(-8) to 6.9 X 10(2) mM. Possible mechanisms of action for substances active at only high levels are discussed, but no satisfactory explanation is available at this time. The relevance of tests conducted at concentrations high enough to alter significantly the osmolarity and other culture conditions is considered, and caution urged in the interpretation of test results obtained under physiologically stressful conditions. The clastogenic potential was compared quantitatively using an index of effective concentration (D20) and one which estimates the number of cells with exchange aberrations expected per mg/ml (TR) for data obtained by using a uniform protocol and cultures of Chinese hamster lung (CHL) cells. Both values were distributed over a wide range, demonstrating the variety of genotoxic potential in chemicals. In general, a substance which was active at only high concentrations produced fewer exchange-type aberrations. In vivo activity, as measured by tumourigenic effect and formation of micronuclei in bone marrow, tended to be greater for substances with a D20 below 10(-2) mg/ml and a TR value over 10(3).(ABSTRACT TRUNCATED AT 400 WORDS)     

Selective sensitive period in chick embryo: toxic effect of exogenous neurotransmitters

The phenomenon of sudden mortality in the chick embryo, induced by the exogenous neurotransmitters norepinephrine, epinephrine, dopamine, serotonin, carbachol, and by the beta-blockers propranolol and atenolol, is described. When introduced singly into eggs (albumen) in doses of 0.1 mg per egg, these substances induced highly significant, sharply increased mortality (60% to 100%) when the introduction was on embryonic (incubation) days 8 to 12 (hereafter called E8 and E12), but none if introduction was earlier. These ages follow the appearance of functional receptors (or receptor-effectors) for these substances. However, the involvement of receptors here has not been proved. Solvent alone (Ringer's solution for chick) had no effect, indicating that the procedures used were in themselves not lethal. Possibly, the above neurotransmitters became lethal to the embryo because they were introduced in excess of the amounts which were produced and needed at that time by the embryo for optimal development.     

Inhibition of chemical induction of porphyrin synthesis in chick embryo liver cells by partially purified human chorionic gonadotropin

Commercial preparations of human chorionic gonadotropin (hCG) inhibited chemical induction of δ -aminolevulinic acid synthetase and porphyrin formation in chick embryo liver cell cultures. The inhibition was not attributable to hCG since highly purified preparations of the hormone were not inhibitory. After fractionation of crude hCG on Sephadex G-100, inhibitory activity was found in two fractions, one of slightly smaller and one of much smaller molecular weight than hCG. Thus partially purified hCG may have other biologic effects than those caused by the hormone itself. Moreover, the occurrence of substances in crude hCG which at low concentrations can interfere with drug and hormone effects on liver cells is of biologic and potential clinical interest.     

Mesoderm-inducing factors: a small class of molecules

Mesoderm-inducing factors (MIF's) from chick embryos, XTC cells and WEHI-3 cells were studied using various procedures. The object was to find whether they are similar to heparin-binding growth factors (HBGFs-the only known pure mesoderm-inducing substances) and, if not, whether they are similar to each other. The major active components from all three MIF sources behave as somewhat hydrophobic, acid-stable molecules and do not bind to heparin. They all have relative molecular masses of about 13,000 measured by HPLC size exclusion chromatography. The isoelectric points measured by chromatofocusing were 6.7 (WEHI) and 7.7 (XTC). The chick MIF seemed somewhat heterogeneous by chromatofocusing and a portion of its activity bound to heparin sepharose. All three MIFs have similar effects on explants of Xenopus blastula ectoderm to the heparin-binding growth factors, causing an elongation at the time of gastrulation followed by the development of mesenchyme, mesothelium and muscle cells, the proportion of muscle increasing with dose. Unlike the HBGFs they all also induce notochord if sufficiently high concentrations are used. Our study shows that the MIFs examined here form a small group of potent agents distinct from the HBGFs and from other known growth and differentiations factors. Their occurrence in various tissues and cell lines suggests that they have functions in the adult organism as well as during early development.     

