2. Materials and methods
2.1. Chemicals
Chloroform, methanol, isohexane and diethyl ether were HPLC
grade from Fisher (Loughborough, Leicestershire, UK). Concentrated
sulphuric acid (Aristar grade) and Merck silica gel 60 thin
layer chromatography (TLC) plates (no. 5721) and high performance
TLC (HPTLC) plates (no. 5633) were obtained from VWR
(Lutterworth, Leicestershire, UK). All other chemicals were from
Sigma (Poole, Dorset, UK).