Functional components, antidiabetic, anti-Alzheimer’s disease, and antioxidant activities of Salvia syriaca L.

Figures & data

Table 1. Chemical composition of the essential oil from the aerial parts of Salvia syriaca.

Number	Compound	Percentage	RT	RI	Identification method^a
1	α-Thujene	0.1	4.38	924	RI, MS
2	trans-Pinocarveol	0.1	8.91	1132	RI, MS
3	Pinocarvone	0.3	9.10	1139	RI, MS
4	α-Terpineol	0.1	10.12	1180	RI, MS
5	Myrtenol	0.1	10.24	1185	RI, MS
6	Bornyl acetate	2.7	12.67	1277	RI, MS
7	Spathulenol	87.4	20.18	1572	RI, MS, Co-I
8	α-Humulene oxide	0.2	20.37	1586	RI, MS
9	Humulene epoxide	0.1	20.75	1602	RI, MS
10	Isospathulenol	7.6	21.23	1624	RI, MS
11	α-Cadinol	0.1	21.72	1646	RI, MS
12	α-Bisabolol	0.1	22.26	1670	RI, MS
Monoterpene hydrocarbons		0.1
Oxygenated monoterpenes		0.6
Sesquiterpene hydrocarbons		—
Oxygenated sesquiterpenes		95.5
Other		2.7
Total identified		98.9

^aRI: retention index, MS: mass spectra, Co-I: co-injection.

Figure 1. Major compounds found in A: methanolic extract; and B: the essential oil of Salvia syriaca.

Table 2. Antioxidant activity, total bioactive compounds, and toxicity of the essential oil and extracts of S. syriaca.^a

Samples	DPPH (IC50:µg/mL)	FRAP (SRP)		TP (mg GAE/g)		TF (mg QE/g)		BSLA (LC50:µg/mL)
Essential oil	45 ± 2.2	0.98 ± 0.04		-		-		85 ± 10.2
n-hexane	210 ± 11.5	0.64 ± 0.03		86 ± 4.0		77 ± 5.6		450 ± 24.4
Dichloromethane	245 ± 12.0	0.55 ± 0.02		67 ± 3.5		83 ± 4.4		285 ± 16.0
Methanol	70 ± 2.6	0.89 ± 0.05		255 ± 15.0		128 ± 6.8		775 ± 35.3
Standard^b	66 ± 1.8	1.01 ± 0.06		-		-		40 ± 1.5

^aValues expressed are mean ± SEM of three independent experiments.

^bButylated hydroxy toluene, ascorbic acid and podophyllotoxin were used as standard reagents in DPPH, FRAP, and BSLA assays, respectively.

Table 3. Enzyme inhibitory activity of the extracts and essential oil of Salvia syriaca.^a

Samples	α-amylase (IC50:mg/mL)	α-glucosidase (IC50:mg/mL)	Acetylcholinesterase (IC50:mg/mL)	Butyrylcholinesterase (IC50:mg/mL)	Tyrosinase (IC50:mg/mL)
Essential oil	1.54 ± 0.1	1.18 ± 0.03	1.90 ± 0.1	3.06 ± 0.1	na^b
n-hexane	2.68 ± 0.05	7.18 ± 1.8	1.14 ± 0.1	na	na
Dichloromethane	2.70 ± 0.05	4.14 ± 0.2	1.08 ± 0.1	1.10 ± 0.02	na
Methanol	3.99 ± 0.3	2.13 ± 0.1	11.69 ± 1.4	2.63 ± 0.10	na
Standard ^c	1.33 ± 0.03	9.6 ± 0.8	2.59 ± 0.01^d	5.18 ± 0.44^d	0.20 ± 0.01

^aValues expressed are mean ± SEM of three independent experiments.

^bNot active.

^cAcarbose was used as the standard drug in α-amylase and α-glucosidase assays, galantamine in acetylcholinesterase and butyrylcholinesterase assays, and kojic acid in tyrosinase assay.

^dµg/mL.

Table 4. Quantitative results for determination of phenolic components in the methanol extract of S. syriaca.

			Analytical characteristics
Number	Phenolic compounds	µg/g extract	Linear range (mg/L)	r^2	LOD (mg/L)	LOQ (mg/L),/TH>
1	Gallic acid	nd^a	—	—	—	—
2	Protocatechuic acid	70 ± 4	0.20–25.0	0.9991	0.086	0.260
3	(+)-Catechin	nd	—	—	—	—
4	p-Hydroxybenzoic acid	94 ± 2	0.20–25.0	0.9994	0.007	0.020
5	Chlorogenic acid	31 ± 1	0.35–45.0	0.9988	0.080	0.241
6	Caffeic acid	95 ± 2	0.16–21.0	0.9993	0.054	0.162
7	(-)-Epicatechin	nd	—	—	—	—
8	Syringic acid	nd	—	—	—	—
9	Vanillin	nd	—	—	—	—
10	p-coumaric acid	48 ± 1	0.04–6.0	0.9996	0.066	0.199
11	Ferulic acid	186 ± 3	0.12–17.0	0.9993	0.004	0.011
12	Sinapic acid	nd	—	—	—	—
13	Benzoic acid	nd	—	—	—	—
14	o-Coumaric acid	nd	—	—	—	—
15	Rutin	9425 ± 163	0.40–56.0	0.9989	1.113	3.373
16	Naringin	nd	—	—	—	—
17	Hesperidin	19 ± 1	0.43–55.0	0.9992	1.080	3.280
18	Rosmarinic acid	629 ± 19	0.02–7.0	0.9998	0.148	0.447
19	Eriodictyol	nd	—	—	—	—
20	trans-Cinnamic acid	nd	—	—	—	—
21	Quercetin	145 ± 2	0.40–55.0	0.9999	0.013	0.040
22	Luteolin	88 ± 3	0.13–17.0	0.9999	0.020	0.060
23	Kaempferol	97 ± 2	0.05–15.0	0.9996	0.021	0.062
24	Apigenin	243 ± 5	0.17–11.0	0.9997	0.034	0.104

^aNot detected.

Figure 2. HPLC chromatograms of A: standard phenolic compounds; and B: the methanolic extract of S. syriaca. Standard phenolics used for analysis are 1: gallic acid, 2: protocatechuic acid, 3: (+)-catechin, 4: p-hydroxybenzoic acid, 5: chlorogenic acid, 6: caffeic acid, 7: (-)-epicatechin, 8: syringic acid, 9: vanillin, 10: p-coumaric acid, 11: ferulic acid, 12: sinapic acid, 13: benzoic acid, 14: o-coumaric acid, 15: rutin, 16: naringin, 17: hesperidin, 18: rosmarinic acid, 19: eriodictyol, 20: trans-cinnamic acid, 21: quercetin, 22: luteolin, 23: kaempferol, and 24: apigenin.