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Journal of Cleaner Production 219 (2019) 846e855
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Journal of Cleaner Production
journal homepage: www.elsevier .com/locate/ jc lepro
Lemna gibba and Eichhornia crassipes extracts: Clean alternatives fordeacidification, antioxidation and fungicidal treatment of historicalpaper
Wafaa A. Mohamed a, Maisa M.A. Mansour a, Mohamed Z.M. Salem b, *
a Conservation Department, Faculty of Archaeology, Cairo University, Giza, 12613, Egyptb Forestry and Wood Technology Department, Faculty of Agriculture (EL-Shatby), Alexandria University, Alexandria, Egypt
a r t i c l e i n f o
Article history:Received 30 May 2018Received in revised form6 February 2019Accepted 9 February 2019Available online 14 February 2019
Keywords:Antioxidant activityAntifungal activityAntiradical activityInk corrosionMetal chelatingPlant extracts
* Corresponding author.E-mail addresses: [email protected], m
(M.Z.M. Salem).
https://doi.org/10.1016/j.jclepro.2019.02.0970959-6526/© 2019 Elsevier Ltd. All rights reserved.
a b s t r a c t
In this research Lemna gibba (L) and Eichhornia crassipes (E) ethanolic extracts were added to pure cel-lulose substrate to produce impregnated interleaving papers (LIP) and (EIP). These products are proposedto cure historical paper undergoing acidification, oxidation and fungal infection. The extracts wereanalysed using Gas Chromatography/Mass Spectrometer (GC/MS) and polyphenolic compounds wereassessed. The products were tested on model decayed paper showing identical characteristics of his-torical paper, on which pH values were measured, transition metals concentrations were evaluated usingInductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES) and samples were investigatedusing Scanning Electron Microscope combined with Energy Dispersive Spectroscopy (SEM-EDX)respectively. Radical scavenging and antioxidation activities of the extracts were also assessed using 1,1-diphenyl-2-picryl-hydrazyl free radical DPPH$. Results demonstrated a significant increase (P < 0.01) inthe DPPH$ free radical scavenging with increasing concentration in the following order vitaminC> BHTz (L) extract> (E) extract. Results showed also that both (LIP) and (EIP) products effectivelyneutralized the acidity of decayed paper after 7 day treatment and evidently chelated transition metals.Zn2þ and Fe2þ were better chelated by (LIP) treatment in the order; Zn2þ> Fe2þ> Pb2þ> Cu2þ, whilePb2þ and Cu2þ were greater removed by (EIP) treatment in the order Pb2þ> Cu2þ> Zn2þ> Fe2þ. Up to90% radical scavenging was achieved at 320.00 mg/mL concentration of (L) extract and 667.296 mg/mLconcentration of (E) extracts. Aspergillus niger, Penicillium roqueforti and Eurotium chevalieri growth areinhibited at 1000 mg/mL concentration of LIP with considerable fungal spots elimination. Our findingsestablished LIP and EIP products as novel natural origin alternative for effective synergic deacidification,antioxidation, antiradical, metal chelation and fungicidal treatment of historical paper.
© 2019 Elsevier Ltd. All rights reserved.
1. Introduction
Historical paper and archival objects are mostly damagedbecause of iron gall ink (IGI); the most commonwritingmedia usedfor ages till the 20th century (Kolar et al., 2006;Male�si�c et al., 2005).This kind of ink causes series of destructive alterations (Bulska andWagner, 2004) leading to the degradation of paper cellulose(Neevel, 1995). This process comprises acid hydrolysis (Kolar et al.,2006), metal-catalyzed oxidation and ink corrosion (Neevel, 1995;Male�si�c et al., 2005). Transition metals originated from IGI, such as
Fe2þ, Cu2þ and Zn2þ play a part in the formation of organic radicalsand peroxides through Fenton and Fenton-like reactions and resultin the oxidative decay and breakdown of paper cellulose (Zucchiattiet al., 2005; Hastrup et al., 2011). Accordingly, paper fragmentationtakes place causing massive loss of the original text (Poggi et al.,2010). In favorable conditions of relative humidity and tempera-ture, molds grow on cellulosic substrates (Zotti et al., 2008; Kavkleret al., 2011). Trichoderma, Aureobasidium, Penicillium, Geosmithia,Aspergillus, and Paecilomycescan were found on many archival andhistorical objects (Ljaljevi�c-Grbi�c et al., 2013; Hassan and Mansour,2018) causing further degradation through dehydration and hy-drolysis (Zabel and Morrell, 1992). These processes representcrucial threats for our precious archival objects.
