SUNScholar - Browsing by Author "Fawole, Olaniyi A."

Browsing by Author "Fawole, Olaniyi A."

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Antibacterial, antioxidant and tyrosinase-inhibition activities of pomegranate fruit peel methanolic extract
(BioMed Central, 2012-10) Fawole, Olaniyi A.; Makunga, Nokwanda P.; Opara, Umezuruike L.
Abstract Background This study evaluated, using in vitro assays, the antibacterial, antioxidant, and tyrosinase-inhibition activities of methanolic extracts from peels of seven commercially grown pomegranate cultivars. Methods Antibacterial activity was tested on Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Klebsiella pneumonia) using a microdilution method. Several potential antioxidant activities, including radical-scavenging ability (RSA), ferrous ion chelating (FIC) and ferric ion reducing antioxidant power (FRAP), were evaluated. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin and kojic acid as positive controls. Furthermore, phenolic contents including total flavonoid content (TFC), gallotannin content (GTC) and total anthocyanin content (TAC) were determined using colourimetric methods. HPLC-ESI/MSn analysis of phenolic composition of methanolic extracts was also performed. Results Methanolic peel extracts showed strong broad-spectrum activity against Gram-positive and Gram-negative bacteria, with the minimum inhibitory concentrations (MIC) ranging from 0.2 to 0.78 mg/ml. At the highest concentration tested (1000 μg/ml), radical scavenging activities were significantly higher in Arakta (83.54%), Ganesh (83.56%), and Ruby (83.34%) cultivars (P< 0.05). Dose dependent FIC and FRAP activities were exhibited by all the peel extracts. All extracts also exhibited high inhibition (>50%) against monophenolase and diphenolase activities at the highest screening concentration. The most active peel extract was the Bhagwa cultivar against monophenolase and the Arakta cultivar against diphenolase with IC50 values of 3.66 μg/ml and 15.88 μg/ml, respectively. High amounts of phenolic compounds were found in peel extracts with the highest and lowest total phenolic contents of 295.5 (Ganesh) and 179.3 mg/g dry extract (Molla de Elche), respectively. Catechin, epicatechin, ellagic acid and gallic acid were found in all cultivars, of which ellagic acid was the most abundant comprising of more than 50% of total phenolic compounds detected in each cultivar. Conclusions The present study showed that the tested pomegranate peels exhibited strong antibacterial, antioxidant and tyrosinase-inhibition activities. These results suggest that pomegranate fruit peel could be exploited as a potential source of natural antimicrobial and antioxidant agents as well as tyrosinase inhibitors.
Applications of cytokinins in horticultural fruit crops : trends and future prospects
(MDPI, 2020-08-22) Aremu, Adeyemi O.; Fawole, Olaniyi A.; Makunga, Nokwanda P.; Masondo, Nqobile A.; Moyo, Mack; Buthelezi, Nana M. D.; Amoo, Stephen O.; Spichal, Lukas; Dolezal, Karel
Cytokinins (CKs) are a chemically diverse class of plant growth regulators, exhibiting wide-ranging actions on plant growth and development, hence their exploitation in agriculture for crop improvement and management. Their coordinated regulatory effects and cross-talk interactions with other phytohormones and signaling networks are highly sophisticated, eliciting and controlling varied biological processes at the cellular to organismal levels. In this review, we briefly introduce the mode of action and general molecular biological effects of naturally occurring CKs before highlighting the great variability in the response of fruit crops to CK-based innovations. We present a comprehensive compilation of research linked to the application of CKs in non-model crop species in different phases of fruit production and management. By doing so, it is clear that the effects of CKs on fruit set, development, maturation, and ripening are not necessarily generic, even for cultivars within the same species, illustrating the magnitude of yet unknown intricate biochemical and genetic mechanisms regulating these processes in different fruit crops. Current approaches using genomic-to-metabolomic analysis are providing new insights into the in planta mechanisms of CKs, pinpointing the underlying CK-derived actions that may serve as potential targets for improving crop-specific traits and the development of new solutions for the preharvest and postharvest management of fruit crops. Where information is available, CK molecular biology is discussed in the context of its present and future implications in the applications of CKs to fruits of horticultural significance.
