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ISSN: 2210-2892 ― Volume 10, 2020

Chemical Composition, Free Radical Scavenging and Antimicrobial Activities of Essential Oil of Mariscus alternifolius Vahl



Patricia A. Onocha*, Ganiyat K. Oloyede, Jamiu A. Akintola
Natural Products/Medicinal Chemistry Unit, Department of Chemistry, University of Ibadan, Oyo State, Nigeria

Abstract

Introduction:

The study of medicinal plants in different parts of the world has led to major breakthroughs in drug chemistry. The increased interest in discovering drugs from natural source led to our investigation of the chemical composition, antioxidant and antimicrobial activities of the essential oil of Mariscus alternifolius Vahl, used in the treatment of wounds, bacterial and infectious diseases in ethno medicine.

Methods:

The plant essential oil was collected over hexane by Hydro distillation technique and Gas Chromatography-Mass Spectrometry (GC- MS) was employed for analysis. Antioxidant activity of the essential oil was evaluated using the 2,2-diphenylpicrylhydrazyl (DPPH) method while the antimicrobial screening was determined by the agar well diffusion method.

Results:

GC-MS analysis revealed the presence of a total of 10 constituents representing 71.91% with tricosane (19.45%) as the most abundant constituent in the essential oil of the plant while others with relatively high percentages include z-14-nonacosene (13.37%) and octacosyltriflouroacetate (10.91%). The free radical scavenging activity of the essential oil gave percentage inhibition of 97.95% at 5 mg/ml which was comparable to that of the standard antioxidant ascorbic acid (97.88%) used for the assay. The essential oil inhibited the growth of Staphylococcus aureus, Escherichia coli, Bacillus substilis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Candida albicans and Aspergillus niger used in this study. The minimum inhibitory concentration (MIC) of 25 mg/ml was observed for Staphylococcus aureus and Escherichia coli.

Conclusion:

In summary, the essential oil of M. alternifolius Vahl. possesses high antimicrobial and antioxidant activities.

Implications:

This study therefore provide some scientific basis for its utilization in ethno medicine.

Keywords: 2,2-diphenylpicrylhydrazyl, Hydrodistillation, Mariscus alternifolius, MIC, Tricosane.


Article Information


Identifiers and Pagination:

Year: 2016
Volume: 07
First Page: 160
Last Page: 167
Publisher Id: TOPROCJ-7-1-160
DOI: 10.2174/2210289201607010160

Article History:

Received Date: 01/01/2016
Revision Received Date: 29/09/2016
Acceptance Date: 17/10/2016
Electronic publication date: 30/12/2016
Collection year: 2016

© Onocha et al.; Licensee Bentham Open

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0) (https://creativecommons.org/licenses/by-nc/4.0/legalcode), which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.


* Address correspondence to this author at the Department of Chemistry, University of Ibadan, Nigeria; Tel: +2348023144743; E-mail: triciaonocha@yahoo.com





INTRODUCTION

Mariscus alternifolius belongs to a family of monocotyledonous flowering plants known as Cyperaceae which resemble grasses otherwise known as sedges found in tropical Asia, Africa and South America. It has been reported to be effective in the treatment of wounds, stomach troubles, diarrhoea, gonorrhea and as an insecticide while the rhizome is aromatic and used as a food-flavouring agent [1Burkill, H.M. The useful plants of west tropical Africa, 1st ed; Royal Botanical Gardens: Kew, United Kingdom, 1985, vol. 1, p. 635.-7Adeniyi, T.A.; Adeonipekun, P.A.; Omotayo, A.E. Investigatig the phytochemicals and antimicrobial properties of three sedge (cyperaceae) species. Int. J. Trop. Med., 2013, 8(4), 92-98.]. The biologically active constituents of medicinal, poisonous and commercial plants, many of which are secondary metabolites: alkaloids, flavonoids, terpenoids, essential oils amongst others have been studied in medicinal chemistry. Artemisinin for instance, is an anti-malarial drug isolated from Artemisia annua, sweet wormwood, a Chinese herb [1Burkill, H.M. The useful plants of west tropical Africa, 1st ed; Royal Botanical Gardens: Kew, United Kingdom, 1985, vol. 1, p. 635., 8Finar, I.L. Organic Chemistry; , 1982. -10Ganesan, S.; Suresh, N.; Kesaven, L. Ethnomedicinal survey of lower Palni Hills of Tamil Nadu. Indian. J. Tradit. Knowl., 2004, 3, 299-304.].

