Professor Michael Bowyer

This study examined the ability of L-arginine, L-cysteine and L-methionine, to inhibit postharvest senescence of broccoli. Florets were dipped in aqueous solutions of the amino acids at concentrations from 1.0 to 100 mM and stored at 10 °C. A 5 mM dip was found to be optimal in delaying senescence as measured by retention of green colour, vitamin C and antioxidant activity, and a lower level of ethylene production, respiration, weight loss, phenylalanine ammonia lyase (PAL) activity and ion leakage with the benefits being similar for all three amino acids. Arginine, cysteine and methionine have Generally Recognised As Safe (GRAS) status and should have few impediments in obtaining regulatory approval for commercial use if similar effects were found for other leafy vegetables.

Alternaria alternata and Alternaria citri are two major pathogens affecting sweet cherries and citrus respectively which can lead to significant postharvest losses. Alternaria sp. can be controlled with synthetic fungicides, but due to the development of resistance and the need to find sustainable disease control solutions, alternative control measures need to be developed. We have previously shown that extracts derived from lemon waste (pomace) contain bioactive compounds with high levels of antioxidant, antifungal, and antibacterial activities. The aim of this study was to investigate the in vitro antifungal activity of lemon waste aqueous extracts at different concentrations (14, 7, 3.5 and 1 mg mL-1) against both A. alternata and A. citri. The results showed that lemon aqueous extracts suppressed the mycelial growth and spore germination of both species in a concentration-dependent manner. The mycelial growth inhibition (MGI) for A. alternata varied between 31 to 68%, while for the A. citri the MGI varied between 14 to 49%. Scanning electron microscopy showed that lemon waste extracts affected the morphology of both species.These results indicate that the aqueous extracts of lemon by-products contain bioactive compounds which could be potentially useful as an alternative to synthetic fungicides for controlling Alternaria.

Scientific thinking is more than just critical thinking. Teaching the full range of ways to think like a scientist who practices high quality science is rare. A new core subject in the Bachelor of Science at the University of Newcastle was developed to allow students to explore six different ways to thinking scientifically through understanding what high-quality science is and contrasting it with poor science and non-science (pseudoscience). Our evaluation indicates that learning about how to think scientifically and be a scientist who practices high quality science is a skill that is valued by and relevant to first year undergraduate students. An evidence-based pedagogy including active learning, participatory learning, student-centred learning, constructive alignment and quality formative and summative feedback to students can support high learning outcomes.

The aim of this study was to compare phytochemical and antioxidant properties of different parts of Salacia chinensis L. The root of S. chinensis had the highest content of phenolics, flavonoids, proanthocyanidins and saponins (64.4 mg gallic acid equivalent /g dried weight (DW), 106 mg catechin equivalent (CE)/g DW, 43.5 mg CE/g DW and 799.9 mg escin equivalent /g DW, respectively), followed by the stem and leaf. Similarly, results from the four antioxidant assays (ABTS, DPPH, FRAP and CUPRAC) showed that the root of S. chinensis had the highest antioxidant capacity (632.2, 577.1, 443.3 and 365.0 µM trolox equivalent/g DW, respectively), followed by the stem while the leaf had the lowest antioxidant capacity. From HPLC chromatograms, three major compounds were detected from the root and stem of S. chinensis, while more major individual compounds in lower quantities were seen in the leaf. As the root contained high phytochemical and antioxidant properties, future studies are recommended to isolate and identify the major bioactive compounds from the root for further industrial utilization.

Xao tam phan (Paramignya trimera (Oliv.) Guillaum) has been used as an herbal medicine for the treatment of cancer or cancer-like diseases in recent years, particularly in Vietnam. Drying is an important step for preparation of dried materials for storage and further investigation; however, the effects of drying must be taken into account when processing samples, because this can have profound effects on the stability of phytochemical compounds and the biological activity of the dried P. trimera root. As such, this study assessed the effects of four different drying methods (conventional, hot air, vacuum, and microwave) on phytochemical retention and antioxidant capacity of P. trimera root, to identify an optimal drying method for P. trimera root. The results showed that the drying methods significantly affected phytochemical levels and antioxidant capacity of P. trimera root and that among the four drying methods tested, microwave drying (400¿W) had the highest levels of phytochemical compounds, with total phenolic, total flavonoid, proanthocyanidin, and saponin contents of 11.27¿mg GAE, 19.88¿mg RE, 3.98¿mg CE, and 267.15¿mg EE/gram of dried sample, respectively. Dried sample prepared using this method had antioxidant capacity comparable to that of other drying methods. In addition, this method had the shortest drying time (0.28¿h) and consumed the least energy (0.28¿kWh). Therefore, microwave drying should be considered for drying P. trimera root for further investigation and utilization.

