Antibacterial activity of sugar maple autumn-shed leaf extract: Identification of the active compound

Ethanolic crude extract prepared from autumn-shed leaves of sugar maple (Acer saccharum Marsh.) was recently shown to have antibacterial activity against Pseudomonas cichorii and Xanthomonas campestris pv. vitians, two bacteria causing diseases in lettuce production. In this study, antibacterial activity of sugar maple autumn-shed leaves (SMASL) extract was further investigated. SMASL ethanolic crude extract was fractionated using HPLC system and geraniin was identified as the antibacterial compound by UPLC/Q-Tof-MS system. Geraniin, an ellagitannin, was then purified from SMASL crude extract using a glass chromatographic C18-reversed phase silica gel column (purification Step 1) and a semi-preparative HPLC system equipped with 5 μm XTerra Prep MS C18 column (purification Step 2). Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of purified geraniin (purity of 96%) against P. cichorii and X. campestris pv. vitians were determined. X. campestris pv. vitians (MIC of 0.024 mg ml⁻¹ and MBC of 3.125 mg ml⁻¹) was more sensitive to geraniin than P. cichorii (MIC of 0.781 mg ml⁻¹ and MBC of 6.25 mg ml⁻¹). In the present study, geraniin is reported for the first time as the main antibacterial compound present in SMASL.     

Kinetic analysis of glucoamylase-catalyzed hydrolysis of starch granules from various botanical sources

The kinetics of glucoamylase-catalyzed hydrolysis of starch granules from six different botanical sources (rice, wheat, maize, cassava, sweet potato, and potato) was studied by the use of an electrochemical glucose sensor. A higher rate of hydrolysis was obtained as a smaller size of starch granules was used. The adsorbed amount of glucoamylase on the granule surface per unit area did not vary very much with the type of starch granules examined, while the catalytic constants of the adsorbed enzyme (k(0)) were determined to be 23.3+/-4.4, 14.8+/-6.0, 6.2+/-1.8, 7.1+/-4.1, 4.6+/-3.0, and 1.6+/-0.6 s(-1) for rice, wheat, maize, cassava, sweet potato, and potato respectively, showing that k(0) was largely influenced by the type of starch granules. A comparison of the k(0)-values in relation to the crystalline structure of the starch granules suggested that k(0) increases as the crystalline structure becomes dense.     

Identification of active constraints in dynamic flux balance analysis

This study deals with the calibration of dynamic metabolic flux models that are formulated as the maximization of an objective subject to constraints. Two approaches were applied for identifying the constraints from data. In the first approach a minimal active number of limiting constraints is found based on data that are assumed to be bounded within sets whereas, in the second approach, the limiting constraints are found based on parametric sensitivity analysis. The ability of these approaches to finding the active limiting constraints was verified through their application to two case studies: an in‐silico (simulated) data‐based study describing the growth of E. coli and an experimental data‐based study for Bordetella pertussis (B. pertussis). © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:26–36, 2017     

Identification and immunochemical analysis of biologically active Drosophila P element transposase

We have identified proteins encoded by P transposable elements expressed in transformed Drosophila tissue culture cells. Two proteins have been identified by immunochemical techniques. One, an 87,000 dalton polypeptide, is encoded by a P element mRNA lacking the third (ORF2-ORF3) intervening sequence. The other protein, a 66,000 dalton polypeptide, is encoded by an mRNA that retains the third intron and is found in somatic tissues. Furthermore, tissue culture cell lines expressing the 87,000 dalton polypeptide are able to catalyze both the precise and imprecise excision of a nonautonomous P element. The 87,000 dalton protein is encoded by sequences from all four P element open reading frames. Taken together, these data strongly suggest that the 87,000 dalton polypeptide is the P element transposase.     

