INTRODUCTION:

Date palm belongs to family of Arecaceae, which consists of about 2500 species and 200 genera1. About 14 species belong to the genera of Phoenix, including Phoenix dactylifera L. The name dactylifera translates to “finger-bearing” which represents the fruit clusters produced by this plant2. Mesopotamia, the lands between the Euphrates and Tigris rivers, in what is Iraq today before 6000 years ago the was the first domestication of the date palm3.

The biological activities of date palm was estimated in many studies that conducted on date palm, whereas its appeared to have antioxidant properties4-5, anticancer Activity 6-7 and anti-diabetic activity8-9. Date palm was reported to have Mg, Ca, K, P, Cu, Fe and Zn10. Moreover dates palm appeared to contain many chemical compositions such as, carbohydrate 83.1, oil 10.19, protein 5.56 and Ash 1.1511. This study was the first report about the chemical composition and biological activities of essential oil of zahdi date palm variety fruits in Iraq.

MATERIALS AND METHODS:

Plant sample:

Sample of palm dates variety (P. dactylifera L.) (500 gm) was collected in October 2018 from the farm in Babylon, city of ijbala. The dates was in Tamer stage and locally known zahdi variety. The sample was in good conditions.

Extraction of volatile compositions:

Fresh fruits of zahdi date palm (500g) was subjected to hydrodistillation using Clevenger apparatus for 8 hours for isolation of volatile composition. The oil sample was stored at 5°C after drying them over anhydrous sodium sulfate in air-tight containers.

GC-MS analysis:

The volatile compositions from zahdi fruits were analyzed by GC-FID on a Agilent 7890B equipped with a 30m× 0.25mm i.d. × 0.25mm DB-5ms fused silica capillary columns. Helium was the carrier gas at a flow rate of 1mL/min. Column temperature was initially at 60°C for 3 min and then gradually increased to 230°C at a 4°C/min rate and held for 10 min. Injector and detector temperatures were set at 230°C and 250°C, respectively. mass spectrometry detection, an electron ionization system with ionization energy of 70 eV was used, mass range – 35–400m/z Run Time 77.667min. Injector 0.50 ml and MS transfer line temperatures were set at 230°C and 250°C, respectively.

Identification of the compounds:

Compound identification was done by comparing the Wiley library data of the peaks with those reported in literature, mass spectra of the peaks with literature data.

Determination of Antioxidant (DPPH assay):

The amount of Eos that necessary to reduce the initial DPPH radicals in 50% (IC50), was evaluated according to Aldulaimi12. Absorbance of samples were done by spectrophotometer model brand/model G10S UV. Vis, USA at 517nm against blank. The IC50 value of volatile composition sample was expressed in mg/mL. For DPPH assay, Preparation different concentrations were diluted of essential oil (25, 50, 100, 200 and 400μg/ml) in petroleum ether, flowing by adding 3ml of DPPH solution to 2ml of diluted volatile composition. The mixture of sample and DPPH were shaking properly and incubated for 30 min at room temperature in dark place to allow the maximum inhibition take place. A typical blank solution contained of methanol solution of DPPH and petroleum ether. The ascorbic acid was the positive control and DPPH scavenging activity was calculated by the following equation:

A blank – A sample

Scavenging activity (%) = ––––––––––––––––––– X 100

A blank

A blank: The absorbance of blank.

A sample: Absorption of EOs containing solution.

Antimicrobial Test:

The disc diffusion assay was conducted for antibacterial test of the essential oil13. The volatile compositions were dissolved in petroleum ether (concentrations ranging from 15 to 35mg/mL). A filter papers with 1.6 mm were saturated with the solution of sample and negative control petroleum ether and placed on the surface of agar. The plates were incubated for 48 hours at 37^oC. The diameter of zone inhibitions were measured in millimeter (mm) to evaluate the effect of volatile oils against the microbial used.

