A lemon myrtle extract inhibits glucosyltransferases activity of Streptococcus mutans

Figures & data

Table 1. Effect of acarbose on GTF activity.

Concentration (mM)	Inhibition (%)
1	40.0 ± 4.2
0.5	29.4 ± 5.2
0.1	14.9 ± 6.2

All data are expressed as the mean ± SD of three independent experiments. Percent inhibition was calculated by considering the control to have maximum GTF activity (100%).

Table 2. Effect of herbal tea extracts on GTF activity.

	Inhibition (%)
Herbal tea	5.00 mg mL^−1	2.50 mg mL^−1	1.25 mg mL^−1
Lemon myrtle	124.9 ± 0.5	117.8 ± 2.2	103.7 ± 4.1
Wild strawberry	122.0 ± 1.4	104.5 ± 4.3	81.8 ± 3.3
Guava leaf	111.8 ± 1.3	94.9 ± 2.2	71.6 ± 2.8
Spearmint	109.6 ± 0.9	92.2 ± 2.8	58.2 ± 6.1
Linden	108.3 ± 1.3	77.4 ± 2.5	73.6 ± 3.3
St.john’s wort	103.4 ± 2.4	91.8 ± 4.0	71.6 ± 3.2
Tian cha	100.6 ± 2.1	78.5 ± 3.3	54.1 ± 2.9
Eucalyptus	100.1 ± 1.4	76.5 ± 3.3	52.9 ± 1.4
Japanese medlar (Loquat)	94.7 ± 3.4	60.9 ± 3.6	26.0 ± 3.5
Stevia	94.7 ± 2.7	74.9 ± 3.4	49.4 ± 2.9
Raspberry	94.6 ± 1.3	69.0 ± 3.6	39.8 ± 2.2
Red wine leaf	91.3 ± 3.1	60.4 ± 3.6	53.4 ± 2.1
Dokudami	88.8 ± 3.3	77.8 ± 5.8	38.9 ± 2.6
Lemon balm	87.0 ± 2.8	63.1 ± 2.0	31.7 ± 2.7
Hub tea	83.7 ± 4.1	65.9 ± 6.7	27.9 ± 3.1
Shiso	81.5 ± 5.2	61.2 ± 3.4	42.3 ± 5.7
Thyme	79.7 ± 1.1	57.9 ± 2.2	23.3 ± 9.0
Pennyroyal	75.3 ± 3.8	16.3 ± 4.8	13.5 ± 1.9
Lemon verbena	74.2 ± 9.8	49.2 ± 4.5	28.7 ± 7.9
Lady’s mantle	73.6 ± 3.9	40.7 ± 2.0	36.8 ± 3.3
Hops	72.6 ± 0.7	31.8 ± 5.6	−2.4 ± 4.3
Savory winter	67.3 ± 4.0	50.8 ± 6.6	8.6 ± 3.4
Mate	64.5 ± 5.6	37.8 ± 3.4	32.7 ± 3.4
Japanese mugwort	58.6 ± 6.2	42.0 ± 5.4	19.6 ± 4.2
Angelica	57.0 ± 2.1	36.7 ± 7.6	20.1 ± 3.3
Hibiscus	56.8 ± 3.0	29.9 ± 3.5	24.0 ± 2.6
Rosemary	56.2 ± 3.7	42.6 ± 3.3	26.0 ± 3.4
Ashitaba	54.9 ± 6.3	30.9 ± 3.3	23.7 ± 5.0
Sage	53.4 ± 4.8	16.0 ± 3.2	−4.2 ± 3.0
Hyssop	51.1 ± 3.5	29.6 ± 3.2	16.4 ± 5.5
Sunflower petal	50.7 ± 2.7	53.5 ± 9.5	30.4 ± 6.1
Roman chamomile	46.4 ± 5.0	27.0 ± 5.0	27.7 ± 1.5
Eyebright	46.2 ± 3.4	13.5 ± 4.6	3.1 ± 4.4
Tochu tea	45.5 ± 3.2	39.6 ± 6.3	27.1 ± 4.3
Safflower	45.0 ± 4.4	20.1 ± 7.3	16.8 ± 9.4
Lavender	43.7 ± 2.6	21.8 ± 2.3	17.8 ± 2.8
Anise seed	39.8 ± 4.6	21.0 ± 5.3	18.9 ± 1.9
Candle bush	39.8 ± 3.1	34.6 ± 4.6	12.1 ± 4.3
Peppermint	32.7 ± 5.2	25.7 ± 13.9	15.6 ± 2.8
Catnip	27.8 ± 2.0	18.7 ± 3.1	18.1 ± 4.8
German chamomile	25.7 ± 5.4	13.2 ± 3.4	7.0 ± 3.2
Cardamon	25.5 ± 4.3	15.3 ± 1.6	2.7 ± 3.5
Mulberry	24.0 ± 2.7	20.6 ± 2.7	11.2 ± 2.8
Kuma bamboo grass	12.8 ± 4.9	8.9 ± 4.3	1.5 ± 1.8

All data are expressed as the mean ± SD (n = 8). The procedures are described in the Materials and Methods.

