Medicinal Tiger Milk Mushroom Lignosus rhinocerus TM02® (Agaricomycetes) Sclerotia Supplementation Mitigates Hypertension and Alleviates Vascular Dysfunction Partly through Oxidative Stress Modulation in Spontaneously Hypertensive Rats

Abstract

Hypertension is a risk factor for cardiovascular diseases such as coronary artery disease, heart failure, and stroke. <i>Lignosus rhinocerus </i>(Cooke) Ryvarden (also known as tiger milk mushroom), has been reported to exhibit a range of pharmacological effects, such as anti-inflammatory, anti-proliferative, antioxidative, immunomodulatory and anti-asthmatic activities. Thus far, there is limited research that has explored its ability to mediate vascular effects <i>in vivo</i>. Therefore, this study investigated the antihypertensive and vascular protective effects of <i>L. rhinocerus</i> TM02^® sclerotia supplementation in spontaneously hypertensive rats (SHR). Wistar Kyoto (WKY) rats served as a normotensive control group. SHR were orally administered with <i>L. rhinocerus </i>TM02^® sclerotia (100 mg/kg and 300 mg/kg, respectively) for 8 weeks, and blood pressure was monitored every 2 weeks. Vascular function was evaluated using an organ bath (aorta) and wire myograph (renal artery) at the treatment endpoint. The levels of reactive oxygen species (ROS) and nitric oxide (NO) in the aorta and renal artery were evaluated using dihydroethidium (DHE) and difluoro fluorescein acetate (DAF-FM) fluorescence assays, respectively. Total plasma nitrate/nitrite and tumor necrosis factor alpha (TNF-&alpha;) levels were evaluated via colorimetric assays. <i>In vivo</i> treatment with <i>L. rhinocerus </i>TM02^® sclerotia significantly attenuated the increase in systolic blood pressure (SBP). It also alleviated vascular dysfunction and decreased elevated ROS in the aorta and renal arteries of the treated SHRs. Moreover, <i>L. rhinocerus</i> TM02^® sclerotia attenuated plasma TNF-&alpha; level but increased total plasma nitrate/nitrite, albeit slightly, coupled with significantly increased NO at the vascular level. Collectively, the present study demonstrated that<i> L. rhinocerus </i>TM02^® sclerotia supplementation exerted blood pressure lowering effects, partly attributed to improvements in vascular function via reduction in vascular oxidative stress.