Moringa oleifera impedes protein glycation and exerts reno-protective effects in streptozotocin-induced diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Moringa oleifera is a valued plant with wide distribution in tropical and subtropical regions of the world. It is traditionally used for the treatment of fever, infections, rheumatism, cancer, improving cardiac, renal and hepatic functions, and regulating blood glucose level. The plant has been scientifically reported for the anti-inflammatory, antioxidant, renoprotective, and anti-diabetic properties. Diabetic patients are prone to develop end-stage renal diseases due to incidence of diabetes-induced renal dysfunctions. Given that, increased production and accumulation of advanced glycation end-products (AGEs) play a conspicuous role in the development of diabetes-linked renal dysfunctions, nature-based interventions with AGEs inhibitory activity can prevent renal dysfunctions leading to renoprotection. AIM OF THE STUDY: The study aimed to demonstrate the preventive effects of the ethanolic extract of the leaves of Moringa oleifera (EEMO) on protein glycation and its further assessment for the renoprotective effect in diabetic rats. MATERIALS AND METHODS: Antiglycation activity of EEMO was assessed in vitro using bovine serum albumin. For reno-protective activity assessment, streptozotocin (STZ)-induced diabetic rats were orally treated with EEMO (100 mg/kg) or standard antiglycation agent aminoguanidine (100 mg/kg) for consecutive 8 weeks. The effects on glucose homeostasis, renal functions, and renal morphology were assessed by clinical biochemistry, molecular and histological examination. RESULTS: Presence of EEMO efficiently prevented glucose-, fructose- or methylglyoxal-mediated glycation of protein. Under in vivo set-up, compared to diabetic control rats, EEMO treatment effectively improved the glucose tolerance and body weight, and reduced the serum levels of triglycerides and total cholesterol. Additionally, EEMO administration significantly ameliorated renal dysfunctions in diabetic rats characterized by improved levels of creatinine, urea nitrogen, and uric acid in serum, and total protein level in urine, accompanied by improved kidney morphology. The diabetes-associated pro-inflammatory response characterized by upregulated expression of the inducible nitric oxide synthase (iNos), activation of nuclear factor kappa B (NF-κB) and the raised levels of inflammatory factors, interleukin-1 beta (IL-1ß) and interleukin-6 (IL-6) in renal tissue was significantly attenuated in EEMO-treated rats. Moreover, EEMO treatment diminished renal reactive oxygen species (ROS) levels in diabetic animals. CONCLUSIONS: Our study demonstrated that EEMO prevented AGEs formation and ameliorated renal dysfunctions in diabetic rats by blocking inflammatory/oxidative pathways. Our observations justify M. oleifera as a potential source of therapeutic interventions for diabetic nephropathy management.

Identification of Natural Products as Potential Pharmacological Chaperones for Protein Misfolding Diseases.

Defective protein folding and accumulation of misfolded proteins is associated with neurodegenerative, cardiovascular, secretory, and metabolic disorders. Efforts are being made to identify small-molecule modulators or structural-correctors for conformationally destabilized proteins implicated in various protein aggregation diseases. Using a metastable-reporter-based primary screen, we evaluated pharmacological chaperone activity of a diverse class of natural products. We found that a flavonoid glycoside (C-10, chrysoeriol-7-O-ß-D-glucopyranoside) stabilizes metastable proteins, prevents its aggregation, and remodels the oligomers into protease-sensitive species. Data was corroborated with additional secondary screen with disease-specific pathogenic protein. In vitro and cell-based experiments showed that C-10 inhibits α-synuclein aggregation which is implicated in synucleinopathies-related neurodegeneration. C-10 interferes in its structural transition into ß-sheeted fibrils and mitigates α-synuclein aggregation-associated cytotoxic effects. Computational modeling suggests that C-10 binds to unique sites in α-synuclein which may interfere in its aggregation amplification. These findings open an avenue for comprehensive SAR development for flavonoid glycosides as pharmacological chaperones for metastable and aggregation-prone proteins implicated in protein conformational diseases.

Flavonoids from Polyalthia longifolia prevents advanced glycation end products formation and protein oxidation aligned with fructose-induced protein glycation.

Advanced glycation end products (AGEs) are reactive chemical entities formed by non-enzymatic reaction between reducing sugars and amino group of proteins. Enhanced accumulation of AGEs and associated protein oxidation contribute to pathogenesis of diabetes-associated complications. Here, we evaluated the inhibitory activity of flavonoid compounds isolated from the leaves of Polyalthia longifolia on formation of AGEs and protein oxidation. Antiglycation activity was determined by measuring the formation of AGE fluorescence intensity, Nε-(carboxymethyl) lysine, and level of fructosamine. Protein oxidation was examined using levels of protein carbonyls and thiol group. Compounds significantly (p < 0.001) restricted the formation of fluorescent AGEs in fructose- BSA and methylglyoxal-BSA systems. Furthermore, there was a decrease in levels of fructosamine and protein carbonyls, and elevation in level of thiol group in fructose-BSA in presence of flavonoids. In summary, flavonoids from Polyalthia longifolia inhibit fructose-mediated protein glycation and oxidation, and can be potential agent for preventing AGE-mediated diabetic complications.

