Isolation and characterization of antioxidant and antimicrobial compounds from Anacardium occidentale L. (Anacardiaceae) leaf extract

AbstractThe extracts obtained from Anacardium occidentale leaf were investigated for antioxidant and antimicrobial activities. Bioassay-guided fractionation using DPPH autobiographic analysis of the EtOAc soluble fraction of the crude extract resulted in the isolation of agathisflavone (1) and a mixture of quercetin 3-O-rutinoside (2) and quercetin 3-O-rhamnoside (3). Characterization of the isolated compounds was carried out using nuclear magnetic resonance (1D and 2D) and mass spectrometry. The antioxidant activities of the samples were determined using three complementary tests, namely; DPPH-radical scavenging, total antioxidant capacity (TAC) and ferric reducing antioxidant power (FRAP). The antimicrobial activity of the samples was evaluated using the disc diffusion and broth microdilution methods. The results indicated that the mixture (ratio 2:1) of compounds (2) and (3) was most active in its capacity to scavenge free radicals in the DPPH assay [IC50=0.96±0.01μg/mL] compared to the ethyl acetate (EtOAc) fraction, the ascorbic acid and quercetin standards. The mixture of compounds (2) and (3) exhibited the highest activities in the TAC assay (5332.00±3.38mgAAE/g, 8562.00±5.43mgQE/g) and FRAP assay (15,136.00±7.14mgAAE/g, 199,530.00±94.12mgQE/g) compared to the EtOAc fraction. The fractions of the extract showed comparatively better activities against gram-negative than the gram positive ones with the broadest spectrum of activities demonstrated for the ethyl acetate fraction. No inhibitions were obtained against the fungal strains investigated. The isolated compounds from the plant possess essentially inhibitory rather than cidal activities against these organisms with the Minimum Bactericidal Concentrations (MBCs) >2.0mg/mL in all cases. The mixture of compounds 2 and 3 showed higher activity than compound 1 with the former having MIC as low as 0.25mg/mL against Pseudomonas aeruginosa and Clostridium sporogens, 0.5mg/mL against Staphylococcus aureus and 1.0mg/mL against Escherichia coli and Klebsiella pneumonia strains investigated while the latter has an MIC of 1.0mg/mL against most of the organisms.This study concluded that the extracts and isolated compounds had strong antioxidant and moderate antibacterial activities and could be effective in the management of oxidative stress related diseases. These findings also justified the use of this plant’s extracts in folk medicine

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Antioxidant activities of Terminalia ivorensis leaf extracts and its isolated constituent

This study evaluated antioxidant activities of the Terminalia ivorensis leaf extracts. One compound was isolated using open column chromatography and activity directed fractionation methods. The compound was characterised using Nuclear Magnetic Resonance Spectroscopy (1H and 13C NMR) technique. Isolated compound (1) was identified as methyl-3,4,5-trihydroxybenzoate (methyl  gallate) and reported from this plant for the first time. Quantitative antioxidant activities of the crude extract, various solvent   fractions and the isolated compound (1) were evaluated using: DPPH, nitric oxide scavenging, ferric reducing power (FRAP) and total antioxidant capacity assays. The samples demonstrated varying degrees of antioxidant activities and isolated compound (1)   exhibited the best activity. This study demonstrated that Terminalia ivorensis leaf extracts and the isolated compound (1) possessed potent antioxidant activities. Isolated compound (1) is several times better than the standard (ascorbic acid) in some of the assays. Compound (1) could be effective in the management of oxidative stress related diseases and may assist in drug development

Isolation and characterization of antioxidant compounds from Annona senegalensis leaf extracts

Annona senegalensis leaf extract is used in the management of oxidative related diseases. In this work, we investigated the plant’s crude extracts for its bioactive constituents with a view to identify new and potent natural antioxidant compounds from natural source. A DPPH assay directed fractionation of the ethyl acetate fraction was achieved by open column chromatography using silica gel or Sephadex LH-20 as a stationary phase. Two compounds were isolated and characterized using Nuclear Magnetic Resonance (NMR) and infrared spectroscopy. The compounds were identified as: 2-(3,4-dihydroxyphenyl)- 3,4-chroman-3,5,7-triol, catechin (1), and quercetin-O-glycoside (2). Quantitative antioxidant activities of the extracts and isolated compound (1) were evaluated using: Total Antioxidant Capacity (TAC), Ferric Reducing Antioxidant Power (FRAP), DPPH spectrophotometric, Nitric Oxide scavenging (NO) and Ferrous Ion Chelation assays. In addition, Total Phenol Content (TPC) of each of the samples was determined. In DPPH assay, compound 1 exhibited highest activity, IC50 = 0.03 ± 0.01 mg/mL. The ethyl acetate and butanol fractions were the most active fractions. All the samples tested in this assay are less potent than the ascorbic acid used as a standard, IC50 = 0.01 ± 0.00 mg/mL. In NO assay, ethyl acetate fraction was the most potent among the solvent fractions but less potent than the ascorbic acid (standard). Compound 1 demonstrated comparable activity to the standard with an IC50 = 0.05 ± 0.00 mg/ mL. In ferrous ion chelation assay, ethyl acetate fraction exhibited the highest chelating activity followed by catechin (1) with IC50 of 0.24 ± 0.01 and 1.29 ± 0.03 mg/mL respectively. Both samples are less potent (IC50 =0.05 ± 0.00) than ethylenediamine tetraacetic acid used as a standard. In TAC assay, ethyl acetate fraction exhibited the best activity followed by catechin which showed a better activity expressed as ascorbic acid equivalence per gram (66.57 ± 2.73 and 40.12 ± 3.17 mg AAE/g) respectively. The reverse was observed in FRAP assay, catechin exhibited the best activity with 30.02 ± 0.21 mg AAE/g followed by ethyl acetate fraction which showed a better activity (22.09 ± 2.69 mg/mL). The amount of Total Phenolic Content in the samples ranged from 13.50 to 51.91 gallic acid equivalents (GAE mg/g) with catechin having the highest phenolic content followed by the ethyl acetate fraction. This study concluded that A. senegalensis leaf extracts and its constituent (catechin) possessed moderate antioxidant activity providing rationale for the ethnomedicinal uses of this plant in the management of oxidative stress related diseases.Keywords: Annona senegalensis, Annonaceae, antioxidant activit

