Humulus lupulus L. is a well known traditional medicinal plant. Recently, pyranoflavonoids of hops were identified as potent inducers of neuronal differentiation in adult neuronal stem cells.[1,2] Unfortunately, the lipophilic side chain results in low water solubility and this makes an application in vivo difficult. To overcome this hurdle, (2-hydroxypropyl)-β-cyclodextrin is used to enhance solubility.
This cyclodextrine is water-soluble, non-toxic and has already been applied in numerous pharmaceutical preparations.[3] The maximum solubility of xanthohumol C in water is 2 µg/mL. Using cyclodextrin the solubility can be increased to 1300 µg/mL, confirmed by using HPLC analysis. In vitro, encapsulated xanthohumol C is as active as the pure flavonoid, making the cyclodextrin complex a suitable form of application for future in vivo studies.
References:
[1] Oberbauer E, Urmann C, Steffenhagen C, Bieler L, Furtner T, Humpel C, Baumer B, Bandtlow C, Couillard-Despres S, Rivera FJ, Riepl H, Aigner L. Journal of Nutritional Biochemistry 2013, 24: 1953-1962.
[2] Urmann C, Oberbauer E, Couillard-Despres S, Aigner L, Riepl H. Planta Medica 2015, 4: 305-311.
[3] T. Irie, K. Uekama, Journal of pharmaceutical Science, 86 (1996) 147-162.