GC–MS analysis of D-pinitol in carob: Syrup and fruit (flesh and seed)

Abstract

D-pinitol (3-O-methyl-D-chiro-inositol) is a well-known bioactive compound with anti-diabetic and anti-oxidant biological functions. A gas chromatography–mass spectrometry (GC–MS) method was developed for its quantitation in carob syrup, flesh and seed samples originated from Cyprus. The analysis was performed after derivatization of carbohydrates and polyols into trimethylsilyl ether derivatives. D-pinitol was determined in 13 carob syrup samples, in concentrations ranging 65.71 ± 4.60 – 77.72 ± 5.44 mg/g (mean: 68.58 ± 4.80 mg/g, n = 13). In two commercial samples, it was determined in relative medium-low concentrations (21.96 ± 1.54 and 44.71 ± 3.13 mg/g), revealing possible adulteration; however, this needs further investigation. Similarly, it was determined in high concentrations in carob flesh samples, in concentrations ranging 53.20 ± 3.72 – 54.58 ± 3.82 mg/g (mean: 53.81 ± 3.76 mg/g, n = 3). On the other hand, seed samples proved very poor in D-pinitol (<LOD). Therefore, bioprospecting of carob fruit and syrup is highlighted. Compared to other plants or legumes, carob appears to be the richest source of D-pinitol, highlighting carobs role as a functional organic food. The historical and cultural association of Cyprus with carobs is linked with traditional foods and habits.