Enhancement of amygdalin activated with β-d-glucosidase on HepG2 cells proliferation and apoptosis

The growth inhibition and induction of apoptosis brought by amygdalin and activated with β-d-glucosidase were tested for cytoactivity in HepG2 cells. The MTT viability assay showed that all samples had effects on HepG2 proliferation in dose and time response manners. IC₅₀ of stand-alone amygdalin and activation with β-d-glucosidase on the proliferation of HepG2 cells for 48 h were 458.10 mg/mL and 3.2 mg/mL, respectively. Moreover, apoptotic cells were determined by AO/EB (acridine orange/ethidium bromide) fluorescent staining method and Annexin V-FITC/PI staining flow cytometry cell cycle analysis. With increasing of amygdalin concentration and the incubation time, the apoptotic rate was heightened. Compared with the control, there was significant difference (p < 0.01). Together, these findings indicate that amygdalin had no strong anti-HepG2 activity; however the ingredients of amygdalin activated with β-d-glucosidase had a higher and efficient anti-HepG2 activity. It was therefore suggested that this combination strategy may be applicable for treating tumors with a higher activity.     

Design,synthesis and biological evaluation of hydroxy substituted amino chalcone compounds for antityrosinase activity in B16 cells

A series of hydroxy substituted amino chalcone compounds have been synthesized. These compounds were then evaluated for their inhibitory activities on tyrosinase and melanogenesis in murine B16F10 melanoma cell lines. The structures of the compounds synthesized were confirmed by ¹H NMR, ¹³C NMR, FTIR and HRMS. Two novel amino chalcone compounds exhibited higher tyrosinase inhibitory activities (IC₅₀ values of 9.75 μM and 7.82 μM respectively) than the control kojic acid (IC₅₀: 22.83 μM). Kinetic studies revealed them to act as competitive tyrosinase inhibitors with their K_i values of 4.82 μM and 1.89 μM respectively. Both the compounds inhibited melanin production and tyrosinase activity in B16 cells. Docking results confirm that the active inhibitors strongly interact with mushroom tyrosinase residues. This study suggests that the depigmenting effect of novel amino chalcone compounds might be attributable to inhibition of tyrosinase activity, suggesting amino chalcones to be a promising candidate for use as depigmentation agents or as anti-browning food additives.     

Design,synthesis and in vitro cytotoxicity evaluation of 5-(2-carboxyethenyl)isatin derivatives as anticancer agents

Forty four di- or trisubstituted novel isatin derivatives were designed and synthesized in 5–6 steps in 25–45% overall yields. Their structures were confirmed by ¹H NMR and ¹³C NMR as well as LC–MS. The anticancer activity of these new isatin derivatives against three human tumor cell lines, K562, HepG2 and HT-29, were evaluated by MTT assay in vitro. SAR studies suggested that the combination of 1-benzyl and 5-[trans-2-(methoxycarbonyl)ethen-1-yl] substitution greatly enhance their cytotoxic activity, whereas an intact carbonyl functionality on C-3 as present in the parent ring is required to such a potency. This study leads to the identification of two highly active molecules, compounds 2h (IC₅₀ = 3 nM) and 2k (IC₅₀ = 6 nM), against human leukemia K562 cells.     

Synthesis and biological activity of aminophthalazines and aminopyridazines as novel inhibitors of PGE2 production in cells

This Letter reports the synthesis and biological evaluation of a collection of aminophthalazines as a novel class of compounds capable of reducing production of PGE₂ in HCA-7 human adenocarcinoma cells. A total of 28 analogs were synthesized, assayed for PGE₂ reduction, and selected active compounds were evaluated for inhibitory activity against COX-2 in a cell free assay. Compound 2xxiv (R¹ = H, R² = p-CH₃O) exhibited the most potent activity in cells (EC₅₀ = 0.02 μM) and minimal inhibition of COX-2 activity (3% at 5 μM). Furthermore, the anti-tumor activity of analog 2vii was analyzed in xenograft mouse models exhibiting good anti-cancer activity.     

