Nanoemulsion for improving solubility and permeability of Vitex agnus-castus extract: formulation and in vitro evaluation using PAMPA and Caco-2 approaches

Figures & data

Figure 1. HPLC profile of VAC extract at 260 nm. 1. 3,4-Dihydroxybenzoic acid; 2. 4-Hydroxybenzoic acid; 3. Isoorientin; 4. Agnuside; 5. Isovitexin; 6. Luteolin; 7. Apigenin; 8. Penduletin; and 9. Casticin.

Table 1. Intermediate precision: RSD % values intraday and interday.

		RSD % Intraday			RSD % Interday
Extract (mg/mL)	Day	Agnuside	Casticin	Isovitexin	Agnuside	Casticin	Isovitexin
2.08	1	1.672	1.807	0.704	1.632	0.919	0.878
	2	1.949	0.429	0.247
	3	1.276	0.523	1.685
3.17	1	1.835	0.211	1.984	1.776	1.281	2.348
	2	1.975	2.487	2.616
	3	1.519	1.203	2.444
4.26	1	1.365	0.863	0.364	1.574	0.749	1.362
	2	1.785	0.859	1.491
	3	1.574	0.525	2.231

Table 2. Solubility of VAC constituents in different vehicles (mean ± S.D., n = 3).

	Flavonoids (mg/mL)	Iridoids (mg/mL)
Oils
Olive oil	0.107 ± 0.046	–
Triacetin	0.136 ± 0.036	–
Tocopheryl acetate	0.008 ± 0.001	–
Labrafil	0.014 ± 0.003	0.01
Sunflower oil	0.058 ± 0.001	–
Hempseed oil	0.057 ± 0.010	–
Almond oil	0.022 ± 0.006	–
Wheat germ oil	0.066 ± 0.017	–
Borage oil	0.053 ± 0.013	–
Oleic acid	0.082 ± 0.001	–
Surfactant/cosurfactant
Tween 20	0.080 ± 0.016	0.065 ± 0.001
Tween 40	0.078 ± 0.016	0.023 ± 0.005
Cremophor EL	0.367 ± 0.008	0.303 ± 0.022
Labrasol	0.178 ± 0.012	0.130 ± 0.015
Capryol 90	0.057 ± 0.011	0.019 ± 0.002
PEG 400	0.214 ± 0.021	0.228 ± 0.041
Transcutol HP	0.206 ± 0.008	0.123 ± 0.037
Ethanol	0.163 ± 0.017	0.142 ± 0.017
Propylene glycol	0.170 ± 0.006	0.172 ± 0.062
Glycerol	0.043 ± 0.001	-

Figure 2. Pseudo ternary phase diagram of microemulsion (S _mix: 1:1, Labrasol and Cremophor EL). Light gray: turbidity; gray: NE; and black: gel.

Table 3. Solubility of VAC extract into NE.

Sample	Total flavonoids (mg/mL)	Total iridoids (mg/mL)
5 mg/mL of extract	0.26	0.11
10 mg/mL of extract	0.41	0.16
15 mg/mL of extract	0.75	0.26
40 mg/mL of extract	2.41	0.60
60 mg/mL of extract	3.47	1.75
Water	0.31	0.17

Figure 3. Chemical stability of flavonoids and iridoids of VAC extract formulated into NE after storage at 4 °C for 2 months (each data point represents the average of three samples).

Figure 4. Comparative PAMPA permeability: micrograms of total flavonoids (F) and iridoids (I) of extract of VAC permeated from NE and from saturated aqueous solution (W). Average values ± S.D. of experiments carried out in triplicate are presented. *p < 0.05.

Figure 5. Caco-2 permeability of flavonoids (a) and iridoids (b) loaded into NE (each data point represents the average of three samples).