Pharmacogn. J. 2016;8(5):451-458 A multifaceted peer reviewed journal in the field of Pharmacognosy and Natural Products Original Article www.phcogj.com | www.journalonweb.com/pj Gas Chromatography - Mass Spectrometry Analysis and In vitro Antioxidant Activity of the Ethanolic Extract of the Leaves of Tabernaemontana divaricata Muniyandi Anbukkarasi1, Philip A Thomas2, Mahalingam Sundararajan1, Pitchairaj Geraldine1* 1Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli- 620 024, Tamil Nadu, INDIA. 2Department of Ocular Microbiology, Institute of Ophthalmology, Joseph Eye Hospital, Tiruchirappalli- 620 001, Tamil Nadu, INDIA. ABSTRACT Objective: To identify phytoconstituents present in an ethanolic extract exhibited 68% and 78%, respectively, chelation of ferrous ions; at the of the leaves of Tabernaemontana divaricata and to evaluate its in-vitro same concentration, the reducing power of the extract and that of a butylated antioxidant potential. Methods: The extract was subjected to gas chro- hydroxytoluene standard was found to be 3.855 and 4.308, respectively. matography-mass spectrometry analysis to identify phytoconstituents, Conclusion: These observations strongly suggest that the ethanolic and screened for hydroxyl, superoxide and 1, 1-diphenyl-2-picrylhydrazyl extract of T. divaricata leaves has potent in-vitro antioxidant activity and (DPPH) radical scavenging activity, reducing power and metal-chelating thereby could act as a possible therapeutic agent for oxidative stress- activity as a measure of potential antioxidant activity. Results: GC-MS induced pathological states. analysis of the extract revealed the presence of 96 phytoconstituents, of which 17 are reported to be bioactive and 11 of these to possess antioxidant Key words: Tabernaemontana divaricata, GC-MS analysis, Phytoconstitu- potential. When tested in-vitro, the extract exhibited the most potent ents, Antioxidant activity, Reducing power, Metal chelating activity. radical-scavenging activity at a maximum concentration of 10 mg/ml, scav- enging effects of 64%, 67% and 69% and corresponding half maximal Corresponding author: Dr. P.Geraldine, Department of Animal Science, inhibitory concentration (IC50) values of 6.7 mg/ml, 6.8 mg/ml and 6.2 mg/ml School of Life Sciences, Bharathidasan University, Tiruchirappalli-620 024, on hydroxyl, superoxide and DPPH radicals, respectively. Ascorbic acid Tamil Nadu, INDIA. used as a standard (10 mg/ml) showed scavenging effects of 73%, 73% Tel: Phone: +91-431-2407040, Fax: +91-431-2414969 and 75% and corresponding IC50 values of 5.3 mg/ml, 5.8 mg/ml and 5.2 mg/ml, respectively, on hydroxyl, superoxide and DPPH radicals. Email: [email protected] At 10 mg/ml, the extract and an ethylenediaminetetraacetic acid standard DOI : 10.5530/pj.2016.5.7 INTRODUCTION effects, medicinal plants are reported to be more biologically active than their purified constituents.15 An antioxidant is a compound that inhibits or retards the oxidation of Tabernaemontana divaricata (T. divaricata) is one such medicinally- substrates even if it is present in a significantly lower concentration than important plant belonging to the family Apocynaceae.16 It is a glabrous, that of the oxidised substrate.1 A possible mechanism of antioxidant evergreen, dichotomously-branched shrub, locally known as ‘nandiya- activity is scavenging of reactive oxygen species (ROS); others include vattom’ (synonyms: Tabernaemontana coronaria, Ervatamia coronaria, the prevention of ROS formation by binding of metal or inhibition of Ervatamia divaricata and Ervatamia microphylla) and is believed to enzyme. ROS may initiate several human degenerative diseases, and anti- exhibit antioxidant, anti-infectious, anti-tumorogenic, anti-bacterial oxidants may exert defensive and therapeutic effects on many metabolic 17-18 19 2 and analgesic properties. Jain et al. also reported that aqueous and disorders. Interestingly, clinical and epidemiologic studies in some cases ethanolic extracts of T. divaricata leaves were able to scavenge superox- have pointed out that antioxidant nutrients may be effective in disease ide radicals in-vitro. Hence, in the present investigation, an attempt was 3 prevention. However, the use of synthetic antioxidative agents, such as made to identify bioactive constituents of the leaves of T. divaricata and butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), to elucidate various antioxidant characteristics such as potential radical- propylgallate (PG), and tertiary-butyl hydroxytoluene is restricted as scavenging and metal-chelating activities and reducing power of the leaf they are suspected to be carcinogenic despite exhibiting potent free extract. radical-scavenging effects.4-6 Therefore, there is an