Heat stress reduces the accumulation of rosmarinic acid and the total antioxidant capacity in spearmint (Mentha spicata L)

Abstract

Selected high-phenolic lines of spearmint were subjected to a constant 30 • C heat regimen for a period of 4 weeks to determine the effects of heat stress on soluble phenolics, phenols and rosmarinic acid biosynthesis and antioxidant capacity. Heat stress significantly reduced levels of total phenolic acids (71-87%) and soluble phenols (75-87%). This loss was concomitant with a loss of total antioxidant capacity of 21-60% after week 1 and up to 95% by week 4. High-performance liquid chromatography profiling of heat-stressed plants at 270 and 320 nm detected nearly a complete loss of rosmarinic acid in all seven chemotypes. High-temperature drying of non-heat-stressed plants at 80 • C resulted in a similar loss of total antioxidant capacity and rosmarinic acid content an effect not observed in material that was subjected to low-temperature drying first, followed by exposure to high temperature. This suggests that heat stress negatively regulates rosmarinic acid biosynthesis and causes a potential rapid biological breakdown of rosmarinic acid in tissues. 2,2-Diphenyl-1-picrylhydrazyl radical assays of heat-stressed and non-stressed plants clearly show that rosmarinic acid is the major contributor to the antioxidant capacity in spearmint.

Algerian mint species: high performance thin layer chromatography

“…These results are in line with previous studies [13] , which demonstrated that many phenolic acids, including rosmarinic acid and related polyphenols, significantly contribute to the antioxidant capacity of many fruits and vegetables. The present study opens the eventuality to explore the possible use of M. spicata L. (spearmint), which contains a considerable amount of rosmarinic acid, as a preventive and therapeutic approach in disorders related to oxidative stress but also as an antioxidant for agri-food storage.…”

“…Previous HPLC analyses of spearmint (M. spicata) clones grown in a normal, controlled environment revealed that rosmarinic acid was the primary phenolic compound present. The rosmarinic acid content ranged from 55% to 85% of the total phenolics profile with the remainder of the phenolics was m-coumaric, p-coumaric, caffeic and ferulic acids [13] . Kivilompolo and Hyotylainen measured, using two-dimensional liquid chromatography with mass detection, an amount of 0.56% w/w (dry weight) of rosmarinic acid in spearmint leaves [27] .…”

“…Based on non-specific spectrophotometric methods, Wang et al reported a rosmarinic acid content of 0.71%-1.43% w/w for M. spicata [29] ; Fletcher et al reported a M. spicata clone (HMS-21) with enhanced rosmarinic acid levels of up to 6% w/w [13] .…”

“…Rosmarinic acid attracts major current interest for its antibacterial, antioxidant, anti-carcinogenic, anti-inflammatory, anti-viral, immunosuppressant, hepato-and neuroprotective activities [12] . It is also investigated for the effect on autoimmune arthritis, heart disease, suppression of autoimmune rejection in human skin transplant patients, as well as for its multipurpose activities against reverse transcriptase, integrase and RNase H in HIV infections [13] . Moreover, rosmarinic acid has recently been reported to inhibit the hemorrhagic effect of snake venoms [14] , and for its positive effects on Alzheimer's disease [15] .…”

Environmental Factors Affecting the Accumulation of Rosmarinic Acid in Spearmint (Mentha spicata L.) and Peppermint (Mentha piperita L.)

“…These factors have a direct impact on biochemical pathways, thus affecting the metabolism of secondary products. For example, spearmint plants enriched for RA exhibit a direct, negative correlation between the accumulation of RA and the antioxidant capacity spearmint extracts from plants grown at high temperatures [11]. Other researchers have found that cold temperatures can enhance the accumulation of RA in rosemary but is dependent on the chemotype [12].…”