In vitro gastrointestinal digestion of buckwheat (Fagopyrum esculentum Moench) protein: release and structural characteristics of novel bioactive peptides stimulating gut cholecystokinin secretion.

Satiety hormone cholecystokinin (CCK) plays a vital role in appetite inhibition. Its secretion is regulated by dietary components. The search for bioactive compounds that stimulate CCK secretion is currently an active area of research. The objective of this study was to evaluate the ability of buckwheat (Fagopyrum esculentum Moench) protein digest (BPD) to stimulate CCK secretion in vitro and in vivo and clarify the structural characteristics of peptides stimulating CCK secretion. BPD was prepared by an in vitro gastrointestinal digestion model. The relative molecular weight of BPD was <10 000 Da, and peptides with <3000 Da accounted for 70%. BPD was rich in essential amino acids Lys, Leu, and Val but lacked sulfur amino acids Met and Cys. It had a stimulatory effect on CCK secretion in vitro and in vivo. Chromatographic separation was performed to isolate peptide fractions involved in CCK secretion, and five novel CCK-releasing peptides including QFDLDD, PAFKEEHL, SFHFPI, IPPLFP, and RVTVQPDS were successfully identified. A sequence length range of 6-8 and marked hydrophobicity (18-28) were observed among the most CCK-releasing peptides. The present study demonstrated for the first time that BPD could stimulate CCK secretion and clarify the structural characteristics of bioactive peptides having CCK secretagogue activity in BPD.

Investigation of cytochrome P450 inhibitory properties of deoxyshikonin, a bioactive compound from Lithospermum erythrorhizon Sieb. et Zucc.

Deoxyshikonin, a natural naphthoquinone compound extracted from Lithospermum erythrorhizon Sieb. et Zucc (Boraginaceae), has a wide range of pharmacological activities, including anti-tumor, anti-bacterial and wound healing effects. However, the inhibitory effect of deoxyshikonin on cytochrome P450 (CYP) remains unclear. This study investigated the potential inhibitory effects of deoxyshikonin on CYP1A2, 2B1/6, 2C9/11, 2D1/6, 2E1 and 3A2/4 enzymes in human and rat liver microsomes (HLMs and RLMs) by the cocktail approach in vitro. The single-point inactivation experiment showed that deoxyshikonin presented no time-dependent inhibition on CYP activities in HLMs and RLMs. Enzyme inhibition kinetics indicated that in HLMs, deoxyshikonin was not only a competitive inhibitor of CYP1A2 and 2E1, but also a mixed inhibitor of CYP2B6, 2C9, 2D6 and 3A4, with Ki of 2.21, 1.78, 1.68, 0.20, 4.08 and 0.44 µM, respectively. In RLMs, deoxyshikonin not only competitively inhibited CYP2B1 and 2E1, but also exhibited mixed inhibition on CYP1A2, 2C11, 2D1 and 3A2, with Ki values of no more than 18.66 µM. In conclusion, due to the low Ki values of deoxythiokonin on CYP enzymes in HLMs, this may lead to drug-drug interactions (DDI) and potential toxicity.

[Regulation of inflammatory bowel disease by amino acids].

Inflammatory bowel disease (IBD) is a chronic, recurrent inflammatory disease of the gastrointestinal tract that includes Crohn's disease and ulcerative colitis. IBD patients are numerous and a complete cure is difficult to achieve. Due to impaired digestive function, food is not easily absorbed and malnutrition often occurs in patients. Nutritional therapy is often used to overcome nutritional deficiency and change the inflammatory state in the clinic. Amino acids are adjuvant therapeutic candidates that may help maintain intestinal integrity in patients with IBD. It maypromote the treatment of IBD through reducing the level of inflammation, oxidative stress, and intestinal cell death. Recent studies in animals have demonstrated the potential of using amino acids for treating IBD. The supply and metabolism of amino acids may be a promising adjuvant therapy. This review summarized the immunomodulatory effects of specific amino acids such as glutamine, arginine, and glycine, with the aim to provide new ideas for the treatment of IBD.

Secondary metabolites of endophytic fungi isolated from Huperzia serrata.