Pharmacokinetics, metabolism, bioavailability, tissue distribution and excretion studies of 16α-hydroxycleroda-3, 13(14) Z -dien-15, 16-olide-a novel HMG-CoA reductase inhibitor.

The present study was designed to investigate the oral bioavailability, metabolism, tissue disposition and excretion of 16α-hydroxycleroda-3, 13(14) Z -dien-15, 16-olide (4655K-09), a novel HMG-CoA reductase inhibitor in male Sprague Dawley (SD) rats. Tissue distribution, oral bioavailability and excretion studies of 4655K-09 were carried out in male SD rats through oral administration at active dose of 25 mg/kg. In vitro metabolism studies were carried out in different rat tissues S9 fractions to evaluate primary organs responsible for conversion of parent 4655K-09 to its major active metabolite K-9T. The quantification of both parent and metabolite in different biological matrices was performed using LC-MS/MS method. The oral bioavailability of 4655K-09 was found to be 30% in male SD rats. The biodistribution study was illustrated in terms of tissue to plasma area under curve (AUC)0-∞ ratio (Kp) revealed the preferential distribution of 4655K-09 and K-9T to target site, i.e. liver. In vitro tissue S9 fraction stability assay demonstrated the rapid and extensive metabolic conversion of 4655K-09 to K-9T, primarily through liver and kidney. Very low amount of parent and metabolite were excreted unchanged in urine and faeces. The present studies established 4655K-09 bioavailability, tissue disposition, excretion and tissue-specific metabolic conversion to K-9T which could assist in its further development as antihyperlipidemic drug.

Lipid lowering agents of natural origin: An account of some promising chemotypes.

The role of natural products in the drug development and discovery has been phenomenal. There has been an enormous interest in exploring all possible natural sources to identify structures exhibiting pronounced hypolipidemic activity albeit with no toxicity. The present review describes the profile of some interesting naturally occurring compounds and their derivatives as potential hypolipidemic agents. Some of the interesting natural chemotypes that can control the increased levels of plasma lipids and discussed in this review are compactin, lovastatin, gugglesterone, berberine, lupeol, phytol, polyprenol, aegeline, 4-hydroxyisoleucine, α-asarone, resveratrol, esculeoside A, swertiamarin, rutin, saucerneol B, curcumin and a clerodane diterpene.

A phenolic glycoside from Flacourtia indica induces heme mediated oxidative stress in Plasmodium falciparum and attenuates malaria pathogenesis in mice.

BACKGROUND: Flacourtia indica is especially popular among the various communities of many African countries where it is being used traditionally for the treatment of malaria. In our previous report, we have identified some phenolic glycosides from the aerial parts of F. indica as promising antiplasmodial agents under in vitro conditions. PURPOSE: Antimalarial bioprospection of F. indica derived phenolic glycoside in Swiss mice (in vivo) with special emphasis on its mode of action. METHODS: Chloroquine sensitive strain of Plasmodium falciparum was routinely cultured and used for the in vitro studies. The in vivo antimalarial potential of phenolic glycoside was evaluated against P. berghei in Swiss mice through an array of parameters viz., hematological, biochemical, chemo-suppression and mean survival time. RESULTS: 2-(6-benzoyl-ß-d-glucopyranosyloxy)-7-(1α, 2α, 6α-trihydroxy-3-oxocyclohex-4-enoyl)-5-hydroxybenzyl alcohol (CPG), a phenolic glycoside isolated from the aerial parts of F. indica was found to exhibit promising antiplasmodial activity by arresting the P. falciparum growth at the trophozoite stage. Spectroscopic investigations reveal that CPG possesses a strong binding affinity with free heme moieties. In addition, these interactions lead to the inhibition of heme polymerization in malaria parasite, augmenting oxidative stress, and delaying the rapid growth of parasite. Under in-vivo condition, CPG exhibited significant antimalarial activity against P. berghei at 50 and 75mg/kg body weight through chemo-suppression of parasitemia and ameliorating the parasite induced inflammatory and oxidative (hepatic) imbalance in the experimental mice. CONCLUSION: CPG was found to be a potential antimalarial constituent of F. indica with an explored mechanism of action, which also offers the editing choices for developing CPG based antimalarial chemotypes.