Essential oils contain interesting natural plant secondary metabolites which possess various biological properties. Some of these secondary metabolites like mono- and sesquiterpenoids, benzenoids, phenylpropanoids, have been reported to exert pharmacological effect as antimicrobial, anti- inflammatory and anti oxidant to mention a few. They have also been used in the food industry as seasoning agents, as scents in soaps, cosmetics or perfumes [11Saleh, M.A.; Clark, S.; Woodard, B.; Deolu-Sobogun, S.A. Antioxidant and free radical scavenging activities of essential oils. Ethn. Dis., 2010, 20(1)(Suppl. 1), S1-S78, 82.
[PMID: 20521390]
, 12Warnke, P.H.; Becker, S.T.; Podschun, R.; Sivananthan, S.; Springer, I.N.; Russo, P.A.; Wiltfang, J.; Fickenscher, H.; Sherry, E. The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections. J. Craniomaxillofac. Surg., 2009, 37(7), 392-397.
[http://dx.doi.org/10.1016/j.jcms.2009.03.017] [PMID: 19473851]
]. Phyto-remediation study of four common Nigerian weeds among which was Mariscus alternifolius Vahl has been investigated [13Ogbo, E.M.; Avwerosovwe, U.; Odogu, G. Screening of four common Nigerian weeds for use in phytoremediation of soil contaminated with spent lubricating oil. Afr. J. Plant Sci., 2009, 3(5), 102-106.]. However, very little is known in literature about the composition of the leaf essential oil and its antimicrobial and antioxidant properties. Due to the various medicinal applications of essential oils in ethno medicine and coupled with the fact that the crude extracts of M. alternifolius have been shown to demonstrate appreciable activities as antimicrobial [2Adeniyi, T.A.; Adeonipekun, P.A.; Omotayo, E.A. Investigating the Phytochemicals and Antimicrobial Properties of Three Sedge (Cyperaceae) Species. Not. Sci. Biol., 2014, 6(3), 276-281.
[http://dx.doi.org/10.15835/nsb.6.3.9356]
] and antioxidant agents in our previous work on the plant [3Onocha, P.A.; Oloyede, G.K.; Abegunde, L.M.; Oluwafemi, A.K. Antioxidant, Toxicity and Phytochemical Screening of Extracts Obtained from Mariscus alterifolious Vahl. J. Natural Sci. Res., 2016, 6(5), 1-7.], we now report the biological activities of the essential oil of this plant.

MATERIALS AND METHODS

Plant collection and identification

Mariscus alternifolius plant was collected in June 2014 from the Botanical garden of the University of Ibadan and identified by Dr Ayodele of the Botany Department, University of Ibadan.

Reagents

Methanol and hexane obtained from Sigma Aldrich were used.

Test Organisms

Staphylococcus aureus, Escherichia coli, Bacillus substilis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Candida albicans, Aspergillus niger, Penicillium notatum, Rhizophus stolonifer.

Reference Standards

Antibacterial and antifungal standards: gentamicin® (10 μg/ml) and tioconazole® (70%) respectively, were obtained from the University Medical Hospital, Jaja Clinic Pharmacy. Ascorbic acid obtained from the same place was used as an antioxidant standard.

Major Equipment Used

The following equipment and apparatus were used: heating mantle, Clavenger apparatus, electronic weighing balance (OHAUS), Oven (Carbolite), round bottom flask, syringe, Gas chromatograph/GC-MS Agilent 7890B, CE 2021, 2000 series double beam UV-Vis spectrophotometer.

Isolation of Essential Oil

The Clavenger apparatus and a heating mantle set at a thermo-stated temperature of 100oC were the major apparatus used for extracting the essential oil in accordance with the European Pharmacopoeia, 1996 in a technique known as the hydro distillation method. Freshly collected plant (874 g) of M. alternifolius was air dried for 5 days. This yielded 367 g which was transferred into a 10 litres distillation flask and distilled water was added until the sample was completely submerged. The flask was then placed on a heating mantle and fitted with a glass Clavenger. At a thermo-stated temperature of 100oC, hydro-distillation was carried out for a period of 3 hours under close monitoring to ensure continuous flow of cold water through the condenser and to ensure that the distillate (essential oil) was not lost due to its volatile nature. After 3 hours, the essential oil which was made to dissolve in a known quantity of n-Hexane, was collected from the receiving arm of the Clavenger into a vial bottle of known weight and stored at 4oC [14Onocha, P.A.; Oloyede, G.K.; Bamkole, O.A. Volatile Oil Composition, Cytotoxicity and free radical scavenging of leaves and twigs of the Chenille plant (Acalypha hispida). Int. J. Essent. Oil Ther., 2010, 4, 86-89.].

