Vanda roxburghii chloroform extract as a potential source of polyphenols with antioxidant and cholinesterase inhibitory activities: identification of a strong phenolic antioxidant.

BACKGROUND: Alzheimer's disease (AD) is a progressively developing neurodegenerative disorder of the brain in the elderly people. Vanda roxburghii Rbr. root has been used traditionally in Bangladesh as tonic to brain and in the treatment of nervous system disorders including AD. Therefore, we aimed to investigate the cholinesterase inhibitory activities and antioxidant properties of the extracts from V. roxburghii. METHODS: The crude methanol extract from the roots of plant was sequentially fractionated with petroleum ether, chloroform, ethylacetate and water to yield their corresponding extracts. The extracts were assessed for acetylcholinesterase and butyrylcholinesterase inhibitory activity by modified Ellman method and antioxidant property by several assays including ferric reducing antioxidant power, scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and hydroxyl radical, and inhibition of lipid peroxidation. Endogenous substances in the extracts were analyzed by the standard phytochemical methods and active compound was isolated by the chromatographic methods. RESULTS: Chloroform extract was shown to demonstrate strong ferric-reducing antioxidant power and scavenging activity against DPPH and hydroxyl free radicals when compared with the other extracts and the reference standard catechin. The antioxidant effect was further verified by inhibition of lipid peroxidation in rat brain homogenates. Likewise, the chloroform extract exhibited the highest inhibition against both the acetylcholinesterase and butyrylcholinesterase enzymes with IC50 values of 221.13 and 82.51 µg/ml, respectively. Phytochemical screening revealed a large amount of phenolics and flavonoids in the chloroform extract. Bioactivity guided separation techniques led to the isolation of a strong antioxidant from the chloroform extract and its structure was determined as gigantol on the basis of spectral studies. CONCLUSION: These results suggest that the chloroform extract of V. roxburghii, possibly due to its phenolic compounds, exert potential antioxidant and cholinesterase inhibitory activities, which may be useful in the treatment of AD.

In vitro acetylcholinesterase inhibitory activity and the antioxidant properties of Aegle marmelos leaf extract: implications for the treatment of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative disorder clinically characterized by loss of memory and cognition. The effective therapeutic options for AD are limited and thus there is a demand for new drugs. Aegle marmelos (Linn.) (A. marmelos) leaves have been used in traditional medicine to promote intellect and enhance memory. In this study, we evaluated A. marmelos for its acetylcholinesterase (AChE) inhibitory activity and antioxidant property in vitro in the treatment of AD. METHODS: A crude methanol extract and four fractions (petroleum ether, chloroform, ethyl acetate and aqueous) were prepared from the leaves of A. marmelos. The preparations were assessed for AChE inhibitory activity by the Ellman method, and their antioxidant properties were assessed by several assays: reducing power, scavenging of 1,1-diphenyl-2-picrylhydrazyl free radical and hydroxyl radical, and inhibition of lipid peroxidation. Qualitative and quantitative analyses of endogenous substances in A. marmelos were performed by the standard phytochemical methods. RESULTS: Among the different extracts tested, the ethyl acetate fraction exhibited the highest inhibition of AChE activity. In the same way, ethyl acetate fraction showed the highest reducing activity and radical scavenging ability towards the 1,1-diphenyl-2-picrylhydrazyl (half maximal inhibitory concentration = 3.84 µg/mL) and hydroxyl free radicals (half maximal inhibitory concentration = 5.68 µg/mL). The antiradical activity of the ethyl acetate fraction appeared to be similar to that of the reference standard butylated hydroxytoluene and catechin used in this study. In addition, the ethyl acetate fraction displayed higher inhibition of brain lipid peroxidation. Phytochemical screening of different extractives of A. marmelos showed the presence of phenols and flavonoids, alkaloid, saponin, glycoside, tannin and steroids. Quantitative analysis revealed higher contents of phenolics (58.79-mg gallic acid equivalent/g dried extract) and flavonoids (375.73-mg gallic acid equivalent/g dried extract) in the ethyl acetate fraction. CONCLUSION: The results suggest that the ethyl acetate fraction of A. marmelos is a significant source of polyphenolic compounds with potential AChE inhibitory property and antioxidant activity and, thus, may be useful in the treatment of AD.