The effects of different solvents on the recovery of (i) extractable solids (ES), (ii) total phenolic compounds (TPC), (iii) total flavonoid content (TFC), (iv) vitamin C, and (v) antioxidant activity from lemon pomace waste were investigated. The results revealed that solvents significantly affected the recovery of ES, TPC, TFC, and antioxidant properties. Absolute methanol and 50% acetone resulted in the highest extraction yields of TPC, whereas absolute methanol resulted in the highest extraction of TFC, and water had the highest recovery of vitamin C. 50% ethanol, and 50% acetone had higher extraction yields for TPC, and TFC, as well as higher antioxidant activity compared with their absolute solvents and water. TPC and TFC were shown to be the major components contributing to the antioxidant activity of lemon pomace.

Summary: The papaya (Carica papaya) leaf (PL) contains high levels of saponins and polyphenolic compounds, and historically, it has been used as a folk medicine for numerous ailments, including cancer. PL is traditionally prepared by hot water extraction; however, optimised extraction conditions have not been assessed. This study optimised conditions for the extraction of saponins from PL and assessed their antioxidant capacity and antipancreatic cancer activity. Optimisation was achieved using response surface methodology. Saponins and total phenolic compounds were assessed for their antioxidant, free radical scavenging, ion-reducing capacity, and antipancreatic cancer activity. Optimal aqueous extraction conditions were 85 °C, 25 min. and a water-to-leaf ratio of 20:1 mL g-1. Ethanol extracts demonstrated higher antioxidant, free radical scavenging and ion-reducing capacity, as well as antipancreatic cancer activity. This study revealed that the PL contains numerous bioactive compounds, with significant anticancer activity warranting further studies on the isolation and characterisation of individual bioactive compounds from the PL.

Xao tam phan (. Paramignya trimera (Oliv.) Guillaum) is a Vietnamese traditionally medicinal plant used in the treatment of numerous cancers. The preparation of Xao tam phan extracts including solvent type and extraction method have significant effects on extraction efficiency, phytochemical profile and biological activity. This study aimed to investigate the effects of five various solvents (water, acetonitrile, methanol, ethyl acetate and hexane) and three different extraction methods (conventional, ultrasound-assisted and microwave-assisted) on phytochemical yield and antioxidant capacity of P. trimera root from Vietnam. The results indicate that methanol extracted the maximal yield of phytochemicals from P. trimera and exhibited the greatest antioxidant capacity, with eleven compounds were identified and quantified. Microwave-assisted extraction produced the maximal phytochemical yields (except for total flavonoids) and antioxidant capacity, when compared to conventional and ultrasound-assisted extractions. These data reveal that the use of methanol and microwave-assisted extraction are recommended for extraction of biologically active phytochemicals from P. trimera root for application in the nutraceutical and/or pharmaceutical industries.

The acid dissociation constants (pKas) of a number of novel polymerisable vinyl biaryl compounds, 4-(4'-ethenylphenyl)-pyridine (M1), 4'-ethenyl-(1,1'-biphenyl)-4-ol (M2), 4'-ethenyl-N,N-dimethyl-(1,1'-biphenyl)-3-amine (M3), 4'-ethenyl-(1,1'-biphenyl)-4-methanol (M4), 4'-ethenyl-N,N-dimethyl-(1,1'-biphenyl)-4-amine (M5), 4'-ethenyl-(1,1'-biphenyl)-4-carboxylic acid (M6), 4'-ethenyl-4-hydroxy-5-methyl-(1,1'-biphenyl)-3-carboxaldehyde (M7) were determined in a mixed solvent (THF-water) potentiometric titration at 25 °C and subsequent extrapolation to pure water via the Yasuda-Shedlovsky method. The acidity and basicity of the compounds in THF-water mixtures was observed to decrease with increasing THF fraction and is attributed to the corresponding decrease in the dielectric constant of the solution. To the best of our knowledge, this is the first reported study of pKa values undertaken for this class of compounds. The biaryls, M1-M7, were prepared by microwave-assisted Suzuki cross coupling of 4-vinylphenyl boronic acid with the appropriate aryl bromide and were custom designed for use as functional monomers in the synthesis of molecularly imprinted polymers.

© 2015 Wiley Periodicals, Inc. Vitex agnus-castus (VitexAC) leaves have been used for medicinal purposes for many years. Drying is important to prepare starting materials for further processing, as it is associated with production cost and quality of the materials. Herein, the effects of five different drying conditions on the physical, chemical and antioxidant properties of VitexAC were evaluated. The results showed that 30% of dried leaves with moisture content of less than 7% could be produced from fresh leaves. VitexAC leaves dried by freeze and vacuum drying at 65C had higher levels of bioactive compounds as well as higher antioxidant capacity in comparison with other drying conditions, revealing that these drying conditions are more suitable for drying VitexAC leaves. However, freeze drying is costly and time-consuming; thus, vacuum drying at 65C is suggested for drying the VitexAC leaves as the starting materials for further processing steps. Practical Applications: As drying is an important process to prepare starting materials for further processing steps, it is important to compare different drying methods to identify the most suitable method with low cost and less effect on material quality. The results showed that inappropriate drying conditions resulted in big loss of bioactive compounds and antioxidant capacity. Vacuum drying at 65C was found to be the most suitable method, which can be easily applied for drying Vitex agnus-castus leaves in the industrial scale.

