Chemical composition and anti-in fl ammatory activity of Boswellia ovalifoliolata essential oils from leaf and bark

Introduction

In India,plant parts of species of Boswellia are used to treat arthritis,pain,and respiratory ailments.Boswellic acid,the main compound in Boswellia species is used to treat several in fl ammatory conditions of the skin,eye,and other organs,and the gum is used to treat respiratory disorders such as asthma,bronchitis and laryngitis(Anderson and Davis 2007).Boswellia ovalifoliolata(BO)is an endangered Medicinal Plant of the family Burseraceae that grows in the Seshachalam hill range of the Eastern Ghats of India(Anitha and Sudarsanam 2013;Prabhakar et al.2013).Ten compounds and three new compounds with anti-in fl ammatory activity were isolated from the oleo-gum resin of the plant(Chib et al.2014).Crude extracts of B.ovalifoliolata have traditionally been used for their antimicrobial,antiadipogenesis,and antihyperlipidemic properties,and for their cardiotoxicity,antidiabetic and hepatoprotective activities(Anitha and Sudarsanam 2013;Prabhakar et al.2013;Mahesh et al.2014;Marella et al.2014).Essential oils of B.elongata,B.socotrana,B.dioscorides,B.sacra and B.carteii have been reported.The essential oil of B.elongata,B.socotrana and B.dioscorides were shown to have antimicrobial activity and weak antioxidant activity(Mothana et al.2011).The essential oil of B.sacra and B.carterii is 68.2 and 37.3%α-pinene,respectively(Woolley et al.2012).Al-Harrasi and Al-Saidi(2008)reported the essential oil of B.sacra contains β-Ocimene and limonene as major constituents.Because they contain terpenoids,Boswellia species have commonly been used to treat in fl ammatory conditions;however,the anti-in fl ammatory activity of the essential oil from B.ovalifoliolata had previously not been studied.

Essential oil is a complex mixture of a low molecular weight compound extracted from plants mainly using steam distillation,hydrodistillation,solvents,or supercritical fl uid extraction.Distillation methods are appropriate for powdered material,which remains loose in boiling water,whereas in the case of steam distillation it forms lumps that cannot penetrate the plant material.The advantages of hydrodistillation are as follows:the setup is inexpensive,easy to construct,and suitable for fi eld operations.Modern supercritical fl uid extraction allows extraction at high speed and ef fi ciency,without harmful organic solvents.The use of CO2in supercritical fl uid extraction isrelatively nontoxic,non fl ammable,and available at high purity and low cost.Disadvantages of conventional methods are low yield,loss of volatile compounds,long extraction time,and degradation of the unsaturated compounds(Sodei fi an etal.2016a,b),whereas for supercritical fl uid extraction the primary disadvantage is that the extraction must be operated at 1000–5000 psi,to maintain the solvent in a supercritical state,which results in high costs.A modi fi er can be used to separate the polar analyte from the nonpolar analyte,which is comparatively dif fi cult to achieve without the use of modi fi er.An essential oil(or volatile or ethereal oil)is a lipophilic liquid comprising the volatile aroma compounds of plants,which comprise the ‘essence’of the fragrance of a particular plant.They are used in food products,perfumeries,drinks,pharmaceuticals,and cosmetics as fl avoring agents.An essential oil comprises terpenoids and phenylpropanoids as major constituents,and a few aromatic and aliphatic components are also present. Chemical entities such as monoterpenes,sesquiterpenes,and oxygenated derivatives are also present in the essential oil.The chemical compound of essential oil consists of hydrogen and carbon as the building blocks,which are isoprene in structure.Essential oil may also possess various biological activities such as antimicrobial, antiviral, anti-mutagenic, anticancer,antioxidant,anti-in fl ammatory,immunomodulatory,and antiprotozoal activities(Raut and Karuppayil 2014;El Asbahani et al.2015).

The aim of this work was to study the chemical composition and variability between the essential oils from leaves and bark of B.ovalifoliolata grown in Seshachalam hill range of India using gas chromatogtraphy-mass spectrometry,UV–visible and fl uorescence spectroscopy and cyclic voltammetry.

Materials and methods

Collection of plant material

The plant materials of leaves and bark were collected from the Seshachalam hills of Andhra Pradesh during February 2015.Species identi fi cation was con fi rmed by Prof.Jayaraman,Presidency College,Chennai.The plant parts were thoroughly washed with distilled water to remove contaminants and then shade dried and ground into fi ne powder using a mechanical grinder.The powder was stored in an airtight container for future analyses.