The natural product Huperzine A isolated from Huperzia serrata is a targeted inhibitor of acetylcholinesterase that has been approved for clinical use in the treatment of Alzheimer's disease. Given the large demand for natural sources of Huperzine A  (Hup. A), efforts have been made to explore whether it is also produced by endophytic fungi from H. serrata and, if so, identify its biosynthetic pathway. These studies have indicated that endophytic fungi from H. serrata represent a huge and largely untapped resource for natural products (including Hup. A) with chemical structures that have been optimized by evolution for biological and ecological relevance. To date, more than three hundred endophytic fungi have been isolated from H. serrata, of which 9 strains can produce Hup. A, whilst more than 20 strains produce other important metabolites, such as polyketones, xanthones, alkaloids, steroids, triterpenoids, furanone derivatives, tremulane sesquitepenes and diterpenoids. In total, 200 secondary metabolites have been characterized in endophytic fungi from H. serrata to date. Functionally, some have cholinesterase-inhibitory or antibacterial activity. This review also considers the different classes of secondary metabolites produced by endophytic fungi, along with their possible applications. We systematically describe the taxonomy, biology, and chemistry of these secondary metabolites. It also summarizes the biosynthetic synthesis of metabolites, including that of Hup. A. The review will aid researchers in obtaining a clearer understanding of this plant-endophyte relationship to better exploit the excellent resources it offers that may be utilized by pharmaceutical industries.

In vitro antiviral, anti-inflammatory, and antioxidant activities of the ethanol extract of Mentha piperita L.

The objective of this study is to investigate the antiviral, anti-inflammatory, and antioxidant effects of the ethanol extract of Mentha piperita L. leaves (MPE). M. piperita L. leaves were extracted by reflux with ethanol. Total phenolic acid and total flavonoid content were determined. The antiviral activity of MPE against the respiratory syncytial virus (RSV) and the anti-inflammatory activity were evaluated in vitro. The levels of key pre-inflammatory mediators and cytokines including nitric oxide (NO), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and prostaglandin E2 (PGE2) were determined. The antioxidant activities were also evaluated using a colorimetry method. MPE contained high levels of phenolic acid and flavonoid, showed antiviral activity against RSV with a high selectivity index, and significantly decreased the production of NO, TNF-α, IL-6, and PGE2 in lipopolysaccharide-stimulated RAW 264.7 cells. Meanwhile, MPE showed potential free-radical scavenging activities. These results indicate that Mentha piperita L. might be a good source of medicinal plants.

Production of the angiotensin I converting enzyme inhibitory peptides and isolation of four novel peptides from jellyfish (Rhopilema esculentum) protein hydrolysate.

BACKGROUND: Angiotensin I converting enzyme (ACE) plays an important role in regulating blood pressure in the human body. ACE inhibitory peptides derived from food proteins could exert antihypertensive effects without side effects. Jellyfish (Rhopilema esculentum) is an important fishery resource suitable for production of ACE inhibitory peptides. The objective of this study was to optimize the hydrolysis conditions for production of protein hydrolysate from R. esculentum (RPH) with ACE inhibitory activity, and to isolate and identify the ACE inhibitory peptides from RPH. RESULTS: Rhopilema esculentum protein was hydrolyzed with Compound proteinase AQ to produce protein hydrolysate with ACE inhibitory activity, and the hydrolysis conditions were optimized using response surface methodology. The optimum parameters for producing peptides with the highest ACE inhibitory activity were as follows: hydrolysis time 3.90 h, hydrolysis temperature 58 °C, enzyme:substrate ratio 2.8% and pH 7.60. Under these conditions, the ACE inhibitory rate reached 32.21%. In addition, four novel ACE inhibitory peptides were isolated, and their amino acids sequences were identified as Val-Gly-Pro-Tyr, Phe-Thr-Tyr-Val-Pro-Gly, Phe-Thr-Tyr-Val-Pro-Gly-Ala and Phe-Gln-Ala-Val-Trp-Ala-Gly, respectively. The IC50 value of the purified peptides for ACE inhibitory activity was 8.40, 23.42, 21.15 and 19.11 µmol L(-1) . CONCLUSION: These results indicate that the protein hydrolysate prepared from R. esculentum might be a commercial competitive source of ACE inhibitory ingredients to be used in functional foods. © 2015 Society of Chemical Industry.

Chemical Composition and Anti-Inflammatory, Cytotoxic and Antioxidant Activities of Essential Oil from Leaves of Mentha piperita Grown in China.

The chemical composition, anti-inflammatory, cytotoxic and antioxidant activities of essential oil from leaves of Mentha piperita (MEO) grown in China were investigated. Using GC-MS analysis, the chemical composition of MEO was characterized, showing that it was mainly composed of menthol, menthone and menthy acetate. MEO exhibited potent anti-inflammatory activities in a croton oil-induced mouse ear edema model. It could also effectively inhibit nitric oxide (NO) and prostaglandin E2 (PGE2) production in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. The cytotoxic effect was assessed against four human cancer cells. MEO was found to be significantly active against human lung carcinoma SPC-A1, human leukemia K562 and human gastric cancer SGC-7901 cells, with an IC50 value of 10.89, 16.16 and 38.76 µg/ml, respectively. In addition, MEO had moderate antioxidant activity. The results of this study may provide an experimental basis for further systematic research, rational development and clinical utilization of peppermint resources.