Analysis of the Essential Oils

Gas Chromatography–Mass Spectrometry

GC-MS Agilent 7890B - Gas Chromatograph coupled with MS Agilent technologist 5975 series MSD was used to analyse the essential oil. The capillary column used had 30.0 m column length, 320 μm internal diameter and 0.5 μm film thickness. The carrier gas was helium at a constant flow rate of 1.4123 ml/min and an average velocity of 43.311 cm/sec. The pressure was maintained at 1.5 psi. The initial column temperature was set at 50oC for 5mins at the rate of 5oC/min and increased to 280oC for 9 mins. The volume injected was 3 μl and the split ratio was 50:1 at the split flow rate of 70.615 ml/min.

Identification of Components

Flame Ionization Detector (FID) set at a temperature of 300oC was used to determine the compositions of the various constituent, by recording the peak numbers and relative percentages of the characterized compounds. Identification of individual component was done by comparing their retention time to identical compounds known from literature data and their spectral with NIST 0.8L/Database/chemstation data system [15Mclafferty, F.W.; Stauffer, D.B. The Willey/NBS Registry of Mass Spectral Data; John Wiley & Sons: New York, 1989. -17Adams, R.P. Identification of essential oils by ion trap mass spectrometry; Academic Press Limited: United Kingdom, 2007. ]. The peak numbers and relative percentages of the essential oil component are shown in Table 1.

Table 1
Chemical composition of the essential oil from the Mariscus alternifolius*.


Free Radical Scavenging Activity

The free radical scavenging activity of the essential oil of M. alternifolius Vahl, was studied using the DPPH free radical scavenging method [11Saleh, M.A.; Clark, S.; Woodard, B.; Deolu-Sobogun, S.A. Antioxidant and free radical scavenging activities of essential oils. Ethn. Dis., 2010, 20(1)(Suppl. 1), S1-S78, 82.
[PMID: 20521390]
, 18Oloyede, G.K.; Onocha, P.A.; Soyinka, J.; Oguntokun, O.; Thonda, E. Phytochemical screening, antimicrobial and antioxidant activities of four Nigerian medicinal plants. Ann. Biol. Res., 2010, 1(2), 114-120.]. Dilutions (5 mg/ml, 25 mg/ml and 100 mg/ml) of 1.5 ml of the essential oil was mixed with a 0.5 mM methanol DPPH solution (2.0 ml) prepared by dissolving 240 mg of DPPH in 1 L of methanol. This was incubated in the dark for 15 min at room temperature and the absorbance at 517 nm was recorded using CE 2021, 2000 series double beam UV-Vis spectrophotometer. In its radical form, DPPH absorbs, but upon reduction by antioxidant specie, its absorption reduces and is decolorized. A blank experiment was carried out by applying the same procedure but without the test material (DPPH and Methanol) and the absorbance values were recorded. The standard ascorbic acid was also examined for its antioxidant activity using the same method. The free radical scavenging activity of the test oil solutions was then calculated [11Saleh, M.A.; Clark, S.; Woodard, B.; Deolu-Sobogun, S.A. Antioxidant and free radical scavenging activities of essential oils. Ethn. Dis., 2010, 20(1)(Suppl. 1), S1-S78, 82.
[PMID: 20521390]
, 18Oloyede, G.K.; Onocha, P.A.; Soyinka, J.; Oguntokun, O.; Thonda, E. Phytochemical screening, antimicrobial and antioxidant activities of four Nigerian medicinal plants. Ann. Biol. Res., 2010, 1(2), 114-120.].