Extraction of essential oils

Yield of essential oil

Isolation and identi fi cation of essential oil

Essential oils were analyzed using a GC-2010 Plus High-end gas chromatograph(GC;Shimadzu,Kyoto,Japan)with a fl ameionizationdetector(FID)andanRtx-1crossbond100%dimethyl polysiloxane column(30 m×0.32 mm)(Restek,Bellefonte,PA,USA); fi lm thickness was 0.5 μm.The fl ow rate was 1 mL/min using helium as the carrier gas.The injector temperature was 250°C and the oven temperature was maintained at 300°C for 6 min.The oven temperature wasincreasedfrom50to270 °C(4 min)atarateof3 °C/min and held for 6 min.The GC–MS was carried out using a Clarus 680 GC coupled with a Clarus 600(EI)mass spectrometer(Perkin Elmer,Waltham,MA,USA)and the same conditions as for the GC.The compounds were identi fi ed by calculatingtheretentionindexofeachpeakandcomparingthe mass spectra fragmentation with those from the National Institute of Standards and Technology(NIST)Library(Babushok and Zenkevich 2009;Babushok et al.2011).

FT-IR analysis

Infrared(IR)spectra were obtained using a Shimadzu(Japan)Infrared spectrophotometer(400–4000 cm-1)with resolution IV.The sample was dissolved in dilute chloroform solution for the analysis.

Fig.1 Essential oils from bark and leaves viewed in daylight and UV light

Fig.2 GC-MS chromatogram of essential oils of Boswellia ovalifoliolata.a Bark.b Leaf

UV–visible spectroscopy analysis

There is also a small variation in the essential oil concentration,which is in fl uenced by the sample size(Charles and Simon 1990).

相应地，若要实现离散小波变换，则需先离散化伸缩参数a和平移参数b，下面对其进行详细叙述。若存在常数A和B，且满足如下公式：

Fluorescence spectroscopy analysis

Sesquiterpenoids were the major constituents in leaves andbark.Sesquiterpenoidsareaclassofterpenewithagroup of15carboncompoundsconsistingofthreeisoprenoidunits.These are used as fi xatives in the perfume industry,and in higher plants,they function as pheromones and juvenile hormones.The major constituents of essential oils were identi fi ed in leaves and bark from the plant.The identi fi ed compoundβ-farneseneisaclear,colorlessliquidthatisused asa fl avoringadditiveinfoodandbeverages.Caryophyllene oxide is also used to fl avor food and beverages.Spathulenol is used in aromatizing compositions for food and as a fl avoring agent in the food and cosmetics industries.Compounds such as caryophyllene oxide have antifungal properties,spathulenol is antibacterial,and farnesene has an insect repellant property.The variation in the results obtainedby Prasanna Anjaneya Reddy and Venkata Ratnam(2015)may have been due to the presence of a high monoterpene content;however,in our case,sesquiterpene content was high because the essential oils were extractedfrom fresh plant material and dry,powdered material.Monoterpene content extracted from fresh plant material is higher than from dry powder because some oil is lost when the material is dried(Ichi 2016).On the other hand,the total essential oil content on a mass basis is higher in the dry powder material than in the fresh plant material because it has less water.Similarly,less dry plant material is needed than fresh material to achieve equivalent percentage yields.

Cyclic voltammetry analysis

The electrochemical study of leaf and bark essential oils was done by cyclic voltammetry(CV)using chloroform solution at different scan rates.A three electrode system was used for the measurement of the potential using a CHI 440B electrochemical workstation(CH Instruments,Austin,TX,USA)with a glassy carbon electrode as the working electrode(WE),a platinum counter electrode and saturated silver and silver chloride as the reference electrode(RE).A 5 μL sample was dissolved in 500 μL ethanol(stock solution)and drop casted on a pretreatedglassy carbon electrode(GCE)and potential cycled at a scan rate of 50 mV/s.A cyclic voltammogram was obtained using 0.1 M phosphate buffer solution(pH 7.0.)at a potential window from+1 to-1 V versus silver/silver chloride(Basappa et al.2015;Masek et al.2014;Nicolson 1965;Carriedo 1988).