Changes in physical properties, chemical and elemental composition and antioxidant capacity of pomegranate (cv. Ruby) fruit as five maturity stages
(Elsevier, 2013) Fawole, Olaniyi A.; Opara, Umezuruike Linus
This study was conducted to investigate the physical and compositional changes as well as antioxidant properties of pomegranate fruit (cv. Ruby) at five distinct maturity stages between 54 and 139 days after full bloom (DAFB). Physico-chemical properties such as fruit mass, size, juiciness, colour, total soluble solids (TSS), pH, titratable acidity (TA), individual organic acids and sugars, and phenolic composition were investigated. Mineral element concentrations were determined using inductively coupled plasma optical emission spectrometry (ICP-OES) while total antioxidant capacity was measured by DPPH scavenging activity (DPPH) and ferric ion reducing power (FRAP). Results showed that major compositional changes in fruit are developmentally regulated. Significant increases in total soluble solids (TSS), sugars (glucose and fructose) and anthocyanins composition, coupled with significant decline in titratable acidity (TA), organic acids and total phenolics occurred with advancing maturity. Principal component analysis (PCA) showed that fruit at advanced maturity stages (132 and 139 DAFB) were characterized by intense peel and aril pigmentation and better juice quality. PCA results also showed that peel and aril colour attributes and indices of sugar/acid ratio (TSS/TA and BrimA index) could be useful measures of fruit maturity and ripeness for ‘Ruby’ pomegranate cultivar, and therefore might be suitable for the development of reliable fruit maturity index to assess fruit optimal maturity.
Chemical and phytochemical properties and antioxidant activities of three pomegranate cultivars grown in South Africa
(Springer Verlag, 2011-02) Fawole, Olaniyi A.; Opara, Umezuruike Linus; Theron, K. I.
A comparative study of chemical contents and antioxidant activities of three pomegranate cultivars (‘Arakta’, ‘Bhagwa’ and ‘Ruby’) grown in South Africa was conducted. Fresh pomegranate juice (PJ) of each cultivar were assessed for soluble solid contents (SSCs), pH and titratable acidity (TA), while extracted juice samples were evaluated for total phenolic (TP), including total tannins (TT), proanthocyanidins (Pcy), total flavonoids, anthocyanins and gallic acids (GA) using spectrophotometric methods. The antioxidant properties of the juice samples were evaluated against stable 2, 2– diphenyl–1–picryl hydrazyl, as well as in ferric reducing ability of plasma (FRAP) and QuantiChrom™ (TAC) antioxidant assays. There were significant differences in the chemical properties of the cultivars. SSC, TA and pH varied between the range of 14.07–15.10 °Brix, 0.22– 0.28 g/100 ml and 3.32–3.64, respectively. ‘Bhagwa’ had the highest TP (449.9 mg/100 ml), 1.3-fold and 1.6-fold higher than ‘Arakta’ and ‘Ruby’, respectively. The strongest total antioxidant activity was exhibited by ‘Bhagwa’ with an antioxidant index of 95.7%, followed by ‘Arakta’ (93.2%) and ‘Ruby’ (79.9%). PJ phytochemical properties (TP, TT, Pcy, GA) and antioxidant activity (FRAP and TAC) were significantly correlated (r2= 0.509–0.885) with each other.
Classification of 'Granny Smith' apples with different levels of superficial scald severity based on targeted metabolites and discriminant analysis
(German Botanical Society, 2016) Mditshwa, Asanda; Fawole, Olaniyi A.; Vries, Filicity; Van der Merwe, Kobus; Crouch, Elke; Opara, Umezuruike Linus
To study the metabolic changes in ‘Granny Smith’ apples with different severities of superficial scald, fruit were stored in normal refrigerated air (0°C, 95% RH) for 12 weeks followed by 7 d shelf-life under room conditions (20°C, 65% RH). Fruit were graded to five groups based on scald severity and analysed for ethylene, α-farnesene and 6-methyl-5-hepten-2-one (MHO) levels. Reactive oxygen species (ROS) were measured by confocal laser-scanning microscopy on apple peel treated with fluorescent probe 2’,7’-dichlorodihydrofluorescein diacetate. Ethylene production rate, α-farnesene and MHO contents and ROS intensity increased with increasing scald severity but declined in severely scalded fruit. Malondialdehyde (MDA) concentration in fruit peel, a measure of membrane damage, increased linearly (R=0.891) with increase in scald severity. Discriminant analysis was used to classify fruit by scald severity on the basis of metabolites accumulated. The stepwise model indicated that three attributes (ROS, ethylene production and MDA) contributed significantly (R2≥0.5) to the separation of the five scald severity indexes, with ROS having the highest contribution (partial R² =0.961; p<0.0001), followed by ethylene (R2=0.718; p<0.0001) and MDA (R2=0.578; p<0.0001).
