Synthesis of silver nanoparticles using plant derived 4-N-methyl benzoic acid and evaluation of antimicrobial,antioxidant and antitumor activity

The present study is to investigate the antitumor, antioxidant and antibacterial potential of silver nanoparticles (Ag NPs) synthesized from a phenolic derivative 4-N-methyl benzoic acid, isolated from a medicinal plant (Memecylon umbellatum Burm F). The Bio-inspired nanoparticles (NPs) were analyzed by using UV–vis spectroscopy, FTIR, HRTEM, Zeta potential and XRD techniques. The UV–vis spectroscopy study at the band of 430 nm confirmed the nanoparticles formation. HRTEM report showed that the AgNPs synthesized were in the size range 7–23 nm. The harvested nanoparticles were subjected to anti-bacterial assay and a dose dependent inhibitory action was observed against the tested human pathogens. Among the tested bacteria, Acinetobacter baumannii was found to be highly sensitive to AgNPs (diameter of zone of inhibition was 31 mm). Further, the silver nanoparticles exhibited a good anti-tumor activity against the breast cancer cell line (MCF 7) with an IC₅₀ value of 42.19 µg/mL. As the present study confirmed a good antibacterial, antioxidant and antitumor activity in the nanoparticles synthesized using 4-N-methyl benzoic acid derived from a medicinal plant, the product can be further tested to formulate a good lead compound for biomedical applications.     

Controlled silver nanoparticles synthesis in semi-hydrogel networks of poly(acrylamide) and carbohydrates: A rational methodology for antibacterial application

In the present study, we report the preparation of semi interpenetrating hydrogel networks (SIHNs) based on cross-linked poly (acrylamide) prepared through an optimized rapid redox-solution polymerization with N,N′-methylenebisacrylamide (MBA) in presence of three different carbohydrate polymers, namely gum acacia (GA), carboxymethylcellulose (CMC) and starch (SR). Highly stable and uniformly distributed silver nanoparticles have been obtained with hydrogel networks as nanoreactors via in situ reduction of silver nitrate (AgNO₃) using sodium borohydride (NaBH₄) as reducing agent. The formation of silver nanoparticles has been confirmed with ultraviolet visible (UV–vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analyses. Thermogravimetric analysis (TGA) provides the amounts of silver nanoparticles exist in the hydrogel networks. Transmission electron microscopy (TEM) results demonstrate that acacia employed hydrogels have regulated the silver nanoparticles size to 2–5 nm where as CMC and starch composed hydrogel networks result in a heterogeneous size from 2 to 20 nm. The preliminary antibacterial activity performed to these hydrogel–silver nanocomposites.     

Investigations of Antibacterial,Antioxidant, and Antidiabetic Potential of Extract and Its Active Fractions from the Leaves of Horsfieldia spicata (Roxb.) J. Sinclair

This study was undertaken to analyse the potential bioactivities including antibacterial, antioxidant and antidiabetic derived from the methanolic extract and the column chromatography ethyl acetate fraction (AcOEt Fr) of Horsfieldia spicata leaves. Methanolic extract and 4 other fractions was calculated for total phenol and flavonoid contents along with tested for antibacterial, antioxidant and antidiabetic properties. Interestingly, the AcOEt Fr had the highest value for total flavonoid content and the best antioxidant, and antidiabetic activities. Therefore, the AcOEt Fr was further separated using column chromatography technique for obtaining 9 selected fractions namely fraction 1 (F1) - fraction 9 (F9) which were further tested. The results showed that the AcOEt column chromatography fractions namely F2, F3, F4 and F6 had the best clear inhibition antibacterial value against all bacterial tested. In addition, these fractions also exhibited better Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) values than others. Antioxidant, 2,2-diphenylpicrylhydrazyl (DPPH) assayed indicated that AcOEt Fr had the strongest IC₅₀ value of 47.30 μg/mL. Further, F4 column chromatography fraction showed the best inhibition against α-Glucosidase enzyme related to antidiabetic activity with an IC₅₀ value of 6.11 μg/mL. Liquid chromatography tandem-mass spectrometry (LC/MS/MS) analysis identified that F4 derived from AcOEt fraction had several compounds belonging to the flavonoid and phenolics such as 3′,5-dihydroxy-7,4′-dimethoxyflavone, 5,7-dihydroxy-3-(4′-hydroxybenzyl)chromone, and Kadsurenin I.     