Thiadiazole derivatives as New Class of β-glucuronidase inhibitors

Thiadiazole derivatives 1–24 were synthesized via a single step reaction and screened for in vitro β-glucuronidase inhibitory activity. All the synthetic compounds displayed good inhibitory activity in the range of IC₅₀ = 2.16 ± 0.01–58.06 ± 1.60 μM as compare to standard d-saccharic acid 1,4-lactone (IC₅₀ = 48.4 ± 1.25 μM). Molecular docking study was conducted in order to establish the structure–activity relationship (SAR) which demonstrated that thiadiazole as well as both aryl moieties (aryl and N-aryl) involved to exhibit the inhibitory potential. All the synthetic compounds were characterized by spectroscopic techniques ¹H, ¹³C NMR, and EIMS.     

Novel pyrazole integrated 1,3,4-oxadiazoles: Synthesis,characterization and antimicrobial evaluation

A novel series of 2-(5-methyl-1,3-diphenyl-1H-pyrazol-4-yl)-5-phenyl-1,3,4-oxadiazoles 7(a–m) were synthesized either by cyclization of N′-benzoyl-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 4a using POCl₃ at 120 °C or by oxidative cyclization of hydrazones derived from various arylaldehyde and (E)-N′-benzylidene-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 5(a–d) using chloramine-T as oxidant. Newly synthesized compounds were characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR and LC–MS) methods. The synthesized compounds were evaluated for their antimicrobial activity and were compared with standard drugs. The compounds demonstrated potent to weak antimicrobial activity. Among the synthesized compounds, compound 7m emerged as an effective antimicrobial agent, while compounds 7d, 7f, 7i and 7l showed good to moderate activity. The minimum inhibitory concentration of the compounds was in the range of 20–50 μg mL⁻¹ against bacteria and 25–55 μg mL⁻¹ against fungi. The title compounds represent a novel class of potent antimicrobial agents.     

Development of hydroxylated naphthylchalcones as polyphenol oxidase inhibitors: Synthesis,biochemistry and molecular docking studies

Polyphenol oxidase (Tyrosinase) has received great attention, since it is the key enzyme in melanin biosynthesis. In this study, novel hydroxy naphthylchalcone compounds were synthesized, and their inhibitory effects on mushroom tyrosinase activity were evaluated. The structures of the compounds synthesized were confirmed by ¹H NMR, ¹³C NMR, FTIR and HRMS. Two of the compounds synthesized inhibited the diphenolase activity of tyrosinase in a dose dependent manner and exhibited much higher tyrosinase inhibitory activities (IC₅₀ values of 10.4 μM and 14.4 μM, respectively) than the positive control, kojic acid (IC₅₀: 27.5 μM). Kinetic analysis showed that their inhibition was reversible. Both the novel compounds displayed competitive inhibition with their K_i values of 3.8 μM and 4.5 μM, respectively. Docking results confirmed that the active inhibitors strongly interacted with the mushroom tyrosinase residues. This study suggests hydroxy naphthylchalcone compounds to serve as promising candidates for use as depigmentation agents.     

Synthesis and in silico studies of novel sulfonamides having oxadiazole ring: As β-glucuronidase inhibitors

Novel sulfonamides having oxadiazole ring were synthesized by multistep reaction and evaluated to check in vitro β-glucuronidase inhibitory activity. Luckily, except compound 13, all compounds were found to demonstrate good inhibitory activity in the range of IC₅₀ = 2.40 ± 0.01–58.06 ± 1.60 μM when compared to the standard d-saccharic acid 1,4-lactone (IC₅₀ = 48.4 ± 1.25 μM). Structure activity relationship was also presented. However, in order to ensure the SAR as well as the molecular interactions of compounds with the active site of enzyme, molecular docking studies on most active compounds 19, 16, 4 and 6 was carried out. All derivatives were fully characterized by ¹H NMR, ¹³C NMR and EI-MS spectroscopic techniques. CHN analysis was also presented.     

