A New Source of Natural D-Borneol and Its Characteristic
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Journal of Medicinal Plants Research Vol. 5(15), pp. 3440-3447, 4 August, 2011 Available online at http://www.academicjournals.org/JMPR ISSN 1996-0875 ©2011 Academic Journals Full Length Research Paper A new source of natural D-borneol and its characteristic Lei Chen 1, Jianyu Su 1*, Lin Li 1, Bing Li 1 and Wang Li 2 1Department of Food Science and Technology, South China University of Technology, 510642 Guangzhou, Peoples Republic of China. 2Food Safety Key Laboratory of Guangdong Province, College of Food Science, South China Agricultural University, 510642 Guangzhou, Peoples Republic of China. Accepted 28 February, 2011 The essential oils from leaves of Mei Pian tree (a Cinnamomun burmannii physiological type), were obtained by hydro-distillation and analyzed by gas chromatography and mass spectrometry (GC/MS). Forty compounds representing 99.61% of the total oil containing D-borneol (78.6%) as the major component were obtained. D-borneol was purified by sublimation, and the characteristic of the refined D-borneol was compared with standard D-borneol and synthetic borneol by infrared spectra analysis and optical activity analysis. The chemical composition and the optical rotation of refined D-borneol from leaves of Mei Pian tree were extremely similar to the standard D-borneol and materially surpass synthetic borneol. Antioxidant activities of the refined D-borneol and standard D-borneol were determined by testing their DPPH and hydroxyl radicals scavenging activities and the reducing power. The refined D-borneol and standard D-borneol had the same antioxidant activity. They exhibited higher hydroxyl radicals scavenging activity, but weaker reducing power, compared with the synthetic borneol. Key words: Borneol, D-borneol, synthetic borneol, gas chromatography and mass spectrometry (GC-MS), antioxidant activity. INTRODUCTION Borneol (C 10 H18 O), a bi-cyclic mono-terpenoid alcohol, toxic effects of camphor is to use natural borneol instead one of the valuable medical material, senior aromatic of synthetic borneol in different borneol products. Natural spices, chemical materials, has been used in food and borneol is mainly extracted from the essential oils of also folk medicine in China and India. According to the numerous medicinal plants of the families Pharmacopoeia of People's Republic of China (2005), Dipterocarpaceae (for example, Dipterocarpus turbinatus borneol is an important ingredient among about 63 herbal tree), Lamiaceae (for example, Rosmarinus officinalis or products. There are two different kinds of borneol; (a) Salvia officinalis ), Valerianaceae (for example, Valeriana synthetic borneol which is a mixture of DL-borneol and officinalis ) or Asteraceae (for example, Matricaria isoborneol, in which the DL-borneol content should be no chamomilla ), etc., (Tabanca et al., 2001) . Since there was less than 55.0%, and; (b) natural borneol whose main a shortage of natural source, the price of natural borneol component is D-borneol, which should be >95.0% of was gradually increased. New sources of natural borneol natural borneol. Previous studies showed that synthetic would be urgently needed. Luckily, the newly discovered borneol degraded slowly during storage and noxious source of natural borneol in China has provided this camphor level might be as high as 45 to 97% with opportunity. concomitant lower levels of synthetic borneol (Zeng and Recent studies showed that natural borneol can also be He, 2004). These results indicated that camphor was a extracted from the leaves of Cinnamomum camphora (L.) degradation product of synthetic borneol. It is widely Presl. plants grown in Jiangxi province and Hunan known that camphor is toxic, whereas natural borneol is province in China (Li, 1992). Wang et al. (2003) and Hu nontoxic. Therefore, a management strategy to avoid the et al. (2006) had evaluated the potential toxicity of natural borneol from the plants and found that it was safe for consumption since it neither induced red blood cell micronuclei nor inhibit the bone marrow of mice. Thus, it *Corresponding author. E-mail: [email protected] Tel:/Fax: +86- can be safely used to replace synthetic borneol. 02-87113252. Additionally, we recently found a plant of Cinnamomum Chen et al. 3441 burmannii physiological type called Mei Pian tree growing Thermofinnigan Trace GC/Trace DSQ/6890 (E.I.Quadrapole) wildly in the Guangdong province of China. The essential equipped with a HP-5MS fused silica capillary column (30 mm × oil from the leaves of this species was rich in D-borneol. 