Antiparasitic and antimicrobial indolizidines from the leaves of Prosopis glandulosa var. glandulosa.

A new indolizidine alkaloid, named Δ¹,6-juliprosopine (1), together with previously known indolizidine analogs (2- 6), was isolated from the leaves of Prosopis glandulosa var. glandulosa, collected from Nevada, USA; while two other known indolizidines, juliprosopine (6) and juliprosine (7), were isolated from P. glandulosa leaves collected in Texas, USA. The structures of compound 1 and 7 were determined using a combination of NMR and MS techniques. Compound 7 exhibited potent antiplasmodial activity against Plasmodium falciparum D6 and W2 strains with IC (50) values of 170 and 150 ng/mL, respectively, while 1 was found to be less active (IC50 values 560 and 600 ng/mL, respectively). Both compounds were devoid of VERO cells toxicity up to a concentration of 23 800 ng/mL. The antileishmanial activity of indolizidines was evaluated against Leishmania donovani promastigotes, axenic amastigotes, and amastigotes in THP1 macrophage cultures. When tested against macrophage cultures, the tertiary bases (1, 3, 6) were found to be more potent than quaternary salts (2, 5, 7), displaying IC50 values between 0.8-1.7 µg/mL and 3.1-6.0 µg/mL, respectively. In addition, compound 7 showed potent antifungal activity against Cryptococcus neoformans and antibacterial activity against Mycobacterium intracellulare, while 1 was potent only against C. neoformans and weakly active against other organisms.

Hanultarin, a cytotoxic lignan as an inhibitor of actin cytoskeleton polymerization from the seeds of Trichosanthes kirilowii.

Bioactivity-directed fractionation of extracts from the seeds of Trichosanthes kirilowii led to the isolation of (-)-1-O-feruloylsecoisolariciresinol (2), named hanultarin, In addition, four known lignans were also isolated, including (-)-secoisolariciresinol (1), 1,4-O-diferuloylsecoisolariciresinol (3), (-)-pinoresinol (4), and 4-ketopinoresinol (5). Their structures were elucidated on the basis of spectroscopic data. Compounds 2 and 3 exhibited strong cytotoxic effects against human lung carcinoma A549 cells, melanoma SK-Mel-2 cells, and mouse skin melanoma B16F1 cells with IC(50) ranges of 3-13 microg/mL. Compound 2 showed an inhibitory effect on the polymerization of the actin cytoskeleton in normal epidermal keratinocyte (HaCaT cells), suggesting unique biological properties of compound 2 compared to those of the other isolates.

Antimicrobial phenolic derivatives from Dendranthema zawadskii var. latilobum Kitamura (Asteraceae).

A phytochemical study on the root of Dendranthema zawadskii var. latilobum Kitamura, using a series of silica gel column chromatography and reversed phase C-18 HPLC chromatography, led to the isolation of (1S, 2S)-1, 2, 3-trihydroxy-1-(3, 4-methylenedioxyphenyl)propane (1), 4-methoxycinnamic acid (2), acacetin (3) and caffeic acid methyl ester (4). The structures of these compounds were determined using spectroscopic analyses (UV, IR, HRTOFMS and NMR), with comparison of their spectral data with previously reported values. Compound 1 was isolated for the first time, with compounds 2 and 4 from this plant reported for the first time. The antibacterial and antifungal activities of the isolated compounds were measured using the disc diffusion method. Also, their cytotoxicities against the cancer cell lines, A549, B16F1 and SK-Mel-2, and brine shrimp lethalities were evaluated.

In vivo sedative and cytotoxic activities of methanol extract of leaves of Crataeva nurvala Buch-Ham.