核桃楸叶乙醇提取物杀虫活性及活性成分

采用常规提取法浸提核桃楸叶的杀虫活性成分.结果表明,核桃楸叶乙醇提取物和乙醇提取物氯仿萃取相对舞毒蛾幼虫和甘蓝夜蛾幼虫具有杀虫活性.施药5 d,药液浓度≥10g.L-1时,核桃楸叶乙醇提取物和氯仿萃取相对舞毒蛾幼虫和甘蓝夜蛾幼虫的触杀作用和胃毒作用的校正死亡率均超过50%.核桃楸叶乙醇提取物对舞毒蛾幼虫和甘蓝夜蛾幼虫的触杀作用和胃毒作用强于氯仿萃取相.采用气-质联用技术GC-MS分析核桃楸叶乙醇提取物中氯仿萃取相的化学组成和相对含量.结果表明:核桃楸叶乙醇提取物中氯仿萃取相的主要杀虫活性成分为相对含量最高的胡桃醌,即5-羟基-1,4-萘醌;其他杀虫活性成分可能为对称2,2’-亚甲基6-(1,1-二甲乙基)4-甲基双酚和2-甲氧基4-乙烯基苯酚.     

Identification of SARS-CoV-2 RNA-dependent RNA polymerase inhibitors from the major phytochemicals of Nigella sativa: An in silico approach

The coronavirus disease 2019 (COVID-19), which emerged in December 2019, continues to be a serious health concern worldwide. There is an urgent need to develop effective drugs and vaccines to control the spread of this disease. In the current study, the main phytochemical compounds of Nigella sativa were screened for their binding affinity for the active site of the RNA-dependent RNA polymerase (RdRp) enzyme of the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). The binding affinity was investigated using molecular docking methods, and the interaction of phytochemicals with the RdRp active site was analyzed and visualized using suitable software. Out of the nine phytochemicals of N. sativa screened in this study, a significant docking score was observed for four compounds, namely α-hederin, dithymoquinone, nigellicine, and nigellidine. Based on the findings of our study, we report that α-hederin, which was found to possess the lowest binding energy (–8.6 kcal/mol) and hence the best binding affinity, is the best inhibitor of RdRp of SARS-CoV-2, among all the compounds screened here. Our results prove that the top four potential phytochemical molecules of N. sativa, especially α-hederin, could be considered for ongoing drug development strategies against SARS-CoV-2. However, further in vitro and in vivo testing are required to confirm the findings of this study.     

Bezielle selectively targets mitochondria of cancer cells to inhibit glycolysis and OXPHOS

Bezielle (BZL101) is a candidate oral drug that has shown promising efficacy and excellent safety in the early phase clinical trials for advanced breast cancer. Bezielle is an aqueous extract from the herb Scutellaria barbata. We have reported previously that Bezielle was selectively cytotoxic to cancer cells while sparing non-transformed cells. In tumor, but not in non-transformed cells, Bezielle induced generation of ROS and severe DNA damage followed by hyperactivation of PARP, depletion of the cellular ATP and NAD, and inhibition of glycolysis. We show here that tumor cells' mitochondria are the primary source of reactive oxygen species induced by Bezielle. Treatment with Bezielle induces progressively higher levels of mitochondrial superoxide as well as peroxide-type ROS. Inhibition of mitochondrial respiration prevents generation of both types of ROS and protects cells from Bezielle-induced death. In addition to glycolysis, Bezielle inhibits oxidative phosphorylation in tumor cells and depletes mitochondrial reserve capacity depriving cells of the ability to produce ATP. Tumor cells lacking functional mitochondria maintain glycolytic activity in presence of Bezielle thus supporting the hypothesis that mitochondria are the primary target of Bezielle. The metabolic effects of Bezielle towards normal cells are not significant, in agreement with the low levels of oxidative damage that Bezielle inflicts on them. Bezielle is therefore a drug that selectively targets cancer cell mitochondria, and is distinguished from other such drugs by its ability to induce not only inhibition of OXPHOS but also of glycolysis. This study provides a better understanding of the mechanism of Bezielle's cytotoxicity, and the basis of its selectivity towards cancer cells.     

