Volatile constituents and biological activities of Pycnostachys abyssinica and Pycnostachys eminii extracts

Figures & data

Table 1.  Constituents of the essential oils of P. abyssinica and P. eminii.

RRI*	Compound	EO composition (% peak area)
		PAS	PAR	PEL	PES	PER
939	α-Pinene	0.16	0.27	0.39	0.87	1.88
954	Camphene	0.07	0.26	0.61	1.49	1.03
975	Sabinene	0.07	tr	0.12	0.34	–
979	β-Pinene	–	0.24	1.1	0.72	2.35
991	β-Myrcene	0.49	–	–	–	–
1003	α-Phellandrene	0.05	–	–	–	–
1017	α-Terpinene	0.03	–	–	–	–
1025	p-Cymene	0.27	0.23	–	–	tr
1026	ο-Cymene	–	–	–	–	0.3
1029	Limonene	8.0	1.21	0.14	0.47	1.53
1037	(Z)-Ocimene	2.94	0.13	–	–	–
1050	(E)-Ocimene	0.2	0.1	–	–	–
1060	γ-Terpinene	3.8	1.74	–	–	–
1087	Fenchone	2.37	–	–	–	–
1089	Terpinolene	4.06	1.39	–	0.16	0.38
1097	Linalool	–	–	0.74	–
1117	endo-Fenchol	0.05	0.18	–	–	–
1122	exo-Fenchol	0.11	–	–	–	–
1146	Camphor	0.06	–	–	–	–
1169	Borneol	tr	–	–	–	–
1177	4-Terpineol	0.06	–	–	–	–
1196	Estragole	70.4	tr	–	–	0.66
1220	endo-Fenchyl acetate	0.18	–	–	–	13.76
1223	exo-Fenchyl acetate	5.18	30.6	–	–	–
1235	Thymol methyl ether	–	0.56	–	–	–
1285	(E)-Anethole	0.11	–	–	–	–
1289	Bornyl acetate	–	2.82	–	–	4.34
1351	α-Cubebene	–	–	0.39	–	–
1375	α-Ylangene	–	–	0.29	0.34	–
1377	α-Copaene	–	–	1.63	0.69	–
1388	β-Bourbonene	–	–	0.46	0.92	–
1391	β-Elemene	–	–	0.2	0.36	0.38
1410	α-Gurjunene	–	0.35	0.22	–	–
1413	(Z,Z)-α-Bergamotene	–	–	–	–	0.35
1419	β-Caryophyllene	–	5.33	21.64	28.85	18.08
1434	β-Gurjunene	–	0.3	0.33	0.26	–
1435	(Z,E)-α-Bergamotene	–	0.67	–	–	0.35
1440	α-Guaiene	–	–	0.1	0.21	0.57
1455	α-Caryophyllene	–	6.61	1.81	2.72	7.1
1457	(E)-β-Farnesene	0.22	–	0.15	–	tr
1480	γ-Muurolene	–	–	1.92	0.44	10.54
1485	Germacrene D	–	0.36	21.97	22.06	15.1
1490	β-Selinene	–	0.46	0.38	0.25	3.0
1496	Viridiflorene	–	–	–	–	2.89
1498	α-Selinene	–	–	0.56	1.2	1.53
1506	(E,E)-α-Farnesene	–	–	4.59	3.68	–
1506	β-Bisabolene	0.04	–	–	–	–
1514	γ-Cadinene	–	–	4.99	5.43	–
1523	δ-Cadinene	–	–	4.07	1.85	–
1557	Elemicin	0.08	1.26	0.2	0.77	1.12
1563	(E)-Nerolidol	–	16.8	10.95	3.79	1.5
1578	Spathulenol	–	1.56	–	–	–
1583	Caryophyllene oxide	–	4.05	6.55	9.34	5.05
1601	Guaiol	–	1.23	–	–	–
1640	τ-Muurolol	–	–	1.29	0.98	–
1642	τ-Cadinol	–	4.61	0.93	0.47	–
1651	β-Eudesmol	–	11.09	–	–	1.31
1654	α-Eudesmol	–	5.38	1.94	1.93	4.86
	Total identified (%)	99.0	99.79	90.66	90.59	99.96

*Relative retention indices on an apolar column (CP-Sil 5); tr, trace (<0.01%); –, not detected; PAS, P. abyssinica stem; PAR, P. abyssinica root; PEL, P. eminii leaf; PES, P. eminii stem; PER, P. eminii root.

Table 2.  Zone of inhibition produced by petroleum ether (PE), chloroform (CHCl₃) and methanol (MeOH) extracts of P. abyssinica against bacterial and fungal strains (n = 3, average ± SD).

