The potential of MLC901 (NeuroAiD II™), a traditional Chinese medicine
Suhua Huang 1,#, Mingxia Lin 1,#, Xiaowei Pan 1,#, Qiwen Tan 2, and Kai-Leng Tan 2,*
1 School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangdong, Guangzhou, P.R. China 510006.
2 Institute of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangdong, Guangzhou, P.R. China 510006.
# Equal contributors
* Correspondence: firstname.lastname@example.org; Tel.: +86-13119517706
Received: 31 March 2019; Accepted: 12 May 2019; Published: 22 May 2019
Edited & Reviewed by: King Hwa Ling (Universiti Putra Malaysia, Malaysia)
ABSTRACT: Stroke, also known as cerebral ischemia, is a common neurological disease. The therapeutic potential of MLC901 (NeuroAiD II™) has been reported in clinical trials on traumatic brain injury as well as in animal and cell models. MLC901 reduced the infarction size, ischemia-induced neurological deficits and pro-inflammatory infiltration of phagocyte. It also inhibited the ischemia-induced expression of pro-inflammatory mediators and Prx6, TLR4 signalling, and phosphorylation of NFκB. We found that the beneficial effects of MLC901 are in coherent with studies performed on the individual active ingredient. MLC901 may develop its efficacy through a synergistic effect via nine herbal extracts. MLC901 is a multifaceted traditional Chinese medicine. A cocktail of herbs provides a broader spectrum of targets. This may surpass single-target drug treatment in terms of side effect and therapeutic efficacy. MLC901 leads to various potential research directions on the development or improvement of a feasible, effective and promising herbal formulation for treating stroke patients.
Keywords: MLC901; cerebral ischemia; traditional Chinese medicine;
©2019 by Huang et al. for use and distribution in accord with the Creative Commons Attribution (CC BY-NC 4.0) license (), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited.
Stroke, also known as cerebral ischemia, is a common neurological disease with cognitive function impairment and long-term disability [, ]. In 2010, there were 5.9 million deaths and 102 million disability-adjusted life-years were lost because of stroke, making stroke the second leading cause of death . Stroke is a clinical manifestation resulted from occlusion in the blood vessels that leads to the lack of oxygen and nutrient in the infarcted brain . Its representative symptoms include sudden unilateral weakness, numbness, visual loss, diplopia, altered speech, and non-orthostatic vertigo .
Nowadays, the standard stroke treatment is based on the use of a thrombolytic agent such as tissue plasminogen activator (tPA) within 4.5 hours after a stroke incidence . Aspirin and clopidogrel are the common post-stroke treatment used on stroke patients . However, there is limited effective treatment for post-stroke recovery. Scientists have been working on developing a better alternative for post-stroke treatment such as N-methyl-D-aspartate (NMDA) receptor antagonists  and low molecular weight (LMW) heparin . These drugs succeed in improving post-stroke outcome based on the animal study but not in clinical trials [, ]. This "bench-to-bed" approach seems not promising. Recently, Widmann et al. (2018) studied MLC901 , also known as NeuroAiD II™, is one of the traditional Chinese medicine with a combination of nine herbal extracts . It is the second generation of NeuroAiD™ (MLC601) with a more straightforward formula . MLC901 has remarkedly improved post-traumatic brain injury recovery in clinical trial phase two . However, a little is known about how it works. Therefore, the study done by Widmann et al. (2018)  provides a credible research direction with a feasible target, signalling pathway, and assessment parameter to develop a potential therapeutic medicine for the stroke patient.
Widmann et al. (2018) demonstrated that (1) MLC901 reduced the infarction size and ischemia-induced neurological deficits, which were measured by neurological Bederson scores in the treated group . (2) 24-hour post-ischemia, MLC901 significantly attenuated the stroke-induced pro-inflammatory infiltration of phagocytes. (3) MLC901 attenuated the increasing stroke-induced expression of pro-inflammatory mediators (IL11, IL1β, IL6, and TNFα) in the brain. (4) MLC901 remarkedly diminished the middle cerebral artery occlusion (MCAO)-induced expression of peroxiredoxin 6 (Prx6), Toll-like receptor 4 (TLR4) signalling and phosphorylation of NFκB . Prx6 is a significant contributor to immunomodulation and neuroinflammation after ischemic stroke . TLR4 has been linked to inflammation and the pathological progression of cerebral ischemia [- ]. The NFκB activation is the primary signalling system associated with TLR4, and the NFκB signalling pathway has been implicated in immune responses in the ischemic brain [, ]. In summary, MLC901 is a potent therapeutic agent for stroke treatment that significantly improves post-stroke recovery via the suppression of ischemia-induced inflammation processes.