Effect of drying on the bioactive compounds, antioxidant, antibacterial and antityrosinase activities of pomegranate peel
(BioMed Central, 2016) Mphahlele, Rebogile R.; Fawole, Olaniyi A.; Makunga, Nokwanda P.; Opara, Umezuruike L.
The use of pomegranate peel is highly associated with its rich phenolic concentration. Series of drying methods are recommended since bioactive compounds are highly sensitive to thermal degradation. The study was conducted to evaluate the effects of drying on the bioactive compounds, antioxidant as well as antibacterial and antityrosinase activities of pomegranate peel. Methods Dried pomegranate peels with the initial moisture content of 70.30 % wet basis were prepared by freeze and oven drying at 40, 50 and 60 °C. Difference in CIE-LAB, chroma (C*) and hue angle (h°) were determined using colorimeter. Individual polyphenol retention was determined using LC-MS and LC-MSE while total phenolics concentration (TPC), total flavonoid concentration (TFC), total tannins concentration (TTC) and vitamin C concentration were measured using colorimetric methods. The antioxidant activity was measured by radical scavenging activity (RSA) and ferric reducing antioxidant power (FRAP). Furthermore, the antibacterial activity of methanolic peel extracts were tested on Gram negative (Escherichia coli and Klebsiella pneumonia) and Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) using the in vitro microdilution assays. Tyrosinase enzyme inhibition was investigated against monophenolase (tyrosine) and diphenolase (DOPA), with arbutin as positive controls. Results Oven drying at 60 °C resulted in high punicalin concentration (888.04 ± 141.03 mg CE/kg dried matter) along with poor red coloration (high hue angle). Freeze dried peel contained higher catechin concentration (674.51 mg/kg drying matter) + catechin and –epicatechin (70.56 mg/kg drying matter) compared to oven dried peel. Furthermore, freeze dried peel had the highest total phenolic, tannin and flavonoid concentrations compared to oven dried peel over the temperature range studied. High concentration of vitamin C (31.19 μg AAE/g dried matter) was observed in the oven dried (40 °C) pomegranate peel. Drying at 50 °C showed the highest inhibitory activity with the MIC values of 0.10 mg/ml against Gram positive (Staphylococcus aureus and Bacillus subtili. Likewise, the extracts dried at 50 °C showed potent inhibitory activity concentration (22.95 mg/ml) against monophenolase. Principal component analysis showed that the peel colour characteristics and bioactive compounds isolated the investigated drying method. Conclusions The freeze and oven dried peel extracts exhibited a significant antibacterial and antioxidant activities. The freeze drying method had higher total phenolic, tannin and flavonoid concentration therefore can be explored as a feasible method for processing pomegranate peel to ensure retention of the maximum amount of their naturally occurring bioactive compounds.
Food preservative capabilities of grape (vitis vinifera) and clementinemandarin (citrus reticulata) by-products extracts in South Africa
(MDPI, 2019-03-22) Pfukwa, Trust M.; Fawole, Olaniyi A.; Manley, Marena; Gouws, Pieter A.; Opara, Umezuruike Linus; Mapiye, Cletos
The drive towards sustainable food systems coupled with increased consumer sophistication have prompted innovation in waste valorization. Grape and citrus processing by-products, abundant in the Mediterranean and tropical regions, respectively, are expanding and are sustainable sources of bioactive phytochemicals that can be used as natural preservatives for foods. Phytochemical composition, antioxidant, and antimicrobial properties of extracts from grape pomace (GPE), seeds (GSE), and clementine mandarin peel and pulp (MPE) grown in South Africa were analyzed. Total phenols and carotenoids were highest in GPE followed by GSE and MPE (p ≤ 0.05). Flavonoids and anthocyanins were higher (p ≤ 0.05) in GPE and GSE compared to MPE. The GSE had the highest proanthocyanidins content followed by GPE and MPE (p ≤ 0.05). Ascorbic acid was only detected in MPE, which also had the highest titratable acidity and lowest pH values (p ≤ 0.05). The GSE had the highest antioxidant potency composite index followed by GPE and MPE (p ≤ 0.05). The order of antimicrobial activity of the extracts was MPE > GSE > GPE (p ≤ 0.05). Current findings show that GSE is a potential antioxidant while MPE holds promise as an antimicrobial for the food industry.