随着精英文化的衰落和大众文化的崛起，以身体消费为中心的感官刺激和感性化追求逐渐成为大学生审美情趣的主流。同时，文化符号也开始由先前的文字、语言更多地被图形图像所替代。这就导致当今部分大学生在审美活动中过多地去注重体验，而不是去多加思考，使他们的审美价值观发生了严重错位，并始终处于被重构、被改革的过程中。而审美价值观与世界观中的社会观、政治观、文化观，与人生观中的自我观、道德观等是密切渗透、相互影响的。因此，这对当今大学生思想政治教育工作来说也是一个极大的挑战。

Table 1 Essential oil composition of bark and leaves from Boswellia ovalifoliolata

Serial.no. Compound RI Bark(%) Leaf(%)1 2-Nonanol 1089 – 1.1 2 Carveol,cis 1208 – 1.0 3 Carvyl acetate,trans- 1325 – 0.74 4 Diphenylmethane 1380 1.74 –5 Carvyl acetate,trans- 1313 0.59 0.74 6 α-Gurjunene 1405 – 0.91 7 Decyl acetate 1404 1.41 6.3 8 Aromadendrene 1433 1.25 –9 Longifolene 1425 0.32 –10 Germacrene D 1477 0.57 2.3 11 Longifolene 1425 0.96 –12 β-Farnesene 1453 13.44 1.5 13 β-Bisabolene 1495 1.54 –14 α-Calacorene 1530 – 3.3 15 Nerolidol,(Z) 1535 2.43 3.1 16 Spathulenol 1552 6.6 11.1 17 Caryophyllene oxide 1574 10.45 9.0 18 Caryophyllene oxide 1574 5.5 1.9 19 Caryophyllene oxide 1572 2.7 –20 Longiborneol 1592 – 1.6 21 α-Cadinol 1640 – 0.77 22 α-Eudesmol 1646 – 1.1 23 Farnesol,(2Z,6E)- 1667 3.66 1.2 24 α-Sinensal 1740 0.965 0.65 25 2-Pentadecanone 1682 – 1.27 26 α-Selinene 1740 1.56 2.9 27 Tetradecanoic acid 1765 1.633 2.4 28 Benzyl benzoate 1758 0.35 –29 Myrtenol 1788 1.01 3.2 30 Hexahydrofarnesylacetone 1832 1.76 –31 Ethyl dodecanoate 1839 – 1.84 32 Pentadecanoic acid 1853 0.94 1.1 33 Hexadecyl acetate 1862 – 0.66 34 Farnesyl acetone,(5E,9E) 1913 – 0.39 35 1-Hexadecanol 1870 – 0.4 36 2-Methyl-1-nonadecene 1892 1.55 –37 Methyl hexadecanoate 1913 – 1.3 38 Hexadecanoic acid 1965 – 0.56 39 Palustrol 1936 0.37 40 Eicosene 1950 0.70 –41 Manoyl oxide 1989 – 0.94 42 13-epi-Manool 2005 – 0.27 43 Methyl eugenol 2008 – 2.7 44 Abietatriene 2039 – 0.28 45 Octadecanol 2089 0.70 –46 Tetracosane 2424 0.63 –47 Octanoic acid 2058 – 0.24 48 Manool 2042 – 0.27 49 Hexahydrofarnesyl acetone 2122 – 0.61 50 Undecanoic acid 2390 – 0.49

Table 1 continued

β-Farnesene is the main compound in the bark(13.44% of total)and caryophyllene oxide in leaf(9.0% of total)RI retention index

Serial.no. Compound RI Bark(%) Leaf(%)51 Pentacosane 2490 1.06 –TotalEssential oil identi fi ed–96.8%96.09%

In vitro anti-in fl ammatory activity

The GC–MS for the essential oils from the bark and leaves showed that caryophyllene oxide and spathulenol are the two major compounds common to both plant parts.In addition,the chemical composition,appearance,and percentage yield of the essential oils differed between the leaf and bark.

Results and discussion

Twenty- fi ve grams of fi nely powdered plant material was mixed with 250 mL of distilled water for hydrodistillation at 100 °C for 5–6 h using a Clevenger type apparatus.The extracted essential oils were separated from the water phase using chloroform in a separating funnel.Essential oils were dried using anhydrous magnesium sulfate and then stored at 4°C in the dark.The percentage yield of essential oils was calculated(Li et al.2013).All reagents were analytical grade from SD- fi ne chem,Mumbai,India.

