Neuroprotective effect of Alpinia galanga (L.) fractions on Aβ(25-35) induced amnesia in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The rhizomes of Alpinia galanga (L.) Willd (Zingiberaceae), a ginger substitute for flavouring food was traditionally used as nervine tonic and stimulant.

AIM OF THE STUDY

This investigation is designed to screen cognitive improvement of Alpinia galanga (AG) fractions in Alzheimer's type of amnesia in mice induced by Aβ((25-35)).

MATERIALS AND METHODS

Alzheimer's disease induced mice treated with fractions (n-hexane, chloroform and ethyl acetate) of AG in 200 and 400mg/kg. Neurotoxicity was induced by intracerebroventricular injection of Aβ((25-35)) on the 14th day of 21 days drug treatment. Open field and water maze were carried to determine habituation memory and hippocampal memory. Na(+)/K(+)-ATPase, acetylcholinesterase (AChE) and antioxidant enzymes (SOD, GPx, catalase and vitamin C) were determined in brain tissue homogenate to estimate the brain biochemical changes and its anti-amnesic potential with intensity of oxidative stress signaling. Further bioactive (chloroform) fraction was eluted through column chromatography to identify the lead molecules.

RESULTS

Increased habituation memory and decreased escape latency in behavioral parameter are the indicative of the cognitive enhancement after treatment with Alpinia galanga fractions. Increment in Na(+)/K(+)-ATPase and antioxidant activity depicts brain membrane integrity improvement and free radical scavenging property. AChE level was decreased to improve the cognition by enhancing cholinergic transmission.

CONCLUSION

Anti-amnesic effect was exerted by various fractions of Alpinia galanga. Among all fractions, preeminent neuroprotection was exerted by chloroform fraction, which has compound, 1'δ-1'-acetoxyeugenol acetate and it may be a potential therapeutic agent for Alzheimer's type of amnesia. These results further motivate us to explore the activity of lead compound's anti-amnesic effect on transgenic mice model of AD.

Neuroprotective potential of ethanolic extract of Pseudarthria viscida (L) Wight and Arn against beta-amyloid(25-35)-induced amnesia in mice

The neuroprotective potential of ethanolic extract of roots of Pseudarthria viscida (L) Wight and Arn (EEPV) was investigated against beta-amyloid(25-35)-induced amnesia in mice which is a suitable animal model for Alzheimer's disease (AD). The senile plaques of beta-amyloid (Abeta) are major constituents accumulated during the progression of AD as a potent neurotoxicant. In our investigation, intracerebroventricular injection of Abeta(25-35) in mice induced the neurodegeneration, exhibited the increased time of escape latency in behavioral pattern using water maze and decreased the levels of antioxidants namley superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and vitamin C with elevated level of acetylcholinesterase enzyme (AChE). The neuroprotective potential of EEPV was determined by behavioral pattern using water maze and biochemical parameters such as SOD, CAT and GPx and vitamin C content as well as AChE. Mice were treated with EEPV at 200 and 400 mg/kg doses for 21 days. Except control, all animals received a single injection of neurotoxicant Abeta(25-35) on 14th day. In behavioural assessment, treatment with ethanolic extract improved the cognitive function in the water maze and attenuated the elevated levels of AChE with increase in antioxidant enzymes, indicating the neuroprotection with increased levels of vitamin C. These findings suggest that ethanolic extract of P. viscida exerts anti-amnesiac effects and enhances cognitive function.