In vitro antioxidant and antidiabetic activities of zinc oxide nanoparticles synthesized using different plant extracts

Phytofabricated green synthesis of zinc oxide (ZnO) nanoparticles using different plant extracts of Azadirachta indica, Hibiscus rosa-sinensis, Murraya koenigii, Moringa oleifera, and Tamarindus indica for biological applications has been reported. ZnO nanoparticles were also synthesized by chemical method to compare the efficiency of the green synthesized nanoparticles. FT-IR spectra confirmed the functional groups involved in the green synthesis of ZnO nanoparticles and the powder XRD patterns of the ZnO nanoparticles revealed pure wurtzite structure with preferred orientation at (100) reflection plane. SEM and TEM analysis revealed the spherical shape of the synthesized ZnO nanoparticles with the particle size between 54 and 27 nm. The antioxidant activity was evaluated by five different free radical scavenging assays. The present study also intends to screen α-amylase and α-glucosidase activity of ZnO nanoparticles synthesized using natural sources, which may minimize the toxicity and side effects of the inhibitors used to control diabetes. The ZnO nanoparticles synthesized using T. indica extract displayed remarkable antioxidant and antidiabetic activities.

     

In vitro antidiabetic,antioxidant, antimicrobial,and cytotoxic activity of Murraya koenigii leaf extract intercedes ZnO nanoparticles

Nanotechnology is an emerging field with tremendous potential and usage of medicinal plants and green preparation of nanoparticles (NPs) is one of the widely explored areas. These have been shown to be effective against different biological activities such as diabetes mellitus, cancer, antioxidant, antimicrobial, etc. The current studies focus on the green synthesis of zinc NPs (ZnO NPs) from aqueous leaf extract of Murraya koenigii (MK). The synthesized Murraya koeingii zinc oxide NPs (MK ZnO NPs) were characterized using UV–visible spectroscopy, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive spectrum (EDS) and cyclic voltammetry (CV). The synthesized MK ZnO NPs were evaluated for their in vitro antidiabetic, antioxidant, antimicrobial, and cytotoxic activity. They demonstrated significant antidiabetic and cytotoxic activity, as well as moderate free-radical scavenging and antibacterial activity.     

Facile synthesis,physiochemical characterization and bio evaluation of sulfadimidine capped cobalt nanoparticles

Due to their less expensive, environment friendly nature, and their natural abundance of cobalt have attained more significant attention for the synthesis of cobalt nanoparticles. In the present study, we report the facile synthesis of cobalt nanoparticles using a straight forward chemical reduction approach of cobalt chloride with sodium borohydride and capping of sulfadimidine. sulfadimidine has strong capping eligibility on the surface of nanoparticles due to its chemical stability and is an applicable as stabilizer due to the existence of an amine bond. The as-synthesized sulfadimidine stabilized cobalt nanoparticles (Co-SD NPs) were characterized by using various spectroscopic and microscopic analysis like UV–Visible spectroscopy (UV–Vis), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), High-Resolution Transmission electron microscopy (HR-TEM), and Fourier-transform infrared spectroscopy (FT-IR). The XRD analysis exhibited the triclinic crystal structure of the as-synthesized cobalt nanoparticles and FT-IR analysis confirmed the capping of sulfadimidine via monodentate interaction. The HR-TEM analysis displayed the size of the cobalt nanoparticles approximately 3–5 nm. The antibacterial properties of the sulfadimidine stabilized cobalt nanoparticles (Co-SD NPs) were tested against various bacterial strains such as Klebsiella pneumonia (KP), Escherichia coli (EC) and Pseudomonas syringae (PS) by using agar disc diffusion approach. The results of sulfadimidine capped cobalt nanoparticles displayed the enhanced biological properties against the tested gram-negative bacteria.     

Lactam nonanic acid,a new substance from <Emphasis Type="Italic">Cleome viscosa</Emphasis> with allelopathic and antimicrobial properties

Cleome viscosa L. (Capparidaceae) is well known for its medicinal properties. Lactam nonanoic acid (LNA) [2-amino-9-(4-oxoazetidin-2-yl)-nonanoic acid; C₁₂H₂₂N₂O_3, mol. wt. 242] has been isolated and purified from the root exudates of Cleome viscosa. The aqueous solution of this pure compound has been tested on bacteria (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus) and fungi (Aspergillus fumigatus, A. niger and A. tamarii). At a dosage of 500 ppm and above, P. aeruginosa and S. aureus were totally inhibited while E. coli remained unaffected. On the other hand, growth of A. niger and A. tamarii was stimulated while there was no effect on A. fumigatus. This pure compound showed concentration-dependent inhibitory activity on rice, gram and mustard seeds.     