Structure of a cDNA for the pro alpha 2 chain of human type I procollagen. Comparison with chick cDNA for pro alpha 2(I) identifies structurally conserved features of the protein and the gene

Nucleotide sequences were determined for cloned cDNAs encoding for more than half of the pro alpha 2 chain of type I procollagen from man. Comparisons with previously published data on homologous cDNAs from chick embryos made it possible to examine evolution of the gene in two species which have diverged for 250-300 million years. The amino acid sequence of the alpha-chain domain supported previous indications that there is a strong selective pressure to maintain glycine as every third amino acid and to maintain a prescribed distribution of charged amino acids. However, there is little apparent selective pressure on other amino acids. The amino acid sequence of the C-propeptide domain showed less divergence than the alpha-chain domain. The 5' end or N terminus of the human C-propeptide, however, contained an insert of 12 bases coding for 4 amino acids not found in the chick C-propeptide. About 100 amino acid residues from the N terminus, two residues found in the chick sequence were missing from the human. In the second half of the C-propeptide, there was complete conservation of a 37 amino acid sequence and conservation of 50 out of 51 amino acids in the same region, an observation which suggested that the region serves some special purpose such as directing the association of one pro alpha 2(I) C-propeptide with two pro alpha 1(I) C-propeptides so as to produce the heteropolymeric structure of type I procollagen. In addition, comparison of human and chick DNAs for pro alpha 2(I) revealed three different classes of conservation of nucleotide sequence which have no apparent effect on the structure of the protein: a preference for U on the third base position of codons for glycine, proline, and alanine; a high degree of nucleotide conservation in the 51 amino acid highly conserved region of the C-propeptide; a high degree of nucleotide conservation in the 3'-noncoding region. These three classes of nucleotide conservation may reflect unusual features of collagen genes, such as their high GC content or their highly repetitive coding sequences.     

Analysis of possible mechanisms of regulation of root branching

The formation of lateral roots under the influence of growth inhibitors and phytohormons were studied with germs of corn and flax. All corn primordiums develop into the lateral roots without dormancy period, while some flax primordiums are delayed in development. Removal of root apical meristem (decapitation) does not result in the increase in number of lateral roots of corn germs. Decapitation of flax germs induces the development of some dormant primordiums, that leads to the considerable increase in number of lateral roots. Formation of additional primordium under decapitation does not take place. Auxin stimulates the formation of additional primordiums in flax, but does not effect the number of mature lateral roots. In corn germs synthetic auxin stimulates the development of additional primordiums in root zone, where primordiums are forming after the disturbance. It is shown that the time of primordium development does not change under inhibitor influence, if they do not selectively effect mitoses. It seems that auxins regulate initiation of pericycle division and formation of primordiums of lateral roots on the stage of development of meristematic protuberance. Cytokinins influence the development of already existed primordiums of lateral roots but do not effect the formation of new ones. Constancy of time of primordium formation and independence of their development on the state of the main root need future investigations. The authors suppose that regulation of these processes is non-hormonal.     

Probability screening model

A comparative analysis is given of various types of systems of selecting biologically active substances. A theoretical probability model of tests on chemical compounds for biological activity (screening) has been constructed which permits an evaluation of the efficacy of screening on the basis of fairly reasonable assumptions. It has been shown that this efficacy decreases in time with a fixed number of types of activity taken into consideration and rises sharply with an increase in the number of types of activity of chemical compounds taken into account in the tests.     

Transferrin is required for early tooth morphogenesis

Abstract. The role of circulating molecules during early tooth morphogenesis was studied in organ cultures of mouse embryonic molar-tooth germs. Special attention was focused on the effect of transferrin and insulin, which are necessary for the growth of most cells in culture. The requirement of serum factors for tooth morphogenesis was shown to diminish as the developmental stage advances from the bud stage in day-13 embryos to the cap stage at day 15. The day-15 teeth underwent morphogenesis and cell differentiation in unsupplemented basal culture medium, but the addition of transferrin (50 μg/ml) was necessary for the morphogenesis of day-14 tooth germs. We demonstrated, by using transferrin-depleted serum, that transferrin is also necessary for the morphogenesis of day-13 tooth germs. However, some still-unidentified serum components are also required for the morphogenesis of the bud-stage day-13 teeth. These factors apparently do not include insulin, since it was shown to inhibit tooth development. Analysis of the DNA content of tooth germs cultured in various culture media showed that the ability of transferrin to sup port tooth morphogenesis correlated with a stimulation of growth. The results support our earlier suggestions that transferrin functions as a fetal growth factor. The availability of the transferrin-containing chemically defined medium facilitates studies on the roles of other growth factors during tooth development.     