0.25 mm, film thickness 0.25 µm). For GC–MS detection, an electron ionization system with ionization energy of 70 eV was The purposes of the present studies were; (i) to obtain used. Carrier gas was helium at a flow rate of 2 ml/min. Injector and the essential oil from Mei Pian tree by using a Clevenger MS transfer line temperatures were set at 250 and 300°C distillation apparatus and the chemical composition of the respectively. The oven temperature was programmed from 80 to essential oil was evaluated by using gas 250°C at 20°C /min, then held isothermal for 5min. Diluted samples chromatography-mass spectroscopy (GC-MS); (ii) to (1/100, v/v, in methylene chloride) of 0.5 µl were injected manually in the splitless mode. The identification of individual compounds separate and purify D-borneol from the essential oil by was based on comparison of their relative retention times with those freezing centrifugation, then sublimation, and then, of authentic samples on HP-5 capillary column, and by matching of evaluate the in vitro antioxidant properties of D-borneol their mass spectra of peaks with those obtained from authentic by determining its 2,2-diphenyl-1- picrylhydrazyl (DPPH), samples and, or the Wiley 7N and TRLIB libraries spectra and hydroxyl radicals scavenging activities and the reducing published data (Adams, 2007). power. As to our knowledge, there were few reports on the essential oil composition and the characteristic of D- FT-IR analysis borneol of Mei Pian tree. Therefore, our study would be the first to report this new natural source for producing D- All analyses were carried out using a Varian (formerly BioRad) FTS borneol and evaluate its characteristic and antioxidant 6000 FT-IR spectrometer. Spectral collection was conducted under ambient conditions. The operating range was from 4000 to 400 cm -1 activity. -1 with a resolution of 4 cm using a DTGS detector. In all cases, 64 interferograms per sample were co-added and averaged for each MATERIALS AND METHODS spectrum. Following the pellet preparation, KBr pellets were immediately placed into the sample compartment (refined D- Chemicals and reagents borneol，synthetic borneol ，standard D-borneol) of the spectrometer, left to purge with dry air for 15 min to remove ambient Synthetic borneol (chemical purity >98.0%) were purchased from water vapor and FT-IR spectra were subsequently recorded. All Huangpu Chemical Plant, Guangzhou, China. Standard D-Borneol spectra were measured with a blank KBr pellet as the background (batch number ：110743-200504) was obtained from the Natural and were ratioed against the background. Institute for the Control of Pharmaceuticals and Biological Products, Beijing, China. Chromatographic Grade hexane was purchased from SK Chemicals, Korea. Ethanol and sodium sulphate were Optical rotation analysis analytical grades, which were purchased locally. 0.1 g samples (refined D-borneol, synthetic borneol, standard D- borneol) were dissolved in 1ml dehydrated alcohol respectively, Plant material configured as the solution of 0.1g/ml, and the specific rotation of the solutions were determined by Digit automatic polarimeter. Fresh leaves of Mei Pian tree were obtained from South China Botanical Garden, Chinese Academy of Sciences (Guangzhou, China). Taxonomic identification of the plant material was confirmed Antioxidant activity of refined D-borneol and standard D- by professor Liangfeng Zhu, South China Botanical Garden, borneol Chinese Academy of Sciences. Scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical Extraction of the essential oil The hydrogen atoms or electron donation ability of the Fresh leaves of the plants were submitted for 2 h to water corresponding extracts and some pure compounds were measured distillation using a Clevenger distillation apparatus. The obtained from the bleaching of purple colored methanol solution of DPPH. essential oil was dried over anhydrous sodium sulphate and after This spectrophotometric assay uses stable radical DPPH as a filtration, stored at + 4°C until tested and analyzed. The extraction reagent (Cuendet et al., 1997; Burits and Bucar, 2000). The effect yield was determined by the method of Zhang, Bi, and Liu (2007). of methanolic extracts on DPPH radical was estimated according to The dried extract was weighed, and the extract yield was then Hatano et al. (1988). 2 ml of various concentrations (0.02 to 0.50 calculated and expressed as the percentage of the weight of the mg/ml) of refined D-borneol and standard D-borneol in ethanol were crude extract to the raw material. added to 2 ml of DPPH radical solution in ethanol (the concentration of DPPH was 0.2 mM). After 30 min incubation at Purification of D-borneol 20°C, the absorbance was read against a blank at 517 nm. BHT at 0.2 mg/ml were used as the control. The D-borneol was extracted by freezing centrifugation from the essential oil and then sublimated by the transpiration method as was described by Zielenkiewicz et al. (1999). Hydroxyl radical scavenging activity assay The assay of scavenging activity for hydroxyl radical was based on GC/MS analysis Fenton reaction (Yu et al., 2004). After incubation at 37°C for 45 min, the absorbance at 536 nm was measured. BHT at 0.4 g/ml The analysis of the essential oil was performed with a was used as the control. 3442 J. Med. Plant. Res. Abundance 5.914 40000 00 350000 300000 250000 20000 00 1500000 1000000 50000 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 n Figure 1.