Antimicrobial Screening

M. alternifolius Vahl has been reported to be used locally as an antimicrobial agent. Agar well diffusion method was used to establish this fact [14Onocha, P.A.; Oloyede, G.K.; Bamkole, O.A. Volatile Oil Composition, Cytotoxicity and free radical scavenging of leaves and twigs of the Chenille plant (Acalypha hispida). Int. J. Essent. Oil Ther., 2010, 4, 86-89., 18Oloyede, G.K.; Onocha, P.A.; Soyinka, J.; Oguntokun, O.; Thonda, E. Phytochemical screening, antimicrobial and antioxidant activities of four Nigerian medicinal plants. Ann. Biol. Res., 2010, 1(2), 114-120.]. The essential oil (0.50 ml) was dissolved into 5 ml of hexane to give 100 mg/ml. Hexane (2.5 ml) was poured into five other test tubes to get the stock solution which was serially diluted until concentration of 6.25 mg/ml was achieved in the fifth test tube. Two other test tubes representing the sixth and seventh test tubes contained hexane and gentamicin/tioconazole as the negative and positive controls for bacteria/fungi, respectively. An overnight culture (0.2 ml) of test micro-organisms was added to 20 ml of cooled molten agar and maintained for 8 hours on nutrient agar slants at 12°C, sub cultured in nutrient broth and preserved at 4-5°C prior to each antimicrobial assay. Pour plate method for bacteria and surface plate method for fungi were employed in the antimicrobial screening [14Onocha, P.A.; Oloyede, G.K.; Bamkole, O.A. Volatile Oil Composition, Cytotoxicity and free radical scavenging of leaves and twigs of the Chenille plant (Acalypha hispida). Int. J. Essent. Oil Ther., 2010, 4, 86-89., 18Oloyede, G.K.; Onocha, P.A.; Soyinka, J.; Oguntokun, O.; Thonda, E. Phytochemical screening, antimicrobial and antioxidant activities of four Nigerian medicinal plants. Ann. Biol. Res., 2010, 1(2), 114-120.].

In the Agar diffusion pour plate method for anti-bacterial screening, molten sterile agar prepared according to the manufacturer's standard was poured (pour plate) asceptically into sterile petri dishes in triplicate and allowed to set on the bench for 45 minutes. Inoculation of the test organisms from the broth culture into the agar prepared plate was achieved with the aid of flamed and cooled wire loops. The inoculated plates were allowed to solidify. Thereafter, 9mm wells were asceptically bored into the solid nutrient agar using a sterile cork borer. The test solutions of the oil at various concentrations (6.25 - 100 mg/ml) were introduced into each of the designated wells with the aid of sterile syringes in each plate ensuring that no spillage occurred. The same amount of the solvent (hexane) and standard antibacterial agent (gentamicin) were introduced into the 6th and 7th wells to act as negative and positive controls, respectively. The plates were left at room temperature for two hours, to allow diffusion into the medium, turned upside down and thereafter, incubated at 37°C. After 24 hours, the plates were removed from the incubator and diameter of clear zones of inhibition of test organisms and control were measured in millimeters (mm) using a transparent well calibrated ruler (Table 2).

Table 2
Antimicrobial activity of Essential oil of Mariscus alternifolius*.


In the Agar diffusion surface plate method for antifungal screening, sterile sabourand dextrose agar (SDA) prepared according to the manufacturer's standard was poured asceptically into sterile petri dishes in triplicate and allowed to cool down for 45 minutes. 0.2 ml of the fungal strain from the broth culture was spread on the surface (surface plate or spread drop) of the prepared SDA plate using a sterile spreader and allowed to dry and solidify. Subsequently, the same procedure described for antibacterial assay above was carried out. All the plates for the antifungal assay were incubated at 27°C. After 72 hours, the plated were again removed from the incubator and clear zones of inhibition were measured and recorded using the same method as described in the case of antibacterial assay (Table 2).

Minimum inhibitory concentration was determined for all the tested organisms.

Determination of Minimum Inhibitory Concentration

Dilution method [19Vanden-Berghe, D.A.; Vlietinck, A.J. Methods in plant biochemistry. Assay for bioactivity. In: Screening methods for antibacterial and antiviral agents from higher plants; Dey, P.M.; Harbone, J.B.; Hostettman, K., Eds.; Academic press: London, 1991; vol. 6, pp. 47-69.] was used for the determination of the minimum inhibitory concentration (MIC) of the essential oil of M. alternifolius. Tubes of nutrient broth containing various concentrations of volatile fractions mentioned in Table 3 were inoculated with microbial strains from the broth cultures. They were incubated in a shaker (120rpm) at 37°C for 24 hours and 27°C for 72 hours for bacteria and fungi, respectively. Control tubes without tested samples were assayed simultaneously. All samples were tested in triplicate. The MIC is defined as the lowest concentration of the test samples at which the organisms do not demonstrate visible growth.

Table 3
Minimum Inhibitory Concentration (MIC) of Essential oil of Mariscus alternifolius*.