Synthesis and pharmacological investigation of novel 1-substituted-4-(4-substituted phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones as a new class of H1-antihistamine agents

A series of novel 1-substituted-4-(4-substituted phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones was synthesized by the cyclization of 2-hydrazino-3-(4-substituted phenyl)-3H-quinazolin-4-one with various one-carbon donors. The starting material, 2-hydrazino-3-(4-substituted phenyl)-3H-quinazolin-4-one, was synthesized from 4-substituted aniline by a novel innovative route. When tested for in-vivo H1-antihistamine activity on conscious guinea-pigs, all the test compounds significantly protected the animals against histamine-induced bronchospasm. The compound 1-methyl-4-(4-chloro phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-one (VII) was more potent (72.71% protection), and 1-methyl-4-(4-methoxy phenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-one (II) was equipotent (71% protection), when compared with the reference standard, chlorpheniramine maleate (71% protection). Compounds II and VII showed negligible sedation (5% and 8% respectively) when compared with chlorpheniramine maleate (25%). Compounds II and VII could serve as prototype molecules for further development as a new class of H1-antihistamines.

4-(3-Methoxyphenyl)-1-substituted-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones: new class of H1-antihistaminic agents

A series of 1-substituted-4-(3-methoxyphenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones were synthesized by the cyclization of 2-hydrazino-3-(3-methoxyphenyl)-3H-quinazolin-4-one with various electrophile. The starting material 2-hydrazino-3-(3-methoxyphenyl)-3H-quinazolin-4-one was synthesized from 3-methoxy aniline by an innovative route. Title compounds were tested for their in vivo H1-antihistaminic activity on guinea pigs; all the tested compounds protected the animals from histamine induced bronchospasm significantly. Compound 1-methyl-4-(3-methoxyphenyl)-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-one (II) emerged as the most active compound of the series and was more potent (72.76%) than the reference standard chlorpheniramine maleate (71%). Compound II showed negligible sedation (10%) when compared to chlorpheniramine maleate (25%). Hence it could serve as prototype molecule for further development as a new class of H1-antihistaminic agents.

Synthesis of 3-(2-pyridyl)-2-substituted-quinazolin-4(3H)-ones as new analgesic and anti-inflammatory agents

A new series of 3-(2-pyridyl)-2-substituted-quinazolin-4(3H)-ones were synthesized by reacting the amino group of 2-hydrazino-3-(2-pyridyl)-quinazolin-4(3H)-one with a variety of aldehydes and ketones. The starting material 2-hydrazino-3-(2-pyridyl)-quinazolin-4(3H)-one was synthesized from 2-aminopyridine. The title compounds were investigated for analgesic, anti-inflammatory and ulcerogenic index activities. While the test compounds exhibited significant activity, compound 2-(1-ethylpropylidene)-hydrazino-3-(2-pyridyl)-quinazolin-4(3H)-one (AS2) showed moderate analgesic activity and compound 2-(1-methylbutylidene)-hydrazino-3-(2-pyridyl)-quinazolin-4(3H)-one (AS3) showed realistic anti-inflammatory activity when compared to the reference standard diclofenac sodium. Interestingly the test compounds showed only mild ulcerogenic side effect when compared to aspirin.

Synthesis of Novel 3-Butyl-2-Substituted Amino-3H-Quinazolin-4-ones as Analgesic and Anti-inflammatory Agents

A variety of novel 3-butyl-2-substituted amino-3H-quinazolin-4-ones were synthesized by reacting the amino group of 3-butyl-2-hydrazino-3H-quinazolin-4-one with various aldehydes and ketones. The title compounds were investigated for analgesic, anti-inflammatory and ulcerogenic index activities. The compound 3-butyl-2-(1-methylbutylidene-hydrazino)-3H-quinazolin-4-one (AS3) emerged as the most active analgesic agent. Compound 3-butyl-2-(1-ethylpropylidene-hydrazino)-3H-quinazolin-4-one (AS2) emerged as the most active anti-inflammatory agent and is moderately more potent when compared to the reference standard diclofenac sodium. Interestingly, the test compounds showed only mild ulcerogenic potential when compared to aspirin.