Plant part	Fraction	Concentration (µg/µL)	Zone of inhibition (mm)
			Sa^s	Pa^s	Ca^i	Cn^i
Leaf	PE	12.5	–	–	6.3 ± 0.5	11.3 ± 1.5
		25	6.0 ± 2.0	–	8.0 ± 1.0	12.7 ± 1.1
		50	7.0 ± 1.0	–	10.3 ± 1.1	14.3 ± 1.5
	CHCl3	12.5	–	–	–	5.7 ± 0.5
		25	–	4.3 ± 0.5	–	10.0 ± 1.0
		50	–	5.7 ± 1.1	–	11.3 ± 1.1
	MeOH	12.5	–	–	–	–
		25	4.0 ± 1.0	–	–	–
		50	8.0 ± 2.6	–	–	–
Stem	PE	12.5	–	–	–	–
		25	6.3 ± 1.5	–	–	–
		50	8.7 ± 2.1	–	–	–
	CHCl3	12.5	–	–	–	–
		25	–	–	–	–
		50	5.3 ± 2.1	–	–	–
	MeOH	12.5	–	–	–	–
		25	–	–	–	–
		50	–	–	–	–
Root	PE	12.5	7.3 ± 1.5	8.0 ± 2.0	–	–
		25	10.3 ± 2.0	12.3 ± 0.5	–	–
		50	12.0 ± 1.7	13.3 ± 1.5	–	–
	CHCl3	12.5	–	–	9.3 ± 1.1	–
		25	4.0 ± 1.0	–	11.3 ± 0.5	–
		50	7.3 ± 1.1	–	12.7 ± 0.5	–
	MeOH	12.5	–	–	–	–
		25	6.7 ± 2.0	–	–	–
		50	11.0 ± 2.6	–	–	–
Gentamycin sulfate		0.1	27.0 ± 1.1	18.0 ± 0.5	x	–
Ketoconazole		0.3	x	x	23.3 ± 0.5	29.0 ± 1.1
Dimethyl sulfoxide		50% (v/v)90% (v/v)	x-	x-	-x	-x
Methanol		80% (v/v)			–	–

Sa^s, Staphylococcus aureus (standard); Pa^s, Pseudomonas aeroginosa (standard); Caⁱ, Candida albicans (clinical isolate); Cnⁱ, Cryptococcus neoformans (clinical isolate); –, no inhibition zone; x, not tested.

Table 3.  Zone of inhibition produced by petroleum ether (PE), chloroform (CHCl₃) and methanol (MeOH) extracts of P. eminii against bacterial and fungal strains (n = 3, average ± SD).

Plant part	Fraction	Concentration (µg/µL)	Zone of inhibition (mm)
			Sa^s	Ca^i	Cn^i
Leaf	PE	12.5	8.3 ± 1.1	13.3 ± 0.5	–
		25.0	10.3 ± 0.5	14.3 ± 1.5	–
		50.0	12.3 ± 1.5	15.0 ± 1.0	–
	CHCl3	12.5	–	–	7.7 ± 2.0
		25.0	–	–	12.3 ± 1.1
		50.0	–	–	14.3 ± 1.1
	MeOH	12.5	–	–	–
		25.0	5.3 ± 0.5	–	–
		50.0	9.7 ± 2.0	–	–
Stem	PE	12.5	–	8.3 ± 1.0	7.3 ± 0.5
		25.0	–	9.0 ± 2.0	8.0 ± 1.0
		50.0	–	11.3 ± 0.5	9.7 ± 1.1
	CHCl3	12.5	–	–	–
		25.0	–	–	–
		50.0	–	–	–
	MeOH	12.5	–	–	–
		25.0	–	–	–
		50.0	–	–	–
Root	PE	12.5	–	9.7 ± 0.5	11.7 ± 1.1
		25.0	5.3 ± 0.5	11.7 ± 1.1	14.7 ± 1.5
		50.0	6.0 ± 1.0	14.3 ± 1.5	15.3 ± 1.5
	CHCl3	12.5	–	–	6.7 ± 0.5
		25.0	–	–	9.7 ± 1.5
		50.0	5.7 ± 1.1	–	11.3 ± 1.1
	MeOH	12.5	–	–	–
		25.0	–	–	–
		50.0	–	–	–
Gentamycin sulfate		0.1	27.0 ± 1.1	x	x
Ketoconazole		0.3	x	29.3 ± 0.5	29.0 ± 1.1
Dimethyl sulfoxide		50% (v/v)	x	–	–
		90% (v/v)	–	x	x
Methanol		80% (v/v)	x	–	–

Caⁱ, Candida albicans (clinical isolate); Cnⁱ, Cryptococcus neoformans (clinical isolate); Sa^s, Staphylococcus aureus (standard); –, no inhibition zone; x, not tested.

Table 4.  In vitro mortality of earthworms (in %) observed upon treatment with methanol fractions of P. abyssinica and P. eminii (n = 3, average ± SD).

	Fraction	P. abyssinica		P. eminii
		Leaf MeOH	Root MeOH	Leaf MeOH	Leaf MeOH
Test solutions (µg/mL)	125	–	–	–	–
	250	–	13.3 ± 0.5	13.3 ± 0.5	23.3 ± 0.5
	500	13.3 ± 0.5	23.3 ± 0.5	36.7 ± 0.5	50.0 ± 1.0
	1000	36.7 ± 0.5	43.3 ± 0.5	53.3 ± 0.5	63.3 ± 0.5
	1500	56.7 ± 0.5	50.0 ± 1.0	63.3 ± 1.1	73.3 ± 0.5
Control	Niclosamide (84.5 µg/mL)	100 ± 0.0
	Dechlorinated tap water	–
	Tween 80 (0.5% v/v)	–

–, no death recorded.