Shows the potential targets of PH-induced lipid peroxidation.
Abstract
The use of more than one herb in a medicinal preparation also known as polyherbal has increased geometrically in recent times. Over a hundred thousand scientists have cited “herbal” to strengthen its ethnopharmacological relevance in literature. Polyherbal (PH) is effective potential therapeutic compound used globally to treat oxidative stress-induced injuries which give credence for their traditional applications. However, some issues related to safety and adverse reactions due to PH have raised important public health debates. Lipid peroxidation (LPO) assay is widely used to assess the toxic endpoint of PH. This paper discusses some important roles that PH plays during oxidation–reduction processes.
Keywords
- Polyherbal
- Lipid Peroxidation
- Oxidative Stress
- Antioxidant
- Ethnopharmacology
1. Introduction
Lipid peroxidation (LPO) is one of the oldest risk factors for oxidative stress and its mechanistic processes in disease modulation were first observed during the oxidative deterioration of edible materials [1]. The independent works of scientists in the identification of membrane shedding formed the earliest breakthrough for the study of lipid peroxidation [1, 2]. The biochemistry of oxygenase moiety was a light to the further understanding of the peroxidation of lipids [2]. The central roles play by small lipid molecules, free radicals and cytochrome p450 have been well established [3, 4]. The small lipid molecules are transformed into low-density lipoprotein (LDL). LDL modulations have contributed immensely to the studies on cellular biology. Both enzymatic and non-enzymatic approaches to scavenging LPO have been reported [5]. LPO has its root in several diseases including neurodegeneration, cardiovascular, respiratory, and cancers [2]. Consequently, the chemopreventive and protective roles of several antioxidants with proven efficacies have been documented in the literature. Although the different compounds of antioxidants have been identified, researchers have shown that it is by coordinated efforts that they can quench oxidative damage [6]. Evidence abounds of the involvement of LPO in several diseases and the protective roles of medicinal plant antioxidants [7, 8]. Often time in traditional medicine practices, medicinal compounds that perform a similar function are combined to obtain synergy [9, 10]. Thus, potential antioxidants are capable of preventing, protecting, and eliminating any form of identifiable oxidants [11]. The medicinal effects of functional food have been known for a long time. This observation was the result of preservative, anti-oxidative and antimicrobial actions found in ginger, nutmeg, turmeric, etc. These help arrest, repair, and restore potential injuries [12]. The scavenging efforts by antioxidants provide auto-inhibition or sometimes intervention to the activity of LPO metabolites [13]. Interestingly, in the case of progressive disease, the presence of combined efforts of antioxidants can offer a cascade of reactions to stop the process involved. Despite the tremendous roles of natural product medicines, some issues related to safety and adverse reactions due to PH have raised important public health debates [14]. Lipid peroxidation assay is one of the simplest methods widely used to assess the toxic endpoint of PH. Thus, this paper discusses some important roles that PH plays during oxidation–reduction processes.
2. Polyherbal (PH)
The use of herbal medicinal products has become popular for several reasons since they have always been the last order of resort when conventional therapy failed [15, 16]. Majorly, Polyherbal (PH, also known as herbal or traditional medicines) are used as complementary and alternative medicines [17]. The direct and indirect effects of polyherbal (PH) involvement in modulating LPO product formation have attracted scientific debates in recent times [15, 18]. Among the many reasons for use are that they are natural supplements, relatively safe, less toxic, and cheaper [15, 19]. The largest conventional therapy is obtained from plant sources, and many of them are nurtured within the neighborhood [20]. As the usual practice in traditional medicine, any substance or medicinal agent of natural origin may be used alone or with other agents as a polyherbal formulation which often requires less expertise [14]. PH is considered to be supplements and so boycotted major laws [21]. Thus, in most cases, measures for dose regulation are lacking in PH preparations as prohibition is difficult to reach [22]. This makes regulating agencies find it difficult to gather and provide the necessary implementation in many countries of the world. Despite the effort of the World Health Organization (WHO) to issue a certification scheme for the regulation of PH, the problem of non-compliance has been on the high side [23]. To this end, important PH like the
3. Importance of PH as Ethnomedicines
There are some conditions of inadequate efficacy, side effects, and pharmacokinetic problems of conventional drugs used for disease modulation [14]. Recent studies focused on the pharmacology and feasibility of herbal compounds as a potential strategy for alternative therapy. Now the discovery of novel therapeutic agents with multi-targeted potential is desirable [13, 20, 28]. Protective properties of phytochemicals combat numerous diseases and their vast acceptance and demand in human beings encouraged scientists to assess their effective activities [9, 11]. Artemisinin for instance has been known for decades and forms one of the most commonly prescribed medicinal agents [25]. The same has now emerged into an antimalarial drug used as first-line medication in this regard in addition to its adjuvant anticancer potential [10, 13]. Also, ethnomedicine has risen to provide an alternative to biofilm infections to improve medical treatments by the use of combinatorial treatment of bacterial biofilms as re-potentiators of classical antibiotics [9]. Actions related to anti-growth, anti-biofilm, or anti-quorum-sensing activities, to control bacterial infections have been associated with the use of PH including
4. Risk factors for PH-induced LPO
There are several setbacks to draw from the recent criticisms of PH applications [14, 25, 30]. This is the reason for the suggestions on standardization developments [15, 24, 28, 31]. The latter may help gain insight into their mechanisms as well as potentials for toxicity.