Poliothrysoside and its derivatives as novel insulin sensitizers potentially driving AMPK activation and inhibiting adipogenesis.

In our efforts to develop safe and active chemical entities from nature, we first identified poliothrysoside (1), a phytoconstituent isolated from Flacourtia indica, possessing antidiabetic potential. Subsequently, fifteen derivatives (2-16) were synthesized to assess the activity profile of this class. All the compounds were analyzed for their glucose uptake potency in chronic insulin-induced insulin resistant 3T3-L1 adipocytes. Interestingly, compound 2 exhibited strong ability to increase the insulin sensitivity, primarily activating the AMPK signaling pathway and also inhibited the adipogenesis in 3T3-L1 adipocytes, in concentration dependent manner. Overall, these studies suggest the potential of poliothrysoside and its derivatives as promising leads for non-insulin dependent type 2 diabetes (T2D).

Isolation and identification of ß-hematin inhibitors from Flacourtia indica as promising antiplasmodial agents.

An ethanolic extract (A001) of the leaves and twigs of Flacourtia indica (Burm.f.) Merr., was purified to give a new phenolic glycoside, 2-(2-benzoyl-ß-D-glucopyranosyloxy)-7-(1α,2α,6α-trihydroxy-3-oxocyclohex-4-enoyl)-5-hydroxybenzyl alcohol (1) together with poliothrysoside (2), catechin-[5,6-e]-4ß-(3,4-dihydroxyphenyl)dihydro-2(3H)-pyranone (3), 2-(6-benzoyl-ß-D-glucopyranosyloxy)-7-(1α,2α,6α-trihydroxy-3-oxocyclohex-4-enoyl)-5-hydroxybenzyl alcohol (4), chrysoeriol-7-O-ß-D-glucopyranoside (5), and mururin A (6). Compound 6 significantly inhibited the in vitro growth of both a chloroquine-sensitive (3D7) and a chloroquine-resistant (K1) strain of Plasmodium falciparum. It forms a complex with hematin and inhibits ß-hematin formation, suggesting that this compound act on a heme polymerization target.

Main extracts and hypolipidemic effects of the Bauhinia racemosa Lam. leaf extract in HFD-fed hamsters.

The lipid lowering effects of ethanolic extract (BR) obtained from leaves of Bauhinia racemosa on hyperlipidemic hamsters were examined. BR showed significant lowering of lipid profile at a dose of 250 mg kg(-1) body-wt of hamster. Chloroform fraction (F2) obtained from BR showed pronounced activity at lower dose of 100 mg kg(-1). F2 gave two most active fractions (L and T) whose chromatographic separations led to the isolation of constituents 1-5, which are being reported for the first time from this natural source. The results of activity profile of the plant were found to be better than the standard drug lovastatin.

Galactolipids from Bauhinia racemosa as a new class of antifilarial agents against human lymphatic filarial parasite, Brugia malayi.

Bioassay guided fractionation of ethanolic extract of the leaves of Bauhinia racemosa led to the isolation of galactolipid and catechin class of the compounds (1-7) from the most active n-butanol fraction (F4). Among the active galactolipids, 1 emerged as the lead molecule which was active on both forms of lymphatic filarial parasite, Brugia malayi. It was found to be better than the standard drug ivermectin and diethylcarbamazine (DEC) in terms of dose and efficacy.

Simultaneous estimation of 16α-hydroxycleroda-3,13(14) Z-dien-15,16-olide from Polyalthia longifolia and its metabolite in hamster plasma: application to pharmacokinetic study.

A selective and sensitive LC-MS-MS method was developed and validated for simultaneous estimation and pharmacokinetic studies of 16α-hydroxycleroda-3,13(14) Z-dien-15,16-olide (K-09) obtained from Polyalthia longifolia and its metabolite (K-9T), a novel antidyslipidemic agent. Sample clean-up involved liquid-liquid extraction of both the analytes and internal standard (rosuvastatin) from 200 µL of hamster plasma. The analytes were chromatographically separated on a Symmetry-Shield C18 (5 µm, 4.6 × 150 mm) column, using acetonitrile-0.1% aqueous formic acid (92:08, v/v) as the mobile phase. Detection was performed using negative ion electrospray ionization in multiple reaction monitoring mode. The MS/MS response was linear over the concentration range 1.56-200 ng/mL, with a correlation coefficient (r²) of 0.998 or better. The within- and between-batch precisions (relative standard deviation, %RSD) and the accuracy (percentage bias) were within acceptable limits as per FDA guidelines. The validated method was successfully applied to reveal the pharmacokinetic parameters of K-09 and metabolite after oral administration. This method will therefore be highly useful for future studies of K-09 and metabolite K-9T pharmacokinetics in preclinical and clinical studies.

