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Ponnurengam Malliappan Sivakumar

Bio: Ponnurengam Malliappan Sivakumar is an academic researcher from Duy Tan University. The author has contributed to research in topics: Quantitative structure–activity relationship & Antibacterial activity. The author has an hindex of 20, co-authored 58 publications receiving 1195 citations. Previous affiliations of Ponnurengam Malliappan Sivakumar include University of Pisa & Indian Institutes of Technology.


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TL;DR: Quantitative structure activity relationships (QSAR) were developed on chalcones, chalcone-like compounds, flavones and flavanones to understand the relationship between biological activity and structural features.
Abstract: Design of compounds having good anti-tubercular activity is gaining much importance in the field of tuberculosis research due to reemergence of antibiotic resistance strains. In this paper quantitative structure activity relationships (QSAR) were developed on chalcones, chalcone-like compounds, flavones and flavanones to understand the relationship between biological activity and structural features. Genetic function approximation (GFA) method was used to identify the descriptors that would lead to good regression equations. The best molecular descriptors identified were Jurs descriptors (Jurs charged partial surface area), hydrogen bond donor, principal moment of inertia, molecular energy, dipole magnetic, molecular area, absorption, distribution, metabolism and excretion (ADME) properties and Chi indices (Kier & Hall chi connectivity indices). Excellent statistically significant models were developed by this approach (r(2)=0.8-0.97) for the four groups of compounds. The cross validated r(2) (XV r(2)) which is an indication of the predictive capability of the model for all the cases was also very good (=0.79-0.94).

128 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis, antioxidant activity, and quantitative structure-activity relationship (QSAR) of 25 chalcone derivatives were reported, which were synthesized by the Claisen-Schmidt reaction and were characterized by FTIR, NMR, and mass spectroscopy.
Abstract: Synthesis, antioxidant activity, and quantitative structure–activity relationship (QSAR) of 25 of chalcone derivatives is reported here. They were synthesized by Claisen–Schmidt reaction and were characterized by FTIR, NMR, and mass spectroscopy. Antioxidant activity is evaluated through four different methods namely, superoxide radical-scavenging, hydrogen peroxide scavenging, reducing power, and DPPH radical-scavenging assays. Generally, compounds with –SCH3 and –OCH3 in the para position of the A-ring and –OH in the B-ring were more active than others. In few cases some of the compounds were more active than ascorbic acid or butylated hydroxytoluene. QSAR was developed correlating the antioxidant activity with the structural features of the compounds and the predictive capability of the models was estimated using internal and external validation methods. All the predictions were within the 99% confidence level. Spatial, structural, and lipophilic properties of the compounds determine their antioxidant properties.

115 citations

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TL;DR: In order to develop relatively small molecules as antimycobacterial agents, twenty-five chalcones were synthesized, their activity was evaluated, and quantitative structure-activity relationship (QSAR) was developed.

113 citations

Journal ArticleDOI
TL;DR: In this article, the antibacterial activity of the coated cotton was tested against three organisms namely Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa in terms of live bacterial load, as measured by the colony forming units (CFU), adhered on the cotton surface.

89 citations

Journal ArticleDOI
TL;DR: Topology, shape, charge distribution and hydrophobic nature of the molecules had pronounced effect on the antibacterial activity of these dispiropyrrolidines.

82 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

01 Feb 2009
TL;DR: eMedicine创建于1996年,由近万名临床医师作为作者或编辑参与此临校医学知识库。
Abstract: eMedicine创建于1996年,由近万名临床医师作为作者或编辑参与此临床医学知识库的建设,其中编辑均是来自美国哈佛、耶鲁、斯坦福、芝加哥、德克萨斯、加州大学等各分校医学院的教授或副教授。

1,459 citations

Journal ArticleDOI
TL;DR: This review article focuses on the recent developments (2010-2014) on various pharmacological and medicinal aspects of chalcones and their analogues.

521 citations

Journal ArticleDOI
Jianbo Xiao1
TL;DR: With in vivo (oral) treatment, flavonoids glycosides showed similar or even higher antidiabetes, anti-inflammatory, antidegranulating, antistress, and antiallergic activity than their flavonoid aglycones.
Abstract: The dietary flavonoids, especially their glycosides, are the most vital phytochemicals in diets and are of great general interest due to their diverse bioactivity. The natural flavonoids almost all exist as their O-glycoside or C-glycoside forms in plants. In this review, we summarized the existing knowledge on the different biological benefits and pharmacokinetic behaviors between flavonoid aglycones and their glycosides. Due to various conclusions from different flavonoid types and health/disease conditions, it is very difficult to draw general or universally applicable comments regarding the impact of glycosylation on the biological benefits of flavonoids. It seems as though O-glycosylation generally reduces the bioactivity of these compounds - this has been observed for diverse properties including antioxidant activity, antidiabetes activity, anti-inflammation activity, antibacterial, antifungal activity, antitumor activity, anticoagulant activity, antiplatelet activity, antidegranulating activity, antitrypanosomal activity, influenza virus neuraminidase inhibition, aldehyde oxidase inhibition, immunomodulatory, and antitubercular activity. However, O-glycosylation can enhance certain types of biological benefits including anti-HIV activity, tyrosinase inhibition, antirotavirus activity, antistress activity, antiobesity activity, anticholinesterase potential, antiadipogenic activity, and antiallergic activity. However, there is a lack of data for most flavonoids, and their structures vary widely. There is also a profound lack of data on the impact of C-glycosylation on flavonoid biological benefits, although it has been demonstrated that in at least some cases C-glycosylation has positive effects on properties that may be useful in human healthcare such as antioxidant and antidiabetes activity. Furthermore, there is a lack of in vivo data that would make it possible to make broad generalizations concerning the influence of glycosylation on the benefits of flavonoids for human health. It is possible that the effects of glycosylation on flavonoid bioactivity in vitro may differ from that seen in vivo. With in vivo (oral) treatment, flavonoid glycosides showed similar or even higher antidiabetes, anti-inflammatory, antidegranulating, antistress, and antiallergic activity than their flavonoid aglycones. Flavonoid glycosides keep higher plasma levels and have a longer mean residence time than those of aglycones. We should pay more attention to in vivo benefits of flavonoid glycosides, especially C-glycosides.

394 citations