The essential oils present in leaf and bark are shown in the GC–MS chromatogram(Fig.2),and the chemical composition of the essential oils are listed in Table 1.Around 38 compounds were identi fi ed and quanti fi ed from leaves(96.1% of all essential oils)and 26 compounds from bark(96.8%).Essential oil of bark contained 13.4%β-Farnesene(sesquiterpene),10.5%caryophylleneoxide(sesquiterpene),6.6% spathulenol(sesquiterpene)3.7% 2Z,6E-farnesol(sesquiterpene alcohol)2.4%nerolidol(sesquiterpene)and 1%myrtenol(monoterpene alcohol).Leaves contained 11.1% spathulenol (sesquiterpene alcohol), 9.0%caryophyllene oxide(sesquiterpene)6.3%decyl acetate(ester),3.3%calacorene(sesquiterpene),3.2%myrtenol(monoterpene alcohol),3.1%nerolidol(sesquiterpene),1.0%carveol(monoterpene alcohol),and 0.6% of manool(diterpene alcohol)as major compounds(Fig.2).

（2）供试品溶液的制备 将准噶尔乌头药材用水浸泡24 h，加水煮5、50、240、720 min不同时间段，取出，切片，60 ℃以下烘干。

The identi fi cation and chemical composition of essential oil by GC–MS analysis

The essentialoilsfrom leavesand bark contained sesquiterpenes,saturated fatty acids,and hydrocarbons.The essential oil from leaves was yellow and green from bark withacharacteristicsmell(Fig.1).Theyieldofessentialoils from leaves was 0.35%(w/w)and 3.7%(w/w)from bark.The yield from leaves was lower than from bark,as also reported by Li et al.(2013).The higher oil yield from bark wasduetothesmallerparticlesize(0.8–3.4 mm)oftheplant material,which not only increased the interfacial area but alsoreleasedmoreoilfrombrokencells.Thesmallerparticle sizesresultinhigherextractionef fi ciencies,increaseinmass transfer surface and quantity of soluble fraction on the surface.The maximum essential oil yield from B.ovalifoliolata was 0.35%for leaves and 3.7%for bark,which was higherthanthepreviouslyreportedyieldof0.17%forleaves and 0.2%for bark(Prasanna Anjaneya Reddy and Venkata Ratnam 2015;Kirti et al.2013;Maksimovic et al.2012).

针对上述情况，普遍采用淋水降温消除制动轮毂刹车片的热衰退效应，保持有效制动力，来满足钻机车连续下长坡时的制动要求[9-10]。该措施虽然取得了一些效果，但只是保证行车制动器工作在合适温度，减少其热衰退，下坡过程中仍要频繁使用行车制动器，其耗损很大，同时还带来如下不安全因素：①在喷水冷却不均匀时，由于局部应力过大易导致制动毂破裂。②冬天洒水导致路面结冰，影响到后续车辆的行驶安全，增加不安全因素。③钻机车制动相比普通车辆要求更多次的喷淋降温，用水量大，需经常停车补水，行驶有效里程缩短，降低了运行效率。

综上所述，家庭教育是基础工程，对幼儿未来的成长非常重要。良好的家庭教育使幼儿外向、热情、活泼可爱；反之，幼儿则内向、孤独、缺乏活力。

Fluorescence was measured using Hitachi(Tokyo,Japan)F-7000 FL fl uorescence spectrophotometer.The samples were dissolved in chloroform solution for the analysis.

The UV–visible absorption spectra were determined using a JASCO(Great Dunmow,UK)V-670 spectrophotometer in the absorption wavelength of 200–800 nm at room temperature.

Table 2 Major compounds in essential oils of Burseraceae family(Boswellia genus)and their biological activities(Perez et al.2011)

