Antioxidant properties of guava fruit : comparison with some local fruits

Two varieties of guava fruit were analyzed for total phenol contents, ascorbic acid contents and antioxidant activities. The antioxidant activities were assessed based on the ability of the fruit extracts in 50% ethanol to scavenge DPPH, reduce Fe(III) to Fe(II) and to bind to Fe(II) ion. The results were compared to several other local fruits as well as orange. It was found that the guava fruit contains relatively high amounts of antioxidant. It also has high primary, but low secondary antioxidant potential. Storage at 4oC has the effect of increasing ascorbic acid content, and the non-peeled fruit has higher total phenol and ascorbic acid contents compared to the peeled fruit. The length and width of the seedy guava were also monitored over a period of 17 weeks to define specific stages of fruit ripening

Optimization of reaction conditions for preparing carboxymethyl cellulose from sago waste

Sago pulp (57% w/w) isolated from sago waste was converted to carboxymethyl cellulose (CMC) by etherification using sodium monochloroacetate and sodium hydroxide. The reaction was optimized against temperature, concentration and reaction time. The optimized product has a large degree of substitution (DS) of 0.821, which compared favorably to other forms of cellulose. Fourier Transform Infrared spectra (FTIR) were used to characterize the product and starting sago pulp. Digital photographs of sago waste and sago pulp showed the expected rough woody structure while that of the CMC generated from the pulp showed a smooth surface morphology

Lipase-catalyzed acylation of quercetin with cinnamic acid

Acylation of quercetin with cinnamic acid catalyzed by Candida antarctica lipase B (CAL-B) or Pseudomonas cepacia lipase C (PCL-C) was investigated. Specifically, the effects of reaction duration, incubation temperature, and molar ratio of substrates on bioconversion yield, initial rate of reaction, and regioselectivity were investigated. Three new acylated quercetin analogues were produced: quercetin 4′-cinnamate (C24H16O8), quercetin 3′,4′-dicinnamate (C33H22O9), and quercetin 7,3′,4′-tricinnamate (C42H28O10). The effects of the lipase-catalyzed acylation conditions on the bioconversion yields varied across the conditions. The initial rate of reaction of acylation of quercetin with cinnamic acid catalyzed by CAL-B and PCL-C was similar. In the presence of CAL-B, acylation mainly took place at the C-4′-OH, generating mostly quercetin 4′-cinnamate; whereas with PCL-C, acylation mainly took place at both the 4′- and 3′-hydroxyls, generating quercetin 3′,4′-dicinnamate. Thin-layer-chromatography analysis showed that the three acylated quercetin analogues had higher lipophilicity when compared with quercetin. In silico investigation revealed that quercetin 4’-cinnamate and quercetin 3′,4′-dicinnamate are likely to be orally active pharmacological drugs

Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia

Background: Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family. Methods: Acacia auriculiformis, Bauhinia kockiana, Bauhinia purpurea, Caesalpinia pulcherrima, Calliandra tergemina, Cassia surattensis, Leucaena leucocephala, Peltophorum pterocarpum, and Samanea saman were extracted with aqueous methanol and dichloromethane:methanol mixture to test for antioxidant and antibacterial activities. The Folin-Ciocalteu assay was conducted to quantify the total phenolic content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antibacterial activity was assessed using disc diffusion (Kirby-Bauer) assay. Screening for major classes of phytochemical was done using standard chemical tests. Results: B. kockiana flowers and C. pulcherrima leaves contained high total phenolic content (TPC) and strong DPPH radical scavenging ability with TPC of 8280 ± 498 mg GAE/100 g, IC50 of 27.0 ± 5.0 μg/mL and TPC of 5030 ± 602 mg GAE/100 g, IC50 of 50.0 ± 5.0 μg/mL respectively. Positive correlation was observed between TPC and free radical scavenging ability. Most extracts showed antibacterial activity against Gram positive bacteria at 1 mg, while none showed activity against Gram negative bacteria at the same dose. All extracts (except Samanea saman flower) showed antibacterial activity against two strains of methicillin resistant Staphylococcus aureus (MRSA) with MID values ranging between 100 μg/disc and 500 μg/disc. Conclusion: The potential source of antioxidant and antibacterial agents, especially for MRSA infection treatments were found in B. kockiana, C. pulcherrima, C. tergemina and P. pterocarpum. These preliminary results would be a guide in the selection of potential candidates for further pharmacological study and in search of new drug candidate in treating MRSA infections