RESULTS AND DISCUSSION:

The dark yellow color volatile oils, were obtained from fruits of zahdi variety dates palm (Phoenix dactylifera) in tamer stage by hydrodistillation using clevenger apparatus. The chemical compositions of the fruit oils were analyzed by GC, GC-MS and tabled in Table 1. In total seventeen chemical compounds of zahdi volatile oils were identified, the major compounds were cyclododecane (66.97%), dodecane (5.05%), 1-eicosene (4.99%), 1-pentadecanol (4.75%) and 1-hexadecene (3.37%). The antibacterial activities of the zahdi variety dates volatile composition were measured by the disc diffusion Table 2. The volatile oils showed antibacterial activity with zones of inhibition ranging from 7.6–11.8 mm and appeared significant activity against S. aureus, B. subtilis, E. coli and P. aeruginosa. The tested sample appeared less activity against the Gram-negative compare to Gram positive bacteria. This result was acceptable with many previous studied conducted on essential oil of other plant species13-14. According to several studied, the Gram-negative bacteria showed to be less sensitive to essential oils15-17. The differences in the cell membrane of Gram-negative bacteria could be the reason for the resistance to these bacterial. Moreover, highly hydrophilic surface of Gram-negative case the main reason for resistance toward the nonpolar essential oil compounds, whereas the Gram-positive bacteria have lipophilic ends of lipoteichoic acids which may increase the possibility to nonpolar essential oils to pass through the cell membrane of these group of bacteria18-20. In this study, the radical scavenging activity is measured by DPHH analysis technique on volatile oil. The scavenging activity of oil was estimated at different concentrations (10-320 g/mL). The results were presented in Table 3. The outcome showed that volatile oil was able to decrease the stable, purple color radical DPPH to the yellow color DPPH-H. Additionally, compared to Ascorbic acid as a standard, the oil extract exhibited high antioxidant activity with IC50 22.15µg/ml.

CONCLUSION:

This is the first study on biological activities and chemical composition of the volatile composition from the fruits of zahdi variety dates palm (Phoenix dactylifera). In total seventeen chemical components were identified and using GC-MS and GC-FID. The antibacterial assay of the oil sample exhibited broad spectrum of antibacterial activities. The antibacterial properties of oils could be for the main components presence in the complex. The antioxidant activity of volatile oil showed significant potential to reduce the radicals of DDPH and the IC50 value was close to that of stranded ascorbic acid used in the study. Thus, the volatile from the fruits of zahdi variety dates palm could be serve as a potential bioactive natural product in the pharmaceutical industry.

Table 1: Chemical composition of volatile oils

S. No	Compound	Percentage	RT
1	Hexenol (4Z)	0.65	6.394
2	Hexalactone	1.05	6.486
3	2, 4-Decadienal	1.53	30.100
4	Decanoic acid	1.53	33.654
5	Isoamyl benzoate	2.03	46.997
6	Hexadecanol <n->	66.97	50.202
7	Triacontane	1.45	51.895
8	Nonadecane	0.78	53.744
9	Methyl palmitate	1.14	54.711
10	Eicosane <n->	0.77	57.125
11	1-Hexadecene	3.37	61.674
12	Docosane	1.60	63.454
13	Tricosane	0.45	66.423
14	Verbanol	1.84	67.482
15	1-Eicosene	4.99	67.946
16	1-Pentadecanol	4.75	72.546
17	Dodecane	5.05	74.783

RT = Retention time of chemical composition

Table 2: Antibacterial activity of volatile composition

Volatile oil		Gram positive		Gram negative
		*S. aureus*	*B. subtilis*	*E. coli*	*P. aeruginosa*
	IZ	10.4	11.8	8.2	7.6
	MIC	100	100	150	200

Table 3: Antioxidant of volatile composition

Compound	Antioxidant activity (IC₅₀µg/mL)
Essential oils	22.15 ± 0.82
Ascorbic acid	19.8 ± 0.45

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Received on 25.10.2019 Modified on 20.01.2020

Research J. Pharm. and Tech. 2020; 13(11):5207-5209.

DOI: 10.5958/0974-360X.2020.00910.5