RESULTS AND DISCUSSION

GC-MS Analysis of Essential Oil from Mariscus alternifolius

M. alternifolius Vahl essential oil contained 10 constituents totalling 71.91% (Table 1). The percentage yield of the essential oil was 0.47%. Tricosane (19.45%) was the most abundant primary active constituent. Other primary active constituents with relatively high percentages include (Z)-14-nonacosene (13.37%) and Octacosyltriflouroacetate (10.91%). Some derivatives of these primary active constituents and a number of the minor constituents of the essential oil of M. alternifolius have been reported to possess antimicrobial, antioxidant and other properties. The most abundant constituent tricosane, is one of the major constituents of the essential oil of Rosa damascena which has been shown to have strong radical scavenging effect [20Yassa, N.; Masoomi, F.; Rohani Rankouhi, S.E.; Hadjiakhoondi, A. Chemical composition and antioxidant activity of the extract and essential oil of Rosa damascena from Iran, Population of Guilan. DARU. J. Pharm. Sci., 2009, 17, 175-180.]. Nonacosane, a saturated derivative of (Z)-14-nonacosene, another major active constituent of the essential oil has been reported to possess antibacterial activity [21kalaisezhiyen, C.P.; Sasikumar, V. GC- MS Evalution of chemical constituents from methanolic leaf extract of Kedrostis foetidissima (Jacq.). Asian J. Pharm. Clin. Res., 2012, 5(4), 77-81.]. Nonacosane is also one of the major constituents of the seed hexane extract of Hypericum scabrum L [22Shafaghat, A. Antioxidant, antimicrobial activities and fatty acid components of flower, leaf, stem and seed of Hypericum scabrum. Nat. Prod. Commun., 2011, 6(11), 1739-1742.
[PMID: 22224301]
]. and essential oil from the leaves of Moringa oleifera [23Marrufo, T.; Nazzaro, F.; Mancini, E.; Fratianni, F.; Coppola, R.; De Martino, L.; Agostinho, A.B.; De Feo, V. Chemical composition and biological activity of the essential oil from leaves of Moringa oleifera Lam. cultivated in Mozambique. Molecules, 2013, 18(9), 10989-11000.
[http://dx.doi.org/10.3390/molecules180910989] [PMID: 24022760]
] which have been shown to exhibit high radical scavenging activity. Octacosyltriflouroacetate, one of the primary active constituents of the essential oil of M. alternifolius is the trifluoroacetate derivative of n-octacosane. N-octacosane has been confirmed to have significant antioxidant activity [24Hassan, R.A.; Tawfeek, W.A.; Habeeb, A.A.; Mohamed, M.S.; Abdelshafeek, K.A. Investigation of some chemical constituents and antioxidant activity of Asparagus sperngeri. Int. J. Pharm. Pharm. Sci., 2014, 6(11), 46-51., 25Ali, A.; Waly, M.; Bhatt, N.; Al-Saady, N.A. Proximate and Phytochemical composition and antioxidant properties of Indigenous Land races of Omanifenu greek seeds. Afr. J. Tradit. Complement. Altern. Medicines, 2015, 12(2), 149-154.
[http://dx.doi.org/10.4314/ajtcam.v12i2.22]
]. Another derivative cyclooctacosane on the other hand, has been reported to exhibit significant antibacterial activity [26Fan, P.; Manoli, D.S.; Ahmed, O.M.; Chen, Y.; Agarwal, N.; Kwong, S.; Cai, A.G.; Neitz, J.; Renslo, A.; Baker, B.S.; Shah, N.M. Genetic and neural mechanisms that inhibit Drosophila from mating with other species. Cell, 2013, 154(1), 89-102.
[http://dx.doi.org/10.1016/j.cell.2013.06.008] [PMID: 23810192]
]. 2-Decanone, one of the constituents of the study plant has been shown to possess antifungal activities [27Arif, T.; Bhosale, J.D.; Kumar, N.; Mandal, T.K.; Bendre, R.S.; Lavekar, G.S.; Dabur, R. Natural productsantifungal agents derived from plants. J. Asian Nat. Prod. Res., 2009, 11(7), 621-638.
[http://dx.doi.org/10.1080/10286020902942350] [PMID: 20183299]
] while hexadecane, a derivative of the constituent 2-methyl-1-hexadecanol has been reported to be responsible for the anti-bacterial and antioxidant properties of the essential oil of Cestrum noctrunum [28Al-Reza, S.M.; Rahman, A.; Kang, S.C. Chemical composition and inhibitory effect of essential oil and organic extracts of Cestrum nocturnum L. on food-borne pathogens. Int. J. Food Sci. Technol., 2009, 44, 1176-1182.
[http://dx.doi.org/10.1111/j.1365-2621.2009.01939.x]
] and Monochaetia kansensis [29Yogeswari, S.; Ramalakshmi, S.; Neelavathy, R.; Muthumary, J. Identification and Comparative Studies of Different Volatile Fractions from Monochaetia kansensis by GCMS. Global J. Pharmacol., 2012, 6(2), 65-71.]. Eicosane, a derivative of the constituent 1-Eicosene is reported to be one of the main constituents in the Aloe vera extract responsible for high antimicrobial activity against clinical pathogens [30Arunkumar, S.; Muthuselvam, M. Analysis. of Phytochemical Constituents and Antimicrobial Activities of Aloe vera L. against Clinical Pathogens. World J. Agric. Sci., 2009, 5(5), 572-576.] while 9-Eicosene has been shown to have potent antimicrobial property [31Hsouna, A.B.; Trigui, M.; Mansour, R.B.; Jarraya, R.M.; Damak, M.; Jaoua, S. Chemical composition, cytotoxicity effect and antimicrobial activity of Ceratonia siliqua essential oil with preservative effects against Listeria inoculated in minced beef meat. Int. J. Food Microbiol., 2011, 148(1), 66-72.
[http://dx.doi.org/10.1016/j.ijfoodmicro.2011.04.028] [PMID: 21601302]
]. The presence of these constituents in the essential oil justifies the ethno medicinal uses of the plant.

