Antibacterial, antioxidant and hypoglycaemic effects of Thymus capitatus (L.) Hoffmanns. et Link leaves' fractions

Figures & data

Table 1. Major nonpolar components tentatively identified in T. capitatus leaves—n-hexane and methanol fractions.

		Abundance^†
Compound	I*	n-Hexane fraction (HF)	Methanol fraction (MF)	Identification^‡
α-Pinene	936	0.9 ± 0.01	0.5 ± 0.03	A
p-Cymene	1025	0.6 ± 0.03	2.1 ± 0.01	B
γ-Terpenene	1059	1.8 ± 0.07	4.5 ± 0.01	A
Terpinen-4-ol	1178	1.3 ± 0.02	0.4 ± 0.01	B
Thymol	1290	0.8 ± 0.03	1.6 ± 0.05	A
Carvacrol	1298	35.7 ± 1.9	63.8 ± 2.6	A
β-Caryophyllene	1415	0.7 ± 0.05	2.9 ± 0.12	A
α-Humulene	1447	tr	0.5 ± 0.03	A
γ-Cadinene	1513	0.3 ± 0.03	0.5 ± 0.01	B
δ-Cadinene	1522	tr	tr	B
Caryophyllene  oxide	1592	2.8 ± 0.03	0.3 ± 0.03	B
Tetradecanal	1614	0.6 ± 0.05	—	B
Heptadecane	1700	1.4 ± 0.01	0.6 ± 0.04	B
Pentadecanal	1707	1.6 ± 0.01	0.1 ± 0.01	B
Hexadecanal	1811	1.7 ± 0.03	0.8 ± 0.03	B
Neophytadiene	1830	0.5 ± 0.03	2.2 ± 0.01	B
Methyl palmitate	1934	10.3 ± 0.03	1.1 ± 0.01	A
Palmitic acid	1969	4.2 ± 0.22	8.1 ± 0.27	A

*I, Retention index on MS HP-5 nonpolar column.

^†Abundance calculated as % peak area mean values, mean ± standard deviation (n = 3).

^‡The reliability of the identification proposal is indicated by the following: A, mass spectrum and retention index agreed with standards; B, mass spectrum and retention index agreed with database or literature; tr, < 0.1%. —, not detected.

Table 2. MIC values of T. capitatus fractions against pathogenic bacteria.

Strains	MIC (μg/mL)
		MF	HF	A	B
Gram-positive bacteria
S. aureus	ATCC 29213	250	>1000	>1000	>1000
S. aureus	MetR	250	>1000	>1000	>1000 >1000
S. aureus	MetR	250	>1000	>1000
Str. pneumoniae	ATCC 49619	62.5	>1000	>1000		>1000
Str. pneumoniae	PenR	62.5	>1000	>1000	>1000
Str. pneumoniae	PenR	125	>1000	>1000	>1000
Str. pneumoniae	EryR	62.5	>1000	>1000	>1000
Str. pneumoniae	EryR	62.5	>1000	>1000	>1000
Str. pneumoniae	PenR EryR	125	>1000	>1000	>1000
Str. pneumoniae	PenR EryR	125	>1000	>1000	>1000
Str. pyogenes	EryS	125	>1000	>1000	>1000
Str. pyogenes Str. pyogenes	EryR	125	>1000	>1000	>1000
	EryR	250	>1000	>1000	>1000
	Gram-negative  bacteria
H. influenzae	ATCC 49247	250	>1000	>1000	>1000
H. influenzae	AmpR	250	>1000	>1000	>1000
H. influenzae	AmpR	250	>1000	>1000	>1000
M. catarrhalis	ATCC 25238	62.5	>1000	>1000	>1000

MF, methanol fraction; HF, n-hexane fraction; A, methanol; B, n-hexane; MetR, methicillin-resistant; PenR, penicillin-resistant; EryR, erythromycin-resistant; EryS, erythromycin-susceptible; AmpR, ampicillin-resistant.

Table 3. The antioxidant properties of T. capitatus leaves' methanol and n-hexane fractions.

T. capitatus	β-Carotene bleaching test (IC50 μg/mL)		DPPH assay (IC50 μg/mL)	ABTS assay (IC50 μg/mL)	FRAP assay (μmol/L Fe(II)/g)
	30 min	60 min
Methanol fraction	0.7 ± 0.03*	1.9 ± 0.6*	44.5 ± 1.9^†	8.7 ± 0.2^†	27.7 ± 2.6^†
n-Hexane fraction	27.9 ± 0.9†	42.9 ± 2.3†	38.2 ± 1.2†	4.0 ± 0.8†	32.7 ± 3.5†
Ascorbic acid			5.0 ± 0.8	1.7 ± 0.03	—
BHT			—	—	63.2 ± 4.5
Propyl gallate	1.0 ± 0.04	1.0 ± 0.04

Data are expressed as means ± SD (standard deviation; n = 3). Ascorbic acid, BHT and propyl gallate were used as positive control. One-way ANOVA, ***p < 0.0001. Dunnett's multiple comparison test: DPPH test, †p < 0.01 (MeOH and n-hexane versus ascorbic acid); ABTS test, †p < 0.01 (MeOH and n-hexane versus ascorbic acid); FRAP test, †p < 0.01 (MeOH and n-hexane versus BHT); β-carotene bleaching test 30-min incubation, †p < 0.01 (n-hexane versus propyl gallate), *p > 0.05 (MeOH versus propyl gallate); β-Carotene bleaching test 60-min incubation, *p < 0.01 (n-hexane versus propyl gallate), †p > 0.05 (MeOH versus propyl gallate).

Table 4. T. capitatus hypoglycaemic activity [IC₅₀ (μg/mL)].

T. capitatus	α-Amylase	α-Glucosidase
Methanol fraction	565.9 ± 2.5**	> 1000
n-Hexane fraction	422.5 ± 2.0**	> 1000
Acarbose	50.0 ± 0.9	35.5 ± 1.2

Data are expressed as means ± SD (n = 3). Differences within and between groups were evaluated by one-way analysis of variance (ANOVA) test completed with a multicomparison Dunnett's test. **p < 0.01 compared with the positive control (acarbose).