Writing in Beverages, researchers from Mexico looked into two commercial varieties of fruits of chayote (Sechium edule) – a non-traditional vegetable in the Cucurbitaceae family, along with melons, cucumbers and squash). Native to Mesoamerica and predominantly cultivated in Veracruz, Mexico as well as Costa Rica, the researchers said that despite Mexico being the world's main producer, “little is known about the nutraceutical potential”.
Widely consumed across Latin America and valued for its vitamin, mineral, fiber and amino acid content, the researchers said the “tuberous rooted perennial” was normally cooked and consumed in the same manner as vegetables. But in juice form, the researchers said chayote had nutraceutical potential.
The aim of the study, therefore, was to compare the bioactivity of two dominant varieties in juice form – virens levis (VL), typically produced in subtropical and tropical regions, and nigrum spinosum (NS) which was cultivated in temperate zones and high valleys at altitudes of 2,000-2,800m.
One variety 'particularly promising'
Recent research around chayote showed diuretic, anti-inflammatory, and hypotensive activities, they said, although specific varieties had rarely been defined or compared.
“...This report is the first to compare the bioactivities of two commercial varieties of chayote with potential application as nutraceuticals and, in this respect, the NS variety appears to be particularly promising,” the researchers wrote.
Whilst both varieties had similar concentrations of vitamin C, the phenolic and flavonoid content in the NS variety was higher than in VL.
Total concentration of phenolics in the NS extracts were 1,005mg per 100g-1 dry weight, compared to VL at 856mg per 100g-1 dry weight. Total flavonoid contents were “similar” in NS versus VL at 27 and 26mg per 100g-1 dry weight, respectively. Four flavonols (rutin, myricetin, quercetin, and galangin), two dihydrochalcones (phloretin and phlorizidin), and one flavanone (naringenin) were present “unambigously” in extracts of both chayote fruit varieties.
Rich in curcurbitacins – toxic goodness?
Chemical analysis on both chayote varieties also showed high levels of curcurbitacins - tetracyclic triterpenes that imparted a bitter taste to plant tissues and were consequently toxic. Despite this, they were often used in traditional medicine and pharmaceuticals because they possessed a “wide range of therapeutic activities”.
“Melon (Cucumis melo L.), a fruit that is much appreciated in many parts of the world, contains significant amounts of cucurbitacins B and E and is used in Chinese traditional medicine as a liver protector agent. Cucurbitacin B also exhibits cytotoxic activity against HeLa and KB cell lines and antitumor activity against sarcoma 280 and Ehrlich's ascites carcinoma, while cucurbitacins D and E have also been shown to inhibit the growth of carcinoma cells,” they wrote.
Importantly, the researchers established high levels of cucurbitacins B, D, E and I in the ethanol extracts of both chayote varieties. The methanol extracts contained cucurbitacins D and E in the VL variety and B and E in the NS variety. The most abundant in both chayote varieties was cucurbitacin D.
Establishing these levels within the chayote plant, they said, showed the “novelty of the research” because it never previously been quantified.
Stevia, pineapple blend
Within the study, the researchers mixed the two chayote varieties with pineapple juice and stevia to add density and flavor to improve consumer acceptance of the drink.
Whilst the addition of pineapple reduced the pH level of the chayote juice, the stevia leaves increased total phenols.
“...The chayote juice combined with stevia and pineapple maintains the original nutraceutical characteristics of the fruit, and can be an option to increase the consumption of this vegetable,” they wrote.
Published online May 2018: doi 10.3390/beverages4020037
Title: “Nutraceutic Characteristics of the Extracts and Juice of Chayote (Sechium edule (Jacq.) Sw.) Fruits”
Authors: Luz Riviello-Flores et al.