increasing interest in the extraction of antioxidants from natural sources by various tech- MATERIALS AND METHODS niques7-9 as well as identification of compounds with antioxidant activity to replace synthetic food additives.10-11 Preparation of an ethanolic extract of T. divaricata The developed world is witnessing increasing interest in complementary leaves and alternative medicine (CAM), particularly herbal remedies. Herbal The leaves of T. divaricata plant were collected from within the Bharathi- medicines include herbs, herbal materials, herbal preparations, and dasan University campus, Tiruchirappalli, Tamilnadu, India. The plant finished herbal products that contain parts of plants or other plant was identified by the Rapinat Herbarium and Centre for Molecular materials as active ingredients.12 Medicinal plants, unlike pharmacological Systematics, St.Joseph’s College, Tiruchirappalli, India. The voucher drugs, commonly contain several chemicals working together catalyti- specimen (No: KV 001) has been preserved in the Department of Animal cally and synergistically since they possess different phytochemicals, that Science, Bharathidasan University, Tiruchirappalli, India. is, secondary metabolites, that produce a combined effect that surpasses The leaves (fresh and disease-free) were shade-dried and finely the total activity of the individual constituents.13-14 So also, due to synergistic powdered. Thirty grams of the powder were extracted with 300 ml of Pharmacognosy Journal, Vol 8, Issue 5, Sep-oct, 2016 451 Anbukkarasi et al.: GC-MS analysis and In vitro Antioxidant activity of T. divaricata Leaves 95% ethanol using a Soxhlet apparatus. The solvent was evaporated (2 to 10 mg/ml) in water. The reaction was initiated by adding 1.0 ml of under reduced pressure at 55-60°C and dried in a vacuum. The residue PMS (10 μM) solution to the mixture. The reaction mixture was incu- was filtered and concentrated to a dry mass by vacuum distillation. This bated at 100°C for 5 minutes and the absorbance was measured at 560 dried ethanolic extract of T. divaricata was used for further analyses. nm against a blank. L-ascorbic acid was used as a standard. Decreased absorbance of the reaction mixture indicated increased superoxide GC-MS analysis of the T. divaricata extract anion-scavenging activity. The percentage (%) inhibition of superoxide The ethanolic extract of T. divaricata underwent gas chromatography-mass anion generation was calculated using the same formula that was used to spectrometry (GC-MS) analysis (GC-MS - QP-2010 Plus, Shimadzu, calculate the OH--scavenging activity. Tokyo, Japan) with the thermal desorption (TD) system 20. Experimental conditions of the GC-MS system were as follows: Trace-5 mass spec- Determination of possible 1, 1-diphenyl-2- trometry capillary standard non-polar column, dimension: 30 meters; picrylhydrazyl (DPPH) radical-scavenging activity in internal diameter: 0.25 mm; film thickness: 0.25 μm. The flow rate of the the T. divaricata extract mobile phase (carrier gas: helium) was set at 1.2 ml/min. In the gas The potential of the T. divaricata extract to scavenge the stable radical chromatography phase, the temperature programme (oven temperature) DPPH (1, 1-diphenyl-2-picrylhydrazyl) was measured by the method was 80°C, which was raised to 250°C at 10°C/min, and the injection described by Kikuzaki and Nakatani,23 with slight modifications. In this volume was 1 μl. Samples dissolved in chloroform were run fully at a experiment, 1.0 ml of 0.1 mM DPPH prepared in methanol was mixed range of 50-650 mass-to-charge ratio (m/z) and the results were com- with 1.0 ml of the extract (ranging from 2 to 10 mg/ml). The reaction pared by using the Wiley Spectral Library Search Programme (http:// mixture was shaken vigorously and left in the dark at room temperature www.sisweb.com/software/ms/wiley-search.html). for 30 minutes. The absorbance was then measured at 517 nm against Determination of putative in vitro antioxidant a blank; L-ascorbic acid was used as a standard. Decreased absorbance of the reaction mixture indicated higher free radical-scavenging activity. activities of the ethanolic extract of T. divaricata DPPH radical-scavenging activity was calculated using the same formula leaves as that used to calculate the OH--scavenging activity. Determination of possible hydroxyl radical- Determination of putative reducing power in the T. scavenging activity in the T. divaricata extract divaricata extract The hydroxyl radical (OH-)-scavenging capacity of the T. divaricata The putative reducing power of the T. divaricata extract was determined extract was measured according to the modified method of Halliwell by the method of Oyaizu.24 Various concentrations of the extract