Cytotoxic action of the chemical substances found as admixtures in medical immunobiological preparations

The cytotoxic action (CTA) of chemical substances contained as admixtures in medical immunobiological preparations on human diploid cells has been studied. Such chemical substances as rivanol and merthiolate in admissible concentrations show the highest degree of CTA. The results obtained in this investigation indicate that different concentrations of chemical substances may produce equal CTA; thus, thiolate in toxic in a dose of 0.8 microgram/ml; the same CTA is produced by aluminium sulfate in a concentration of 500 micrograms/ml. Small doses of chemical substances, producing no explicit manifestations of the cytotoxic effect, may have latent CTA determined by additional methods of investigation. CTA may be manifested as lethal, sublethal and latent cell lesions. In working out regulations on the test for CTA it is expedient to indicate admissible residual amounts of chemical substances contained in finished medical immunobiological preparations, considering that these amounts must be incapable of producing CTA in cell cultures. The conclusion has been made on the expediency of denoting small amounts of chemical substances capable of producing latent CTA as tentatively tolerable doses.     

Actions of Ginkgo Biloba related to potential utility for the treatment of conditions involving cerebral hypoxia

Neuronal hypoxia results from a variety of cerebrovascular accidents or 'normal' age-associated anatomic changes. The consequences vary from mild deficits in neurologic function to massive neuropathology. Present pharmacotherapeutic therapy is not ideal. Two apparently disparate approaches to the search for better treatment or prevention-one involving reassessment of herbal remedies as 'alternative' medicine and the other one involving the desirability of increased structural diversity in HTS (high-throughput screening) libraries and as combinatorial chemistry templates-have converged in a rekindling of interest and a reevaluation of the pharmacologic properties of substances such as extract from the leaves of Ginkgo biloba Linne (form. Salisburia adiantifolia Sm.). There are reports of positive results from a small number of controlled clinical trials (albeit with small numbers of patients) sufficient to suggest that 'Ginkgo' might have therapeutic benefit in some situations or subset of patients. The pharmacologic mechanism by which Ginkgo might be able to provide the observed effect is not clear. However, it is believed that the flavonoid and terpenoid components of Ginkgo extract might produce beneficial therapeutic effects through mechanisms acting separately or in concert, such as the antagonism of PAF (platelet activating factor), antioxidant and metabolic actions, and effects on neurotransmitters. These mechanisms are reviewed in this article.     

Development of spontaneous motility in chick embryos. Effects of drugs acting on monoaminergic synaptic receptors.

The development of the effect of agonists of monoaminergic transmitters--LSD (20 and 200 micrograms/kg egg weight), apomorphine (1 and 3 mg/kg e.w.) and clonidine (2.5 mg/kg e.w.)--was studied on 11- to 19-day chick embryos. All three substances already significantly depressed spontaneous motility in 11 and 13-day-old embryos and their depressant effect increased as embryogenesis progressed. In chronically decapitated embryos (Sedlácek and Doskocil 1978) they had practically the same depressant effect as in normal embryos, showing that their activity is not bound unconditionally to supraspinal compartments of the CNS. These results are further evidence of the participation of central monoaminergic systems in embryonal motility. The finding that the three test drugs take effect during embryogenesis before sensitivity to monoaminergic transmitters appears remains unexplained.     

The development of nervous tissue to experimental manipulation in vitro (author's transl)

Explants of nervous tissue (CNS: hippocampus from fetal rats, telencephalon and PNS: ganglion trigeminale from chick embryos) were cultivated in maximow chambers. Biological extracts (brain and embryo extract) or chemical agents (aminoacid mixtures and peptides with known sequence of amino acids) were tested. Biological extracts and aminoacid mixtures stimulated the differentiation in PNS and CNS cultures. A stimulating effect of peptides seems to exist only on PNS explants. The fundamental importance of suitable reference systems, parameters, optimal concentrations and periods of application of effective substances for the evaluation of the results is discussed.     

