Identification of Novel Iso-Esculeoside B from Tomato Fruits and LC–MS/MS-Based Food Screening for Major Dietary Steroidal Alkaloids Focused on Esculeosides

Abstract

Plants from the Solanaceae family are known to be sources of several nutritionally relevant steroidal glycoalkaloids (SGAs). With the aim of quantitatively investigating the occurrence of the main SGA from tomatoes, eggplants, and potatoes in various food samples and evaluating their relevance in the human diet, a rapid single-step extraction liquid chromatography–tandem mass spectrometry method was developed. Over the course of isolating several commercially unavailable SGAs from tomato products to use them as reference standards, a previously unknown derivative was detected, structurally characterized, and identified as a novel isomer of esculeoside B-1 and B-2. After validation of the method, 36 food items exclusively derived from Solanaceae plants were analyzed for their SGA contents and a specific occurrence of each alkaloid in tomato, eggplant, or potato products was revealed. This is the first study reporting quantitative data on the occurrence of esculeoside A, B-1, B-2, and iso-esculeoside B in tomato products obtained by using appropriate reference compounds rather than applying a semi-quantitative approach based on α-tomatine as a reference. Some of the analyzed tomato products contained the esculeosides in concentrations of >500 mg/kg, clearly indicating their relevance in the human diet and the need of investigating their potential bioactivities in the future.

Biosynthesis of Steroidal Alkaloids Are Coordinately Regulated and Differ Among Tomatoes in the Red-Fruited Clade

“…This finding agrees with the current model that early pathway intermediates are converted to late pathway during ripening (Yamanaka et al, 2009;Itkin et al, 2011). Average values for individual alkaloids ranged between 0.1 and 7.6 mg/100 g fresh weight (Table S1,2), demonstrating tomato steroidal alkaloids exist in concentrations higher than previously thought (Friedman, 2002;Caprioli et al, 2014;Baldina et al, 2016), and consistent with more recent reports (Steinert et al, 2020). Prominent tomato phytochemical classes like carotenoids are often found between 0.09 to 9.93 mg/100 g fresh weight (Dzakovich et al, 2019), suggesting steroidal alkaloids can be found in comparable concentrations.…”

“…In the case of hydroxytomatine, acetoxytomatine, dehydrolycoperoside F/G/dehydroesculeoside A, lycoperoside F/G/esculeoside A, and esculeoside B, multiple peaks are observed, confirming the presence of structural isomers (Manabe et al, 2013;Nohara et al, 2015;Hövelmann et al, 2019;Steinert et al, 2020). For example, lycoperoside F, G, and esculeoside A (C58H95NO29, monoisotopic mass = 1269.5990 Da), are isobaric (Yahara et al, 2004) and exhibit similar fragmentation patterns since their molecular differences are limited to subtle changes in stereochemistry on the F ring (Dzakovich et al, 2020).…”

Steroidal alkaloid biosynthesis is coordinately regulated and differs among tomatoes in the red‐fruited clade

“…Average values for individual alkaloids ranged between 0.1 and 7.6 mg 100 g −1 fresh wt. (Supplemental Tables S1 andS2), demonstrating tomato steroidal alkaloids exist in concentrations higher than previously thought (Baldina et al, 2016;Caprioli et al, 2014;Friedman, 2002) and consistent with more recent reports (Steinert et al, 2020). Prominent tomato phytochemical classes like carotenoids are often found between 0.09 and 9.93 mg 100 g −1 fresh wt.…”

“…In the case of hydroxytomatine, acetoxytomatine, dehydrolycoperoside F/G/dehydroesculeoside A, lycoperoside F/G/esculeoside A, and esculeoside B, multiple peaks are observed, confirming the presence of structural isomers (Hövelmann et al., 2020a; Manabe et al., 2013; Nohara et al., 2015; Steinert et al., 2020). For example, lycoperoside F, G, and esculeoside A (C 58 H 95 NO 29 , monoisotopic mass = 1269.5990 Da) are isobaric (Yahara et al., 2004) and exhibit similar fragmentation patterns since their molecular differences are limited to subtle changes in stereochemistry on the F ring (Dzakovich et al., 2020).…”

Fruit category classification by fractional Fourier entropy with rotation angle vector grid and stacked sparse autoencoder

“…Fruit category classification (FCC) may benefit factory automatic transportation and fruit‐packing (Tian et al, 2020), price and consumer desirability prediction (Kirk et al, 2019), and dietary intake (Steinert et al, 2020). FCC still remains a challenge because it is tough to specify an accurate definition of a type of fruit.…”