Enzymatic synthesis of quercetin oleate esters using Candida antarctica lipase B

Objectives: To investigate the lipase-catalyzed acylation of quercetin with oleic acid using Candida antarctica lipase B. Results: Three acylated analogues were produced: quercetin 4′-oleate (C33H42O8), quercetin 3′,4′-dioleate (C51H74O9) and quercetin 7,3′,4′-trioleate (C69H106O10). Their identities were confirmed with UPLC–ESI–MS and 1H NMR analyses. The effects of temperature, duration and molar ratio of substrates on the bioconversion yields varied across conditions. The regioselectivity of the acylated quercetin analogues was affected by the molar ratio of substrates. TLC showed the acylated analogues had higher lipophilicity (152% increase) compared to quercetin. Partition coefficient (log P) of quercetin 4′-oleate was higher than those of quercetin and oleic acid. Quercetin 4′-oleate was also stable over 28 days of storage. Conclusions: Quercetin oleate esters with enhanced lipophilicity can be produced via lipase-catalyzed reaction using C. antarctica lipase B to be used in topical applications

Bioactivity-guided isolation of anticancer agents from Bauhinia kockiana Korth

Background: Flowers of Bauhinia kockiana were investigated for their anticancer properties. Methods: Gallic acid (1), and methyl gallate (2), were isolated via bioassay-directed isolation, and they exhibited anticancer properties towards several cancer cell lines, examined using MTT cell viability assay. Pyrogallol (3) was examined against the same cancer cell lines to deduce the bioactive functional group of the phenolic compounds. Results: The results showed that the phenolic compounds could exhibit moderate to weak cytotoxicity towards certain cell lines (GI50 30 - 86 µM), but were inactive towards DU145 prostate cancer cell (GI50 > 100 µM). Conclusion: It was observed that pyrogallol moiety was one of the essential functional structures of the phenolic compounds in exhibiting anticancer activity. Also, the carboxyl group of compound 1 was also important in anticancer activity. Examination of the PC-3 cells treated with compound 1 using fluorescence microscopy showed that PC-3 cells were killed by apoptosis

Health care provider's experience and perspective of cervical cancer screening in Singapore: A qualitative study

BackgroundIn Singapore, the current cervical cancer screening (CCS) coverage rate of 48% falls below the national target of 70%. Health care providers (HCPs) play a critical role in promoting CCS uptake. However, there is limited understanding of the perspectives of HCPs regarding CCS. Hence, we aimed to understand the challenges encountered by HCPs delivering CCS in different care settings in the Singapore health system. We also aimed to explore perspectives on newer features of CCS such as self-sampling and HPV genotyping.MethodsPhysicians, nurses, program administrators and laboratory technicians involved with CCS were invited for a one-on-one semi-structured interview conducted over Zoom between May to August 2021. The interviews were transcribed and analyzed using thematic analysis.ResultsEighteen HCPs from 12 institutions were interviewed. Most participants were women (61.1%) and worked in public health institutions (72.2%). For factors influencing CCS, nine key themes were identified and organized into four categories: (1) patient factors, (2) HCP factors, (3) health system factors and (4) health promotion factors. Key themes commonly highlighted by study participants were related to patients' preferences and acceptance for screening, the processes of delivering CCS, the national priority for cervical cancer and the effectiveness of existing health promotion efforts. Five key themes were identified for CCS innovations. Self-sampling was viewed favorably to increase CCS uptake, while primary HPV screening with HPV partial genotyping had higher sensitivities to detect pre-cancers and cancers compared to cytology. Extended HPV genotyping beyond HPV16/18 could play an important role in CCS with increasing HPV vaccination coverage, as well as in the management of persistent HPV infection.ConclusionIn Singapore, HCPs face multiple challenges for CCS in practice. Insights from this study are directly relevant to, and useful for developing policies around national CCS programs and treatment guidelines

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London