The MLC901 consists of the extracts from nine herbs, which are Radix astragali, Radix salvia miltiorrhizae, Radix paeoniae rubra, Rhizoma chuanxiong, Radix angelicae sinensis, Carthamus tinctorius, Prunus persica, Radix polygalae, and Rhizoma acori tatarinowii [, ]. This extract cocktail is rich in active ingredients such as astragaloside IV (AST-IV), salvianolic acid B (SAB), tanshinone IIB (TSB), tetramethylpyrazine (TMP), ferulic acid, ligustilide and butylidenephtalide, β-asarone, hydroxyl safflower yellow A (HSYA), total paeony glycoside (TPG), and presenegenin [, , ]. The improvement of post-stroke recovery from MLC901 treatment most likely due to the synergistic effect of these nine herbal extracts and their active compounds as each of them may target a different mechanism. Some of them, such as AST-IV, ferulic acid, TSB, and β-asarone, have been demonstrated to have a significant therapeutic effect on cerebral ischemia models. These active compounds were shown to improve neurological deficits , reduce infarct volume , reduce blood-brain barrier (BBB) permeability  and reduce nerve damage on the cerebral ischemic models [- ]. Besides, AST-IV showed a neuroprotective effect by inhibiting oxygen and glucose deprivation (OGD) induced mitochondrial dysfunction . Besides, HSYA showed anti-thrombotic , anti-inflammatory  and anti-oxidation effects  on ischemic stroke models. These observations suggest that MLC901 treatment encompasses a broader range of mechanisms and pathway which contributed to the positive outcome.
Inhibition on inflammation and apoptotic pathways are the highlighted effect of these herbs and active compounds on cerebral ischemic models. In terms of neuroinflammation that followed after the cerebral ischemia, TMP plays a role in neuroprotection by inhibiting the activation, migration and aggregation of microglia cells, astrocytes  and other inflammatory cells . Salvianolic acid B, which extracted from Radix salvia miltiorrhizae showed neuroprotective effect via the inhibition of the TLR4/MyD88/TRAF6 signalling pathway in MCAO-induced ischemic rat brain . The blocking of TLR4 by SAB also restrained NFκB transcriptional activity and pro-inflammatory cytokine responses (IL-1β, IL-6, and TNF-α) . Ferulic acid has also been shown that could reduce the phosphorylation of NFκB in the infarcted brain . Mitochondrial-related caspase-3 apoptotic pathway is one of the apoptotic pathways targeted by MLC901. Z-ligustilide (LIG) significantly decreased Bax and caspase-3 protein expression in the ischemic cortex . Rhizoma chuanxiong, Radix Paeoniae Rubra and their combination reduced the infarct size in the brain of MCAO rats . Treatment using the combination remarkedly decreased the levels of IFN-γ, IL-1β, IL-6 and IL-12 in serum and brain tissues of MCAO rats. It also downregulated the expression of caspase-3 and caspase-12 genes as well as decreased IL-1β and IL-6 mRNA levels in MCAO brain tissue . At the same time, a study also showed that β-asarone reduced cerebral autophagy induced by ischemia-reperfusion in rats via modulating c-jun n-terminal kinases (JNK), phospho-JNK (p-JNK), Bcl-2 and Beclin 1 . TPG recovers energy metabolism via increasing the activity of Na+-K+-ATP and Ca2+-ATP enzymes in the cerebral ischemia-reperfusion injured rat . There is limited information about Prunus persica in MLC901. A study showed that the carotenoids and polyphenols in Prunus persica have antioxidant effects, and down-regulation of chemokine ligand 4 (CCL-4) that led to the inhibition of TNF-α, IL-1β, RAGE and NFκB expression in carbon tetrachloride (CCl4)-induced inflammation rat model . In summary, the result of MLC901 shown by Widmann et al. (2018)  is coherent with the reported outcome of studies performed on the individual herb or active compound.