Polysaccharides extraction from Erythirna variegata, chemical characterization and its antioxidant activity.

The objective of this study was to determine the optimum conditions for extracting crude polysaccharides from the bark of Erythirna variegata (EVP) using response surface methodology (RSM). The quantitative effects of extraction time, temperature and the ratio of water to raw material on EVP yields were investigated using Box-Behnken experimental design. The monosaccharide composition was analyzed by 1-phenyl-3-methy-5-pyrazolone pre-column derivatization high performance liquid chromatography, and the molecular weight was measured by high performance gel permeation chromatography. The antioxidant activities were also evaluated. By solving the regression equation and analyzing the data, the optimum conditions were obtained as follows: extracting time 1.52h, extraction temperature 91.40°C, and the ratio of water to raw material at 24.78. Under these conditions, the experiment yield was 2.064%, which well agreed with the predicted value. Chemical composition analysis indicated that EVP was mainly composed of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose, and the mean molecular weight of the two major fractions was about 26.8kDa and 5.5kDa, respectively. EVP had strong scavenging activity against DPPH radicals, potential reducing power and total antioxidant activity. This study provides a scientific basis for the use of this herb in traditional medicine as an antioxidant.

Bioactive saponins from the fruits of Aesculus pavia L.

Continued chemical investigation on the fruits of Aesculus pavia L. resulted in theisolation and identification of two new oleanolic acid saponins, namely vaccaroside A (1) andvaccaroside B (2). The isolated furostanol saponins were evaluated for cytotoxic activity againsthuman normal amniotic and human lung carcinoma cell lines using neutral red and MTT assays.In vitro experiments showed significant cytotoxicity in a dose dependent manner with IC50 valuesin the range of 27.80-79.02 µM.

Antifungal and cytotoxic activities of the secondary metabolites from endophytic fungus Massrison sp.

Three novel compounds with spiro-5, 6-lactone ring skeleton has been isolated from the fermentation broth of Massrison sp. which could be isolated repeatedly from wild Rehmannia glutinosa. Psetariae oryza P-2b was applied to guide fractionation of bioactive compounds produced by Massrison sp. The molecular structures were established by a variety of one- and two-dimensional NMR experiments and the compounds with similar skeleton were reported for the first time from endophytic fungi of terraneous plant. Antifungal and cytotoxic activities of the compounds were tested, compounds 2 and 3 displayed stronger antifungal and cytotoxic activities. The compounds have the potential to be antibiotic against fungal pathogens and tumor cells.

A new hepoprotective saponin from Semen Celosia cristatae.

A new triterpenoid saponin, named semenoside A (1), was isolated from Semen Celosia cristatae. Its structure was elucidated on the basis of 1D, 2D NMR, HR-FAB-MS and ESI-MS techniques, and physicochemical properties. The hepatoprotective activity of semenoside A with an oral dose of 1.0, 2.0 and 4.0mg/kg, respectively, were investigated by carbon tetrachloride (CCl(4))-induced hepatotoxicity in mice. The results indicated that it had significant hepatoprotective effects (p < 0.01).

A new active compound against kidney deficiency from the fruits of Rubus corchorifolius.

Constituents of the fruits of Rubus corchorifolius were investigated. A new compound, namely rubusin A (1), along with three known compounds, was isolated and characterized. Among them, the new compound exhibited significant activity against kidney deficiency, and quercetin and kaempferol were isolated from the fruits of R. corchorifolius for the first time.

A new neuroprotective bakkenolide from the rhizome of Peatasites tatewakianus.

Constituents of the fruits of Peatasites tatewakianus were investigated. A new compound, namely bakkenolide-VI (1), was isolated. The structures was elucidated on the basis of 1D, 2D NMR, TOF-MS and ESI-MS techniques, and physicochemical properties. The neuroprotective activity of the new compound was assayed with primary cultured neurons exposed to oxygen-glucose deprivation and oxidative insults.

Two new hepaprotective saponins from Semen celosiae.

Two new oleanolic acid saponins, namely celosin C (1) and celosin D (2), were isolated from the ethanol extract of Semen celosiae. Their structures were identified as celosin C (1) and celosin D (2) by spectroscopic and chemical analyses. The hepatoprotective activity of 1 and 2 with oral dose 1.0, 2.0 and 4.0 mg/kg, respectively, were investigated by carbon tetrachloride (CCl(4))-induced hepatotoxicity in mice. The results indicate that they have significant hepatoprotective effects (p<0.01).