Conventional treatments of paper are mostly based on wet
W.A. Mohamed et al. / Journal of Cleaner Production 219 (2019) 846e855 847
chemical interventions. Deacidification for example, which is theessential treatment to slow down acid hydrolysis and embrittle-ment of paper, is applied by immersion in aqueous and non-aqueous solutions (Reibland and de Groot, 1999; Poggi et al.,2010). These treatments can raise the pH up to 7e9 (Strli�c et al.,2006), but unfortunately, paper degradation proceeds governedby oxidative processes in the presence of transition metals (Kolar,1997). To hinder the oxidative degradation (Potthast et al., 2008),radical scavenging and inhibition treatments are further applied(Neevel, 2010). Exhaustive chemical interventions usually havedrawbacks (W�ojciak, 2015; Zervos and Alexopoulou, 2015). On thecontrary, the plant kingdom offers enormous number of naturaland clean antioxidant compounds. Polyphenols are excellent ex-amples; they are widely distributed and recently have been studiedfor health (Proch�azkov�a et al., 2011; Ghosh et al., 2015) and foodpurposes (Abootalebian et al., 2016).
Some plant species proved to give a synergic action of freeradical scavenging, antioxidation (Frankel and Meyer, 2000; Prioret al., 2005), superoxide anion radical scavenging and ferrous ionschelating (Pereira et al., 2009; Dai and Mumper, 2010; Gülçin et al.,2010). Moreover, some natural products like; essential oils (Wanget al., 2005; Salem et al., 2016a, 2018) and extracts proved to beeffective to inhibit mold growth over cellulosic materials (Yusufet al., 2012; Salem et al., 2016b, 2019). Aquatic plants biomasseshave earlier been studied for treatment of ink corrosion (Mohamedet al., 2018).
In this study, we propose innovative clean products for thetreatment of decayed historical paper using two naturally grownaquatic plants; Lemna gibba (L) and Eichhornia crassipes (E) extracts.The extracts were impregnated into interleaving paper to performan eco-friendly alternative and non-wet treatment for the conser-vation of archival objects with a synergic action of deacidification,radical scavenging, metal chelating and mold growth inhibition.
2. Materials and methods
2.1. Extraction and analytical procedures
2.1.1. Plant collection and extractionFresh aquatic plants, Lemna gibba L. Lemnaceae (L) and water
hyacinth, Eichhornia crassipes (E) were collected in September 2017from local ponds in Egypt (Lat: 31� 50 49.250400, Long: 30� 180
41.144400). Plants were washed and dried then ground into finepowder using a laboratory mill. For the extraction, 25 g from eachplant were extracted by soaking in a 500-mL conical flask con-taining 200mL of ethanol and wrapped with aluminum foil thenleft for a week (Gülçin et al., 2010). Within this period, theextraction procedure was repeated three times (EL-Hefny et al.,2017) changing the solvent every two days. The chlorophyll pig-ments were removed by passing the extracts through activatedcharcoal (Salem, 2005). Ethanol extracts were filtered throughcotton plugs and filter paper, consecutively; the filtrates werecollected and the solvent was evaporated using a rotary evaporator(Rotavapor RII, BucHI eGermany) at 40 �C. The yield of the etha-nolic extracts of (L) and (E) were 4.12 and 5.30 g/100 of driedsamples respectively. Extracts were stored at 4 �C in sealed brownvials prior to use.
2.1.2. GC-MS analysis of the ethanolic extractsEthanolic extracts were analyzed for their chemical composition
using a Trace GC Ultra-ISQ Mass Spectrometer (Thermo Scientific,Austin, TX, USA) with a direct capillary column TGe5MS apparatus(30m� 0.25mm� 0.25 mm film thickness) at the Atomic andMolecular Physics Unit, Experimental Nuclear Physics Department,Nuclear Research Centre, Egyptian Atomic Energy Authority, Inshas,
Cairo, Egypt. Following conditions described by Salem et al. (2016c).The components were identified by comparing their retentiontimes and mass spectra with WILEY 09 and NIST 11 mass spectraldatabases (Adams, 2007).
2.1.3. Determination of total phenolic, flavonoid and tannincontents
The total phenolic (TP) contents were determined using Folin-Ciocalteu phenolic reagent according to the procedure describedby Slinkard and Singleton (1977) and Gülçin et al. (2010), withminor modification. Gallic acid was used as the standard phenoliccompound. The total flavonoid contents were determined usingaluminum chloride colorimetric method (Marinova et al., 2005;Salem et al., 2016c), with (þ)-catechin as an equivalent to standardflavonoid compound. Total tannins were measured according toMakkar et al. (1993) using tannic acid as the standard for tanninquantification.
2.1.4. Radical scavenging activity by DPPH· assayThe antioxidant activities of ethanolic extracts of (L) and (E)
were evaluated using 1,1-diphenyl-2-picryl-hydrazyl(DPPH$) freeradical scavenging method (Hosseinihashemi et al., 2015) in serialdilution of extracts’ concentrations (5, 10, 20, 30, 40, 50, 60, 70, 80,and 90 mg/mL). Ascorbic acid (vitamin C) and Butylated hydrox-ytoluene (BHT) were used as the reference standards. Experimentswere performed in triplicates, and the average absorbance wascalculated for each concentration.
