Structural characterization of plant glucosylceramides and the corresponding ceramides by UHPLC-LTQ-Orbitrap mass spectrometry

•GlcCERs with 4,8-sphingadienine, 8-sphingenine and 4-hydroxy-8-sphingenine sphingoid bases amid linked to C 14 - 26 FAs were detected.•Lupin bean contains almost single GlcCER species (> 98 %) with comparable yield to that of commercial GlcCER sources.•Mild acid hydrolysis of pretreated plant GlcCERs was effective to produce CERs possessing dihydroxy sphingoid bases.•CERs with both 4,8-sphingadienine and 8-sphingenine sphingoid bases attached with even carbon numbered FAs (C 14-24) were obtained. Ceramides (CERs) play a major role in skin barrier function and direct replacement of depleted skin CERs, due to skin disorder or aging, has beneficial effects in improving skin barrier function and skin hydration. Though, plants are reliable source of CERs, absence of economical and effective method of hydrolysis to convert the dominant plant sphingolipid, glucosylceramides (GlcCERs), into CERs remains a challenge. This study aims at exploring alternative GlcCERs sources and chemical method of hydrolysis into CERs for dermal application. GlcCERs isolated from lupin bean (Lupinus albus), mung bean (Vigna radiate) and naked barley (Hordium vulgare) were identified using ultra high performance liquid chromatography hyphenated with atmospheric pressure chemical ionization - high resolution tandem mass spectrometer (UHPLC/APCI-HRMS/MS) and quantified with validated automated multiple development-high performance thin layer chromatography (AMD-HPTLC) method. Plant GlcCERs were hydrolyzed into CERs with mild acid hydrolysis (0.1 N HCl) after treating them with oxidizing agent, NaIO4, and reducing agent, NaBH4. GlcCERs with 4,8-sphingadienine, 8-sphingenine and 4-hydroxy-8-sphingenine sphingoid bases linked with C14 to C26 α-hydroxylated fatty acids (FAs) were identified. Single GlcCER (m/z 714.5520) was dominant in lupin and mung beans while five major GlcCERs species (m/z 714.5520, m/z 742.5829, m/z 770.6144, m/z 842.6719 and m/z 844.56875) were obtained from naked barley. The GlcCERs contents of the three plants were comparable. However, lupin bean contains predominantly (> 98 %) a single GlcCER (m/z 714.5520). Considering the affordability, GlcCER content and yield, lupin bean would be the preferred alternative commercial source of GlcCERs. CER species bearing 4,8-sphingadienine and 8-sphingenine sphingoid bases attached to C14 to 24 FAs were found after mild acid hydrolysis. CER species with m/z 552.4992 was the main component in the beans while CER with m/z 608.56