Glucosinolates profile, volatile constituents, antimicrobial, and cytotoxic activities of Lobularia libyca

Figures & data

Figure 1. The general structure of glucosinolates and their enzymatic degradation products (adapted from Rask et al. 2000).

Table 1. GC-MS analysis of GLS hydrolysis products of L. libyca.

Parent GLS Identified compound (molecular formulae)	tR (min)	MS spectral data m/z (% relative abundances)		Relative %
		[M^+]	Other mass fragments	Seeds	Leaves
Glucoiberverin
4-(Methylthio) butanenitrile (iberverin nitrile) (C5H9NS)	12.15	115 (77)	74 (13), 68 (16), 61 (100), 41 (29)	3.23	35.7
3-(Methylthio) propyl isothiocyanate (iberverin) (C5H9NS2)	19.05	147 (9)	101 (100), 72 (51), 61 (29), 41(43)	43.98	51.04
Glucoerucin
4-(Methylthio) butyl isothiocyanate (erucin) (C6H11NS2)	22.13	161 (20)	146 (8), 115 (100), 87 (34), 72 (57),61 (80), 55 (21)	0.8	–
Glucoiberin
3-(Methylsulphiny) propyl isothiocyanate (Iberin) (C5H9NOS2)	26.83	163 (1)	130 (6), 116 (21), 100 (20), 86 (10),72 (100), 63 (19), 41 (40)	3.07	–
Total percentage of identified compounds				51.08	86.74

Table 2. GC-MS analysis of miscellaneous volatile compounds of L. libyca seeds.

Identified compound (molecular formulae)	tR (min)	MS spectral data m/z (% relative abundances)
		[M^+]	Other mass fragments	Relative %
Ethyl benzene (C8H10)	5.44	106 (45)	91 (100), 77 (14), 65 (12), 51 (10), 39 (8)	0.92
beta-Pinene (C10H16)	8.65	136 (12)	121 (12), 93 (100), 79 (26), 77 (34), 69 (39), 53 (4)	0.65
2,6-Dimethyl-7-octen-2-ol (Dihydromyrcenol) (C10H20O)	11.72	152 (0)	123 (12), 109 (2), 95 (8), 82 (11), 67 (17), 59 (100), 55 (23), 41 (20)	0.46
Menthone (C10H18O)	14.19	154 (18)	139 (41), 125 (5), 112 (100), 97 (21), 83 (21), 69 (64), 55 (43), 41 (69)	0.73
Cyclohexanol acetate cis-2-tert-butyl (C12H22O2)	18.33	198 (0)	141 (2), 123 (19), 117 (7), 82 (100), 67 (55), 57 (69), 43 (52)	12.66
Tetradecanoic acid (Myristic acid) (C14H28O2)	29.99	228 (14)	185 27), 171 (9), 143 (10), 129 (33), 115 (13), 97 (16), 83 (34), 73 (100), 60 (70), 55 (72), 43 (81)	0.60
n-Hexadecanoic acid (palmitic acid) (C16H32O2)	34.18	256 (22)	213 (20), 129 (32), 115 (23), 97 (21), 83 (30), 73 (100), 60 (63), 43 (85)	2.7
Total percentage of identified compounds				18.72

Table 3. LC-MS analysis of intact glucosinolates of L. libyca seeds.

Identified compound	tR (min)	Mass parent ion (M-1)	MS^2 spectrum ions (base ion in bold)
Glucoiberin	3.06	422	407, 358, 259
Glucoerucin	7.28	420	340, 275, 259, 227
Glucoiberverin	9.08	406	275, 259, 228

Table 4. Antimicrobial activities of L. libyca seed hydrolysate.

Microorganism	Inhibition zone diameter (mm/mg sample)
	Seed hydrolysate	Standard
		Tetracycline	Amphotericin B
Bacillus subtilis	10	31	–
Staphylococcus aureus	14	28	–
Streptococcus faecalis	13	29	–
Escherichia coli	9	28	–
Neisseria gonorrhoeae	9	27	–
Pseudomonas aeruginosa	15	30	–
Aspergillus flavus	0.0	–	17
Candida albicans	16	–	19

Table 5. MIC values of L. libyca seed hydrolysate and standards against S. aureus, P. aeruginosa and C. albicans.

Micro-organism	MIC (μg/mL)
	L. libyca	Tetracycline	Amphotericin B
Staphylococcus aureus	104	46	–
Pseudomonas aeruginosa	82	32	–
Candida albicans	64	–	58

Figure 2. Cytotoxic activity of L. libyca seeds' hydrolysate. N = 3 ± S. D.

Table 6. IC₅₀ of seed hydrolysate and doxorubicin against tested cell lines.

Tested material	IC50 (μg)
	HCT-116	Huh-7	MCF-7	A-549
Seed hydrolysate	0.31	2.25	37	320
Doxorubicin	0.50	1.5	0.64	0.22

MCF-7: human breast cancer; HCT-116: colorectal; HUH-7: hepatic and A-549: hepatic.

Figure 3. Glucosinolates identified in L. libyca plant.

Rask L, Andreasson E, Ekbom B, Eriksson S, Pontoppidan B, Meijer J. 2000. Myrosinase: gene family evolution and herbivore defense in Brassicaceae. Plant Mol Biol. 42:93–113.

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