2.2. Production of (LIP) and (EIP)
2.2.1. Impregnation with plant extractsPlants extracts were prepared at the concentrations; 1000, 500
and 250 mg/mL, by dilution in ethanol. Whatman No. 1 pure cellu-lose filter papers were impregnated with the prepared concentra-tions by soaking for 30min and drying repeatedly for 12 timeswithin 72 h. Three replicates (filter paper) were impregnated witheach concentration in a way that each filter paper received in total30mL of the concentrated extract. Extracts impregnated filter pa-pers were air-dried at the laboratory conditions using fans. This wasthe last step in producing impregnated (L) interleaving paper (LIP)and (E) interleaving paper (EIP). These were cut into 75� 25mmstrips for testing.
2.2.2. Preparation of decayed model paperModel paper is made to substitute historical paper when
destructive tests are undertaken. Model inked paper is prepared byblotting a 1 cmwidth solid iron-gall ink (IGI) line onWhatman filterpaper. This was cut into 75� 25mm strips, and then thermallyaged by heating for 48 h at 90 �C in a sealed box at 75% RH tomaximize paper decay (Poggi et al., 2010).
2.2.3. Testing (LIP) and (EIP) effectivenessDecayed paper strips were placed separately on a glass sheet.
Each strip was overlaid with one of (LIP) or (EIP) strips under 0.013psi pressure by covering with glass slides. This setup was left at28 �C and 70% RH for 1 day and repeated for another 7 day exper-iment. The tests were undertaken on triplicates. The test wasfurther conducted on authentic 19th century fragments of a Copticholy orthodox book, in which, ink writings appeared on both sidesof the papers. The fragments were initially examined and ink lineswere analyzed using Scanning Electron Microscopy with combinedEnergy Dispersive Spectroscopy SEM-EDX (FEI Quanta 200 ESEMFEG, with tungsten electron source, at 20 KV).
W.A. Mohamed et al. / Journal of Cleaner Production 219 (2019) 846e855848
2.2.4. ICP-OES analysis of metalsInductively Coupled Plasma-Optical Emission Spectrometry ICP-
OES (Prodigy7 Simultaneous ICP, Teledyne Leeman Labs, USA) wasused to assess Fe, Cu, Zn and Pb contents in (LIP), (EIP) and to defineany change in the concentrations after treatment. Samples wereinitially digested in acidic reagent (7mL of 65% HNO3 þ 2mL of 30%H2O2) (Merk-Germany). Concentrations were estimated in ppm toexpress the chelated metals amounts. Metal chelating efficienciesof (LIP) and (EIP) were calculated using the following equation;
(I) %¼ 100 (Mt e Mc)/Mc (1)
where I (Chelating efficiency), Mc (metal concentration of controlbefore treatment) and Mt (metal concentration after treatment).
2.2.5. pH measurements of paperDecayed paper strips were subjected to pHmeasurement before
and after treatment with (LIP) and (EIP). According to the standard;SLC 3:1966 (I.U.C./5), 1 g sample of paper was cold extracted in50mL distilled water under agitation for 24 h. The measurementswere performed in triplicate using Radiometer Copenhagen PHM62Standard pH Meter.
2.3. Antifungal trial evaluation
From an initial pilot experiment, only 1000 mg/mL concentration(LIP) positively shown antifungal activity, so the antifungal trialevaluation was continued using this product (Fig. S1).
Model pure cellulose paper (Whatman No. 1) was cut into smallsquare chips (20� 20mm) using scalpel. They were sterilized byexposure to UV light for 48 h, after 6 h autoclaving at 121 �C anddrying in an oven at 105 �C for 24 h (Salem et al., 2016a,b,c). Sporessuspension (2.5mL) of each of the following fungi; Aspergillus niger,Penicillium roqueforti, and Eurotium chevalieri. Additionally, a mixedculture of fungi was taken into test tubes and shacked for 10min(Mansour and Salem, 2015). Paper chips were inoculated separatelywith single suspensions and mixed culture. The colonization wasevaluated after six weeks.
Table 1Chemical composition of Lemna gibba ethanolic extract.
RTa Compound name Class
3.97 1,2-Cyclohexanedione Cycloalkenes or diketon9.13 b-Citronellol Acyclic monoterpenoid9.66 trans-Geraniol Acyclic monoterpenoid17.57 5b,7bH,10a-Eudesm-11-en-1a-ol Sesquiterpenes20.48 Z-(13,14-Epoxy)tetradec-11-en-1-ol acetate Triterpenic acid21.17 Hexahydro farnesyl acetone Isoprenoid ketone21.43 3-Hydroxydodecanoic acid Medium-chain hydroxy22.55 Methyl 14-methylpentadecanoate Fatty acid ester22.72 Dasycarpidan-1-methanol acetate(ester) Nitro compounds23.20 Palmitic acid Saturated fatty acid23.38 Monopalmitin Glycerol esterified fatty23.96 Palmitic acid ethyl ester Fatty acid ester25.05 (9Z)-9-Octadecenyl (9Z)-9-hexadecenoate Fatty acid ester25.78 6-Butyryl-5,7-dimethoxy-4-propylcoumarin Aromatic hydroxyketon25.99 Glyceryl linolenate Fatty acid26.21 Palmitoleic acid Saturated fatty acid26.38 Phytol Acyclic diterpene alcoh26.52 Methyl hexadecadienoate Fatty acid ester26.64 E,E,Z-1,3,12-Nonadecatriene-5,14-diol Alcohol26.95 Ethyl linoleate Fatty acid ester27.15 Oleic acid Saturated fatty acid
a RT: Retention Time (min.).b MW: Molecular Wight (g/mol).c SI: Standard Index.d RSI: Reverse Standard index.