4-Cyclohexyl-1-substituted-4H-[1,2,4]triazolo [4,3-a] quinazolin-5-ones: Novel Class of H1-antihistaminic Agents

A series of novel 1-substituted-4-cyclohexyl-4H-[1,2,4]triazolo [4,3-a] quinazolin-5-ones were synthesized by the cyclization of 3-cyclohexyl-2-hydrazino-3H-quinazolin-4-one with various one carbon donors. When tested for their in vivo H1-antihistaminic activity on guinea-pigs, all the test compounds protected the animals from histamine induced bronchospasm significantly. The compound 4-cyclohexyl-1-methyl-4H-[1,2,4]triazolo[4,3-a] quinazolin-5-one (II) emerged as the most active compound of the series and it is more potent (72.96% protection) when compared to the reference standard chlorpheniramine maleate (71.00% protection). The compound II shows negligible sedation (9%) when compared to chlorpheniramine maleate (30%). Hence, it could serve as prototype molecule for further development as a new class of H1-antihistamines.

Synthesis and Pharmacological Investigation of 3-Subsituted-amino-2-methylsulfanyl-5,6,7,8-tetrahydro-3H-benzo[4,5]thieno[2,3-d]pyrimidin-4-ones as Analgesic and Anti-Inflammatory Agents

In the present work, design, synthesis, and pharmacological evaluation of the analgesic, anti-inflammatory, and ulcerogenic-index activities of new 3-subsituted-amino-2-methylsulfanyl-5,6,7,8-tetrahydro-3H-benzo[4,5]thieno[2,3-d]pyrimidin-4-ones, structurally planed by exploiting a clear concept of bio-isosterism, are reported. All compounds exhibited significant analgesic and anti-inflammatory activity. Compounds A1, A3 showed higher analgesic activity and more potent anti-inflammatory activity than that of the reference compound diclofenac sodium. Interestingly, the test compounds showed only mild ulcerogenic potential when compared to that of acetylsalicylic acid.

Synthesis of 2-mercapto-3-substituted-5,6-dimethylthieno[2,3-d] pyrimidin-4(3H)-ones as new analgesic, anti-inflammatory agents

A new series of 2-mercapto-3-substituted-5,6-dimethylthieno[2,3-d]pyrimidin-4(3H)-ones were synthesised by reacting 3-amino-2-mercapto-5,6-dimethylthieno[2,3-d]pyrimidin-4(3H)-one with different aldehydes and ketones. The starting material 3-amino-2-mercapto-5,6-dimethylthieno[2,3-d]pyrimidin-4(3H)-one was synthesised from 2-amino-3-carbethoxy-4,5-dimethyl thiophene by a novel innovative route. The title compounds were investigated for analgesic, anti-inflammatory and ulcerogenic index activities. While the test compounds exhibited significant activity, among these compound AS1 showed more potent analgesic and anti-inflammatory activities and the compound AS3 showed equipotent analgesic and anti-inflammatory activities when compared to the reference standard diclofenac sodium.

Synthesis and pharmacological investigation of novel 4-benzyl-1-substituted-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones as new class of H1-antihistaminic agents

A series of novel 1-substituted-4-benzyl-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-ones were synthesized by the cyclization of 2-hydrazino-3-benzyl-3H-quinazolin-4-one with various one-carbon donors. The starting material 2-hydrazino-3-benzyl-3H-quinazolin-4-one was synthesized from benzylamine by a new innovative route. When tested for their in vivo H1 -antihistaminic activity on guinea pigs, all the test compounds protected the animals from histamine induced bronchospasm significantly. The compound 1-methyl-4-benzyl-4H-[1,2,4]triazolo[4,3-a]quinazolin-5-one (II) emerged as the most active compound of the series and it is more potent (percent protection 76%) when compared to the reference standard chlorpheniramine maleate (percent protection 71%). Compound II showed negligible sedation (7%) when compared to chlorpheniramine maleate (30%). Hence it could serve as prototype molecule for further development as a new class of H1 -antihistamines.