Some of the constituents have also been shown to possess other medicinal properties beyond the generic anti-microbial and free radical scavenging activities. Tricosane is known to provoke behavioral response in several insect predators and parasitoids while octacosane and (Z)-14-nonacosene (a component of the sex pheromones) play an important role in the control of insects [32Uebel, E.C.; Schwarz, M.; Sonnet, P.E.; Miller, R.W.; Menzer, R.e. Evaluation of the mating Stimulant Pheromones of Fannia canicularis, F. pusio and F. femoralis as attractants. Fla. Entomol., 1978, 61(3), 139-143.
[http://dx.doi.org/10.2307/3494228]
]. Nonacosane has been reported to possess nematicidal activity [21kalaisezhiyen, C.P.; Sasikumar, V. GC- MS Evalution of chemical constituents from methanolic leaf extract of Kedrostis foetidissima (Jacq.). Asian J. Pharm. Clin. Res., 2012, 5(4), 77-81.], antihypertensive, vasodilatory, angiotensin AT2 receptor antagonist and saluretic activities [33Mallikadevi, T.; Paulsamy, S.; Karthika, K.; Jamuna, S. In vitro and in vivo Anti-inflammatory activity of whole plant methanolic extract of Mukia maderaspatana (L.) M.Roem. (cucurbitaceae). Int. J. Pharm. Pharm. Sci., 2012, 4(5), 435-439.]. Hentriacontane, a constituent of M. alternifolius has also been shown to possess anti-cancer, anti-inflammatory [34Kim, S.J.; Chung, W.S.; Kim, S.S.; Ko, S.G.; Um, J.Y. Antiinflammatory effect of Oldenlandia diffusa and its constituent, hentriacontane, through suppression of caspase-1 activation in mouse peritoneal macrophages. Phytother. Res., 2011, 25(10), 1537-1546.
[http://dx.doi.org/10.1002/ptr.3443] [PMID: 21394806]
], anti-tuberculosis [35Liu, Y.W. Antituberculous constituents of Gentiana rhodantha. Zhong Yao Tong Bao, 1985, 10(12), 33-34.
[PMID: 2940022]
] and weak cytotoxic activities [36Quintanilla-Licea, R.; Morado-Castillo, R.; Gomez-Flores, R.; Laatsch, H.; Verde-Star, M.J.; Hernández-Martínez, H.; Tamez-Guerra, P.; Tamez-Guerra, R.; Rodríguez-Padilla, C. Bioassay-guided isolation and identification of cytotoxic compounds from Gymnosperma glutinosum leaves. Molecules, 2012, 17(9), 11229-11241.
[http://dx.doi.org/10.3390/molecules170911229] [PMID: 22996346]
].

