Preparation and in vitro/in vivo characterization of enteric-coated nanoparticles loaded with the antihypertensive peptide VLPVPR

Figures & data

Table 1 Orthogonal design factors and levels for the double emulsion method

Factors	Level
	1	2	3
Inner water phase volume (mL) (A)	0.1	0.2	0.4
VLPVPR (mg) (B)	5	7.5	10
Outer water phase volume (mL) (C)	1	2	3
Ultrasound for double emulsion (D)	5 s ×1	5 s ×2	5 s ×3

Note: (A), (B), (C), and (D) are used to represent different factors.

Abbreviations: s, seconds; VLPVPR, Val-Leu-Pro-Val-Pro-Arg.

Table 2 Results of the orthogonal experiment

	(A) Inner water phase volume (mL)	(B) VLPVPR (mg)	(C) Outer water phase volume (mL)	(D) Ultrasound of double emulsion	DL (%)	ER (%)
1#	0.1	5	1	5 s ×1	2.96	60.97
2#	0.1	7.5	2	5 s ×2	3.67	50.86
3#	0.1	10	3	5 s ×3	2.37	24.25
4#	0.2	5	3	5 s ×2	2.82	57.99
5#	0.2	7.5	1	5 s ×3	6.31	89.8
6#	0.2	10	2	5 s ×1	5.06	53.34
7#	0.4	5	2	5 s ×3	2.28	46.65
8#	0.4	7.5	3	5 s ×1	2.37	32.38
9#	0.4	10	1	5 s ×2	5.07	53.44
DL
K1	9.00	8.06	10.39	14.34	Calibration parameter
K2	14.19	12.36	11.57	11.02	=120.38
K3	9.72	12.50	10.96	7.56
S	5.27	4.26	0.23	7.67
F	23.02*	18.58	1.00	33.51*
ER
K1	136.08	165.61	146.69	204.21	Calibration parameter
K2	201.13	173.04	162.29	150.85	=24,511.03
K3	132.47	131.03	160.70	114.62
S	995.41	335.09	49.13	1,354.03
F	20.26*	6.82	1.00	27.56*

Notes:

* Significant (P<0.05) by Student’s t-test.

Abbreviations: DL, drug loading; ER, encapsulated ratio; F, statistical analysis results for orthogonal experiment; K, the average DL and ER of nanoparticles under the various investigated conditions; S, standard deviation; s, seconds; VLPVPR, Val-Leu-Pro-Val-Pro-Arg.

Table 3 Characterization of nanoparticles prepared by the optimized double emulsion method

Groups	ER (%)	DL (%)	Average diameter (nm)
1	88.22	6.21	76.3±19.8
2	85.30	6.01	79.0±25.6
3	87.29	6.14	70.2±18.9
Average	86.94	6.12	75.2±21.4

Abbreviations: DL, drug loading; ER, encapsulated ratio.

Figure 1 Typical SEM images of mPEG-PLGA-PLL nanoparticles coated with Eudragit S100; bar, 200 nm.

Abbreviations: mPEG-PLGA-PLL, (Methoxy-polyethylene glycol)-b-poly(D,L-lactide-co-glycolide)-b-poly(L-lysine); SEM, scanning electron microscopy.

Figure 2 Particle size of nanoparticles prepared using the double emulsion method.

Figure 3 Cumulative release of free VLPVPR in PBS (pH =7.4).

Abbreviations: h, hours; PBS, phosphate buffered saline; VLPVPR, Val-Leu-Pro-Val-Pro-Arg.

Figure 4 Cumulative release of three enteric-coated nanoparticles in different pH media.

Notes: (A) Cumulative release of enteric-coated nanoparticles (mPEG-PLGA-PLL:Eudragit S100 100:3.5) in pH 1.0, 4.5, and 7.4 media. (B) Cumulative release of enteric-coated nanoparticles (mPEG-PLGA-PLL:Eudragit S100 100:7) in pH 1.0, 4.5, and 7.4 media. (C) Cumulative release of enteric-coated nanoparticles (mPEG-PLGA-PLL:Eudragit S100 100:10.5) in pH 1.0, 4.5, and 7.4 media.

Abbreviations: h, hours; mPEG-PLGA-PLL, (Methoxy-polyethylene glycol)-b-poly(D,L-lactide-co-glycolide)-b-poly(L-lysine).

Figure 5 Effects of a single oral dose of mPEG-PLGA-PLL nanoparticles on SBP in SHR.

Notes: n=8, $\overline{X}\pm \text{s}$. Letters indicate the level of significant difference from control: ^aP<0.01; ^bP<0.05.

Abbreviations: AHP, antihypertensive peptides; mPEG-PLGA-PLL, (Methoxy-polyethylene glycol)-b-poly(D,L-lactide-co-glycolide)-b-poly(L-lysine); s, seconds; SBP, systolic blood pressure; SHR, spontaneously hypertensive rats.