In Vivo Investigation of Cardioprotective Effects of Melilotus officinalis and Melilotus albus Aerial Parts Extracts for Potential Therapeutic Application

Globally, cardiovascular diseases represent a major cause of morbidity and mortality, despite the availability of preventive, diagnostic, and therapeutic measures in contemporary allopathic medicine. In accordance with their ethnomedical applications, herbal medicines may offer valuable options for the prevention, treatment, and management of cardiovascular disorders. Considering that cardioprotective effects are associated with antioxidant mechanisms, and that our knowledge of the antioxidant properties of polyphenolic compounds, as well as of the effects of Melilotus species on the heart, is limited, the present study aimed to evaluate the cardioprotective potential of hydroalcoholic extracts of M. officinalis and M. albus aerial parts. The extracts were evaluated for total phenolic content (TPC), total flavonoid content (TFC), and total coumarin content (TCC) by spectrophotometric methods and by LC-MS/MS. The effect of pretreatment with Melilotus sp. extracts on the isoprenaline-induced infarct-like lesion in rats was evaluated by ECG monitoring and the assessment of serum oxidative stress markers and serum cardiac injury markers. Various polyphenolic compounds were identified by LC-MS/MS in M. officinalis and M. albus aerial parts: catechin, syringic acid, protocatechuic acid, and vanillic acid. Gallic acid and chlorogenic acid were found only in M. officinalis. The extracts showed good in vivo antioxidant activity: M. officinalis and M. albus extracts induced a significant decrease in the levels of oxidative stress index (OSI) and total oxidant status (TOS), while pre-treatment with M. albus extract induced a significant reduction in nitric oxide production, and pretreatment with M. officinalis increased total thiols (SH) levels. In the same way, ECG and cardiac injury markers were also improved. These results show that M. officinalis and M. albus extracts may exert cardioprotective effects against myocardial ischemia by reducing oxidative stress.