**The Potential Effect of Elevated Root Zone Temperature on the Concentration of Chlorogenic, Caffeic, and Ferulic acids and the Biological Activity of Some Pigmented** *Solanum tuberosum* **L. Cultivar Extracts**

**Hildegard Witbooi <sup>1</sup> , Callistus Bvenura <sup>1</sup> , Anna-Mari Reid <sup>2</sup> , Namrita Lall 2,3 , Oluwafemi Omoniyi Oguntibeju <sup>4</sup> and Learnmore Kambizi 1,\***


**Citation:** Witbooi, H.; Bvenura, C.; Reid, A.-M.; Lall, N.; Oguntibeju, O.O.; Kambizi, L. The Potential Effect of Elevated Root Zone Temperature on the Concentration of Chlorogenic, Caffeic, and Ferulic acids and the Biological Activity of Some Pigmented *Solanum tuberosum* L. Cultivar Extracts. *Appl. Sci.* **2021**, *11*, 6971. https://doi.org/10.3390/ app11156971

Academic Editors: Luca Mazzoni, Maria Teresa Ariza Fernández and Franco Capocasa

Received: 16 June 2021 Accepted: 15 July 2021 Published: 29 July 2021

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**Abstract:** Without a doubt, potatoes play a vital food and nutrition security role in the world as more than a billion people consume this vegetable. Furthermore, the polyphenolic constituents of pigmented potato cultivars and their associated health benefits have been reported. However, the antioxidant, anticancer, and antimycobacterial activity of pigmented cultivars are scanty. Therefore, the present study explores the phenolic acids and biological activities of cv. Salad Blue (SB) and non-pigmented control (BP1) extracts. The antiproliferative activity of *S. tuberosum* L. against human hepatocellular carcinoma (HepG2) was investigated, as well as the ability to inhibit *Mycobacterium smegmatis*. Chlorogenic acid was the most prominent phenolic acid in both treatments as well as cultivars. In the current trial, 24 ◦C significantly increased chlorogenic acid in cv. SB and BP1. Ethanolic extracts of all the samples showed no activity at the highest test concentration of 1000 µg/mL (ciprofloxacin MIC of 0.325 µg/mL) against *M. smegmatis*. The antiproliferative activity of the tuber samples against HepG2 liver cells had IC<sup>50</sup> values ranging between 267.7 ± 36.17 µg/mL and >400 µg/mL. Since the health benefits of these cultivars are highly valued, the present study provides useful information for future oncology studies, for human nutrition, as well as for how these underutilized cultivars can be fortified to improve their health benefits.

**Keywords:** *Solanum tuberosum*; antimycobacterial; antioxidant capacity; hepatocellular carcinoma; pigmented potatoes