Potent angiogenic factor, such as vascular endothelium growth factor (VEGF) is also one of the potential targets by MLC901. Dl-3n-butylphthalide (NBP) can be found in both Radix angelicae sinensis and Rhizoma chuanxiong, and it rescued brain tissue by regulating the expression of VEGF and HIF-1 alpha during ischemic stroke . This shows that MLC901 is a multifaceted candidate that potentially targets multiple pathways ranging from the anti-inflammatory pathway to promoting angiogenesis in cerebral ischemic models.
Interestingly, Widmann et al. (2018) reported that MLC901 inhibited the infiltration of neutrophils but not on the T-lymphocytes in the 24-hour study . Studies revealed that regulatory T cells are likely to protect ischemic stroke by suppressing peripheral neutrophil-derived metallopeptidase-9 production that causes BBB leakage [, ] and the activation of CD39/CD73 signalling . Thus, it may be worth to study why and how MLC901 acts on neutrophils and T-lymphocytes. These mechanisms probably will provide new methods for targeted therapy in the future.
Overall, Widmann et al. (2018)  strengthen the idea of using a combination of multiple herbal constituents, both the herbal extract or the active ingredient as an approach to target multiple pathways. Single-target drug treatments for stroke such as NMDA receptor antagonists  and LMW heparin certoparin  have not been promising. It is known that synaptic transmission mediated by the NMDA receptor is critical for neuronal survival and blocking of NMDA receptors triggers apoptosis in the developing brains. Thus the clinical trial of NMDA receptor antagonists has failed due to the difficulty in determining the optimal antagonistic level for stroke patients and improper clinical trial design . In the clinical trial of acute stroke patients, the failure of LMW heparin certoparin attributed to its side-effect, an increased risk for severe bleeding . Normal or increased dose of LMW heparin certoparin did not show any improvement of functional outcome in ischemic stroke patients, while the highest dose group may lead to severe bleeding. Single-targeted drug treatment may disturb the homeostasis in the human body system and potentially exerting severe side-effects. For examples, glutamate could damage [, ] and protect neurons  under different circumstances. In general, it is hard to find a balance or determines the optimal dosage when using single-targeted drug treatment. MLC901 includes a variety of active compounds, has been demonstrated that it has a therapeutic effect on stroke. In this case, it seems that herbal extract cocktail may be better than single-targeted drug treatment.
It is undeniable that MLC901 has significant anti-inflammatory activity in MCAO ischemic mouse model. MLC901 treatment has significantly improved intricate attention and executive functioning on adults with traumatic brain injury (phase two clinical trial) . Even so, we could not help to ignore the failure of MLC601 (NeuroAiD™) phase three clinical trial. MLC601 that contained an additional of five animal components did not significantly improve post-stroke recovery in acute ischemic stroke patients (mean age of 61.4∓11.3 years) . Three months of MLC601 treatment is not statistically better than the placebo group. On the contrary, MLC601 treatment has a persistent beneficial effect up to 24 months in the acute stroke patients from the Philippines (mean age 60.2∓11.1) . These indicate that MLC601 may need a longer duration to improve post-stroke recovery in elder stroke patients. Looking back at MLC901, Widmann et al. (2018)  demonstrated its positive outcomes on the acute cerebral ischemia modelled young adult mice. Perhaps we could have a better and thorough understanding of the MLC901 post-stroke recovery in a spatiotemporal manner if they prolong the study or experimenting on ageing mice. This understanding may potentially prevent MLC901 study from repeating the failure observed in MLC601 phase three clinical trial.
Traditional Chinese medicine has been utilised for thousands of years in Asia, and it usually employs a mixture of herbs and extracts with different herbal formulation for different diseases. In China, there is more than 100 iconic traditional Chinese medicine such as Danqi Piantang Jiaonang (DJ) and Buchang Naoxintong Jiaonang (BNJ), which have been approved by the Chinese National Drug Administration to treat stroke clinically . MLC901 contains nine herbs with more than nine effective ingredients making it a potent medicine to treat stroke patients. The key is to confirm the effective combination of herbs and their interaction. In summary, this provides a potential research direction with a feasible, effective herbal formula to develop or improve a therapeutic intervention for stroke patients.
Acknowledgements: National Natural Science Foundation of China, International (Regional) Cooperation and Exchange Program. Project number: 81850410549.
Author Contributions: SuHua Huang, MingXia Lin and XiaoWei Pan wrote the commentary and contributed their views. Qiwen Tan and Kai-Leng Tan provided intellectual input. Kai-Leng Tan supervised the writing.
Conflicts of Interest: The authors declare no conflict of interest.
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