Lipid photooxidation is the undesirable chemical process in which singlet oxygen result in the peroxidation
of fatty acids. In this study leaves methanolic extracts of peppermint (Mentha piperita L.), marjoram
(Origanum majorana L.), rosemary (Rosmarinus officinalis L.) and sage (Salvia officinalis L.) were applied
as the natural singlet oxygen scavenger. Amount of flavonoid compounds as the singlet oxygen scavenger
agent in these plant species were decreased in the order of peppermint > marjoram> sage > rosemary.
Also, The rate of quenching of singlet oxygen in the presence of 1,4-Diazabicyclo[2.2.2]octane (DABCO)
as a well-known singlet oxygen scavenger and highly effective synthetic antioxidants in food industry such
as Butylated hydroxyanisole (BHA), tert-Butylhydroquinone (TBHQ) and peppermint decreased in the
order of peppermint > BHA > TBHQ > DABCO >. Furthermore, photooxidation of oleic acid as an
unsaturated fatty acid in the presence of DABCO, peppermint, BHA and TBHQ indicated a preservation of
82.77%, 73.39%, 71.57% and 53.10% on peroxidation of oleic acid, respectively which reveals peppermint
has an efficient role on protection of fatty acids from photooxidation.
Practical application: In this study, it was confirmed that peppermint (Mentha piperita L.) performs an
effective role in restricting or limitation of singlet oxygen generation and fatty acid photooxidation. In vitro
study of scavenging effect of peppermint can correlate laboratory results to commercial scale up. However,
this would also necessitate the progress of improved methods for the measurement of lipid peroxidation in
vivo in the presence of peppermint.