Free Radical Scavenging Activity

M. alternifolius Vahl displayed a higher free radical scavenging activity at 5 mg/ml than ascorbic acid when absorbance measurement was done at 517 nm. Fig. (1) shows the % inhibition of the sample and standard as calculated from the absorbance results obtained [18Oloyede, G.K.; Onocha, P.A.; Soyinka, J.; Oguntokun, O.; Thonda, E. Phytochemical screening, antimicrobial and antioxidant activities of four Nigerian medicinal plants. Ann. Biol. Res., 2010, 1(2), 114-120.]. At 5 mg/ml, 97.95% inhibition was observed for the plant essential oil. This was slightly higher than that of ascorbic acid (97.88%). However, at higher concentrations of 25 mg/ml and 100 mg/ml tested, the plant oil exhibited % inhibition of 97.85 and 97.92 respectively. These slightly lower values contradict the usual trend of high % inhibition with high concentration. Percentage inhibition of Ascorbic acid on the other hand, increased with increasing concentration. Nevertheless, the fact that the plant oil exhibited a higher % inhibition than the standard ascorbic acid used at a low concentration (5 mg/ml) is a clear indication of its high free radical scavenging activity.

Fig. (1)
DPPH Scavenging Activity of Mariscus alternifolius Plant (MAP) Oil and Ascorbic acid (ASC).


The essential oil of M. alternifolius Vahl as revealed in this study possesses antioxidant activity. Antioxidants are compounds that can neutralize free radicals by accepting or donating an electron to eliminate the unpaired condition [37Sies, H. Oxidative stress: oxidants and antioxidants. Exp. Physiol., 1997, 82(2), 291-295.
[http://dx.doi.org/10.1113/expphysiol.1997.sp004024] [PMID: 9129943]
-39Oloyede, G.K.; Farombi, E.O. Antioxidant properties of Crinum ornatum bulb extracts. World J. Chem., 2010, 5(1), 32-36.]. They have been reported to have curative effect on Parkinson’s disease, cancer, coronary and other heart related conditions. They also find application in the industry as preservatives in food and cosmetics [11Saleh, M.A.; Clark, S.; Woodard, B.; Deolu-Sobogun, S.A. Antioxidant and free radical scavenging activities of essential oils. Ethn. Dis., 2010, 20(1)(Suppl. 1), S1-S78, 82.
[PMID: 20521390]
, 12Warnke, P.H.; Becker, S.T.; Podschun, R.; Sivananthan, S.; Springer, I.N.; Russo, P.A.; Wiltfang, J.; Fickenscher, H.; Sherry, E. The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections. J. Craniomaxillofac. Surg., 2009, 37(7), 392-397.
[http://dx.doi.org/10.1016/j.jcms.2009.03.017] [PMID: 19473851]
, 40Dabelstein, W.; Reglitzky, A.; Schütze, A.; Reders, K. Automotive Fuels. In: Ullmann's Encyclopedia of Industrial Chemistry; Wiley-VCH: Weinheim, 2007.
[http://dx.doi.org/10.1002/14356007.a16_719.pub2]
].

Antimicrobial Screening of the Essential Oil of Mariscus alternifolius

Zones of inhibition of the essential oil of Mariscus alternifolius measured during the antimicrobial screening are presented in Table 2.

Minimum Inhibitory Concentration (MIC) of Essential Oil of Mariscus alternifolius

The result of the antimicrobial screening of the essential oil of M. alternifolius revealed its inhibitory effect on the growth of all the bacteria: S. aureus, E. coli, B. substilis, P. aeruginosa, S. typhi, K. pneumoniae and on two of the fungi: C. albicans and A. niger used in this assay. No inhibitory effect was observed for P. notatum and R. stolonifer. The minimum inhibitory concentration (MIC) (Table 3) varied with organism: 25 mg/ml for S. aureus and E. coli, 50 mg/ml for B. substilis, S. typhi and C. albicans and 100 mg/ml for P. aeruginosa, K. pneumoniae and A. niger and are comparable to essential oils of other origins [28Al-Reza, S.M.; Rahman, A.; Kang, S.C. Chemical composition and inhibitory effect of essential oil and organic extracts of Cestrum nocturnum L. on food-borne pathogens. Int. J. Food Sci. Technol., 2009, 44, 1176-1182.
[http://dx.doi.org/10.1111/j.1365-2621.2009.01939.x]
, 41Akudor, G.C.; Onyewenjo, S.C.; Anyalewechi, N.A.; Essien, A.D.; Akpan, J.L.; Okoroafor, D.O.; Okere, M.O. In vitro antimicrobial activity of leaf extract of Berlina grandiflora Hutch. and Dalz. Afr. J. Microbiol. Res., 2011, 5(11), 1358-1360.
[http://dx.doi.org/10.5897/AJMR10.692]
, 42Boussaada, O.; Ammar, S.; Saidana, D.; Chriaa, J.; Chraif, I.; Daami, M.; Helal, A.N.; Mighri, Z. Chemical composition and antimicrobial activity of volatile components from capitula and aerial parts of Rhaponticum acaule DC growing wild in Tunisia. Microbiol. Res., 2008, 163(1), 87-95.
[http://dx.doi.org/10.1016/j.micres.2007.02.010] [PMID: 17482441]
]. These results indicate that the essential oil of the plant M. alternifolius possesses antibacterial activity.