Plant name Sample Compounds identi fi ed Activity Boswellia ovalifoliolata(Present work)Dried leaf powder Spathulenol,caryophyllene oxide decyl acetate carveol,myrtenol,manool(38 compounds)Anti-in fl ammatory Dried bark powder β-Farnesene,caryophyllene oxide,spathulenol,farnesol(2Z,6E)-,myrtenol(26 compounds)Anti-in fl ammatory Boswellia ovalifoliolata(Prasanna Anjaneya Reddy and Venkata Ratnam 2015)Oleo gum resin Caryophyllene,α-pinene,β-myrcene,ledol,α-amarphene(25 compounds)Antioxidant,antimicrobial Bark β-Myrcene,caryophyllene,α-amarphene,cyclofenchene,cedr-8-ene(25 compounds)Antioxidant,antimicrobial Leaf α-Pinene,β-pinene,α-terpineol,caryophyllene(30 compounds)Antioxidant,antimicrobial Boswellia rivae Resin Limonene Boswellia ameero Resin (E)-2,3-Epoxycarene,1,5-isopropyl-2-methylbicyclo[3.1.0]hex-3-en-2-ol,acymene(3E,5E)-2,6-dimethyl-1,3,5,7-octatetraene,1-(2,4-dimethylphenyl)ethanol,3,4-dimethylstyrene,α-campholenal,α-terpineol Antioxidant anticholinesterase Boswellia carterii Oleo-gum resin Isoincensole,isoincensole acetate Antifungal Boswellia dalzielii Dried leaf α-Pinene,α-terpinene –Boswellia dioscorides Bark α-Thujene,α-pinene Antimicrobial,antioxidant Boswellia elongate Resin Diterpene verticiol,caryophyllene,methyl cyclo undecane carboxylate Antioxidant,anticholinesterase Bark Incensol Antimicrobial,antioxidant Boswellia frereana Resin p-Cymene –Boswellia neglecta Resin α-Thujene,α-pinene,terpinen-4-ol –Boswellia papyrifera Oleo-gum resin Isoincensole,isoincensole acetate,n-octanol,n-octyl acetate Antifungal Resin – Inhibited Staphylococcus epidermidis and Staphylococcus aureus bio fi lms Branch – Antimicrobial Boswellia pirotta Resin Trans-verbenol,terpinen-4-ol –Boswellia rivae Engler Oleo-gum resin Hydrocarbon,oxygenated monoterpenes Candida albicans Resin – Active against Candida albicans bio fi lms Boswellia sacra Resin E-β-Ocimene,limonene,E-caryophyllene –Resin Boswellic acids Anticancer Branch – Antimicrobial Resin α-Pinene Antibacterial Boswellia serrata Roxb. Oleo-gum resin Isoincensole,isoincensole acetate –Resin α-Thujene –Bark α-Pinene –Resin α-Thujene –Boswellia socotrana Balf.f.Resin (E)-2,3-Epoxycarene,1,5-isopropyl-2-methylbicyclo[3.1.0]hex-3-en-2-ol,and acymene,(3E,5E)-2,6-dimethyl-1,3,5,7-octatetraene,1-(2,4-dimethylphenyl)ethanol,3,4-dimethylstyrene,α-campholenal,aterpineol Antioxidant,anticholinesterase Bark p-Cymene,2-hydroxy-5-methoxyacetophenone,camphor Antimicrobial,antioxidant

Fig.3 FT-IR spectra of essential oils of Boswellia ovalifoliolata

The essential oils in the Burseraceae family have many biologicalproperties such as antifungal,anticancer,antioxidant,anticholinesterase,antibacterial,antimalarial and larvicidal.Cedrelopsis grevei belongs to the Burseraceae family,and its essential oils possess anti-in fl ammatory,anticancer,antimalarial,and antioxidant properties.There are no reports yet on an anti-in fl ammatory property of the essential oil from the Boswellia genus(Murthy et al.2016);however,compounds and their biological activities have been identi fi ed for other species from the Burseraceae family(Table 2).

宫颈癌(cervical cancer)是指发生于子宫颈的一种恶性肿瘤[1],临床较为常见,若不及时治疗,将延误患者病情,严重影响了妇女的身心健康。临床上常采用腹腔镜宫颈癌根治术进行治疗,在有效治疗的基础上,如何进行针对性的护理,对于促进患者病情治愈,具有重要的临床意义。我院选择72例接受腹腔镜宫颈癌根治术治疗的宫颈癌患者为研究对象,探讨聚焦解决理念在腹腔镜宫颈癌根治术围术期护理中的效果。以下是具体的试验报告。

The anti-in fl ammatory activity of the essential oils was determined by the albumin denaturation method according to Chandra et al.(2012)with some modi fi cations.The reaction mixture consisted of 2 mL of different concentrations(100–1000 μg/mL)of leaf or bark oil or the nonsteroidal anti-in fl ammatory drug diclofenac sodium(Sun Pharmaceuticals,Mumbai,India)and 2.8 mL of phosphatebuffered saline(pH 6.4)mixed with 0.2 mL of egg albumin(from fresh hen eggs).The same volume of double-distilled water served as a control.The reaction mixture was incubated at(27 ± 2)°C for 15 min,and the test tubes were heated to induce denaturation at 70°C in a water bath for 20 min.After the reaction mixture cooled,the absorbance was measured at 660 nm,and double-distilled water was usedastheblank.Theexperimentwasdoneintriplicate,and the extract values were averaged.The percentage inhibition ofproteindenaturationwascalculated(Chandraetal.2012).

