INTRODUCTION
Oxidative stress is initiated by reactive oxygen species such as
hydrogen peroxide (H2O2), peroxyl
nitrite, as well as hydroxyl radical (.OH), superoxide anions (O2-),
nitric oxide (NO.) which seek stability through electron pairing with
biological macromolecules such as proteins, lipids and DNA in healthy
human cells and cause protein and DNA damage along with lipid
peroxidation (Hazra et al ., 2008). These changes contribute to
cancer, ageing, inflammation and cardiovascular disease such as
atherosclerosis (Suja et al .,2016; Hazra et al .,2008;
Braca et al .,2002). Atherosclerosis is a multifactorial
complication leading to heart attack and stroke. Oxidation of low
density lipoproteins (LDL) has been suggested to be an initial step in
the development of atherosclerosis (Naidu et al ., 2001). Oxidized
LDL is taken up by macrophages at an enhanced rate via their scavenger
receptors (Aviram et al ., 2000; Parthasarathy et
al .,1986), leading to the formation of lipid-laden foam cells, the
hallmark of the early atherosclerosis (Aviram et al .,2000;
Berliner et al .,1995).
Antioxidants with free-radical scavenging activities could have great
importance as prophylactic and therapeutic agents in diseases in which
oxidants or free radicals are implicated (Vikas et al .,2017;
Marnett et al ., 2000). The most common antioxidants currently in
use include BHA- Butylated hydroxyl anisole, BHT Butylated hydroxyl
toluene, propyl gallate, and tert-butyl-hydroquinone (Gulcin et
al .,2004). However, they have been suspected to be responsible for
liver damage and carcinogenesis in laboratory animals (Biswas et
al .,2010). Therefore, the research on the development of the new, safe
and effective antioxidants are nowadays vivaciously encouraged and
botanicals might be the alternative solution.
Plecthrantus glandulosus Hook. F. (Lamiaceae) is one of natural
products with culinary applications and health benefits. It is a
climbing herbaceous plant widely distributed in West, Central and South
of Africa (Pele et al .,1986). It is used in Cameroon’s
traditional medicine to treat dermatitis, bellyache, venereal diseases,
internal inflammation, lower abdominal and nerve ache. Known as Ava in
Ewondo, the plant is used as condiment in the Ewondo tribe (Peleet al .,1986). Earlier studies reported the antinociceptive and
anti-inflammatory effects (Fongang et al .,2016) as well as
antioxidant and insecticidals activities (Danga et al . 2014;
Danga et al ., 2015; Goudoum et al .,2009). As phytochemical
constituents of P. glandulosus , one new methoxylated flavonoid
derivative, plectranmicin and one new monoterpene derivative,
plectranmicinol, together with seven known compounds including
5-hydroxy-3,7,2′,4′tetramethoxyflavone;
5,7-dihydroxy-3,2′,4′-trimethoxyflavone;
7-hydroxy-5,6,4′trimethoxyflavonen; 3-epi-betulinicacidn;
3O-β-D-glucopyranosylstigmasterol; β-sitosterol and 4-epi-fridelin were
isolated from the whole plant (Tsopmejio et al in 2019).
The present study was undertaken to evaluate the in vitroantioxidant properties of the leaves extracts and fractions as well as
their protective effects against human low density lipoprotein oxidation
induced by copper sulfate (CuSO4).