The antifungal activity of 1000 mg/mL concentration (LIP) wastested on the infected paper chips (Fig. S1). This was carried out byplacing the infected chips between two (LIP) chips, which were cutinto the same size. They were overlaid with glass slides and left atroom temperature for 24, 48, and 72 h periods. After each period,the treated paper chips were removed, then placed in Petri dishescontaining potato dextrose agar (PDA)medium and incubated, thenthe fungal growth was inspected.
Treated paper chips, which showed visually good inhibitionwere subjected to ESEM (SEM model-a FEI Quanta 200 ESEM FEGscanning electron microscope) examination to evaluate the anti-fungal activity of (LIP) by measuring the hyphal growth of thestudied fungi (Hassan and Mansour, 2018).
2.4. Colorimetric measurement
The color change induced by the deliberate fungal inoculation ofpaper chips was determined before and after treatment. This wascarried out using OPTIMATECH 3100 (Nippon Denshoku, Tokyo,Japan) calibrated by a standard white board (D65/10, X ¼ 82.43,Y¼ 87.40, Z¼ 89.77). L*a*b* values were calculated according to theequation described by Ali et al. (2018).
2.5. Statistical analysis
Total phenolics, flavonoids and tannins of (L) and (E) extractspresented as mean± SD, were statistically analyzed with One WayAnova and compared using LSD0.05 (SAS, 2001). Concentration-DPPH$ inhibition regressions were also statically analyzed with theBiostat ver. (2.1) computer program for Probit analysis (2011) tomeasure the IC50.
3. Results
3.1. Chemical compositions, total phenolics, flavonoids and tanninscontents of the extracts
In Table 1, the chemical composition of (L) extract is presented.
Area % Molecular Formula MWb SIc RSId
e 1.60 C6H8O2 112 666 7523.32 C10H20O 156 833 9081.01 C10H18O 154 639 8211.10 C15H26O 222 707 7350.37 C16H28O3 268 705 7394.95 C18H36O 268 770 860
fatty acid 3.23 C12H24O3 216 720 7569.92 C17H34O2 270 785 7871.53 C20H26N2O2 326 703 71911.92 C16H32O2 256 807 843
acid 0.73 C19H38O4 330 723 72611.88 C18H36O2 284 835 8512.21 C34H64O2 504 620 634
es 4.68 C18H22O5 318 708 9354.31 C21H36O4 352 779 8151.23 C16H30O2 254 742 780
ol 12.78 C20H40O 296 810 8617.32 C17H30O2 266 752 7691.75 C19H34O2 294 723 7384.23 C20H36O2 308 778 7837.63 C18H34O2 282 767 780
Table 3Total phenolic, flavonoid and tannin contents of L. gibba and E. crassipes extracts.
Treatment Total phenolics (mgGAE a/mg extract)
Total flavonoids (mgCAE b/mg extract)
Total tannins (mgTAE c/mg extract)
L. gibbaethanolicextract
13.46± 0.60a 6.80± 0.21a 5.27± 0.35a
E. crassipesethanolicextract
7.63± 0.64b 4.20± 0.30b 3.13± 0.25b
All values are mean ± standard deviation of three replicates.Means with the same letter within the same column are not significantly differentaccording to LSD0.05.
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The most abundant components are phytol (12.78%), palmitic acid(11.92%), methyl 14-methylpentadecanoate (9.92%), oleic acid(7.63%), methyl hexadecadienoate (7.32%), hexahydro-farnesylacetone (4.95%), 6-butyryl-5,7-dimethoxy-4-propylcoumarin(4.68%), glyceryl linolenate (4.31%), and ethyl linoleate (4.23%).Table 2 shows that the main chemical constituents of (E) extract arelinoleic acid (47.22%), a-linolenic acid (20.21%) and oleic acid(15.73%).
Table 3 shows that a significant amount of total phenolic(13.46± 0.60 mg GAE/mg extract), flavonoids (6.80± 0.21 mg CAE/mg extract) and tannins (5.27± 0.35 mg TAE/mg extract) is found in(L) extract compared to (E) extract.
a GAE: Gallic acid equivalents.b CAE: (þ)-Catechin equivalents.c TAE: Tannic acid equivalents.
3.2. Antioxidant and antiradical activities
The antioxidant activities of (L) and (E) extracts are comparedwith Vitamin C and BHT (Fig. 1). The linear regression equationswere;
Y1 ¼ 0.69Xþ16.13; R2¼ 0.94 (2)
Y2 ¼ 0.55Xþ13.80; R2¼ 0.84 (3)
Y3 ¼ 0.53Xþ46.30; R2¼ 0.93 (4)
Y4¼ 0.97X-0.80; R2¼ 0.96 (5)
Where Y1 (for L extract), Y2 (for E extract), Y3 (for Vitamin C), andY4 (for BHT).
