Liposomes containing cholesterol analogues of botanical origin as drug delivery systems to enhance the oral absorption of insulin.

•Ergosterol could be a potential candidate for substituting cholesterol in liposomes.•Liposomes containing ergosterol are more stable and have more pronounced protective ability for insulin in gastrointestinal tract than liposomes containing cholesterol and bile salts.•Liposomes containing ergosterol can enhance the oral bioavailability of insulin significantly in comparison with conventional liposomes.