Design and synthesis of 2-methylthio-3-substituted-5,6-dimethylthieno [2,3-d] pyrimidin-4(3H)-ones as analgesic, anti-inflammatory and antibacterial agents

Pain and inflammation are simultaneous responses in bacterial infections. In current clinical practice, two groups of agents like antibacterial and non-steroidal anti-inflammatory drugs (NSAID's) are prescribed simultaneously. Regrettably, none of the drug possesses these activities in a single component. Exploiting the bioisosterism concept, we have documented that 2-phenyl-3-substituted quinazolines, 2,3-disubstituted quinazolines, 2-methyl-3-substituted quinazolin-4-(3H)-ones and 2-methylthio-3-substituted quinazolin-4-(3H)-ones exhibited good analgesic and anti-inflammatory activities. The present work is an extension of our ongoing efforts towards the development and identification of lead molecules by bioisostere concept, for which we designed some of 2-methylthio-3-substituted-5,6-dimethylthieno[2,3-d] pyrimidin-4(3H)-ones. The title compounds were investigated for analgesic, anti-inflammatory and antibacterial activities. While the test compounds exhibited significant activity, the compounds (6-9) showed more potent analgesic activity, and the compounds (8, 9) showed anti-inflammatory activity comparable to the reference standard diclofenac.

Synthesis and pharmacological evaluation of some 3-phenyl-2-substituted-3H-quinazolin-4-one as analgesic, anti-inflammatory agents

A variety of novel 3-phenyl-2-substituted-3H-quinazolin-4-ones were synthesized by reacting the amino group of 2-hydrazino-3-phenyl-3H-quinazolin-4-one with different aldehydes and ketones. The starting material 2-hydrazino-3-phenyl-3H-quinazolin-4-one was synthesized from aniline. The title compounds were investigated for analgesic, anti-inflammatory and ulcerogenic index activities. While the test compounds exhibited significant activity, compounds, 2-(N'-2-butylidene-hydrazino)-3-phenyl-3H-quinazolin-4-one (AS1), 2-(N'-3-pentylidene-hydrazino)-3-phenyl-3H-quinazolin-4-one (AS2) and 2-(N'-2-pentylidene-hydrazino)-3-phenyl-3H-quinazolin-4-one (AS3), exhibited moderate analgesic activity. The compound 2-(N'-2-pentylidene-hydrazino)-3-phenyl-3H-quinazolin-4-one (AS3) showed more potent anti-inflammatory activity when compared to the reference standard diclofenac sodium. Interestingly, the test compounds showed only mild ulcerogenic side effect when compared to aspirin.

Synthesis, analgesic, anti-inflammatory, ulcerogenic index and antibacterial activities of novel 2-methylthio-3-substituted-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-4(3H)-ones

A variety of novel 2-methylthio-3-substituted-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-4(3H)-ones have been synthesized by reacting (2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-3-yl)dithiocarbamic acid methyl ester (5) with a variety of amines. The starting material dithiocarbamate (5) was synthesized from 2-amino-3-carbethoxy-4,5,6,7-tetrahydrobenzo (b) thiophene (1) by a novel innovative route. The title compounds were investigated for analgesic, anti-inflammatory, ulcerogenicity index and antibacterial activities. While the test compounds exhibited significant activity, the compounds 1-methyl-3-(2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-3-yl)thiourea (A1), 1-dimethyl-3-(2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-3-yl)thiourea (A2), 1-diethyl-3-(2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-3-yl)thiourea (A3) and 1-pyrrolidinyl-3-(2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-3-yl)thiourea (A4) showed more potent analgesic activity and the compounds 1-dimethyl-3-(2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d]pyrimidin-3-yl)thiourea (A2), 1-diethyl-3-(2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno-[2,3-d]pyrimidin-3-yl)thiourea (A3) and 1-pyrrolidinyl-3-(2-methylthio-4-oxo-3H-5,6,7,8-tetrahydrobenzo (b) thieno[2,3-d] pyrimidin-3-yl)thiourea (A4) showed more potent anti-inflammatory activity than the reference standard diclofenac sodium.