In-vitro evaluation of antioxidant and anticholinesterase activities of novel pyridine, quinoxaline and s-triazine derivatives

Cholinesterase enzymes such as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) cause hydrolysis of acetylcholine (ACh), a neurotransmitter responsible for the cognitive functions of the brain such as acquiring knowledge and comprehension. Therefore, inhibition of these enzymes is an effective process to curb the progressive and fatal neurological Alzheimer's disease (AD). Herein, we explored the potential inhibitory activities of various pyridine, quinoxaline, and triazine derivatives (3a-k, 6a-j and 11a-h) against AChE and BuChE enzymes by following the modified Ellman's method. Further, anti-oxidant property of these libraries was monitored using DPPH (2,2'-diphenyl-1-picryl-hydrazylhydrate) radical scavenging analysis. From the studies, we identified that compounds 6e, 6f, 11b and 11f behaved as selective AChE inhibitors with IC₅₀ values ranging from 7.23 to 10.35 μM. Further studies revealed good anti-oxidant activity by these compounds with IC₅₀ values in the range of 14.80-27.22 μM. The kinetic studies of the active analogues demonstrated mixed-type of inhibition due to their interaction with both the catalytic active sites (CAS) and peripheral anionic sites (PAS) of the AChE. Additionally, molecular simulation in association with fluorescence and circular dichroism (CD) spectroscopic analyses explained strong affinities of inhibitors to bind with AChE enzyme at the physiological pH of 7.2. Binding constant values of 5.4 × 10⁴, 4.3 × 10⁴, 3.2 × 10⁴ and 4.9 × 10⁴ M^-1 corresponding to free energy changes -5.593, -6.799, -6.605 and -8.104 KcalM^-1 were obtained at 25 °C from fluorescence emission spectroscopic studies of 6e, 6f, 11b and 11f, respectively. Besides, CD spectroscopy deliberately explained the secondary structure of AChE partly unfolded upon binding with these dynamic molecules. Excellent in vitro profiles of distinct quinoxaline and triazine compounds highlighted them as the potential leads compared to pyridine derivatives, suggesting a path towards developing preventive or therapeutic targets to treat the Alzheimer's disease.

Data of antibacterial activity of plant leaves crude extract on bacterial isolates of wound infections

Wound infections are caused by various pathogenic microbes such as S. aureus, Non-coagulase Streptococcus, Enterococci, E. coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Enterobacter, Streptococci, Candida and Acinetobacter. 10-33% of septic wounds infections were seen in India. Multi-drug resistant bacterial infections are increased by day by day and these organisms showed resistant to most available antibiotics. Drug resistance is a common and natural mechanism in microorganisms, because of unbearable use of antibiotics. In this data provides the use of natural plant leaf extracts as alternatives to the multi-drug resistant bacteria. The present article contains the data on the antimicrobial activity of methanol extracts of plant leaves comprising of 11 natural plant species which are widely used as folk medicine. The leaf extracts were used against multi drug resistant bacterial isolates of septic wound infections which were evaluated by the Kirby-beur disk diffusion method. This data showed that among 11 plant methanol leaf extracts; Punica granatum and Syzigium cumini have the potential antibacterial activity against the predominant bacterial isolates of septic wounds that are MDR-P. aeruginosa, S. aureus, K. pneumoniae and E. coli.

Constituents from the leaves of Phellodendron amurense var. wilsonii and their bioactivity

Two new dihydroflavonols, phellodensin-A (1) and phellodensin-C (2); three new coumarins, phellodenol-A (3), phellodenol-B (4), and phellodenol-C (5); one new chlorophyll, phellophyll-a (6); and one new phenyllactate, (2R)-sodium 3-phenyllactate (7), in addition to 35 known compounds have been isolated from the leaves of Phellodendron amurense var. wilsonii. The structures of the new compounds were established based on 1D, 2D NMR and mass spectral analyses. The stereochemistry at the C-2, C-3, and C-2' ' positions of new dihydroflavonol 1 was determined by CD spectroscopy. The known compounds were identified by comparison with authentic samples. The antioxidant and antityrosinase activities were also described.

Constituents from the root and stem of Aristolochia elegans

Four new tetralones, aristelegone-A (1), aristelegone-B (2), aristelegone-C (3), and aristelegone-D (4); one new isoquinoline, pericampylinone-A (5); four new biphenyl ethers, aristogin-A (6), aristogin-B (7), aristogin-D (8), and aristogin-E (9); three new lignans, aristelegin-A (10), aristelegin-B (11), and aristelegin-C (12); and a new dimer, aristolin (13), have been isolated from the root and stem of Aristolochia elegans. The structures were established on the basis of 1D and 2D NMR and mass spectral data. This is the first report of isoquinolones and biphenyl ethers from this plant which may be representative units for the formation of bisbenzylisoquinoline alkaloids that are common metabolites of Aristolochia species. Aristolin (13) is also the first report of a diterpene linked with an aristolochic acid.

7-O-Methyltetrahydroochnaflavone, a new biflavanone from Ochna beddomei

7-O-Methyltetrahydroochnaflavone (1), a new biflavanone, together with nine known flavonoids, afrormosin (2), 2,3-dihydroochnaflavone 7-O-methyl ether (3), kaempferol (4), 2,3-dihydroochnaflavone (5), ochnaflavone (6), (-)-epicatechin (7), kaempferol 3-O-rhamnoside (8), taxifolin 3-O-rhamnoside (9), and kaempferol 3-O-glucoside (10), were isolated from the leaves of Ochna beddomei, and the structures were elucidated by spectral and chemical studies.

A biflavanone from Cycas beddomei

A new biflavanone, 7,7"-di-O-methyltetrahydrohinokiflavone together with tetrahydrohinokiflavone were isolated from the stems of Cycas beddomei. The structures were established on the basis of spectral and chemical studies.

Flavonol glycosides from cassia hirsuta

A new flavonol glycoside, kaempferol 3-O-alpha-L-rhamnopyranosyl (1-->2)-alpha-L-rhamnopyranoside (1), was isolated from the flowers of Cassia hirsuta along with two known flavonol glycosides, kaempferol 3-O-rutinoside and rutin. The structure of compound 1 has been established on the basis of spectral data and by acid hydrolysis.

A new flavone 2'-glucoside from Andrographis alata

A new flavone glucoside, 5,2',6'-trihydroxy-7-methoxyflavone 2'-O-beta-D-glucopyranoside has been isolated from the whole plant of Andrographis alata. The structure was elucidated on the basis of spectral and chemical evidence.