The genus Eucalyptus (Myrtaceae) is mainly native to Australia; however, some species are now distributed globally. Eucalyptus has been used in indigenous Australian medicines for the treatment of a range of aliments including colds, flu, fever, muscular aches, sores, internal pains, and inflammation. Eucalyptus oils containing volatile compounds have been widely used in the pharmaceutical and cosmetics industries for a multitude of purposes. In addition, Eucalyptus extracts containing nonvolatile compounds are also an important source of key bioactive compounds, and several studies have linked Eucalyptus extracts with anticancer properties. With the increasing research interest in Eucalyptus and its health properties, this review briefly outlines the botanical features of Eucalyptus, discusses its traditional use as medicine, and comprehensively reviews its phytochemical and anticancer properties and, finally, proposes trends for future studies.

Lilly pilly (LP) fruit (Syzygium paniculatum Gaertn.) is widely grown in eastern Australia and has been used as food by indigenous Australians. However, there is limited information on its bioactivity. This study investigated the physicochemical and antioxidant properties of the crude fruit extract, identified its bioactive compounds and also assessed its potential anti-proliferative effect on pancreatic cancer cells. Our data showed that the LP extract was water-soluble and possessed a total phenolic content of 96 mg of gallic acid equivalents (GAE)/g, flavonoid levels of 52 mg catechin equivalents (CAE)/g, proanthocyanidin levels of 29 mg CAE/g. Several phenolic compounds such as gallic acid, chlorogenic acid, catechin and epicatechin were identified in the LP extract with levels of 0.39, 2.35, 0.47 and 2.9 mg/g, respectively. Results from six different antioxidant assays revealed that the LP extract pocessed potent antioxidant and free radical scavenging capacity. Although antioxidant capacity of the extract was lower than that of vitamin E, vitamin C and BHT, it could be significantly improved if the extract was to be further purified. We also showed that the LP extract (200 µg/mL) significantly reduced the viability of MiaPaCa-2 and ASPC-1 pancreatic cancer cells to levels comparable to that of the chemotherapeutic agent gemcitabine. For this reason lilly pilly should be further investigated for its health promoting and potential anti-cancer benefits, particularly for pancreatic cancer. © 2014 Elsevier GmbH.

The selectivity and rebinding capacity of molecularly imprinted polymers selective for propranolol (1) using the room temperature ionic liquids [BMIM][BF4], [BMIM][PF6], [HMIM][PF6] and [OMIM][PF6] and CHCl3 were examined. The observed IF (imprinting factor) values for MIPBF4, MIPPF6 and MIP CHCl3 were 1.0, 1.98 and 4.64, respectively. The longer chain HMIM and OMIM systems returned lower IF values of 1.1 and 2.3, respectively. MIP PF6 also showed a ~25% binding capacity reduction vs. MIP CHCl3 (5 µmol g-1vs. 7 µmol g-1 respectively). MIPCHCl3 and MIPPF6 differed in terms of BET surface area (306 m2 g-1vs. 185 m2 g -1), pore size (1.10 and 2.19 nm vs. 0.97 and 7.06 nm), the relative number of pores (Type A: 10.4 vs. 7.5%; Type B: 8.5 vs. 3.0%), and surface zeta potential (-37.9 mV vs. -20.3 mV). The MIP specificity for 1 was examined by selective rebinding studies with caffeine (2) and ephedrine (3). MIP PF6 rebound higher quantities of 2 than MIPCHCl3, but this was largely due to non-specific binding. Both MIPCHCl3 and MIP PF6 showed a higher affinity for 3 than for 2. Reduction in the Room Temperature Ionic Liquid (RTIL) porogen volume had little impact on the polymer morphology, but did result in a modest decrease in IF from 2.6 to 2.3 and in the binding capacity (30% to 19%). MIPCHCl3 retained the highest template specificity on rebinding from CHCl3 (IF = 4.6) dropping to IF = 0.6 in MeOH/[BMIM][PF6]. The MIPCHCl3 binding capacity remained constant using CHCl3, CH2Cl2 and MeOH (46-52%), dropped to 6% on addition of [BMIM][PF6] and increased to 83% in H2O (but at the expense of specificity with IFH2O = 1.4). MIPPF6 rebinding from MeOH saw an increase in specific rebinding to IF = 4.9 and also an increase in binding capacity to 48% when rebinding 1 from MeOH and to 42% and 45% with H2O and CH2Cl2, respectively, although in the latter case the increased capacity was at the cost of specificity with IFCH2Cl2 = 1.2. Overall the MIPPF6 capacity and specificity were enhanced on addition of MeOH. This journal is © the Partner Organisations 2014.