Quantification of Light-Induced Glycoalkaloids, .ALPHA.-Solanine and .ALPHA.-Chaconine, in Four Potato Cultivars (Solanum tuberosum L.) Distributed in Japan by LC/MS

Abstract

The major glycoalkaloids, a-solanine and a-chaconine, in potato tubers were determined by LC/ESI-MS. The average recoveries from spiked samples by the method used in this study were more than 94% with RSD of analytical values less than 5% for both oe-solanine and a-chaconine. The total glycoalkaloid contents in tubers of four potato cultivars distributed in Japan, cv. Irish Cobbler, Touya, May Queen, and Sayaka, were compared. There was no significant difference in glycoalkaloid content between immature and mature tubers among all the cultivars tested. There was also no significant difference among cultivars in glycoalkaloid content at either the immature or mature stage, except for May Queen, which had higher glycoalkaloid contents at both stages. Glycoalkaloid content increased significantly in cv. May Queen and Touya with 7 days of light exposure immediately after harvest. The light exposure increased glycoalkaloid content in the long-term stored tubers of all four cultivars tested and that in the short-term stored tubers, except for Sayaka.Keywords: solanum tuberosum, potato, glycoalkaloids, oe-solanine, oe-chaconine, LC/MS, Iight. IntroductionToxic glycoalkaloids have been found in plants of the Solanaceae family, such as tomato, eggplant and potato. The major potato glycoalkaloids, namely, oc-solanine and cr-chaconine, (Fig. 1) are detected in tissues of tubers except in the pith or center portion (Maga, 1980). It has been reported that these glycoalkaloids show acute toxicity (Jellema et al., 1980; McMillan & Thompson, 1980), chronic toxicity (Mun et al., 1975;Keeler et al., 1976), and have a bitter taste (Sinden & Deahl, 1976; Woolfe, 1987). The intrinsic glycoalkaloid content in tubers of commercial potato cultivars is low due to selection in breeding, but the content may increase in response to environmental stress conditions, such as light (Friedman, 1997;Griffiths et al., 1994;Kozukue et al., 1993;Maga, 1980;Percival & Dixon, 1994;Percival, 1999; Sinden et al., 1984; Woolfe, 1987), frost and hail damage, and wounding during harvesting or postharvest handling (Woolfe, 1987). Among these stress conditions, the stimulation of glycoalkaloid accumulation with light exposure is a major problem for farmers, packers, suppliers, and vendors of potato (Percival & Dixon, 1994). This is because potato is exposed to various lights and illuminations, such as daylight, fluorescent light, and incandescent light, during harvest, transport, and marketing. The E-mail: chuda @ affrc . go . j p increase in glycoalkaloid content lowers the quality of potato tubers for market.The intrinsic glycoalkaloid content and the accumulation of glycoalkaloids with light exposure in potato tubers vary with physiological stages, i.e., immaturity, full maturity and aging (stored potato) as well as with cultivars (Griffiths et al., 1994; Sinden et al., 1984). In Japan, some potato tubers are harvested before full maturity and consumed without storage. Most of them, however, are harvested at full maturity and stored for various periods, ...

Metabolic engineering of betacyanin in vegetables for anti‐inflammatory therapy

“…Likewise, potato tuber extracts were expected to show anti‐inflammatory activity in macrophage cells due to their high content of glycoalkaloids such as α‐solanine, as previously shown (Kenny et al, 2013; Shin et al, 2016). However, this did not hold true in the current study (Figure 2), possibly because the glycoalkaloid content in tubers of Sayaka, the potato cultivar used in this study, is lower than that in other cultivars, as shown in May Queen (Chuda et al, 2004). More intriguingly, although extracts from transgenic potato tubers with enriched betacyanins contain substantial amounts of betanin (239 µM) and isobetanin (20 µM) in the original tuber extract of Pb1 [estimated from Figure 1a]), the extracts at 100~10000 fold dilutions failed to exhibit significant anti‐inflammatory activity (Figure 2).…”

Glycoalkaloids in commercial potato varieties traded in Nairobi, Kenya

“…Glycoalkaloid levels in potatoes traded in the market may be influenced by transportation and storage conditions (Chuda et al, 2004). Potatoes that are sprouting or subjected to light exposure, inappropriate storage, extreme temperature, wounding, and mechanical injury accumulate glycoalkaloids at a faster rate (Cantwell, 1996).…”

Elucidation of the mass fragmentation pathways of potato glycoalkaloids and aglycons using Orbitrap mass spectrometry

“…[1] However, toxic steroidal glycoalkaloids are ubiquitous in potato products because these biotoxins play key roles in natural plant protection from mould and insect infestation. [2] The two major toxins, α-solanine and α-chaconine, usually comprise more than 95% of the total steroidal glycoalkaloid content in potatoes. Although these toxins are present in all parts of the potato plant, the skins and the sprouts contain the highest concentration of glycoalkaloids.…”

“…[1] These compounds play an important role in natural plant protection, [3] and it has also been established that stresses such as exposure to light, frost damage and tissue wounding during harvesting can lead to an accumulation of these toxic glycoalkaloids in potatoes. [2,4,5] Glycoalkaloid content of ca 15 mg/kg can result in a bitter taste in potatoes while levels at or greater than 200 mg/kg are considered hazardous to human health. [5 -7] Lachman et al reported that higher levels of α-solanine can cause a burning sensation in the throat and mouth.…”