Synthesis of 5-aryl-6-cinnamoyl-7-methyl-flavanones as novel antioxidants and antihyperlipidemics

An economical and efficient one-pot synthesis of a series of novel 5-aryl-6-cinnamoyl-7-methyl-flavanones has been developed by simple refluxing of cinnamoyl chalcones with NaOAc in aqueous ethanol in quantitative yields. These flavanones were screened for their in vitro antioxidant and in vivo antidyslipidemic activities. Among 24 compounds screened, four compounds 28, 29, 30, and 48 showed significant antidyslipidemic activities. However, out of all the compounds, only compound 28 exhibited significant antioxidant activity and other compounds showed moderate antioxidant activities.     

Synthesis and antidyslipidemic activity of chalcone fibrates

A series of chalcone based PPAR-α agonists were synthesized and evaluated for their antidyslipidemic activity in high fructose high fat fed dyslipidemic Syrian golden hamsters. Most of the compounds exhibited antidyslipidemic activity. The compounds 4c and 4f have been identified as most potent antidyslipidemics. A definite structure-activity relationship was observed while varying the nature as well as the position of the substituent.     

Syntheses and evaluation of glucosyl aryl thiosemicarbazide and glucosyl thiosemicarbazone derivatives as antioxidant and anti-dyslipidemic agents

A series of N-per-O-acetyl-glucosyl arylthiosemicarbazide and thiosemicarbazone derivatives have been synthesized and evaluated for their in vivo anti-dyslipidemic and in vitro antioxidant activities. Among 16 compounds tested, 3 compounds showed potent anti-dyslipidemic activity and 6 compounds showed potent antioxidant and scavenger of oxygen free radicals activity.     

β-Amyrin acetate and β-amyrin palmitate as antidyslipidemic agents from Wrightia tomentosa leaves

The ethanolic extract and fractions of Wrightia tomentosa Roem. & Schult (Apocynaceae) leaves were tested in vivo for their antidyslipidemic activity in high fat diet (HFD) induced dyslipidemic hamsters. Activity guided isolation resulted in identification of antidyslipidemic compounds β-AA and β-AP. Compounds β-AA and β-AP decrease the levels of LDL by 36% and 44%, and increase the HDL-C/TC ratio by 49% and 28%, respectively, at a dose of 10mg/kg. In addition, the isolated compounds β-AA and β-AP showed significant HMG-CoA-reductase inhibition, which was further established by docking studies.     

5-(4-Hydroxyphenyl)-3H-1,2-dithiole-3-thione-based fibrates as potential hypolipidemic and hepatoprotective agents

Hypolipidemic effects of the newly synthesized 5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione-based fibrates were evaluated in Triton WR-1339 and high-fat diet (HFD)-induced hyperlipidemic mice. Preliminary screening of all the synthesized compounds was done by using an acute model (Triton WR-1339 model), in which compound 6 shown more significant antidyslipidemic activity than fenofibrate (FF). The compound 6 was also found to reduce serum triglyceride (TG), total cholesterol (TC) and low density lipoprotein cholesterin (LDL) in HFD-induced hyperlipidemic mice. Moreover, compound 6 displayed hepatoprotective effect, a significant amelioration in hepatic indices (AST and ALT) toxicity was observed and the histological examination showed that compound 6 inhibited the development of hepatic lipid accumulation and ameliorated the damage in hepatic tissue compared to model mice. Additional effects such as the potent antioxidant and anti-inflammatory action confirmed and reinforced the efficacy of compound 6 as a new agent of dual-effect hypolipidemic and hepatoprotective activities.     

Antidyslipidemic and antioxidant activity of the constituents isolated from the leaves of Calophyllum inophyllum

In continuation of our drug discovery program on Indian medicinal plants, we isolated bioactive compounds (1–5) from the leaves of Calophyllum inophyllum and evaluated their antidyslipidemic activity in triton induced hyperlipidemia model. The calophyllic acid (1A) and isocalophyllic acid (1B) mixture, canophyllic acid (4) and amentoflavone (5) showed dose dependent lipid lowering activity in in vivo experiments. The compounds 1A + 1B mixture and 3 also showed good in vitro antioxidant activity.     