Harvest and postharvest factors affecting bruise damage of fresh fruits
(KeAi Communications Co., Ltd., 2019) Hussein, Zaharan; Fawole, Olaniyi A.; Opara, Umezuruike Linus
Fresh fruits are susceptible to bruising, a common type of mechanical damage during harvest and at all stages of postharvest handling. In quest of developing and adoption of strategies to reduce bruise damage, it is of utmost importance to understand major factors influencing bruise susceptibility of fresh produce at these stages. This review presents a critical discussion of factors affecting bruising during harvest and postharvest handling of fresh fruits. Excessive compression forces during harvesting by handpicking or machines, and a series of impacts during harvesting, transport and packhouse operations can cause severe bruise damage. The review has further revealed that bruising is dependent on a number of other factors such as produce maturity, ripening, harvest time (during the day or season) and time lapse after harvest. The susceptibility to bruising is partly dependent on how these factors alter the produce physiological and biochemical properties, and the environmental conditions such as temperature, humidity and several other postharvest treatments. Hence, the successful applications of harvesting techniques by use of trained personnel and proper harvesting equipment are essential to reduce both the incidence and severity of bruising. Furthermore, the careful selection of postharvest handling temperature and other treatments can increase resistance of fresh produce to bruise damage.
The implication of chemotypic variation on the anti-oxidant and anti-cancer activities of sutherlandia frutescens (L.) R.Br. (Fabaceae) from different geographic locations
(MDPI, 2020) Zonyane, Samkele; Fawole, Olaniyi A.; La Grange, Chris; Stander, Maria A.; Opara, Umezuruike L.; Makunga, Nokwanda P.
Extracts of Sutherlandia frutescens (cancer bush) exhibit considerable qualitative and quantitative chemical variability depending on their natural wild origins. The purpose of this study was thus to determine bioactivity of extracts from different regions using in vitro antioxidant and anti-cancer assays. Extracts of the species are complex and are predominantly composed of a species-specific set of triterpene saponins (cycloartanol glycosides), the sutherlandiosides, and flavonoids (quercetin and kaempferol glycosides), the sutherlandins. For the Folin-Ciocalteu phenolics test values of 93.311 to 125.330 mg GAE/g DE were obtained. The flavonoids ranged from 54.831 to 66.073 mg CE/g DE using the aluminum chloride assay. Extracts from different sites were also assayed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging method and ferric reducing anti-oxidant power (FRAP) methods. This was followed by an in vitro Cell Titer-Glo viability assay of various ecotypes using the DLD-1 colon cancer cell line. All test extracts displayed anti-oxidant activity through the DPPH• radical scavenging mechanism, with IC50 values ranging from 3.171 to 7.707 µg·mL−1. However, the degree of anti-oxidant effects differed on a chemotypic basis with coastal plants from Gansbaai and Pearly Beach (Western Cape) exhibiting superior activity whereas the Victoria West inland group from the Northern Cape, consistently showed the weakest anti-oxidant activity for both the DPPH• and FRAP methods. All extracts showed cytotoxicity on DLD-1 colon cancer cells at the test concentration of 200 µg·mL−1 but Sutherlandia plants from Colesburg (Northern Cape) exhibited the highest anti-cancer activity. These findings confirm that S. frutescens specimens display variability in their bioactive capacities based on their natural location, illustrating the importance of choosing relevant ecotypes for medicinal purposes.
Southern African indigenous fruits and their byproducts : prospects as food antioxidants
(Elsevier, 2020) Pfukwa, Trust M.; Chikwanha, Obert C.; Katiyatiya, Chenaimoyo L. F.; Fawole, Olaniyi A.; Manley, Marena; Mapiye, Cletos
The discourse regarding plant-based preservatives for food application has generally revolved around extracts from commercial fruits, vegetables, herbs and spices with indigenous fruits (IFs) on the periphery, with little investment into their valorisation. While being important food sources at community level, IFs and their byproducts are also incorporated into medicinal remedies, combating various diseases. Their ethnomedicinal usage indicates potent bioactive profile that alleviate effects of oxidative stress, which accompany disease in vivo. This is supported by in vitro antioxidant activity of the IFs and their byproducts. As such, the current review explores the potential of bioprospecting extracts from nine IFs and their byproducts as food antioxidants. Evidence presented shows that IFs have high content of bioactive compounds further translating to high antioxidant activity. Research gaps in information concerning in vitro bioactivity warrant further research to provide impetus for valorisation and food application of IFs.

Browsing by Author "Fawole, Olaniyi A."

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