Table 3. Polyphenol contents of herbal tea extracts.

Herbal tea	Polyphenol content mg g^−1
Lemon balm	5.55 ± 0.77
Mate	4.57 ± 0.34
Lemon myrtle	4.44 ± 0.34
Lady’s mantle	2.75 ± 0.17
Savory winter	2.70 ± 0.70
Eucalyptus	2.61 ± 0.24
Raspberry	2.51 ± 0.12
Lemon verbena	2.50 ± 0.13
Guava	2.49 ± 0.04
Spearmint	2.47 ± 0.04
Tian cha	2.40 ± 0.16
Red wine leaf	2.32 ± 0.17
Shiso	2.31 ± 0.16
Wild strawberry	2.30 ± 0.14
German chamomile	2.26 ± 0.07
Stevia	2.02 ± 0.16
Pennyroyal	1.91 ± 0.15
Thyme	1.89 ± 0.04
St.john’s wort	1.77 ± 0.21
Peppermint	1.73 ± 0.19
Lavender	1.71 ± 0.15
Linden	1.69 ± 0.09
Japanese mugwort	1.68 ± 0.18
Sage	1.65 ± 0.07
Rosemary	1.24 ± 0.08
Eyebright	1.10 ± 0.17
Hops	1.05 ± 0.07
Hyssop	0.94 ± 0.03
Roman chamomile	0.86 ± 0.06
Anise seed	0.85 ± 0.21
Catnip	0.80 ± 0.02
Ashitaba	0.79 ± 0.11
Safflower	0.79 ± 0.07
Tochu tea	0.71 ± 0.07
Kuma bamboo grass	0.66 ± 0.03
Mulberry	0.62 ± 0.09
Dokudami	0.58 ± 0.15
Japanese medlar (Loquat)	0.58 ± 0.04
Candle bush	0.57 ± 0.26
Hibiscus	0.55 ± 0.11
Sunflower petal	0.55 ± 0.02
Hub tea	0.51 ± 0.09
Cardamon	0.46 ± 0.01
Angelica	0.40 ± 0.09

Values were expressed as mg of ferulic acid equivalent per g of herbal tea extract. All data are expressed as the mean ± SD (n = 8).

Table 4. Effect of herbal tea extracts on S. mutans biofilm formation.

Herbal tea	Biofilm formation (%)
Lemon myrtle	55.84 ± 0.05
Wild strawberry	143.94 ± 0.07
Guava	81.29 ± 0.06
Spearmint	160.53 ± 0.11
Linden	74.51 ± 0.11

Two hundred micrograms of herbal tea extracts were added to medium (final concentration; 5 mg mL⁻¹), and the bacterial biofilms formed in microtiter plates were stained with crystal violet. Biofilm formation was quantified by measuring the optical density at 595 nm. The procedures are described in the Materials and Methods. All data are expressed as the mean ± SD (n = 4).

Figure 1. Effect of herbal tea extracts on S. mutans growth.

S. mutans was grown in 50 mL of brain heart infusion broth supplemented with 255 mg herbal tea extracts (final concentration was 5 mg mL⁻¹) at 37°C for 30 h. The growth of S. mutans was quantified by measuring the optical density at 600 nm. All data are expressed as the mean ± SD (n = 6).

Table 5. Effect of ellagic acid, quercetin, hesperetin, and myricetin on GTF activity.

	Inhibition (%)
Polyphenol	1.00 mM	0.50 mM	0.25 mM
Ellagic acid	45.6 ± 0.9	28.4 ± 7.5	22.2 ± 1.8
Quercetin	39.9 ± 4.0	24.1 ± 4.2	15.6 ± 2.0
Hesperetin	1.93 ± 0.5	ND	ND
Myricetin	48.3 ± 2.1	35.5 ± 2.4	31.4 ± 7.1

All data are expressed as the mean ± SD (n = 4). The procedures are described in the Materials and Methods. ND, not determined