2-(4-Fluorophenyl)-quinazolin-4(3H)-one as a novel tyrosinase inhibitor: Synthesis,inhibitory activity,and mechanism

2-(4-Fluorophenyl)-quinazolin-4(3H)-one (FQ) was synthesized, and its structure was identified with ¹H nuclear magnetic resonance (¹H NMR), ¹³C nuclear magnetic resonance (¹³C NMR), fourier transform infrared spectroscopy (FTIR), and high resolution mass spectrometry (HRMS). From the enzyme analysis, the results showed that it could inhibit the diphenolase activity of tyrosinase (IC₅₀ = 120 ± 2 μM). Furthermore, the results of kinetic studies showed that the compound was a reversible mixed-type inhibitor, and that the inhibition constants were determined to be 703.2 (K_I) and 222.1 μM (K_IS). The results of fluorescence quenching experiment showed that the compound could interact with tyrosinase and the substrates (tyrosine and l-DOPA). Molecular docking analysis revealed that the mass transfer rate was affected by FQ blocking the enzyme catalytic center. In brief, current study identified a novel tyrosinase inhibitor which deserved further study for hyperpigmentation drugs.     

Synthesis,in vitro β-glucuronidase inhibitory activity and in silico studies of novel (E)-4-Aryl-2-(2-(pyren-1-ylmethylene)hydrazinyl)thiazoles

Current research is based on the synthesis of novel (E)-4-aryl-2-(2-(pyren-1-ylmethylene)hydrazinyl)thiazole derivatives (3–15) by adopting two steps route. First step was the condensation between the pyrene-1-carbaldehyde (1) with the thiosemicarbazide to afford pyrene-1-thiosemicarbazone intermediate (2). While in second step, cyclization between the intermediate (2) and phenacyl bromide derivatives or 2-bromo ethyl acetate was carried out. Synthetic derivatives were structurally characterized by spectroscopic techniques such as EI-MS, ¹H NMR and ¹³C NMR. Stereochemistry of the iminic double bond was confirmed by NOESY analysis. All pure compounds 2–15 were subjected for in vitro β-glucuronidase inhibitory activity. All molecules were exhibited excellent inhibition in the range of IC₅₀ = 3.10 ± 0.10–40.10 ± 0.90 μM and found to be even more potent than the standard d-saccharic acid 1,4-lactone (IC₅₀ = 48.38 ± 1.05 μM). Molecular docking studies were carried out to verify the structure-activity relationship. A good correlation was perceived between the docking study and biological evaluation of active compounds.     

Chemical constituents from Tribulus terrestris and screening of their antioxidant activity

Two oligosaccharides (1, 2) and a stereoisomer of di-p-coumaroylquinic acid (3) were isolated from the aerial parts of Tribulus terrestris along with five known compounds (4–8). The structures of the compounds were established as O-β-d-fructofuranosyl-(2 → 6)-α-d-glucopyranosyl-(1 → 6)-β-d-fructofuranosyl-(2 → 6)-β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranosyl-(6 → 2)-β-d-fructofuranoside (1), O-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 2)-β-d-fructofuranoside (2), 4,5-di-p-cis-coumaroylquinic acid (3) by different spectroscopic methods including 1D NMR (¹H, ¹³C and DEPT) and 2D NMR (COSY, TOCSY, HMQC and HMBC) experiments as well as ESI-MS analysis. This is the first report for the complete NMR spectral data of the known 4,5-di-p-trans-coumaroylquinic acid (4).The antioxidant activity represented as DPPH free radical scavenging activity was investigated revealing that the di-p-coumaroylquinic acid derivatives possess potent antioxidant activity so considered the major constituents contributing to the antioxidant effect of the plant.     