Synthesis,characterization and biological studies of Schiff bases derived from heterocyclic moiety

Some new Schiff bases (H₁-H₇) have been synthesized by the condensation of 2-aminophenol, 2-amino-4-nitrophenol, 2-amino-4-methylphenol, 2-amino benzimidazole with thiophene-2-carboxaldehyde and pyrrole-2-carboxaldehyde. The structures of newly synthesized compounds were characterized by elemental analysis, FT-IR, ¹ H NMR, UV–VIS, and single crystal X-ray crystallography. The in vitro antibacterial activity of the synthesized compounds has been tested against Salmonella typhi, Bacillus coagulans, Bacillus pumills, Escherichia coli, Bacillus circulans, Pseudomonas, Clostridium and Klebsilla pneumonia by disk diffusion method. The quantitative antimicrobial activity of the test compounds was evaluated using Resazurin based Microtiter Dilution Assay. Ampicillin was used as standard antibiotics. Schiff bases individually exhibited varying degrees of inhibitory effects on the growth of the tested bacterial species. The antioxidant activity of the synthesized compounds was determined by the 1,1-diphenyl-2-picrylhydrazyl(DPPH) method. IC₅₀ value of synthesized Schiff bases were calculated and compared with standard BHA.     

Biophysical and biochemical characterization of active secondary metabolites from Aspergillus allahabadii

Fungal secondary metabolites are a diverse group of natural chemical products with physiological relevance. We aimed to identify bioactive secondary metabolites from Aspergillus allahabadii. We used “activity-guided fractionation” strategy for the isolation of secondary metabolites. Crude extracts showed good antibacterial activity. Two antibacterial secondary metabolites have been isolated from the crude extract. Chemical characterization of these compounds was performed using biophysical techniques (FT-IR, NMR, and mass spectrometry). Structural characterization confirmed these to be pyrone derivatives: 3-hydroxy 2-methyl 4-pyrone and 5-hydroxy-2-(hydroxymethyl)-4H-pyrone. These bioactive pyrone derivatives have been identified as maltol and kojic acid. From our initial observations, we infer that these pyrone derivatives have potent antimicrobial, antioxidant, antidiabetic, and mosquito larvicidal activities and no cytotoxicity. These compounds could have potential therapeutic and biomedical applications, but further mechanistic studies using animal models are very much necessary.     

Plant extract-mediated biogenic synthesis of silver,manganese dioxide,silver-doped manganese dioxide nanoparticles and their antibacterial activity against food- and water-borne pathogens

Silver nanoparticles (AgNPs), manganese dioxide nanoparticles (MnO₂NPs) and silver-doped manganese dioxide nanoparticles (Ag-doped MnO₂NPs) were synthesized by simultaneous green chemistry reduction approach. Aqueous extract from the leaves of medicinally important plant Cucurbita pepo was used as reducing and capping agents. Various characterization techniques were carried out to affirm the formation of nanoparticles. HR-TEM analysis confirmed the size of nanoparticles in the range of 15–70 nm and also metal doping was confirmed through XRD and EDS analyses. FT-IR analysis confirmed that the presence of biomolecules in the aqueous leaves extract was responsible for nanoparticles synthesis. Further, the concentration of metals and their doping in the reaction mixture was achieved by ICP–MS. The growth curve and well diffusion study of synthesized nanoparticles were performed against food- and water-borne Gram-positive and Gram-negative bacterial pathogens. The mode of interaction of nanoparticles on bacterial cells was demonstrated through Bio-TEM analysis. Interestingly, AgNPs and Ag-doped MnO₂ NPs showed better antibacterial activity against all the tested bacterial pathogens; however, MnO₂NPs alone did not show any antibacterial properties. Hence, AgNPs and Ag-doped MnO₂ NPs synthesized from aqueous plant leaves extract may have important role in controlling various food spoilage caused by bacteria.     