Results demonstrated a significant increase (P< 0.01) in theDPPH$ free radical scavenging with increasing concentration in thefollowing order vitamin C> BHTz (L) extract > (E) extract. Ac-cording to the data reported in Table 4, Vitamin C has the highestradical scavenging activity with the lowest IC50 value (10.04 mg/mL). But it can be observed that the (L) extract possesses a higherantioxidant activity with IC50 value (38.16 mg/mL) compared to BHTreference (IC50 44.88 mg/mL). Furthermore, results indicated that50% scavenging of DPPH$ free radicals required 56.99 mg/mL of (E)extract. However, the maximum concentration 667.296 mg/mLresulted in 90% of the DPPH$ free radicals (Fig. S2). On the otherhand, (L) extract proved to have a good antioxidant activity at IC10,IC25, IC50, and IC90.
Table 2Chemical composition of Eichhornia crassipes ethanolic extract.
RTa Compound name
8.17 a-Terpineol15.73 Spiro[bornane-3,2'-[1,3]dioxolan]-2-ol, exo-17.85 5,6,6-Trimethyl-5-(3-oxobut-1-enyl)-1-oxaspiro[2.5]octan-4-one18.61 1-(17-Hydroxy-15,16-dimethoxy-19,21-epoxyaspidospermidin-1-yl)ethanone18.72 E,E,Z-1,3,12-Nonadecatri ene-5,14-diol19.36 Ricinoleic acid19.51 Dasycarpidan-1-methanol, acetate (ester)20.43 Z-(13,14-Epoxy)tetradec-11-en-1-ol acetate21.26 Linoleic acid21.38 a-Linolenic acid23.20 Monopalmitin24.76 1-Linoleoyl glycerol26.04 9,10-Epoxystearic acid27.16 Oleic acid
a RT: Retention Time (min.).b MW: Molecular Wight (g/mol).c SI: Standard Index.d RSI: Reverse Standard index.
3.3. Deacidification
Results of pHmeasurements of decayed paper treated with (LIP)and (EIP) indicated that the products behaved similarly. The pHvalues slightly increased after 1 day treatment period from 5 to 5.5.However, neutrality was achieved after 7 day treatment period.
3.4. Transition metals in iron gall ink (IGI)
Historical paper fragments demonstrated IGI induced corrosionof paper. Results of SEM examination (Fig. 2) showed the charac-teristic signs of decay such as degraded cellulose fibers and crackedink lines. Results of EDX analysis of IGI (Table S1) showed thechemical composition of 19th century IGI with typical catalytictransition metals impurities; Pb, Cu and Zn.
3.5. Metal chelating efficiency
Results of ICP-OES analysis of transition metals concentrationsin (LIP) and (EIP), after 1 day treatment on decayed historical paperand 7 day treatment tests on decayed model paper, are given inTable 5. The increase in Cu2þ, Fe2þ, Zn2þ and Pb2þ concentrationsrepresent the amounts chelated from the decayed paper by treat-ments. Results in Table 5 indicated that considerable amounts oftransition metals were chelated and quantities increased by time.The capacity and preference of chelating transition metals weredifferent. The calculated efficiencies demonstrated that (LIP) gave
Class Area % Molecular Formula MWb SIc RSId
Monoterpene alcohol 0.38 C10H18O 154 652 632Alcohol 0.70 C12H20O3 212 630 593Ketone 0.42 C16H30O2 254 683 667Nitro compounds 0.57 C23H30N2O5 414 768 732Alcohol 0.71 C19H34O2 294 712 707Fatty acid 1.29 C18H34O3 298 733 690Nitro compounds 0.49 C20H26N2O2 326 695 681Triterpenic acid 1.46 C16H28O3 268 735 720Fatty acid 47.22 C18H32O2 280 901 854Fatty acid 20.21 C18H30O2 278 889 885Glycerol esterified fatty acid 0.65 C19H38O4 330 709 708Fatty acid glycerol 2.99 C21H38O4 354 796 782Fatty acid 1.03 C18H34O3 298 713 683Fatty acid 15.73 C18H34O2 282 904 875
Fig. 1. DPPH$ free radical scavenging activities of different concentrations (5e90 mg/mL) of (L) extract, (E) extract, vitamin C and BHT (Butylated hydroxytoluene).
Table 4DPPH$ free radical scavenging of (L)a and (E)b extracts compared to Vitamin C andBHT c.
Tested materials IC50d
(mg/mL)Slope X2 e Lower limit Upper limit
L 38.16 1.41± 0.12 13.74 33.34 43.76E 56.99 1.19± 0.18 25.05 32.25 73.02Vitamin C 10.04 1.12± 0.11 6.36 7.30 12.73BHT 44.88 2.12± 0.15 53.10 33.19 61.94
a L: Lemna gibba ethanolic extract.b E: Eichhornia crassipes ethanolic extract.c BHT: Butylated hydroxytoluene.d IC50: Data expressed as mg/mL. Lower IC50 values indicate the highest radical
scavenging activity.e X2: Chi square.
