Preparation and characterization of standardized pomegranate extract-phospholipid complex as an effective drug delivery tool

Punicalagins, a pair of anomeric ellagitannins, present in Punica granatum (Pomegranates) are known to possess excellent antioxidant activity in vitro, but poor oral bioavailability. The reasons cited for poor bioavailability are their large molecular size, poor lipophilicity, and degradation by colonic microflora into less active metabolites. The objective of the present research work was to complex the standardized pomegranate extract (SPE) with phospholipid to formulate standardized pomegranate extract-phospholipid complex (SPEPC), characterize it and check its permeability through an ex vivo everted gut sac experiment. SPEPC was prepared by mixing SPE (30% punicalagins) and soya phosphatidylcholine (PC) in 1:1 v/v mixture of methanol and dioxane and spray-drying the mixture. The complex was characterized by infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. It was evaluated for its octanol solubility, dissolution, and permeability by everted the gut sac technique. The characterization methods confirmed the formation of complex. Increased n-octanol solubility of the complex proved its increased lipophilicity. Dissolution studies revealed that the phospholipid covering may prevent the punicalagins to be released in gastro-intestinal tract, thus preventing their colonic microbial degradation. SPEPC showed better apparent permeability than SPE in an everted gut sac technique. Hence, it could be concluded that phospholipid complex of SPE may be of potential use in increasing the permeability and hence the bioavailability of punicalagins.