Anti-inflammatory activity of niosomes entrapped with Plai oil (Zingiber cassumunar Roxb.) by therapeutic ultrasound in a rat model

Abstract

Objective: The aim of this study was to evaluate the antioxidant and anti-inflammatory activities of Plai oil-encapsulated niosomes (Zingiber cassumunar Roxb.) on inflamed subcutaneous Wistar rat skin by therapeutic ultrasound.

Methods: Pure oil from Plai rhizomes was extracted by steam distillation, and antioxidant activities were determined by 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Bioactive compounds were analyzed by gas chromatography-mass spectrometry. Niosome particles containing Plai oil were prepared by chloroform film method with sonication before testing for anti-inflammatory activity on locally inflamed subcutaneous rat skin after inducement from lipopolysaccharide with ultrasound once a day for 3 days. Skin temperatures and blood flow were evaluated.

Results: Plai oil presented antioxidant activity that inhibited 2,2-diphenyl-1-picrylhydrazyl radicals. Four active compounds found in the essential oil were sabinene, γ-terpinene, terpinene-4-ol, and (E)-1-(3,4-dimethyoxy phenyl) butadiene. Application of ultrasound (0.2 W/cm², 20%, 3 min) with gel containing Plai oil-encapsulated niosomes decreased skin temperature and blood flow to the lowest level compared to the application of neurofen drug or gel-based control.

Conclusion: Plai oil, which consists of four main bioactive compounds and possesses antioxidant and anti-inflammatory activities, can be applied against local subcutaneous inflammation when used with therapeutic ultrasound via entrapped niosomes.

Keywords: Plai oil; Zingiber cassumunar Roxb; anti-inflammation; antioxidant; niosomes; therapeutic ultrasound.

Figure 1

Ultrasound therapy on local subcutaneous inflammation in rat (A), and skin temperature and blood flow determined by TDR4 instrument (B).

Figure 2

The percentage inhibition of DPPH radicals between standard Trolox (0.2–1.2 mmol/L) (A) and Plai oil (12.5–400 μg/mL) (B). Abbreviation: DPPH, 2,2-diphenyl-1-picrylhydrazyl.

Figure 3

Peaks of four active compounds sabinene, γ-terpinene, terpinene-4-ol, and DMPBD obtained by GS-MS analysis. Abbreviations: DMPBD, E-1-(3,4-dimethoxyphenl) butadiene; GS-MS, gas chro matography-mass spectrophotometry.

Figure 4

Characteristics of niosomes with entrapped pure Plai oil (A) observed under transmission electron microscope at 20,000×, compared to niosomes without entrapped Plai oil (B). Niosomes with encapsulated pure Plai oil (C) observed under optical microscope at 1,000×.

Figure 5

Oil-encapsulated niosomes and gel-based control (A) and pilot gels containing oil-entrapped niosomes (B).

Figure 6

Skin temperature (°C) (A) and blood flow (flux) (B) between the five groups at before (day 0) and during 4 days experiment without or with LPS injection via therapeutic ultrasound treatment with niosome placebo, nioplai or neurofen. Each point presents the mean and standard error of mean from each of five rats. *P<0.01 compared to the control group on each day, and ^#P<0.01 when compared to the LPS group on each day. Abbreviation: LPS, lipopolysaccharide.