FT-IR analysis of essential oils

In the FT-IR analysis of the functional groups,absorption bands at 927,744 and 3020 cm-1corresponded to C=C stretching,and carbonyl C=O stretching was con fi rmed by a peak between 1726 and 1701 cm-1(Fig.3).Signi fi cant stretching for C–O was observed at 1213 cm-1,and the absorption band at 1365 and 669 cm-1indicated –C–H bending and halide stretching of the compounds.

其中COD、TN、TP作为主要污染物去除指标，其每年污染物减少量为：COD：438t/a；TN：291t/a；TP：18.3t/a；HN3-H：109.5t/a。

Photophysical properties of essential oils

In the photophysical study using UV–visible(UV–Vis)and fl uorescence spectroscopy method,the leaf and bark oils yielded three maximum absorption peaks,and the absorption band of the leaf at 250 nm and the bark at 245 nm corresponded to a π–π*conjugation system and electron transfer in the benzene ring(Fig.4a).The peak at 325 and 402 nm indicates an n–π*transition(Fig.4b)and the presence of a keto group in the essential oil.The absorption bands at 285 and 290 con fi rm an n–π*transition.The UV–Vis spectra con fi rmed the presence of a conjugation system in the essential oil.The fl uorescence excitation wavelength of the essential oils from the leaf and bark showed signi fi cant shifts in the emission maxima for each.

The fl uorescent compounds in the essential oil had an emission range from blue to red shifts.Among the three excitation wavelengths,the excitation wavelength at 402 nm of bark and 325 nm of leaf provided a larger emission peak at 456 and 414 nm,respectively.The maximum emission wavelength for bark oil is due to the presence of conjugated double bonds in bark oil.The luminescence is due to the response of the plant to stress and shock.Similarly, fl uorescence may also be correlated with senescence and stress(Boschi et al.2011).The difference in the emission may be associated with chemical compounds,the main component of essential oil is sesquiterpenoids with a different degree of conjugation.

Cyclic voltammetry analysis

Cyclic voltammetry was used to characterize the interaction between electroactive species in the essential oils of the leaf and bark and the platinum electrode surface and to measure the peak reductive potential using an anodic current.Oxidation and reduction peak potentialswere observed between-1.0 and 1.0 eV.The onset oxidation potential of the leaf and bark was observed at 0.75 and 0.74 eV;subsequently,onset reduction potentials were observed at-0.44 for the leaf oil and-0.56 eV for the bark oil.Figure 4c shows the cyclic voltammogram recorded during the cathodic potential sweep of the leaf and bark essential oils of Boswellia ovalifoliolata.The presence of the leaf and bark essential oil reduced the current value,which indicates the inhibition of the charge transfer process as a result of the oxygen electroreduction.Thus,the cyclic voltammetry allows the determination of the antioxidant molecules present in the essential oil of B.ovalifoliolata(Goncalves et al.2009;Masek et al.2013).The presence of a chemical compound in essential oil by photophysical and electrochemical techniques is reported here for the fi rst time(Prasanna Anjaneya Reddy and Venkata Ratnam 2015).

In vitro anti-in fl ammatory activity of essential oil

Fig.4 UV-visible,a and fl uorescence,b spectra and cyclic voltammogram,c for leaf and bark essential oils of Boswellia ovalifoliolata

Table 3 In vitro antiin fl ammatory activity leaf and bark oil

Concentration(μg mL-1) Inhibition(%)Bark oil Leaf oil Diclofenac sodium 200 9±0.8 46.2±2.45 –400 124.4±1.17 195.6±1.55 –600 176.8±2.05 255.2±1.5 37.4±1.05 800 209.2±2.55 303.3±1.66 70.5±0.3 1000 254.8±1.95 360.6±1.96 102.9±0.2 IC50value 271.3 202.1 670.36