CONCLUSION

The essential oil of the plant Mariscus alternifolius is a rich source of hydrocarbons: Octane, α-Cyperene, Decanal, 2-Decanone, 1-Eicosene, 2-methyl-1-hexadecanol, z-14-nonacosene, Hentriacontane, Octacosyltrifluoroacetate and Tricosane. So it can be correlated that the hydrocarbons found in the essential oil of M. alternifolius could also exhibit anti microbial and antioxidant activity, as demonstrated in other essential oils [20Yassa, N.; Masoomi, F.; Rohani Rankouhi, S.E.; Hadjiakhoondi, A. Chemical composition and antioxidant activity of the extract and essential oil of Rosa damascena from Iran, Population of Guilan. DARU. J. Pharm. Sci., 2009, 17, 175-180.-31Hsouna, A.B.; Trigui, M.; Mansour, R.B.; Jarraya, R.M.; Damak, M.; Jaoua, S. Chemical composition, cytotoxicity effect and antimicrobial activity of Ceratonia siliqua essential oil with preservative effects against Listeria inoculated in minced beef meat. Int. J. Food Microbiol., 2011, 148(1), 66-72.
[http://dx.doi.org/10.1016/j.ijfoodmicro.2011.04.028] [PMID: 21601302]
].

Free radical scavenging activity was observed at 5 mg/ml to exhibit 97. 95% inhibition. The essential oil showed free radical scavenging activity comparable to ascorbic acid (97.88%), a known antioxidant agent and also inhibited different strains of gram positive and negative bacteria and fungi.

Thus, this plant is a rich source of plant secondary metabolites of medicinal importance and the results of this study provide some scientific basis for the utilization of the plant in ethno medicine as an insecticide and for the treatment of wounds, bacterial and infectious diseases.

Furthermore, the presence in the essential oil of constituents with proven anti cancer, anti inflammatory [34Kim, S.J.; Chung, W.S.; Kim, S.S.; Ko, S.G.; Um, J.Y. Antiinflammatory effect of Oldenlandia diffusa and its constituent, hentriacontane, through suppression of caspase-1 activation in mouse peritoneal macrophages. Phytother. Res., 2011, 25(10), 1537-1546.
[http://dx.doi.org/10.1002/ptr.3443] [PMID: 21394806]
], anti tuberculosis [35Liu, Y.W. Antituberculous constituents of Gentiana rhodantha. Zhong Yao Tong Bao, 1985, 10(12), 33-34.
[PMID: 2940022]
], nematicidal [21kalaisezhiyen, C.P.; Sasikumar, V. GC- MS Evalution of chemical constituents from methanolic leaf extract of Kedrostis foetidissima (Jacq.). Asian J. Pharm. Clin. Res., 2012, 5(4), 77-81.], antihypertensive, vasodilatory, angiotensin AT2 receptor antagonist, saluretic [33Mallikadevi, T.; Paulsamy, S.; Karthika, K.; Jamuna, S. In vitro and in vivo Anti-inflammatory activity of whole plant methanolic extract of Mukia maderaspatana (L.) M.Roem. (cucurbitaceae). Int. J. Pharm. Pharm. Sci., 2012, 4(5), 435-439.] and insecticidal [32Uebel, E.C.; Schwarz, M.; Sonnet, P.E.; Miller, R.W.; Menzer, R.e. Evaluation of the mating Stimulant Pheromones of Fannia canicularis, F. pusio and F. femoralis as attractants. Fla. Entomol., 1978, 61(3), 139-143.
[http://dx.doi.org/10.2307/3494228]
] capabilities gives further added value to the essential oil of Mariscus alternifolius and suggests new practical uses of the essential oil.

CONFLICT OF INTEREST

The authors confirm that this article content has no conflict of interest.

ACKNOWLEDGEMENTS

The authors appreciate the Department of Chemistry University of Ibadan, Nigeria where the research was carried out. Our appreciation also goes to Mr Festus of Pharmaceutical microbiology Department of the same University for carrying out the antimicrobial screening.

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