Chemical composition, antioxidant activities, and enzyme inhibitory effects of Lespedeza bicolour Turcz. essential oil

Abstract

Lespedeza bicolour Turcz. is a traditional medicinal plant with a wide range of ethnomedicinal values. The main components of L. bicolour essential oil (EO) were β-pinene (15.41%), β-phellandrene (12.43%), and caryophyllene (7.79%). The EO of L. bicolour showed antioxidant activity against ABTS radical and DPPH radical with an IC₅₀ value of 0.69 ± 0.03 mg/mL and 10.44 ± 2.09 mg/mL, respectively. The FRAP antioxidant value was 81.96 ± 6.17 μmol/g. The EO had activities against acetylcholinesterase, α-glucosidase, and β-lactamase with IC₅₀ values of 309.30 ± 11.16 μg/mL, 360.47 ± 35.67 μg/mL, and 27.54 ± 1.21 μg/mL, respectively. Molecular docking showed methyl dehydroabietate docked well with all tested enzymes. Sclareol and (+)-borneol acetate showed the strongest binding affinity to α-glucosidase and β-lactamase, respectively. The present study provides a direction for searching enzyme inhibitors for three tested enzymes and shows L. bicolour EO possesses the potential to treat a series of diseases.

Keywords: Lespedeza bicolour Turcz.; bioactivities; chemical composition; essential oil; molecular docking.

Graphical abstract

Figure 1.

The total ion chromatogram of L. bicolour EO derived from GC–MS data.

Figure 2.

Variation in ABTS radical scavenging percentage with varying concentrations for L. bicolour EO (a), Trolox (b).

Figure 3.

Variation in DPPH radical scavenging percentage with varying concentrations for L. bicolour EO (a), Trolox (b).

Figure 4.

Variation in AChE inhibitory rate (%) with varying concentrations for L. bicolour EO (a), Galantamine (b).

Figure 5.

Docking interactions between selected ligands and AChE. (a) Methyl dehydroabietate; (b) Mintketone; (c) Sclareol; (d) T-Muurolol. From left to right, overall 3D, partial 3D, and 2D images in order. In 3D images, cyan cartoons for AChE protein, green sticks for small molecules, and purple sticks for amino acid residue bonded with small molecules. In 2D images, green dashed lines for hydrogen bonding, orange dashed lines for electrostatic interactions, and pink dashed lines for hydrophobic interactions.

Figure 6.

Variation in α-glucosidase inhibitory rate (%) with varying concentrations for L. bicolour EO (a), Acarbose (b).

Figure 7.

Docking interactions between selected ligands and α-glucosidase. (a) Epimanoyl oxide; (b) Manoyl oxide; (c) Methyl dehydroabietate; (d) Squalene. From left to right, overall 3D, partial 3D, and 2D images in order. In 3D images, palecyan cartoons for α-glucosidase protein, green sticks for small molecules, and purple sticks for amino acid residue bonded with small molecules. In 2D images, green dashed lines for hydrogen bonding, orange dashed lines for electrostatic interactions, and pink dashed lines for hydrophobic interactions.

Figure 8.

Variation in β-lactamase inhibitory rate (%) with varying concentrations for L. bicolour EO (a), Clavulanate Potassium (b).

Figure 9.

Docking interactions between selected ligands and β-lactamase. (a) (+)-Borneol acetate; (b) Farnesyl acetone; (c) Methyl dehydroabietate; (d) Sclareol. From left to right, overall 3D, partial 3D, and 2D images in order. In 3D images, palegreen cartoons for β-lactamase protein, green sticks for small molecules, and purple sticks for amino acid residue bonded with small molecules. In 2D images, green dashed lines for hydrogen bonding, orange dashed lines for electrostatic interactions, and pink dashed lines for hydrophobic interactions.