Synthesis and evaluation of novel N-H and N-substituted indole-2- and 3-carboxamide derivatives as antioxidants agents

We have previously reported on the synthesis of novel indole derivatives where some compounds showed significant antioxidant activity. Here, we report the synthesis of novel N-H and N-substituted indole-2- and 3-carboxamide derivatives and investigated their antioxidant role in order to identify structural characteristics responsible for activity. Although all compounds showed a strong inhibitory (95-100%) effect on superoxide anion (SOD) only compounds 4, 5 and 6 showed simliar potency for the inhibition of lipid peroxidation (81-94%) which revealed that compounds 4, 5 and 6 possessed highly potent antioxidant properties. Substitution in the 1-position of the indole ring caused the significant differences between the activity results regarding lipid peroxidation inhibition.     

Coagulanolide, a withanolide from Withania coagulans fruits and antihyperglycemic activity

One new withanolide, (17S,20S,22R)-14alpha,15alpha,17beta,20beta-tetrahydroxy-1-oxowitha-2,5,24-trienolide) named coagulanolide (4) along with four known withanolides 1-3 and 5 have been isolated from Withania coagulans fruits and their structures were elucidated by spectroscopic techniques. The compounds 1-5 showed significant inhibition on postprandial rise in hyperglycemia post-sucrose load in normoglycemic rats as well as streptozotocin-induced diabetic rats. The compound 5 also showed significant fall on fasting blood glucose profile and improved the glucose tolerance of db/db mice. Further compound 5 showed antidyslipidemic activity in db/db mice. The median effective dose of the compound 5 was determined to be around 25 mg/kg in streptozotocin-induced diabetic rats, which is comparable to the standard antidiabetic drug metformin. Our results provide further support to explain the traditional use of W. coagulans as antihyperglycemic cum antidyslipidemic agent by the traditional medical practitioners.     

Synthesis and evaluation of novel N–H and N-substituted indole-2- and 3-carboxamide derivatives as antioxidants agents

We have previously reported on the synthesis of novel indole derivatives where some compounds showed significant antioxidant activity. Here, we report the synthesis of novel N–H and N-substituted indole-2- and 3-carboxamide derivatives and investigated their antioxidant role in order to identify structural characteristics responsible for activity. Although all compounds showed a strong inhibitory (95–100%) effect on superoxide anion (SOD) only compounds 4, 5 and 6 showed simliar potency for the inhibition of lipid peroxidation (81–94%) which revealed that compounds 4, 5 and 6 possessed highly potent antioxidant properties. Substitution in the 1-position of the indole ring caused the significant differences between the activity results regarding lipid peroxidation inhibition.     

The In vitro antioxidant properties of chinese highland lichens

Antioxidant properties of 46 lichen species collected from high-UV exposed alpine areas of southwestern China were evaluated for their therapeutic utilization. Anti-linoleic acid peroxidation activity, 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) scavenging activity, reducing power and the total phenolic contents were assessed in methanol extract of the lichens in vitro. Extracts of Peltigera praetextata and Sticta nylanderiana exhibited potent activity in all antioxidant tests. Especially, extracts of S. nylanderiana exhibited 1.37 times higher anti-linoleic acid peroxidation activity than ascorbic acid used as a positive control. It also showed the strongest free radical scavenging activity among all the tested species with an inhibition of 90.4% at the concentration of 330microgram/ml. Potent reducing power was also detected in the lichen extract compared with BHA. Generally, the antioxidant lichens contained large amount of phenolic contents. The activity-guided bioautographic TLC and HPLC analysis are used to find out the compounds responsible for the potent antioxidant activities of S. nylanderiana extract. The analysis demonstrated that lecanoric acid is one of the effective antioxidant compounds in S. nylanderiana. The results suggested that several highland lichens can be used as a novel bioresource for natural antioxidants.     

The antioxidant activity of phloretin: the disclosure of a new antioxidant pharmacophore in flavonoids

Phloretin is a dihydrochalcone flavonoid that displays a potent antioxidant activity in peroxynitrite scavenging and the inhibition of lipid peroxidation. Comparison with structurally related compounds revealed that the antioxidant pharmacophore of phloretin is 2,6-dihydroxyacetophenone. The potent activity of 2,6-dihydroxyacetophenone is due to stabilisation of its radical via tautomerisation. The antioxidant pharmacophore in the dihydrochalcone phloretin, i.e., the 2,6-dihydroxyacetophenone group, is different from the antioxidant pharmacophores previously reported in flavonoids.     

