Chemical composition, seasonal variation and antiaging activities of essential oil from Callistemon subulatus leaves growing in Egypt

Figures & data

Figure 1. GC chromatograms of C. subulatus leaves essential oils showing their seasonal variation.

Table 1. GC-MS analysis of C. subulatus leaf oils in the four seasons.

No.	Compound name	Retention time	Molecular formula	RI exp	RI lit	Relative abundance (%)
						Spring	Summer	Autumn	Winter
1.	α-Thujene	7.155	C10H16	908	906	0.64	–	0.25	0.98
2.	α-Pinene	7.365	C10H16	917	917	31.41	26.34	24.68	28.69
3.	β-Pinene	8.576	C10H16	962	963	0.72	0.25	0.52	0.97
4.	β-Myrcene	9.057	C10H16	978	978	–	–	–	0.45
5.	α-Phellandrene	9.460	C10H16	993	994	1.03	0.32	0.64	9.51
6.	2-Carene	9.635	C10H16	999	1000	0.10	–	–	–
7.	3-Carene	9.755	C10H16	1003	1004	0.17	–	–	0.38
8.	Limonene	10.115	C10H16	1016	1018	5.06	2.45	5.41	3.61
9.	Eucalyptol	10.335	C10H18O	1022	1022	44.63	66.87	58.33	46.74
10.	γ-Terpinene	11.165	C10H16	1049	1049	0.76	–	–	0.58
11.	α-Terpinolene	12.067	C10H16	1090	1085	0.74	–	–	0.34
12.	Linalool	12.678	C10H18O	1113	1113	–	–	0.14	–
13.	Pinocarveol	13.633	C10H16O	1138	1138	–	0.23	0.45	0.42
14.	Borneol	14.297	C10H18O	1166	1166	–	–	0.16	–
15.	Terpinen-4-ol	14.860	C10H18O	1168	1168	1.27	0.43	0.89	0.60
16.	α-Terpineol	15.285	C10H18O	1181	1181	3.62	2.67	5.97	4.05
17.	β-Citral	16.795	C10H16O	1232	1232	0.63	–	–	–
18.	α-Citral	17.680	C10H16O	1263	1267	1.27	–	–	–
19.	Eugenol	20.097	C10H12O2	1366	1366	–	–	0.20	–
20.	Geranyl acetate	20.410	C12H20O2	1372	1377	–	–	0.15	–
21.	Caryophyllene	21.797	C15H24	1409	1409	0.27	–	0.18	0.26
22.	Ledene	23.652	C15H24	1500	1495	–	–	0.12	0.26
23.	δ-Cadinene	24.455	C15H24	1512	1515	0.56	0.22	0.34	1.20
24.	flavesone	24.810	C14H20O4	1547	1546	–	–	0.17	–
25.	Spathulenol	26.066	C15H24O	1577	1577	1.39	–	0.14	0.50
26.	Viridiflorol	26.121	C15H26O	1586	1590	0.61	0.21	0.57	–
27.	Guaiol	26.610	C15H26O	1596	1600	0.44	–	0.18	–
28.	Caryophyllene oxide	27.010	C15H24O	1613	1615	2.34	–	0.20	0.39
29.	Guaia-3,9-diene-11-ol	27.790	C15H24O	1647	1649	0.57	–	–	–
30.	Neointermedeol	27.935	C15H26O	1653	1656	0.39	–	–	–
31.	Germacrone	28.850	C15H22O	1693	1696	1.40	–	0.32	–
	Monoterpene hydrocarbons					40.66	29.36	31.5	45.51
	Oxygenated monoterpenes					51.72	70.2	66.29	51.81
	Sesquiterpene hydrocarbons					0.83	0.22	0.64	1.72
	Oxygenated Sesquiterpene					7.14	0.21	1.58	0.89
	Total identified (%)					98.96	99.99	100	99.93
	Yield (mL/100 gm)					0.17	0.26	0.34	0.53

The major oil components are written in bold.

Figure 2. Seasonal variation in the major compounds of C. subulatus leaves oil, showing seasonal variation of the total classes of compounds (A), the four major monoterpenes hydrocarbons (B) and the three major oxygenated monoterpenes (C).

Figure 3. 2D-Binding diagrams of eucalyptol (A), α-pinene (B) and α-phellandrene (C) on the active site of elastase enzyme.

Figure 4. 2D-Binding diagrams of eucalyptol (A), α-pinene (B) and α-phellandrene (C) on the active site of acetylcholinestrase enzyme.

Table 2. Docking binding energies of major identified compounds of C. subulatus winter oil with elastase and acetylcholinesterase enzymes.

Compound	Binding energy (Kcal/mol)
	Elastase	Acetylcholinesterase
Eucalyptol	−8.6	−9.7
α-Pinene	−7.7	−7.9
α-Phellandrene	−7.1	−7.3