Results3.1. Isolation of lignan crystals from sesame oil and their purityassessment by HPLCThe method described in this study yielded on an average of2.8 g/l of lignans from sesame oil. The yellow oil on treatment withisooctane at 4◦C lead to gradual crystallization of lignans and theprocess took 5 days for completing this first step. The gross view ofthe transparent to opaque lignan crystal formed in isooctane envi-ronment is presented in Fig. 1. The analytical HPLC of the lignanisolated gave two peaks (Fig. 2). The large peak showed a reten-tion time (RT) at 23.63 corresponding to the identity of sesaminstandard. The second smaller peak had a RT of 31.71 (Fig. 2). Fromthe published reports it was inferred that this peak identifies withthe RT of sesamolin. Computation of ratio of peak area under theputative metabolite to the total area of the all the peaks (only twoin our case) in the chromatogram revealed that the lignan crystalobtained is a mixture consisting of 88% sesamin and 12% sesamolin.3.2. Preparative separation of sesamin and sesamolinSemi-preparative HPLC of the isolated lignan was done to sep-arate sesamin from sesamolin. The process yielded two fractionsFig which were labelled as F-I and F-II. Analytical HPLC of the F-I showed that it is composed of almost 98.7% pure sesamin asdepicted by a largest peak with a RT of 24.34 and that of the F-II ofhighly pure putative sesamolin denoted similarly by a main peakwith 97.4% purity at a RT of 31.75. These results confirmed the suc-cessful isolation of the sesamin and sesamolin each with more than97% purity. Similarly TLC of a solution of the isolated lignan crystalshowed presence of two bands indicating it is a mixture and that offractions F-I and F-II, from semi-preparative HPLC showed promi-nent bands corresponding to sesamin and sesamolin respectivelyconfirming their isolation with utmost purity (Fig. 3). Semi prepar-ative HPLC though resulted in a reasonably good quality of purelignans, the yield turned out to be very low. In order to obtain a bet-ter yield of putative sesamin and sesamolin an attempt was made torun a large scale TLC on a 20 cm × 20 cm TLC plates in a preparativescale. Three such runs, on recovery, yielded approximately 20 mgand 6 mg of putative sesamin and sesamolin respectively. The lig-nan fractions isolated in such a manner also showed solitary peaksin HPLC confirming their almost 99% purity (the data not shown).