Synthesis, biological evaluation of 5-carbomethoxymethyl-7-hydroxy-2-pentylchromone, 5-carboethoxymethyl-4',7-dihydroxyflavone and their analogues

In this letter, we describe the first synthesis of two recently isolated flavones 5-carbomethoxymethyl-7-hydroxy-2-pentylchromone (3a), 5-carboethoxymethyl-4',7-dihydroxyflavone (3b) and their derivatives (3c-t), evaluated for their antimicrobial, antioxidant and anticancer activities. Most of the synthesized compounds exhibited antimicrobial activity against the tested microbial strains and some of these compounds were found to be more potent as compared to the standard drugs like neomycin and luteolin. Interestingly, some of these synthesized compounds also showed moderate antioxidant property.     

Phenolic thiazoles as novel orally-active neuroprotective agents

Novel phenolic thiazoles compounds were prepared which demonstrated potent antioxidant activity and potent in vivo neuroprotection in mitochondrial toxin models and also possess good oral bioavailability.     

Potential antioxidant activity of Morita-Baylis-Hillman adducts

The wide variety of potent biological activities of Morita-Baylis-Hillman adducts (MBH) encouraged us to synthesize new series of products belonging to this class of compounds, possessing different functionalities and exhibiting potential antioxidant activity.As part of our on-going program on targeting molecules with antioxidant activity, we describe herein different DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activities of MBH alcohols and their derivatives including acetates, phosphonates and hydrazonophosphonates. The obtained results showed that the strongest DPPH radical scavenging activity was observed in the case of hydrazonophosphonates in comparison to the other MBH derivatives.     

Antioxidant phenolic compounds from the stems of Entada phaseoloides

The EtOH extract of the stems of Entada phaseoloides displayed potent antioxidant activity when assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging, reducing power, β-carotene-bleaching, and superoxide radical-scavenging analyses. Fractionation of the EtOH extracts showed that the AcOEt fraction is the most active, followed by the H(2) O fraction, while BuOH fraction was least active. Further activity-guided fractionation studies on the active fractions resulted in the isolation of 22 compounds. The identities of these compounds were established based on extensive spectroscopic studies. Furthermore, the antioxidant activities of the isolated compounds were evaluated by using the above-mentioned five assays. The results demonstrated that the EtOH extract of E. phaseoloides stems exhibits an excellent antioxidant activity and thus presents a great potential as a source of natural antioxidants.     

Antioxidant profile of dihydroxy- and trihydroxyphenolic acids-A structure–activity relationship study

Eight structurally similar dihydroxy and trihydroxyphenolic acids (protocatechuic acid, 3,4-dihydroxyphenylacetic acid, hydrocaffeic acid, caffeic acid, gallic acid, 3,4,5-trihydroxyphenylacetic acid, 3-(3,4,5-trihydroxyphenyl)propanoic acid and 3-(3,4,5-trihydroxyphenyl)propenoic acid) were examined for their total antioxidant capacity (TAC). Furthermore, their ability to scavenge peroxyl radicals, generated by AAPH in liposomes, was determined. The antioxidant/pro-oxidant activity of the compounds was screened using the 2′-deoxyguanosine assay. All compounds behave as radical scavengers, with 3,4,5-trihydroxyphenylacetic acid being the most potent. Nevertheless, in the lipid peroxidation assay an inverse ranking order was observed, 3,4-dihydroxyphenylacetic acid being the most effective compound. All the dihydroxylated compounds showed a pro-oxidant behaviour leading to an increase of 50% in 8-OH-dG induction. From the structure–antioxidant activity relationship studies performed it may be concluded that the number of phenolic groups and the type of the alkyl spacer between the carboxylic acid and the aromatic ring strongly influence the antioxidant activity.     