Various solvent effects on phytochemical constituent profiles,analysis of antioxidant and antidiabetic activities of Hopea parviflora

The current research has been designed to assess the phytochemical composition, antioxidant and antidiabetic properties of Hopea parviflora, sequentially extracted with petroleum ether, chloroform, ethyl acetate, ethanol and methanol. All the five extracts were tested for qualitative and quantitative phytochemicals. DPPH, Superoxide, FRAP, ABTS and metal chelating antioxidant activities were evaluated. Antidiabetic potentials of all the five extracts were tested using standard in vitro α- amylase and α - glycosidase inhibition assays. Qualitative phytochemical screening showed the presence of alkaloids in all the extracts except petroleum ether and ethyl acetate. Steroids were present in the petroleum ether, ethyl acetate and chloroform extracts whereas glycosides were present in all the extracts, except ethanol. The total phenol, flavonoid, tannin and saponins contents varied from solvent to solvent, with the highest values being 18.9, 18.2, 0.98 and 39.9 mg/mL, respectively. Methanolic extract showed the highest antioxidant activities in DPPH, FRAP and superoxide assays. Moreover, effective results were observed for the ethanol and ethyl acetate extracts in the ABTS and metal chelating assays. The methanolic extract showed potential antidiabetic activities with the IC₅₀ values of 230.2 and 308.2 μg/mL in α- amylase and α -glycosidase inhibition assays, respectively.     

Green synthesis of metal oxide nanoparticles and their catalytic activity for the reduction of aldehydes

In the present work, a green synthesis of Metal Oxide nanoparticles was demonstrated using the freshly prepared aqueous extract of the immature fruit of Cocos nucifera and the MO nanoparticles were characterized by the analytical techniques such as UV–vis, FT-IR, XRD, SEM, TEM and EDAX. Characterization techniques confirmed that the biomolecules involved in the formation of nanoparticles and also they stabilized the nanoparticles. The synthesized MO nanoparticles were used as catalysts for the reduction of aromatic aldehydes. The reduction was done at mild reaction conditions using ammonium formate as a green hydrogen donor and the corresponding alcohols were obtained in 2–24 h with excellent yields. The reduction reaction was optimized using various solvents, loading of catalyst and at different temperatures.     

Novel marine Nocardiopsis dassonvillei-DS013 mediated silver nanoparticles characterization and its bactericidal potential against clinical isolates

The sediment marine samples were obtained from several places along the coastline of the Tuticorin shoreline, Tamil Nadu, India were separated for the presence of bioactive compound producing actinobacteria. The actinobacterial strain was subjected to 16Sr RNA sequence cluster analysis and identified as Nocardiopsis dassonvillei- DS013 NCBI accession number: KM098151. Bacterial mediated synthesis of nanoparticles gaining research attention owing its wide applications in nonmedical biotechnology. In the current study, a single step eco-friendly silver nanoparticles (AgNPs) were synthesized from novel actinobacteria Nocardiopsis dassonvillei- DS013 has been attempted. The actinobacterial mediated silver nanoparticles were characterized by TEM, UV–Visible, XRD, FT-IR spectroscopy. The initial detection of AgNPs was identified using UV–Vis spectrum and confirmed by the appearance of absorbance peak at 408 nm. A Fourier transform infrared spectroscopy (FT-IR) result reveals the presence of protein component in the culture supernatant may act as protecting agents. The XRD pattern indicated that the typical peaks reveal the presence of nanoparticles. The TEM morphology confirms the formation of circular and non uniform distributions of AgNPs with the size range from 30 to 80 nm. The antibacterial activity of both isolated actinobacterial (IA) and silver nanoparticles mediated actinobacterial (SNA) of Nocardiopsis dassonvillei- DS013 were done by well diffusion method against selected clinical isolates of bacteria, namely Escherichia coli, Enterococcus sp., Pseudomonas sp., Klebsiella sp., Proteus sp., Shigella sp., Bacillus subtilis, and Streptococcus sp. When compared to isolated actinobacteria, the SNA shows the better antibacterial activity against clinical isolates.     

Antioxidant,antibacterial and cytotoxic potential of silver nanoparticles synthesized using terpenes rich extract of Lantana camara L. leaves

Several attempts have been made for green synthesis of silver nanoparticles (AgNPs) using different plant extracts. Present study revealed that, antioxidant, antibacterial and cytotoxic AgNPs were synthesized using terpenes-rich extract (TRE) of environmentally notorious Lantana camara L. leaves. AgNPs were characterized by advanced techniques like UV–Visible and Infra red spectroscopy; XRD, SEM techniques as terpenes coated sphere shaped NPs with average diameter 425 nm. Further, on evaluation, AgNPs were found to exhibit dose – dependent antioxidant potential, good to moderate antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa; and toxicity on Brine shrimp (A. salinanauplii) with LD₅₀ value 514.50 µg/ml.     