Isolation,chemical characterization and antioxidant activities of two polysaccharides from the gel and the skin of Aloe barbadensis Miller irrigated with sea water

Two polysaccharides, GAPS-1 and SAPS-1, were isolated from the gel and the skin of Aloe barbadensis Miller irrigated with sea water for 3.5 years through a combination of anion-exchange column chromatography and repeated gel chromatography and their chemical characterization and antioxidant activities in vitro were investigated. GAPS-1 and SAPS-1 were composed of Man:Glc:Gal in a ratio of 120:2:3 and 296:36:1 with their molecular weight 1.74 × 10⁵ and 3.97 × 10⁴ Da, respectively. IR and ¹³C NMR study of GAPS-1 and SAPS-1 demonstrated that the main skeletons of GAPS-1 was β-(1 → 4)-D linkaged mannose with acetylation at C-6 and C-3 of manopyranosyl and SAPS-1 was β-(1 → 4)-D linkaged galactoglucomannan with acetylation at C-6 of pyranosyl. In a concentration-dependent manner, GAPS-1 and SAPS-1 were demonstrated to have strong scavenging activities against superoxide radical, moderate ferrous chelating effect, moderate scavenging activities of hydroxyl radical, moderate reductive power and moderate inhibition of lipid peroxidation. Furthermore, GAPS-1 exhibited moderate scavenging activity of hydrogen peroxide, while SAPS-1 exhibited weak scavenging activity of hydrogen peroxide. GAPS-1 demonstrated more effective antioxidant activities than SAPS-1. The more acetyl group in GAPS-1 molecules probably contributes to the activities.     

Synthesis,characterization, and molecular docking analysis of novel benzimidazole derivatives as cholinesterase inhibitors

Two series of novel acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors containing benzimidazole core structure were synthesized by a four-step reaction pathway starting from 4-fluoro-3-nitrobenzoic acid as the basic compound. The structure of the novel benzimidazoles was characterized and confirmed by the elemental and mass spectral analyses as well as ¹H NMR spectroscopic data. Of the 34 novel synthesized compounds, three benzimidazoles revealed AChE inhibition with IC₅₀ < 10 μM. The highest inhibitory activity (IC₅₀ = 5.12 μM for AChE and IC₅₀ = 8.63 μM for BChE) corresponds to the compound 5IIc (ethyl 1-(3-(1H-imidazol-1-yl)propyl)-2-(4-nitrophenyl)-1H-benzo[d]imidazole-5-carboxylate). The relationship between lipophilicity and the chemical structures as well as their limited structure–activity relationship was discussed.     

Development of fluorinated methoxylated chalcones as selective monoamine oxidase-B inhibitors: Synthesis,biochemistry and molecular docking studies

A series of methoxylated chalcones with fluoro and trifluoromethyl derivatives were synthesized and investigated for their ability to inhibit human monoamine oxidase A and B. The chemical structures of the compounds have been characterized by means of their ¹H NMR, ¹³C NMR, Mass spectroscopic datas and elemental analysis. The results demonstrate that these compounds are reversible and selective MAO-B inhibitors with a competitive mode of inhibition. The most potent compound (2E)-1-(4-methoxyphenyl)-3-[4-(trifluoromethyl)phenyl] prop-2-en-1-one showed the best activity and higher selectivity towards hMAO-B with K_i and SI values of 0.22 ± 0.01 μM and 0.05 comparable to that standard drug, Selegiline K_i and SI values were found as 0.33 ± 0.03 μM and 0.04, respectively. Molecular docking studies were carried out to further explain the in vitro results of the new compounds, and to identify the hypothetical binding mode for the compounds inside the inhibitor binding cavity of hMAO-B.     

