Spectrochimica Acta Part A: Molecular and Biomolecular ... Turmeric (Curcuma longa), java turmeric
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 12441249
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Spectrochimica Acta Part A: Molecular andBiomolecular Spectroscopy
journal homepage: www.elsevier .com/locate /saa
Fourier transform infrared spectroscopy combined with chemometricsfor discrimination of Curcuma longa, Curcuma xanthorrhiza and Zingibercassumunar
http://dx.doi.org/10.1016/j.saa.2014.08.1391386-1425/ 2014 Elsevier B.V. All rights reserved.
Corresponding author at: Department of Chemistry, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Jalan Agatis Kampus IPB Drama16680, Indonesia. Tel./fax: +62 251 8624567.
E-mail address: email@example.com (M. Rafi).
Eti Rohaeti a, Mohamad Rafi a,b,, Utami Dyah Syafitri c, Rudi Heryanto a,ba Department of Chemistry, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Jalan Agatis Kampus IPB Dramaga, Bogor 16680, Indonesiab Biopharmaca Research Center Research and Community Empowerment Institute, Bogor Agricultural University, Jalan Taman Kencana No. 3 Kampus IPB Taman Kencana,Bogor 16128, Indonesiac Department of Statistics, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, Jalan Meranti Kampus IPB Dramaga, Bogor 16680, Indonesia
h i g h l i g h t s
Discrimination of C. longa, C.xanthorrhiza and Z. cassumunar byFTIR. Principal component analysis and
canonical variate analysis are used fordiscrimination. Canonical variate analysis gave
clearer discrimination between thethree species.
g r a p h i c a l a b s t r a c t
a r t i c l e i n f o
Article history:Received 22 March 2014Received in revised form 14 July 2014Accepted 31 August 2014
Keywords:C. longaC. xanthorrhizaZ. cassumunarFTIRChemometricsDiscrimination
a b s t r a c t
Turmeric (Curcuma longa), java turmeric (Curcuma xanthorrhiza) and cassumunar ginger (Zingibercassumunar) are widely used in traditional Indonesian medicines (jamu). They have similar color for theirrhizome and possess some similar uses, so it is possible to substitute one for the other. The identificationand discrimination of these closely-related plants is a crucial task to ensure the quality of the raw mate-rials. Therefore, an analytical method which is rapid, simple and accurate for discriminating these speciesusing Fourier transform infrared spectroscopy (FTIR) combined with some chemometrics methods wasdeveloped. FTIR spectra were acquired in the mid-IR region (4000400 cm1). Standard normal variate,first and second order derivative spectra were compared for the spectral data. Principal componentanalysis (PCA) and canonical variate analysis (CVA) were used for the classification of the three species.Samples could be discriminated by visual analysis of the FTIR spectra by using their marker bands.Discrimination of the three species was also possible through the combination of the pre-processed FTIRspectra with PCA and CVA, in which CVA gave clearer discrimination. Subsequently, the developedmethod could be used for the identification and discrimination of the three closely-related plant species.
2014 Elsevier B.V. All rights reserved.
E. Rohaeti et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 137 (2015) 12441249 1245
Turmeric (Curcuma longa), java turmeric (Curcuma xanthorrhiza)and cassumunar ginger (Zingiber cassumunar) cultivated mostly inthe Java Island are widely used in traditional Indonesian medicines(jamu). C. longa and C. xanthorrhiza are usually aromatic and carmi-native, and are used to treat stomachic, hepatitis, jaundice, diabetes,atherosclerosis and bacterial infections , while Z. cassumunar isusually used to treat various diseases such as asthma, carminative,colic, diarrhea, stomachic, muscle and joint pain [2,3].
The color of their rhizome is yellow to orange for C. longa andC. xanthorrhiza, and pale yellow to yellow for Z. cassumunar. Thesethree plants are belongs to the Zingiberaceae family and therefore,they may have some similar chemical components. Phenolic com-pounds (diarylheptanoid, diarylpentanoid, phenylpropene derivative)and terpenoids (monoterpenoid, sesquiterpenoid, diterpenoid, andtriterpenoid) have been identified in C. longa and some of them alsopresent in C. xanthorrhiza. Diarylheptanoids/curcuminoids (curcumin,demethoxycurcumin, bisdemethoxycurcumin, etc.) and sesquiterpe-noids (curcumene, turmerone, zingiberene, etc.) were found as amajor group of compounds in C. longa and C. xanthorrhiza [4,5].While in Z. cassumunar, phenylbutanoids ((E)-1(3,4-dimethyl-phenyl) butadiene), diarylheptanoids (curcumin), monoterpenoids(sabinene) and sesquiterpenoids (zingiberene) were identified .Curcuminoids are responsible for the color of the three plants usedin this study.