Anti-in fl ammatory activity of the essential oils was investigated using the protein denaturation method.Denaturation of a protein is a process whereby the proteins lose their secondary and tertiary structures by external stress or compounds such as an acid or base,an inorganic salt,an organic solvent,or heat.Denaturation occurs when biological proteins lose their biological function.The denaturation of a protein is a well-known method in the cause of in fl ammatory and arthritic diseases.The anti-infl ammatory activity of the leaf and bark oils was compared with that of diclofenac sodium as the reference drug.The IC50value of leaf was 202.1 and 271.3 μg/mL oil for bark;thus,the anti-in fl ammatory activity of the oils was higher than that of diclofenac sodium(Table 3).The essential oil may inhibit the release of the lysosomal content of neutrophils at the in fl ammation site(Govindappa and Poojashri 2011).The neutrophil lysosomal constituents include proteinases and bactericidal enzymes,which lead to tissue in fl ammation and damage upon their extracellular release.Canarium schweinfurthii and Aucoumea klaineana,(Burseraceae)an essential oil using the lipoxygenase method,only the C.schweinfurthii essential oil was active with p-cymene,limonene and a-terpineol as the major compounds(Leelaprakash et al.2011).

Conclusion

In summary,the use of GC–MS,FT-IR,UV–Vis, fl uorescence spectroscopy and cyclic voltammetry provided the necessary information on chemical composition and the variability of the leaf and bark of Boswellia ovalifoliolata essential oils.This study is the fi rst report of the presence of a chemical compound determined using a spectrophotometric and electrochemical technique.Spectrophotometric techniques are faster and more cost-effective than chromatographic methods,which are often time-consuming and may require large amounts of toxic solvents.The fl uorescence of leaf and bark essential oils was high at 414 and 456 nm,and the cyclic voltammetry showed good onsetreduction potentialat-0.44 and -0.56 eV.Caryophyllene oxide and spathulenol were the major constituents of the essential oils and anti-in fl ammatory property of essential oil was reported,and the fl uorescence property of the essential oils needs to be studied for various biological applications.

Acknowledgements The authors thank VIT University,Vellore for providing facilities.

References

Al-Harrasi A,Al-Saidi S(2008)Phytochemical analysis of the essential oil from botanically certi fi ed oleo gum resin of Boswellia sacra(Omani Luban).Molecules 13(9):2181–2189

Anderson J,Davis M(2007)Boswellic acids:potent active ingredients from a traditional remedy.Cosmet Sci Technol 4(2):5–9

Anitha G,Sudarsanam G(2013)Studies on antimicrobial activity of Boswellia ovalifoliolata against Xanthomonas citri and salmonella Typhynurium.Int J Appl Biol Pharm 4(1):243–247

Babushok VI,Zenkevich IG(2009)Retention indices for most frequently reported essential oil compounds in GC.Chromatographia 69(3–4):257–269

Babushok VI,Linstrom PJ,Zenkevich IG(2011)Retention indices for frequently reported compounds of plant essential oils.J Phys Chem Ref Data 40(4):043101

Basappa G,Kumar V,Sarojini BK,Poornima DV,Gajula H,Sannabommaji TK,Rajashekar J(2015)Chemical composition,biological properties of Anisomeles indica Kuntze essential oil.Ind Crops Prod 77:89–96

Boschi F,Fontanella M,Calderan L,Sbarbati A(2011)Luminescence and fl uorescence of essential oils.Fluorescence imaging in vivo of wild chamomile oil.Eur J Histochem 55(2):97–100

Carriedo Gabino(1988)The use of cyclic voltammetry in the study of the chemistry of metal carbonyls.J chem edu 65:1020

Chandra S,Chatterjee P,Dey P,Bhattacharya S(2012)Evaluation of in vitro anti-in fl ammatory activity of coffee against the denaturation of protein.Asian Pac J Trop Biomed 2(1):178

Charles DJ,Simon JE(1990)Comparison of extraction methods for the rapid determination of essential oil content and composition of basil.J Am Soc Hortic Sci 115(3):458–462

Chib R,Kumar M,Rizvi M,Sharma S,Pandey A,Bani S,Shah BA(2014)Anti-in fl ammatory terpenoids from Boswellia ovalifoliolata.RSC Adv 4(17):8632

El Asbahani A,Miladi K,Badri W,Sala M,Addi EA,Casabianca H,El Mousadik A,Hartmann D,Jilale A,Renaud FN,Elaissari A(2015)Essential oils:from extraction to encapsulation.Int J Pharm 483(1–2):220–243

Goncalves RS,Battistin A,Pauletti G,Rota L,Sera fi ni LA(2009)Antioxidant properties of essential oils from Mentha species evidenced by electrochemical methods.Rev Bras Plantas Med 11(4):372–382