Green synthesis of silver nanoparticles using Andean blackberry fruit extract

Green synthesis of nanoparticles using various plant materials opens a new scope for the phytochemist and discourages the use of toxic chemicals. In this article, we report an eco-friendly and low-cost method for the synthesis of silver nanoparticles (AgNPs) using Andean blackberry fruit extracts as both a reducing and capping agent. The green synthesized AgNPs were characterized by various analytical instruments like UV–visible, transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The formation of AgNPs was analyzed by UV–vis spectroscopy at λ_max = 435 nm. TEM analysis of AgNPs showed the formation of a crystalline, spherical shape and 12–50 nm size, whereas XRD peaks at 38.04°, 44.06°, 64.34° and 77.17° confirmed the crystalline nature of AgNPs. FTIR analysis was done to identify the functional groups responsible for the synthesis of the AgNPs. Furthermore, it was found that the AgNPs showed good antioxidant efficacy (>78%, 0.1 mM) against 1,1-diphenyl-2-picrylhydrazyl. The process of synthesis is environmentally compatible and the synthesized AgNPs could be a promising candidate for many biomedical applications.     

Exploring the therapeutic potential of Hibiscus rosa sinensis synthesized cobalt oxide (Co3O4-NPs) and magnesium oxide nanoparticles (MgO-NPs)

Herein, we present a green, economic and ecofriendly protocol for synthesis of cobalt oxide (Co₃O₄-NPs) and magnesium oxide nanoparticles (MgO-NPs) for multifaceted biomedical applications. In the study, a simple aqueous leaf extract of Hibiscus rosa sinensis, was employed for the facile one pot synthesis of Co₃O₄-NPs and MgO-NPs. The well characterized NPs were explored for multiple biomedical applications including bactericidal activity against urinary tract infection (UTI) isolates, leishmaniasis, larvicidal, antidiabetic antioxidant and biocompatibility studies. Our results showed that both the NPs were highly active against multidrug resistant UTI isolates as compared to traditional antibiotics and induced significant zone of inhibition against Proteus Vulgaris, Pseudomonas Aurigenosa and E.coli. The NPs, in particular Co₃O₄-NPs also showed significant larvicidal activity against the Aedes Aegypti, the mosquitoes involve in the transmission of Dengue fever. Similarly, excellent leishmanicidal activity was also observed against both the promastigote and amastigote forms of the parasite. Furthermore, the particles also exhibited considerable antidiabetic activity by inhibiting α-amylase and α-glucosidase enzymes. The biosynthesized NPs were found to be excellent antioxidant and biocompatible nanomaterials. Owing to ecofriendly synthesis, non-toxic and biocompatible nature, the Hibiscus rosa sinensis synthesized Co₃O₄-NPs and MgO-NPs can be exploited as potential candidates for multiple biomedical applications.     

Apoptotic and antiproliferative effects of silk protein sericin conjugated-AgNO3 nanoparticles in human breast cancer cells

Bombyx mori silk sericin is a globular-like protein that is used as an antioxidant, antibacterial, and antitumor agent. In this current research, we isolated sericin by degumming process and formation of sericin-AgNO₃ NPs confirmed by UV–vis spectra, SEM, EDX, FTIR, and XRD patterns. The sericin and sericin-AgNO₃ NPs mediated changes in human breast cancer cells were determined. The antiproliferative activity of sericin-AgNO₃ NPs was analyzed by MTT dye reduction assay. Alterations at molecular levels were investigated by qRT-PCR, while apoptotic effects were studied by nuclear DNA staining. After 72 h treatment, sericin and sericin-AgNO₃ NPs showed significant antiproliferative effects in MDA-MB-231 (26 %) and MCF-7 (41 %) cells. Expression modification showed prominent stimulation of cell cycle arrest and stress related genes such as cyclin-dependent kinase inhibitors (CDKN1A, CDKN1B), and GADD family genes. RT-PCR results of the GADD family include GADD45A, B, G, 34, 153 and cyclin-dependent kinase inhibitors (CDKN1A, 1B) showed pronounced induction of 3.1 to 19.8-folds in MCF-7 cell line while induction in MDA-MB-231 cell line was 2.5 to 34.3-folds. Nuclear DAPI staining showed significant induction of apoptosis and nuclear fragmentation in MDA-MB-231 cells at a concentration of 1 mg/mL for both sericin and sericin-AgNO₃ NPs. Meanwhile, in case of MCF-7 cells, after treatment with sericin and sericin-AgNO₃ NPs (1 mg/mL), the cells changed into a round shape and lost their original spindle outlook in dose-dependent manners. We concluded that sericin-AgNO₃ NPs have significant antiproliferative, apoptosis, and genetic profiling effects in both breast cancer cell lines at the highest concentration.     