Fig. 2. SEM micrograph of ink induced corrosion of a historical fragment.
Table 5Results of ICP-OES of metal concentration analysis of (LIP) and (EIP) before and aftertreatment of decayed paper.
Metal LIP a EIP b
Mc c/ppm Mt d/ppm Mc/ppm Mt/ppm
1 day I % e 7 day I % 1 day I % 7 day I %
Cu 46 53 15 66 43.5 43 55 28 75 74Fe 102 111 8.8 209 105 120 147 22.5 152 27Zn 5 10 100 19 280 5 5.4 8 8.5 70Pb 73 91 24.6 115 57.5 78 96 23 163 109
a LIP: Lemna gibba ethanolic extract (L) impregnated interleaving papers.b EIP: Eichhornia crassipes ethanolic extract (E) impregnated interleaving papers.c Mc: Metal concentration of control before treatment (ppm).d Mt: Metal concentration after treatment (ppm).e I %: Chelating efficiency %.
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better performance of Zn2þ and Fe2þ chelation after 7 day treat-ment in the order Zn2þ> Fe2þ> Pb2þ> Cu2þ. On the other hand,(EIP) behaved differently giving greater removal of Pb2þ and Cu2þ in
the order Pb2þ> Cu2þ> Zn2þ> Fe2þ after the same treatmentperiod.
3.6. Cleaning impact
Results of visual examination of the treated historical paperfragments indicated that the legibility of writing on the manuscriptslightly increased. The IGI halos induced by transition metalsmigration out of ink lines diminished. Chelating of migrated metalsindicated that (LIP) and (EIP) treatments improved the appearanceof the historical paper (Fig. S3).
3.7. Antifungal activity trial
The results of the antifungal trial (Fig. 3) demonstrated that(1000 mg/mL) concentration (LIP) failed to perform any fungal in-hibition after 24 and 48 h periods. Complete fungal growth ofAspergillus niger, Penicillium roqueforti, Eurotium chevalieri and themixed culture occurred. However, fungal growth was slightly
Fig. 3. Treatment tests of A. niger, P. roqueforti, E. chevalieri and their mixed culture inoculated paper using 1000 mg/mL LIP for 12, 48 and 72 h.A Aspergillus nigerB Penicillium roquefortiC Eurotium chevalieriD Mixed culture.
W.A. Mohamed et al. / Journal of Cleaner Production 219 (2019) 846e855 851
inhibited after 72 h.Results of SEM examination (Fig. 4) showed the fungal coloni-
zation. This was accompanied by symptoms of microbial attack; thegrowing hyphae between the fiber cells, the abundant growths ofmycelia over the fiber bundles and the erosion and cavities on fi-bers. These features decreased by (LIP) treatment for 72 h as the
hyphae growth together with the other features were reduced.
3.8. Chromatic enhancement
Table 6 shows that the colour of the paper chips became slightlydarker and spotted due to the fungus colonization. The reference
Fig. 4. SEM micrographs showing 1000 mg/mL (LIP) inhibited growth of A. niger, P. roqueforti and E. chevalieri and their mixed culture.a) SEM micrograph of plain cellulose paper showing clear distribution and bonded fibers.b) SEM micrograph of 1000 mg/mL concentration LIP showing swollen and enlarged fibers due to (L) extract impregnation.c1-c4) SEM micrographs showing A. niger inoculated paper chips, the arrows refer to the intense fungal colonization growing on cellulose fibers.d1-d4) SEM micrographs of P. roqueforti inoculated paper chips showing a dense spread of fungal colonization hyphae and the bundles.e1-e4) SEM micrographs of P. roqueforti inoculated paper after treatment with 1000 mg/mL (LIP) showing reduction in the fungal growth.f1-f3) SEM micrographs E. chevalieri of inoculated paper chips, where Conidia and ascospores are very clear; the arrow refers to the conidial heads of fungal colonization extendedbetween the fiber bundles with noticeable change in the surface features of fibers; the rupture of the cell walls under the fungal infestation, circles refer to that the hyphae causederosion and cavities.g1-g2) SEM micrographs of E. chevalieri inoculated paper after treatment with 1000 mg/mL (LIP), where the arrows refer to the changes in the structure of ascospores and decreasedConidia.h1-h4) SEM micrographs of mixed culture from A. niger, P. roqueforti and E. chevalieri inoculated paper chips, where the hyphae colonization penetrated the fiber bundle andtransferred from a fiber to another through pits.i1-i2) SEM micrographs of mixed culture from A. niger, P. roqueforti and E. chevalieri inoculated paper chips treated with 1000 mg/mL (LIP), where reasonable decrease in the fungalgrowth occurred due to the treatment and fibers appear clear without erosion.
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Table 6Results of Colorimetric measurement, the chromatic parameters L*a*b* of paper chips, tested fungus inoculated and (LIP) treated.