Synthesis and anti-melanogenic activity of hydroxyphenyl benzyl ether analogues

In order to develop potent skin whitening agents, we have synthesized 17 hydroxyphenyl benzyl ether compounds and tested their melanin synthesis inhibitory activity, DPPH free radical scavenging activity and tyrosinase inhibitory activity. Compounds 32, 35 and 36 possessing 4-hydroxyphenyl benzyl ether structure showed excellent inhibitory capacity with almost 50-fold than arbutin used as a reference in the inhibition test of α-MSH stimulated melanin synthesis in B-16 cells. 4-Hydroxyphenyl benzyl ether compounds also showed good antioxidant activity in the DPPH free radical scavenging test. The tyrosinase function was effectively inhibited by 3,5-dihydroxyphenyl benzyl ether analogues, especially compounds 18, 22, and 24.     

Structure-guided design and synthesis of isoflavone analogs of GW4064 with potent lipid accumulation inhibitory activities

Our group has previously reported a series of isoflavone derivatives with antidyslipidemic activity. With this background, a series of isoflavone analogs of GW4064 were designed, synthesized and evaluated the lipid-lowering activity of analogs. As a result, most of compounds significantly reduced the lipid accumulation in 3T3-L1 adipocytes and four of them (10a, 11, 15c and 15d) showed stronger inhibitory than GW4064. The most potent compound 15d exhibited promising agonistic activity for FXR in a cell-based luciferase reporter assay. Meanwhile, 15d up-regulated FXR, SHP and BSEP gene expression and down-regulated the mRNA expression of lipogenesis gene SREBP-1c. Besides, an improved safety profile of 15d was also observed in a HepG2 cytotoxicity assay compared with GW4064. The obtained biological results were further confirmed by a molecular docking study showing that 15d fitted well in the binding pocket of FXR and interacted with some key residues simultaneously.     

Antioxidant activity and phenolic compounds of 112 traditional Chinese medicinal plants associated with anticancer

Cancer prevention and treatment using traditional Chinese medicines have attracted increasing interest. This study characterizes antioxidant activity and phenolic compounds of traditional Chinese medicinal plants associated with anticancer, comprising 112 species from 50 plant families. The improved ABTS(*+) method was used to systematically assess the total antioxidant capacity (Trolox equivalent antioxidant capacity, TEAC) of the medicinal extracts. The TEAC values and total phenolic content for methanolic extracts of herbs ranged from 46.7 to 17,323 micromol Trolox equivalent/100 g dry weight (DW), and from 0.22 to 50.3 g of gallic acid equivalent/100 g DW, respectively. A positive, significant linear relationship between antioxidant activity and total phenolic content (all R(2) values>/=0.95) showed that phenolic compounds were the dominant antioxidant components in the tested medicinal herbs. Major types of phenolic compounds from most of the tested herbs were preliminarily identified and analyzed, and mainly included phenolic acids, flavonoids, tannins, coumarins, lignans, quinones, stilbenes, and curcuminoids. These medicinal herbs exhibited far stronger antioxidant activity and contained significantly higher levels of phenolics than common vegetables and fruits. Traditional Chinese medicinal plants associated with anticancer might be potential sources of potent natural antioxidants and beneficial chemopreventive agents.     

Antioxidant profile of dihydroxy- and trihydroxyphenolic acids--a structure-activity relationship study

Eight structurally similar dihydroxy and trihydroxyphenolic acids (protocatechuic acid, 3,4-dihydroxyphenylacetic acid, hydrocaffeic acid, caffeic acid, gallic acid, 3,4,5-trihydroxyphenylacetic acid, 3-(3,4,5-trihydroxyphenyl)propanoic acid and 3-(3,4,5-trihydroxyphenyl)propenoic acid) were examined for their total antioxidant capacity (TAC). Furthermore, their ability to scavenge peroxyl radicals, generated by AAPH in liposomes, was determined. The antioxidant/pro-oxidant activity of the compounds was screened using the 2'-deoxyguanosine assay. All compounds behave as radical scavengers, with 3,4,5-trihydroxyphenylacetic acid being the most potent. Nevertheless, in the lipid peroxidation assay an inverse ranking order was observed, 3,4-dihydroxyphenylacetic acid being the most effective compound. All the dihydroxylated compounds showed a pro-oxidant behaviour leading to an increase of 50% in 8-OH-dG induction. From the structure-antioxidant activity relationship studies performed it may be concluded that the number of phenolic groups and the type of the alkyl spacer between the carboxylic acid and the aromatic ring strongly influence the antioxidant activity.