The present study was designed to investigate the sedative and cytotoxic activities of a crude methanol extract of leaves of Crataeva nurvala Buch-Ham. Sedative activity was evaluated by using hole cross, open field and Elevated-Plus Maze (EPM) tests at 400 mg kg(-1) body weight. The crude extract decreased the locomotor activity of mice in hole cross, open field and EPM tests. The cytotoxic activity of this extract was determined by brine shrimp lethality bioassay where the LC50 value was found to be 55.46 microg mL(-1) as compared to that of 0.451 microg mL(-1) exhibited by standard vincristine sulphate. The result shows that the crude extract of the leaves of C. nurvala have significant (* p < 0.05) sedative and cytotoxic activities.

Estimation of total phenol and in vitro antioxidant activity of Albizia procera leaves.

BACKGROUND: Research on natural products has gained a wide popularity due to the potential of discovering active compounds. The antioxidant properties contained in plants have been proposed as one of the mechanisms for the observed beneficial effect. Therefore, the present study investigated the antioxidant activity and total phenolic contents of various solvent extracts of Albizia procera leaves. METHODS: Antioxidant activity of the methanol extract and its derived fractions petroleum ether (APP), carbon tetrachloride (APC), dichloromethane (APD), ethyl acetate (APE), and residual aqueous fraction (APA) of the leaves of Albizia procera was performed by in vitro chemical analyses. Total phenolic content of the APM and other five fractions were also determined. APM and its derived fractions were also subjected to preliminary phytochemical screening test for various constituents. RESULTS: Phytochemical screening revealed the presence of saponins, steroids, tannins, glycosides and flavonoids in the extracts. Amongst the extracts, APE showed the highest total phenolic content (449.18 ± 18.41mg of gallic acid equivalent/g of extract). In DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging test, the IC(50) value of APM, APP, APC, APD, APE and APA was 43.43, 63.60, 166.18, 41.15, 11.79, and 63.06 µg/mL, respectively. Therefore, among the APM and its derived fractions, APE showed the highest antioxidant activity which is comparable to that of standard ascorbic acid (AA) (IC(50) 10.12 µg/mL). The total antioxidant capacity was found to be varied in different fractions. The reducing activity on ferrous ion was ranked as APE > APD > APM > APA > APC. CONCLUSION: The above evidences suggest that APE of A. procera leaf is a potential source of natural antioxidant and can be used to prevent diseases associated with free radicals.

A comparative study on the antioxidant activity of methanolic extracts from different parts of Morus alba L. (Moraceae).

BACKGROUND: Antioxidants play an important role to protect damage caused by oxidative stress (OS). Plants having phenolic contents are reported to possess antioxidant properties. The present study was designed to investigate the antioxidant properties and phenolic contents (total phenols, flavonoids, flavonols and proanthrocyanidins) of methanolic extracts from Morus alba (locally named as Tut and commonly known as white mulberry) stem barks (TSB), root bark (TRB), leaves (TL) and fruits (TF) to make a statistical correlation between phenolic contents and antioxidant potential. METHODS: The antioxidant activities and phenolic contents of methanolic extractives were evaluated by in vitro standard method using spectrophotometer. The antioxidant activities were determined by total antioxidant capacity, DPPH (1,1-diphenyl-2-picrylhydrazine) radical scavenging assay, hydroxyl radical scavenging assay, ferrous reducing antioxidant capacity and lipid peroxidation inhibition assay methods. RESULTS: Among the extracts, TSB showed the highest antioxidant activity followed by TRB, TF and TL. Based on DPPH and hydroxyl radical scavenging activity, the TSB extract was the most effective one with IC50 37.75 and 58.90 µg/mL, followed by TRB, TF and TL with IC50 40.20 and 102.03; 175.01 and 114.63 and 220.23 and 234.63 µg/mL, respectively. The TSB extract had the most potent inhibitory activity against lipid peroxidation with IC50 145.31 µg/mL. In addition, the reducing capacity on ferrous ion was in the following order: TSB > TRB > TL > TF. The content of phenolics, flavonoids, flavonols and proanthocyanidins of TSB was found to be higher than other extractives. CONCLUSION: The results indicate high correlation and regression (p-value <0 .001) between phenolic contents and antioxidant potentials of the extracts, hence the Tut plant could serve as effective free radical inhibitor or scavenger which may be a good candidate for pharmaceutical plant-based products. However, further exploration is necessary for effective use in both modern and traditional system of medicines.