Treatment A. niger P. roqueforti E. chevalieri Mixed culture
L* a* b* L* a* b* L* a* b* L* a* b*
T1 42.93 1.2 0.1 46.51 1.05 �0.58 41.52 2.13 13.28 41.09 3.48 6.49T2 43.64 1.19 �0.58 46.71 1.09 �1.18 45.12 0.96 6.12 41.5 1.28 5.25C 47.16 1.35 �2.69 47.16 1.35 �2.69 47.16 1.35 �2.69 47.16 1.35 �2.69D1, L*,a*,b* �4.23 �0.15 2.79 �0.65 �0.3 2.11 �5.64 0.78 15.97 �6.07 2.13 9.18D2, L*,a*,b* �3.52 �0.16 2.11 �0.45 �0.26 1.51 �2.04 �0.39 8.81 �5.66 �0.07 7.94DE1 5.07 2.23 16.95 11.21DE2 4.11 1.60 9.05 9.75
T1¼ Inoculated with the fungus.T2¼ Inoculated with the fungus then treated with 1000 mg/mL (LIP).C¼ Control (impregnated with 1000 mg/mL of L extract).
W.A. Mohamed et al. / Journal of Cleaner Production 219 (2019) 846e855 853
assay L*47.16 a*1.35 b*-2.69 changed after A. niger inoculation toL*42.93 a*1.21 b*0.1 withDE¼ 5.07, which is considered an extremecolour difference was observed after the inoculation with thisfungus. Results of Colorimetric measurement indicated that thecolour was enhanced by the (1000 mg/mL) concentration (LIP)treatment into L*43.64 a*1.19 b*-0.58 with DE ¼ 4.11. Almost thesame trend was observed in P. roqueforti, E. chevalieri and the mixedculture measurements. The initial green colour observed in(1000 mg/mL) concentration (LIP) product may due to the extractcolour.
Values of DE of P. roqueforti, A. niger, the mixed culture andE. chevalieri infected paper were ascending in the order 2.23, 5.07,11.21 and 16.95 changed after (1000 mg/mL) concentration (LIP)treatment into 1.60, 4.11, 9.75 and 9.05 respectively. Reduced DEindicate that the treatment enhanced the chromatic values of thefungal induced spots without affecting the colour of the plain areas.
4. Discussion
The use of aquatic plants to remove heavy metals from waterresources has yet been increasing (Schneider and Rubio, 1999;Varga et al., 2013; Allam et al., 2015). Recently, Lemna gibba andEichhornia crassipes biomass had a new application in the field ofconservation of archival objects (Mohamed et al., 2018). Theyproved to offer deacidification and stabilization against degrada-tion and ink corrosion.
In a closer look to plant products with potential antioxidant andantiradical activities (Erasto et al., 2007; Richard et al., 2008;Vladimir-Kne�zevi�c et al., 2011; Mezni et al., 2014; Elagbar et al.,2016; Kozłowska et al., 2016), the authors found that the com-mon feature in these products is the phenolic constituents(Vladimir-Kne�zevi�c et al., 2011; Pisoschi et al., 2015). The extracts ofLemna gibba (L) and Eichhornia crassipes (E) have considerableamounts of phynolics, flavonoids and tannins. The former demon-strated to have twice the amount of phenolics, in addition togreater amounts of flavonoids and tannins. There is a strong posi-tive correlation between antioxidant activities and contents ofphenolic acids and tannins (Yang et al., 2002; Vladimir-Kne�zevi�cet al., 2011). The study findings closely agree with what waspointed out and so (LIP) demonstrated better performance than(EIP). The redox properties of phenolics make them behave as areducing agents, hydrogen donators and single oxygen quenchers,as well as metal chelators (Rice-Evans et al., 1996; Yang et al., 2001;Pereira et al., 2009; Dai and Mumper, 2010).
Linoleic, a-linolenic, palmitic, stearic and oleic fatty acids arealso known to have great antioxidant activity and radical scav-enging (Erasto et al., 2007; Richard et al., 2008; Mezni et al., 2014;Elagbar et al., 2016; Kozłowska et al., 2016).
This explains the better performances of (L) extract as a
powerful DPPH$ antiradical, giving (90%) inhibition even at(320 mg/mL) concentration. While, (E) extract achieved the sameinhibition efficiency at 667.296 mg/mL. However, the former have apotential antioxidant activity, approaching that's of BHT, but did notovercome Vitamin C's.
