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Phytochemical studies of Gnetum Microcarpum, Gnetum Cuspidatum, Cynometra cauliflora, Bouea oppositifolia and their biological activities / Nik Fatini Nik Azmin
Get PDFIn the present work, phytochemical and pharmacological studies were conducted on four species of plants from three different families. The studied plant samples were the air-dried lianas of two species from Gnetaceae family which are Gnetum microcarpum Blume and Gnetum cuspidatum Blume and the twigs of Cynometra cauliflora Linn from the family of Fabacaeae and Bouea oppositifolia (Roxb.) Meisn from the family of Anacardiaceae. The aims of this study are to isolate the secondary metabolites from the plants, to propose biogenetic pathway of the new isolated compounds, to determine their DPPH scavenging, PGE2 inhibitory and cytotoxic activities and to study the Structure-Activity Relationship (SAR). The isolation process was done by conventional method of maceration, fractionation, separation and purification using several chromatographic techniques and structural elucidation was based on the spectroscopic data evidences and comparison with reported authentic data. Phytochemicals investigation on the lianas of the two Gnetum species yielded 11 known stilbenoid compounds; resveratrol (1), isorhapontigenin (3), gnetol (10), gnetifolin P (18), gnetofuran C (20), gnetucleistol C (21), cuspidan B (24), e-viniferin (31), parvifolol D (44), gnemonol M (48) and malaysianol D (388), two new compounds from G. microcarpum characterized as malaysianol E (25), malaysianol F (389) and one new compound from G. cuspidatum, namely malaysianol G (399). Phytochemicals investigation on C. cauliflora and B. oppositifolia gave 16 known flavonoid compounds; naringenin (263) and eriodictyol (262) were obtained from both species; flavone apigenin, acacetin, luteolin, luteolin 3',5 dimethyl ether, 3',4',7-trihydroxyflavone, 4',7-dihydroxyflavone (392-397) and 5,7-dihydroxychromone (391) from C. cauliflora; chalcone isoliquiritigenin (398), flavanone liquiritigenin and butin (399-400), flavanol taxifolin (260), fustin, garbanzol (401-402) and aurone sulfuretin (403) from B. oppositifolia
Phytochemical studies of Gnetum Microcarpum, Gnetum Cuspidatum, Cynometra Cauliflora, Bouea oppositifolia and their biological activities / Nik Fatini Nik Azmin
Get PDFIn the present work, phytochemical and pharmacological studies were conducted on four species of plants from three different families. The studied plant samples were the air-dried lianas of two species from Gnetaceae family which are Gnetum microcarpum Blume and Gnetum cuspidatum Blume and the twigs of Cynometra cauliflora Linn from the family of Fabacaeae and Bouea oppositifolia (Roxb.) Meisn from the family of Anacardiaceae. The aims of this study are to isolate the secondary metabolites from the plants, to propose biogenetic pathway of the new isolated compounds, to determine their DPPH scavenging, PGE2 inhibitory and cytotoxic activities and to study the Structure-Activity Relationship (SAR). The isolation process was done by conventional method of maceration, fractionation, separation and purification using several chromatographic techniques and structural elucidation was based on the spectroscopic data evidences and comparison with reported authentic data. Phytochemicals investigation on the lianas of the two Gnetum species yielded 11 known stilbenoid compounds; resveratrol (1), isorhapontigenin (3), gnetol (10), gnetifolin P (18), gnetofuran C (20), gnetucleistol C (21), cuspidan B (24), e-viniferin (31), parvifolol D (44), gnemonol M (48) and malaysianol D (388), two new compounds from G. microcarpum characterized as malaysianol E (25), malaysianol F (389) and one new compound from G. cuspidatum, namely malaysianol G (399). Phytochemicals investigation on C. cauliflora and B. oppositifolia gave 16 known flavonoid compounds; naringenin (263) and eriodictyol (262) were obtained from both species; flavone apigenin, acacetin, luteolin, luteolin 3',5 dimethyl ether, 3',4',7- trihydroxyflavone, 4',7-dihydroxyflavone (392-397) and 5,7-dihydroxychromone (391) from C. cauliflora; chalcone isoliquiritigenin (398), flavanone liquiritigenin and butin (399-400), flavanol taxifolin (260), fustin, garbanzol (401-402) and aurone sulfuretin (403) from B. oppositifolia. Both flavonoids and stilbenoids were derived from the combination of shikimate pathway and acetate pathway from a cinnamoyl- CoA starter unit and three molecule of malonyl-CoA extender unit to form intermediate polyketide. The enzyme stilbene synthase (STS) gave resveratrol which then undergo polymerization to produce larger stilbenoid, while chalcone synthase (CS) gave chalcone which then act as precursor for a vast range of flavonoid derivatives. In the DPPH assay, gnemonol M (48) and fustin (260) displayed good scavenging activity with IC50 of 30.07 and 23.93 uM, respectively, higher than that of standard trolox (IC50 83.22 uM). In the PGE2 inhibition assay, gnemonol M (48) and 4',7-dihydroxyflavone (397) exhibited significant activity with IC50 of 1.15 and 3.39 uM, respectively, comparable to the standard, indomethacin (IC50 1.29 uM). For cytotoxicity, all the tested compounds were found to be, either moderate, weak or not cytotoxic against HCT116 cancer cell line. In the SAR study of DPPH scavenging, the number of hydroxyl groups and the presence of an electron donating group are essential for stilbenoids, while the catechol moeity is in the top priority to exert flavonoids activity. Meanwhile, both type of compounds required the substituents which will contribute to their hydrophobicity and balance number of hydroxyl group in their structure in order to exert better PGE2 inhibitory activity
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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