Non-toxic nanoparticles from phytochemicals: preparation and biomedical application

Nanoparticles (NPs) have various applications in biomedicine and drug delivery carriers and also are widely used in cosmetics. However, the preparation of biocompatible and non-toxic nanomaterials is a very important issue as most of the starting materials are synthesized using toxic chemical reagents. This review introduces the preparation of biocompatible NPs in a range of their concentrations using phytochemicals for biomedicine and biotechnology. Phytochemicals are natural products that are extracted from plants, vegetables, and fruits. Phytochemicals serve as reducing agents and stabilizers during NP synthesis to convert metal ions to metal NPs in water. Possible applications of such nanomaterials in biomedical sciences are also described in this review.     

Identification of compounds from the plant species Alepidea amatymbica active against HIV

As Alepidea amatymbica is commonly used and accepted as medicinal plant in South Africa for various indications, the scientific basis of its anecdotally described, putative anti-HIV properties was investigated. To this aim, we used an accelerated extraction–purification approach; extracts and therein sub-fractions of A. amatymbica were assessed in a cell-based assay targeting the replication of prototypic CXCR4-tropic (NL4-3) or CCR5-tropic (NL-AD87) HIV-1 strains.Sub-fractions of the extracts were generated through semi-preparative high performance liquid chromatography (HPLC) fractionation into triplicates of 96-well microtitre plates; they were then separately subjected to biological analysis and ultra performance liquid chromatography (UPLC) time-of-flight (TOF) analysis. A correlation plot was generated between the biological and chemical data to identify the biologically active compounds in those fractions that showed significant selective anti-HIV activity. The results indicated that rosmarinic acid was present in the wells that showed promising anti-HIV activity in vitro indicating that this compound is at least in part responsible for the antiviral properties of the A. amatymbica extracts. However, compared to standard retroviral inhibitor the anti-HIV activity of the pure compound was found to be only quite moderate. Nevertheless, the accelerated approach described herein increases the efficiency of screens towards identifying drug candidates much earlier in the discovery stage.     

正交试验法研究决明子提取工艺

采用正交试验法优选出了决明子中蒽醌衍生物的最佳提取工艺条件为：50％乙醇水为浸提剂;固液比1：5,提取温度70℃,提取时间2h。总蒽醌衍生物的产率为0．83％。如果采用醋酸酸化预处理工艺,可使蒽醌衍生物(抗癌、抗菌有效部位)的产率增加0．19％。通过溶剂萃取和沉淀分离得到两大有效部位：脂溶性部位(蒽醌衍性物)和水溶性部位(蒽醌甙类)。     

Identification of catalytically active groups of lipoxygenase from wheat germ

Catalytically active groups of lipoxygenase in wheat germs have been identified. Blocking of catalytically active groups by specific reagents, dependence of the enzyme activity on pH, enthalpy of ionization of pK1 and pK2, the enzyme photoinactivation allowed to make a conclusion that imidasole and hydroxyl groups take part in lipoxygenase catalytic cycle.     

Use of equivalence classes and factor sets in the analysis of botanical data

The concept of equivalence classes and factor sets known from set theory is applied to the theory and practice of botanical studies. The properties of taxonomic, typological, and gradient factor sets and their connection with a comparative floristic and phytoindicative analysis are considered. The enlarged groups of regimes are proposed for ten ecological factors of Tsyganov’s phytoindication scales. An integrated botanical information system (IBIS) allowing one to perform a computer processing of botanical data using factor sets is described.     

Nutrients and phytochemicals: from bioavailability to bioefficacy beyond antioxidants

The effect of any dietary compound is influenced by the active bioavailable dose rather than the dose ingested. Depending on the individual predisposition, including genetics and medication, a bioavailable dose may cause different magnitudes of effects in different people. Age might affect the predisposition and thus the requirements for nutrients including phytonutrients (e.g. phytochemicals such as flavonoids, phenolic acids and glucosinolates). These are not essential for growth and development but to maintain body functions and health throughout the adult and later phases of life; they are 'lifespan essentials'. Major mechanisms involved in chronic, age-related diseases include the oxidant/antioxidant balance, but the latest research indicates indirect effects of dietary bioactives in vivo and adaptive responses in addition to direct radical scavenging.