High level synthesis of levan by a novel Halomonas species growing on defined media

A novel halophilic isolate from soil samples taken from Çamalt? Saltern area in Turkey, Halomonas sp. AAD6 (JCM 15723) strain, was found to produce high levels of exopolysaccharides (EPS), in the presence of sucrose in defined media, by flasks and bioreactor condition yielded 1.073 g L^?1 and 1.844 g L^?1, respectively. Sugar analysis, methylation studies and NMR analysis of EPS indicated the repeating unit of this polysaccharide was composed of β-(2,6)-d-fructofuranosyl residues. Hence with this work, Halomonas sp. has been described as a levan producer microorganism for the first time. Biocompatibility studies showed this EPS did not affect cellular viability and proliferation of osteoblasts and murine macrophages. The protective effect of the polymer against the toxic activity of avarol implied its additional use as an anti-cytotoxic agent. Halomonas sp. AAD6 could represent an alternative cheap source of levan polymer when grown on defined media hypothesizing its larger employment in industrial application being non pathogenic microorganism.     

Design,synthesis and biological evaluation of novel coumarin thiazole derivatives as α-glucosidase inhibitors

A new series of coumarin thiazole derivatives 7a-7t were synthesized, characterized by ¹H NMR, ¹³C NMR and element analysis, evaluated for their α-glucosidase inhibitory activity. The majority of the screened compounds displayed potent inhibitory activities with IC₅₀ values in the range of 6.24 ± 0.07–81.69 ± 0.39 μM, when compared to the standard acarbose (IC₅₀ = 43.26 ± 0.19 μM). Structure–activity relationship (SAR) studies suggest that the pattern of substitution in the phenyl ring is closely related to the biological activity of this class of compounds. Among all the tested molecules, compound 7e (IC₅₀ = 6.24 ± 0.07 μM) was found to be the most active compound in the library of coumarin thiazole derivatives. Enzyme kinetic studies showed that compound 7e is a non-competitive inhibitor with a K_i of 6.86 μM. Furthermore, the binding interactions of compound 7e with the active site of α-glucosidase were confirmed through molecular docking. This study has identified a new class of potent α-glucosidase inhibitors for further investigation.     

Liquid phase combinatorial synthesis of 1,2,5-trisubstituted benzimidazole derivatives as human DHODH inhibitors

The synthesis of 1,2,5-trisubstituted benzimidazole derivatives was carried out using liquid phase combinatorial approach using soluble polymer assisted support (PEG5000). Synthesised compounds were characterised by FTIR, ESI-MS, ¹H NMR and ¹³C NMR. The purity of compounds was confirmed with HPLC analysis. Compounds were also docked into the binding site of human dihydroorotate dehydrogenase (hDHODH). The synthesised compounds were screened for hDHODH enzyme inhibition assay using brequinar as standard compound. The synthesised compounds demonstrated comparative biological activity. Synthesised compounds 8d and 8e demonstrated IC₅₀ value of 81 ± 2 nM and 97 ± 2 nM, respectively.     

Synthesis,molecular docking studies of hybrid benzimidazole as α-glucosidase inhibitor

Thiourea derivatives having benzimidazole 1–17 have been synthesized, characterized by ¹H NMR, ¹³C NMR and EI-MS and evaluated for α-glucosidase inhibition. Identification of potential α-glucosidase inhibitors were done by in vitro screening of 17 thiourea bearing benzimidazole derivatives using Baker’s yeast α-glucosidase enzyme. Compounds 1–17 exhibited a varying degree of α-glucosidase inhibitory activity with IC₅₀ values between 35.83 ± 0.66 and 297.99 ± 1.20 μM which are more better than the standard acarbose (IC₅₀ = 774.5 ± 1.94 μM). Compound 10 and 14 showed significant inhibitory effects with IC₅₀ value 50.57 ± 0.81 and 35.83 ± 0.66 μM, respectively better than the rest of the series. Structure activity relationships were established. Molecular docking studies were performed to understand the binding interaction of the compounds.