Discovery of a new class of HMG-CoA reductase inhibitor from Polyalthia longifolia as potential lipid lowering agent.

Bioassay guided fractionation of the ethanolic extract of Polyalthia longifolia var. pendula, led to the discovery of the clerodane diterpene, 16α-hydroxycleroda-3, 13 (14) Z-dien-15, 16-olide (1), as a new structural class of HMG-CoA reductase inhibitor. Importantly, the in vivo effects of 1 corroborated well with its molecular docking analysis and also with its hamster plasma pharmacokinetics.

Identification of the antioxidant principles of Polyalthia longifolia var. pendula using TEAC assay.

Activity-guided fractionation of the ethanolic extract of the leaves of the Polyalthia longifolia var. pendula led to the identification of quercetin (1), quercetin-3-O-ß-glucopyranoside (2), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-ß-galactopyranoside (3), kaempferol-3-O-α-rhamnopyranosyl-(1 → 6)-ß-glucopyranoside (4), rutin (5) and allantoin (6) as the active constituents from the butanol fraction. Compounds 2-4 are reported for the first time from this natural source. Structures of the compounds were confirmed on the basis of their 1D and 2D NMR coupled with other spectroscopic methods. All the isolated compounds and the fractions were evaluated for their antioxidant potential using the TEAC assays and it was found that the activity of the active fraction was due to quercetin (1) and its glycosides (2 and 5), with TEAC values of 4.10, 1.91 and 2.38 mM, respectively, while the kaempferol glycosides were found to be inactive. This is the first study on the antioxidant activity of this plant species.

Cytotoxic cycloartane triterpene and rare isomeric bisclerodane diterpenes from the leaves of Polyalthia longifolia var. pendula.

A 24-methylenecycloartane-3 ß, 16 ß, 23 ß-triol, Longitriol (1), rare bisclerodane imides, Longimide A (2) and previously known Longimide B (3) were isolated from ethanolic extract of the leaves of Polyalthia longifolia var. pendula. This is the first example of isolation of any cycloartane triterpene from this plant source. Structures were determined by extensive (1D and 2D NMR) spectroscopic data analysis combined with ESI MS/MS fragmentation and X-ray analysis. Furthermore, Compounds 1 and 2 were evaluated for their cytotoxic effects against four human cancer cell lines and found to be most active against cervical carcinoma cell lines with IC(50) value of 10.03 and 4.12 µg/mL, respectively.

Cytotoxic clerodane diterpenoids from the leaves of Polyalthia longifolia.

The ethanolic extract of Polyalthia longifolia var. pendula was fractionated to get a hexane-soluble residue, which led to the isolation of four clerodane diterpenes: (-)-3α,16α-dihydroxycleroda-4(18),13(14)Z-dien-15,16-olide (1), (-)-3ß,16α-dihydroxycleroda-4(18), 13(14)Z-dien-15,16-olide (2), (-)-16α-hydroxycleroda-3,13(14)Z-dien-15,16-olide (3) and (-)-16-oxocleroda-3,13(14)E-dien-15-oic acid (4). Diterpene 1 is a new compound, while 2 is reported for first time from this plant. Both 1 and 2 were tested for their growth inhibitory activity on four cancer cell lines in vitro. IC(50) values suggest that they are effective as cytotoxic agents.

Antimicrobial evaluation of clerodane diterpenes from Polyalthia longifolia var. pendula.

Phytochemical investigation of the ethanolic extract of leaves of Polyalthia longifolia var. pendula has led to the isolation of seven clerodane diterpenoids and five alkaloids. (-)-14, 15-bisnor-3, 11E-kolavadien-13-one (1), (-)-16-oxocleroda-3,13(14)E-dien-15-oic acid (2), (-)-16alpha-hydroxycleroda-3,13 (14)Z-dien-15,16-olide (3), (+)-(4-->2)-abeo-16(R/S)-2, 13Z-kolavadien-15, 16-olide-3-al (4), (-)-3beta, 16beta-dihydroxycleroda-4(18), 13(14)Z-dien-15,16-olide (5), (-)-3, 12E-kolavadien-15-oic acid-16-al (6), (-)-labd-13E-en-8-ol-15-oic acid (7), liriodenine (8), (-)-anonaine (9), (+)-isoboldine (10), (-)-asimilobine (11) and hordenine (12) have been isolated. This is the first report of 1, 6 and 10 from this plant species while 12 is reported for first time from this genus. Clerodane derivatives 1-7 were evaluated for their antimicrobial activity. Diterpene 3 was found to be most potent agent with MIC value of 6.25 microg/mL against Staphylococcus aureus and Sporothrix schenckii.