The number and position of hydroxyl groups in phenolic acidmolecule enhances its antiradical and antioxidant effects. Thus theantioxidant efficiency of mono-phenols increases by a second hy-droxyl group at the ortho- or para-positions, and further increasesby one or two methoxy substitutions in ortho-positionwith respectto the hydroxyl group (Fukumoto and Mazza, 2000; Dewick, 2002;Erkan et al., 2011). Hydroxyl groups prevent the cyclic generation ofnew radicals by donating hydrogen to react with reactive oxygen(Choi et al., 2002; Heim et al., 2002; Valent~ao et al., 2002a,b). In theink induced corrosion process of historical paper, there is animportant involvement of reactive oxygen species (ROS) in additionto free iron ions. The predominant (ROS) include free radicals suchas superoxide anion radicals (O2
· ), hydroxyl radicals (OH・), andnon-free radical species such as H2O2 and singlet oxygen (Gimatet al., 2016). Even so, free iron ions could produce H2O2 throughoxygen reduction then Fenton reactions leading to highly reactiveand non-selective HO· radicals that attack cellulose and generateRO2
· and HO2· radicals (Emery and Schroeder, 1974; Shafizadeh and
Bradbury, 1979; Neevel, 1995; Gimat et al., 2016). Polyphenoliccompounds as well as flavonoids capture ROS, flavonoids furthercoordinatewith transitionmetals to catalyze electron transport andpromote free radical capture. During oxidation ROS are continu-ously produced. Therefore, antioxidants are important to coun-teract ROS production by defense mechanisms to achieve thebalance between the generation and the inactivation of ROS (Oktayet al., 2003).
This can explain, how chelating transition metal ions Cu2þ, Fe2þ,Zn2þ and Pb2þ supported the antioxidative effects of (LIP) and (EIP)products by retarding metal catalyzed oxidation and scavengingfree radicals. Chelating free migrating metal ions also contributedin the cleaning process by reducing ink halos, which disfigured theappearance of the historical paper and making the writings morelegible. In one of the most popular conservation treatments ofhistorical paper, myo-inositol hexaphosphate (phytate) is used todecrease the catalytic properties of Fe2þ but, these treatmentscould not do the same for other transition metal ions such as Cu2þ,Zn2þ and Pb2þ and they usually left behind. However, these ionscan further enhance the corrosiveness of the ink causing instabilityand rapid deterioration (Maestre et al., 1992; Neevel, 1995; Kolaret al., 2003). In this study the proposed treatment using (LIP) and(EIP) products demonstrated considerable chelating activity of Fe2þ
in addition to other transition metal ions providing stabilizationagainst pro-oxidative metal ions by complextion (Shahidi et al.,2006; Pereira et al., 2009; Porfírio et al., 2014; Samsonowicz
W.A. Mohamed et al. / Journal of Cleaner Production 219 (2019) 846e855854
et al., 2017).In the conservation point of view, it is important for any pro-
posed treatment that, it should not affect the appearance of theartifact in a negative way. This is an essential criterion for acceptinga suggested treatment for application in conservation of culturalobjects. In this research the synergic action of antioxidation, radicalscavenging and metal chelating in addition to simple application ofthe proposed treatment make it a more effective, eco-friendly andnon-wet alternative to conventional chemical treatments.
Several studies have reported the biodegradation of cellulosicmaterials by different mold species (Kavkler et al., 2011; Ljaljevi�c-Grbi�c et al., 2013; Mansour et al., 2015; Ali et al., 2018; Hassanand Mansour, 2018). In the current study, Aspergillus niger, Penicil-lium roqueforti, Eurotium chevalieri and their mixed culture causeddecay features and fungal spots on pure cellulose paper. Hyphaecolonization caused colour change and disfigured the appearanceof the paper substrate. The DE value higher than 5 indicated anextreme colour difference after the inoculation with A. niger andshifted to a darker colour (del Hoyo-Mel�endez and Mecklenburg,2011; Ali et al., 2018). The proposed (1000 mg/mL) concentration(LIP) treatment for 72 h effectively improved the appearance of thepaper. As the inhibition activity reduced the fungal growth. Theresults proved that the product can be a useful biocide for pre-venting mold growth on papers. The proposed treatment can alsobe more advantageous and cleaner than other conventional treat-ments such as freeze-drying, gamma rays, and ethylene oxidefumigation (Michaelsen et al., 2013). The impact of the proposedproducts, on other physical properties of paper, in different treat-ment durations and with different concentrations, is still underinvestigations.
5. Conclusion
The effectiveness of innovated interleaving paper products (LIP)and (EIP), containing Lemna gibba and Eichhornia crassipes etha-nolic extracts as active ingredients, in the treatment of historicalpaper were tested. The pH measurements data confirmed thateffective neutralization of acidic paper was achieved after 7 daytreatment period. Results of DPPH$ free radical scavenging andantioxidation experiments indicated that these propertiesincreased with increasing concentration of active ingredients. Up to90% radical scavenging was achieved at 320 mg/mL of (L) and667.296 mg/mL of (E). Transition metals removal was attained byboth products, although (LIP) chelated more Zn2þ and Fe2þ while(EIP) chelated more Pb2þ and Cu2þ. Microbial inhibition test resultsproved that 1000 mg/mL concentration (LIP) treatment inhibitedthe growth features of Aspergillus niger, Penicilliumroqueforti,Eurotiumchevalieri and their mixed culture with no negative chro-matic change.
Conflicts of interest
All authors declare that there are no present or potential con-flicts of interest among the authors and other people or organiza-tions that could inappropriately bias their work.
Acknowledgements
Authors wish to thank Prof. Ahmad K. Hegazy, from the BotanyDepartment, Faculty of Science, Cairo University, for his sincerehelp in supplying plant samples.
Appendix A. Supplementary data
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.jclepro.2019.02.097.
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