冷冻保护剂DMSO对人骨髓细胞部分化学成份的影响

冻存前的多数骨髓细胞质内充满了深蓝色的POX反应颗粒,棕黄色的ANAE反应颗粒及粉红色的糖原颗粒。用5％和20％BMSO作为低温保护剂于液氮中冻存7天的骨髓细胞含破碎细胞成份较多,完整细胞内POX、ANAE及糖原反应均弱。用10％DMSO作为低温保护剂冻存的骨髓细胞中糖原、ANAE反应减弱不明显,POX反应强度略增加。用MPV-Ⅱ型显微分光光度计对上述样品进行定量测定的结果显示5％、20％DMSO低温冻存组骨髓细胞三种化学成份含量均明显降低,10％DMSO低温冻存组骨髓细胞中糖原、ANAE含量均降低,POX含量稍有增加。结果表明10％DMSO对骨髓细胞某些化学成份影响较小。     

Chemical kin label in seabirds

Chemical signals yield critical socio-ecological information in many animals, such as species, identity, social status or sex, but have been poorly investigated in birds. Recent results showed that chemical signals are used to recognize their nest and partner by some petrel seabirds whose olfactory anatomy is well developed and which possess a life-history propitious to olfactory-mediated behaviours. Here, we investigate whether blue petrels (Halobaena caerulea) produce some chemical labels potentially involved in kin recognition and inbreeding avoidance. To overcome methodological constraints of chemical analysis and field behavioural experiments, we used an indirect behavioural approach, based on mice olfactory abilities in discriminating odours. We showed that mice (i) can detect odour differences between individual petrels, (ii) perceive a high odour similarity between a chick and its parents, and (iii) perceive this similarity only before fledging but not during the nestling developmental stage. Our results confirm the existence of an individual olfactory signature in blue petrels and show for the first time, to our knowledge, that birds may exhibit an olfactory kin label, which may have strong implications for inbreeding avoidance.     

The effect of certain mannich N-bases, derivatives of isatin beta-thiosemicarbazone, on the replication of vaccinia virus in in vitro studies.

Twenty-three Mannich mono- and bis-N-bases, derivatives of isatin beta-thiosemicarbazone (IBT), were synthetized. Eighteen of these were tested for their inhibitory effect on the replication of vaccinia virus (IHD strain) in cultures of chick embryo fibroblasts. All the compounds studied showed antiviral activity, demonstrated by the agar-diffusion method (screening). The concentrations that reduced the number of viral plaques to 50% (PRD50) and the values of the therapeutic index (Th.i.) of the compounds tested were determined by the methyl-cellulose technique. The results obtained permitted analysis of their pharmaceutical effect relative to the chemical structure of the molecule, under the described experimental conditions.     

Imaging and uptake mechanism of 131I-meta-iodobenzylguanidine in medullary thyroid carcinoma

131I-meta-iodobenzylguanidine (131I-MIBG) was also taken up by medullary thyroid carcinoma (MTC) as well as by pheochromocytoma in two patients with Sipple's syndrome. However, the mechanism of 131I-MIBG uptake by MTC has not been clarified yet. We measured tissue catecholamine levels in three MTC, since MTC can produce several active substances. Catecholamines were detected in various amounts in all MTC, but not in normal thyroid tissues. These findings suggest that MTC can produce catecholamines and therefore, 131I-MIBG is taken up and stored in catecholamine vesicles of MTC, like pheochromocytoma and neuroblastoma. We conclude that 131I-MIBG may be applied not only to diagnosis but also for the treatment of patients with MTC.     

The action of cisplatin on the developing meso- and metanephros of chick embryos

Injection of various doses of cisplatin to 2-14-day chick embryos showed that within 2-8 days of incubation cisplatin produces total toxic effect, the number of dead embryos being dependent on a dose of the drug. Within 9-16 days of incubation, i.e. a period when both the mature mesonephros and the developing metanephros are in action, no significant changes were observed in the content of urea and uric acid, the weight of the meso- and metanephros, their water content, and ion content of the blood. Electron microscopic studies revealed no structural changes in the renal tubules. The data obtained suggest that cisplatin does not produce any nephrotoxic effect in chick embryos irrespectively of their age.