Isolation of anti-Candida albicans compounds from Markhamia obtusifolia (Baker) Sprague (Bignoniaceae)

AbstractAn increase in clinical cases of Candidiosis globally as well as fungal resistance to drugs prompted the search for novel anti-Candida albicans agents from plant sources. Leaf extracts of Markhamia obtusifolia were screened for activity against C. albicans in vitro. An acetone extract obtained following serial exhaustive extraction contained mainly the active components with at least four active zones on the bioautogram. Bioassay guided fractionation of this extract led to the isolation of three compounds which inhibited the growth of three C. albicans strains. Based on spectroscopy studies (NMR and MS), the compounds were identified as 3β-hydroxyurs-12-en-28-oic acid, ursolic acid (1) 3β, 19α-dihydroxyurs-12-en-28-oic acid, pomolic acid (2) and 2β, 3β, 19α -trihydroxy-urs-12-en-28-oic acid, 2-epi-tormentic acid (3). The most active compound was 3β, 19α-dihydroxy-12-ursen-28-oic acid (2) with a minimum inhibitory concentration (MIC) value of 12.5 µg/mL for C. albicans isolated from dog and 25.0 µg/mL for C. albicans from cat and ATCC 90028 at 24 h following incubation. However, at 48 h of incubation MICs were >400 µg/mL for all the three compounds isolated. This study indicated that M. obtusifolia could be a potential source of active principles against C. albicans

Antioxidant activity and cytotoxicity study of Leucaena leucocephala (Lam.) de wit leaf extract constituents

Antioxidant activity of the solvent fractions obtained from a 20% aqueous methanol dried leaf extract of Leucaena leucocephala was evaluated using a 1, 1-diphenyl-2-picrylhydrazyl (DPPH) TLC assay. The more polar fractions ethyl acetate and butanol fractions demonstrated strong activity. A DPPH activity-guided fractionation procedure was used to isolate the antioxidant constituents of these active fractions. Separate fractionation of the fractions led to the isolation of epicatechin-3-O-gallate (1) along with two quercetin glycosides: quercetin-3-O-arabinofuranoside (2) and quercetin-3-O-rhamnoside (3) together with apigenin (4). The structures of the isolated compounds were elucidated using spectroscopic techniques NMR (1D and 2D) and mass spectrometry. Compounds 1 and 4 are reported for the first time from this species. In the qualitative antioxidant TLC assay, isolated compounds instantly bleached the DPPH (0.2% in MeOH) purple colour indicating strong antioxidant activity. The antioxidant quercetin glycosides were not cytotoxic at the highest concentration tested (200 ìg/ml), and apigenin was not isolated in sufficient quantity to test for cytotoxicity. Epicatechin-3-O-gallate showed slight cytotoxicity against Vero cells (LC50 = 92 μg/ml).Keywords: Leucaena leucocephala, Fabaceae, antioxidant, DPPH, cytotoxicity.

Antioxidant activities of the extracts and isolated compounds from Treculia africana (Decne) leaf

Antioxidant activities of the crude leaf extract and four solvent fractions: hexane, dichloromethane, ethyl acetate and butanol fractions from Treculia africana leaf were carried out to determine their potentials and suitability in the management of oxidative diseases. Different antioxidant assays (TAC, DPPH, FRAP, inhibition of NO, metal chelating ability were carried out separately to study the activities of the samples. In addition, the total phenolic content of the extracts was evaluated. Bioassay guided fractionation of the most active fraction (ethyl acetate fraction) using repeated column chromatography on Silica gel and Sephadex LH-20 resulted in the isolation of apigenin-6-C-glucopyranoside (isovitexin) (1) and 2,3-dihydrokaempferol-3-O-glucopyranoside (2). The crude extract, solvent fractions and the compounds (1-2) exhibited strong to moderate antioxidant activities in all the tested assays. The two compounds isolated from T. africana are reported for the first time from this plant species. The activities demonstrated by the extracts and isolated compounds could provide rationale for the ethnomedicinal uses of the plant in folk medicine for the management of oxidative stress related diseases.Keywords: Treculia africana, Moraceae, Antioxidant Activity, oxidative stres