Govindappa M,Poojashri MN(2011)Antimicrobial,antioxidant and in vitro anti-in fl ammatory activity of ethanol extract and active phytochemical screening of Wedelia trilobata(L.)Hitchc.J Pharmacogn Phytochem 3(3):43–51

Ichi KEN(2016)Monoterpene composition of the essential oil of the aquatic liverwort Jungermannia vulcanicola Steph.The Bryologist 87(4):323–326

Kirti RJ,Jha SK,Pal RK,Jha GK,Samuel DVK(2013)Effect of species and particle size on essential oil yield of citrus peel(Citrus spp).Indian J Agric Sci 83(12):9–12

Leelaprakash G,Dass SM,Road B(2011)Invitro anti-in fl ammatory activity of methanol extract of Enicostemma axillare.Int J Drug Dev Res 3(3):189–196

Li YQ,Kong DX,Wu H(2013)Analysis and evaluation of essential oil components of cinnamon barks using GC–MS and FTIR spectroscopy.Ind Crops Prod 41:269–278

Mahesh BU,Shrivastava S,Pragada RR,Naidu VGM,Sistla R(2014)Antioxidant and hepatoprotective effects of Boswellia ovalifoliolata bark extracts.Chinese J Nat Med 12(9):663–671

Maksimovic S,Ivanovic J,Skala D(2012)Supercritical extraction of essential oil from Mentha and mathematical modelling–the in fl uence of plant particle size.Proced eng 42:1767–1777

Marella S,Konda PY,Mohammad SA,Nabi SA,Kumar J,Venkateshwarulu M,Chippada AR(2014)Antihyperlipidemic activity of the stem bark of Boswellia ovalifoliolata in high fat diet fed rats.Photon J 107:572–576

Masek A,Chrzescijanska E,Zaborski M(2013)Characteristics of curcumin using cyclic voltammetry,UV–vis, fl uorescence and thermogravimetric analysis.Electrochimica Acta 107:441–447

Masek A,Chrzescijanska E,Kosmalska A,Zaborski M(2014)Characteristics of compounds in hops using cyclic voltammetry,UV–VIS,FTIR and GC–MS analysis.Food Chem 156:353–361

Mothana RAA,Hasson SS,Schultze W,Mowitz A,Lindequist U(2011)Phytochemical composition and in vitro antimicrobial and antioxidant activities of essential oils of three endemic Soqotraen Boswellia species.Food Chem 126(3):1149–1154

Murthy KSR,Reddy MC,Rani SS,Pullaiah T(2016)Bioactive principles and biological properties of essential oils of Burseraceae:a review.J Pharmacogn Phytochem 5(2):247–258

Nicolson RS(1965)Theory and application of cyclic voltammetry for measurementofelectrode reaction kinetics.AnalChem 37(11):1351–1355

Perez GS,Zavala SM,Arias GL,Ramos LM(2011)Anti-in fl ammatory activity of some essential oils.J Essent Oil Res 23(5):38–44

Prabhakar Y,Ali MS,Kumar MJ,Tilak TK,Rao CA(2013)Evaluation of antioxidant activities of aqueous extract of stem bark of Boswellia ovalifoliolata in streptozotocin induced diabetic rats.J Pharm Chem 7(4):19–24

Prasanna Anjaneya Reddy L,Venkata Ratnam L(2015)Chemical pro fi le,antioxidant and antimicrobial activity of essential oils from Boswellia ovalifoliolata Bal.et.Henry.Int J Pharm Clin Res 7(1):96–101

Raut JS,Karuppayil SM(2014)A status review on the medicinal properties of essential oils.Ind Crops Prod 62:250–264

Sodei fi an G,Ardestani NS,Sajadian SA(2016a)Application of supercritical carbon dioxide to extract essential oil from Cleome coluteoides Boiss:experimental,response surface and grey wolf optimization methodology.J Supercrit Fluids 114:55–63

Sodei fi an G,Sajadian SA,Ardestani NS(2016b)Optimization of essential oil extraction from Launaea acanthodes Boiss:utilization of supercritical carbon dioxide and cosolvent.J Supercrit Fluids 116:46–56

Woolley CL,Suhail MM,Smith BL,Boren KE,Taylor LC,Schreuder MF,Young DG(2012)Chemical differentiation of Boswellia sacra and Boswellia carterii essential oils by gas chromatography and chiral gas chromatography–mass spectrometry.J Chromatogr A 1261:158–163