Due to the similarity of the color of their rhizomes which pos-sess some similar uses, substitution for each other could be possi-ble, especially if in the powdered form and if the price ofC. xanthorrhiza is much higher than C. longa or Z. cassumunar. Ifthe substitution occured, it could be a serious problem becauseof inconsistency in their biological properties. In this case, theidentification and discrimination of these closely-related plantsare crucial in order to ensure the quality, safety and efficacy ofthe raw materials before they are converted to final products.Therefore, a rapid, simple and accurate analytical method is essen-tially required for the discrimination of these species.
Several analytical techniques such as spectroscopy (UVVis,FTIR, NMR, and MS) and chromatography (TLC, HPLC, and GC) havebeen used in the development of method for identification and dis-crimination of medicinal plants. Among these techniques, Fouriertransform infrared (FTIR) spectroscopy may be an attractive optionbecause it can meet the criteria of efficient analysis, i.e. easy to use,fast, and inexpensive . Although medicinal plants will contain alarge variety of chemical components, their FTIR spectra some-times are found to differ even in the same species . FTIR hasbeen widely used and is a well-established tool for quality controlin various industries, including herbal industry .
FTIR spectra contain complex data information describing theoverall chemical signal in a sample. Changes in the position andintensity of bands in the FTIR spectra would be associated withthe changes in the chemical composition of a sample. Therefore,FTIR spectra could be used to discriminate closely-related species,although the composition of a chemical compound is certainly notknown . Obvious advantages of FTIR application to discriminatedifferent medicinal plants are not only effective and specific, butalso rapid and non-separative. Discrimination by visual inspectionin the FTIR spectra is not easy because the FTIR spectra pattern isvery complex, and to address this concern, the aid from chemomet-rics methods is needed . The advantage of using chemometricsfor the interpretation of FTIR is the ability to link the spectral patternwith hidden information contained in a sample . FTIR spectralanalysis alone or in combination with chemometrics methods hasbeen extensively used for species identification and discriminationof some closely-related species . Because of the advantages
of FTIR spectroscopy, we used this techniques in combinationwith chemometrics methods for the first time to develop a qualita-tive method for discrimination of C. Longa, C. xanthorrhiza andZ. Cassumunar. This combined method was successfully applied forthe identification and discrimination of the three species.
Material and methods
Potassium bromide (KBr) for spectroscopy was purchased fromSigmaAldrich (St Louis, USA). Analytical-grade ethanol for solventextraction was obtained from Merck (Darmstadt, Germany).
Ninety-nine samples consisting of 35 samples of C. longa, 35samples of C. xanthorrhiza and 29 samples of Z. cassumunar werecollected during 20082010 from 11 regencies (25 samples fromeach regency) in Java Island, Indonesia: Bogor, Sukabumi, Sumed-ang, Purworejo, Wonogiri, Karanganyar, Semarang, Kulonprogo,Pacitan, Ponorogo, and Kediri (Table 1). Voucher specimens weredeposited at Biopharmaca Research Center, Bogor Agricultural Uni-versity, Indonesia. All samples were sieved, dried, and pulverizedprior to use. There are several methods to obtained IR spectra forthe purpose of identification and discrimination as described byZou et al. . In this experiment, the samples were extracted witha solvent and after evaporating the solvent, the extracts wereblended with KBr. This method will provide better resolution inthe identification and discrimination of closely related plants. Ethanol was used to extract the samples and after the extrac-tion process, the ethanol was evaporated by rotary evaporator.These ethanol extracts were then used for FTIR measurement.
FTIR spectroscopy measurement
FTIR spectra were obtained using a Bruker Tensor 37 FTIR spec-trophotometer equipped with deuterated triglycine-sulphate(DTGS) as detector and controlled by OPUS 4.2 software (Bruker,Germany). About 5 mg of ethanol extract of each sample wasmixed with 95 mg of KBr and then pressed to form a tablet. Thesample tablet was placed in the sample compartment and FTIRspectra were recorded in the region of 4000400 cm1 with32 scans/min and resolution of 4 cm1.
FTIR spectral data pre-treatment
Spectral data pre