Unveiling the anticancer and antimycobacterial potentials of bioengineered gold nanoparticles

Synthesis of gold nanoparticles was carried out using Pongammia pinnata (pongam) leaf extract and their anticancer and antimycobacterial activities were studied. Gold nanoparticle formation was confirmed by UV–vis, XRD and HR-TEM. The anticancer efficacies of the biogenic gold nanoparticles were analyzed using cytotoxicity, cell morphology analysis, oxidative DNA damage, apoptosis detection and toxicity studies. Biogenic gold nanoparticles inhibited breast cancer cell line (MCF-7) proliferation with an efficacy of IC₅₀ of 1.85 μg/mL. The antimycobacterial potential of the biogenic gold nanoparticles was screened against M. tuberculosis by Luciferase Reporter Phage (LRP) assay. The gold nanoparticles showed inhibition against sensitive M. tuberculosis with the minimum inhibitory concentration (MIC) of 10 μg/mL whereas no inhibition was found against the rifampicin resistant M. tuberculosis.     

Yeast alpha glucosidase inhibitory and antioxidant activities of six medicinal plants collected in Phalaborwa,South Africa

Recent decades have experienced a sharp increase in the incidence and prevalence of diabetes mellitus. One antidiabetic therapeutic approach is to reduce gastrointestinal glucose production and absorption through the inhibition of carbohydrate-digesting enzymes such as α-amylase and α-glucosidase and α-amylase. The aim of the current study was to screen six medicinal plant species, with alleged antidiabetic properties for α-glucosidase inhibitory activities. Powdered plant materials were extracted with acetone, and tested for ability to inhibit baker's yeast α-glucosidase and α-amylase activities. The largest mass (440 mg from 10 g) of the extract was obtained from Cassia abbreviata, while both Senna italica and Mormordica balsamina yielded the lowest mass of the extracts. Extracts of stem bark of C. abbreviata inhibited baker's yeast α-glucosidase activity with an IC₅₀ of 0.6 mg/ml. This plant species had activity at low concentrations, with 1.0 mg/ml and above resulting in inhibition of over 70%. The other five plant extracts investigated had IC₅₀ values of between 1.8 and 3.0 mg/ml. Senna italica only managed to inhibit the activity of enzyme-glucosidase at high concentrations with an IC₅₀ value of 1.8 mg/ml, while Tinospora fragosa extracts resulted in about 55% inhibition of the activity of the enzyme at a concentration of 3.5 mg/ml, with an estimated IC₅₀ value of 2.8 mg/ml. The bark extract of C. abbreviata was the most active inhibitor of the enzyme, based on the IC₅₀ values (0.6 mg/ml). The bark extract of C. abbreviata contains non-competitive inhibitor(s) of α-glucosidase, reducing V_max value of this enzyme from 5 mM·s^–1 to 1.67 mM·s^–1, while K_m remained unchanged at 1.43 mM for para-nitrophenyl glucopyranoside. Antioxidant activity of the extracts was also investigated. The C. abbreviata extract was more active as an antioxidant than the positive control, trolox. The extracts did not inhibit alphaamylase activity more than about 20% at the highest concentration tested.     

Two new flavonol glycosides from the leaves of Cleome viscosa L.

From the leaves of Cleome viscosa L., two new flavonol glycosides, named visconoside A (1) and visconoside B (2), together with six known flavonol glycosides, vincetoxicoside A (3), vincetoxicoside B (4), kaempferitrin (5), kaempferide 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (6), kaempferol 3-O-β-d-glucopyranoside 7-O-α-l-rhamnopyranoside (7), and isorhamnetin 3-O-β-d-glucopyranoside (8) were isolated by various chromatography methods. Its chemical structure was elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and compared with literatures.