4.1 Dose
Several PH compounds have been extensively used as a traditional medicine for various therapies [18]. Because of the multifaceted component of PH mixture, several of the published articles showed that manufacturers relied mostly on the documented efficacies of the constituent compounds. There is a lack of specifications for the dose selection of subtherapeutic, therapeutic, and supratherapeutic doses which are used in animal studies, and for animal-to-man dose extrapolations [29]. Till now, there is a lack of formula to relate PH constituents; hence, lack of proper dose extrapolation of a single compound when combined with another may result in the potential mechanistic toxicological effect of the constituent mixture [28, 32]. Several misconceptions about dietary supplements being safe to have increased the number of hospital admissions [14, 17]. Recent studies on the PH dietary supplement popularly known as Cellgevity® (CG) confirmed that this premiere antioxidant supplement formula could act as a pro-oxidant, a substance capable of distorting the antioxidant systems [28]. Studies on the effects of therapeutic and supra-therapeutic doses of CG on reproductive function and biochemical indices in animals demonstrated some detrimental effects. CG is one of the most widely used glutathione supplements that has been considered to be harmless, nevertheless, this general assumption should not be overlooked. It is marketed to salvage for the body glutathione and/or complements its production. D-Ribose and L-Cysteine are the active compounds in CG in addition to the presence of vitamin C, selenium, alpha-lipoic, broccoli seed extract, curcumin, resveratrol, grape seed extract, quercetin, milk thistle seed extract, cordyceps, black pepper, aloe leaf. Some convergent opinions have highlighted the antioxidant activity of spices and their impact on human health, in particular, to increase reduced glutathione (GSH) concentration [12]. Whereas the presence of GSH improves protein function in a perturbed environment, its roles in modulating hypoxic apoptosis or oxidative stress is of great concern. This has put the faith of current supplement antioxidants in doubt, such as protein supplements and others, which now beg for safety evaluation. Previous studies have reported that dietary supplements are now being used to prevent and treat various diseases [7]. We have now understood that any excess of antioxidants could be detrimental and can result in adverse events and even death. Reports over the past few years have implicated the use of herbs and herbal products to generate reactive oxygen and nitrogen species. Mahwangyounpae-tang (MGT) is another but very popular antioxidant PH consisting of about 22 compounds [32]. Reports on MGT showed that MGT extract was safe for use in asthma at the sub-acute repeated oral dose levels. However, when the doses were increased per daily in rodents, there were correspondingly increased morphological aberrations and organ histoarchitectural changes characterized by hypertrophy of the heart and tubular necrosis of the kidney [32]. Thus, concerns over the doses of antioxidants when using alone, or with other drugs have arisen (Table 1).
Polyherbal | Uses | Potential Mechanisms | Potential Target |
---|---|---|---|
Mahwangyounpae-tang® [6] | anti-inflammatory and asthma | Immune system, blood, pro-inflammation | Lungs, heart and kidney |
Cellgevity® [28] | Antioxidant supplement formula | Immune system, haematotoxicity, pro-inflammation, elevation of serum low density lipoprotein | Blood, liver, testis, kidneys |
Hydroxycut [30] | Weight loss supplement | Elevation of hepatic biomarkers, pro-inflammation | Liver |
Bon-sante cleanser® [33] | Body hormones booster and energizer | Immune system and body hormones, pro-inflammation | Liver, heart |
Bronco-T® [34] | Anti-inflammatory and lung regeneration | Immune system, blood, pro-inflammation, bronchoconstriction | Lungs |
Jambadyarista® [35] | Diabetes and its associated complications | Hypolipidic, Nuclear factor-κappa B activation | Pancreas |
Shengmai formula® [36] | Cardiovascular diseases | Opening of mitochondrial permeability transition pore, cyclophilin D. | Heart, liver |
Hab-e-Kabad Noshadri Hepatic disorders® [37] | Hepatic disorders, abdominal problems. | Elevation of hepatic and renal biomarkers, inflammation | Liver, kidneys and gastrointestinal system |
4.2 Duration of treatment
Evaluations of most of the PH for toxicological profiles are most unlikely not going to be sufficient to determine the endpoint toxicity [24]. For instance, the majority of the acute to chronic studies found in the literature were between 14 and 90 or 180 days. However, only a few studies show reversibility assessments or show species specifications [38]. Over 80–90% of the toxicological studies published showed few or no adverse drug reactions. Also, the parameters for their toxicological endpoint did not capture genotoxicity potential [39]. As with the case of CG, which supposedly should provide a maximum antioxidant function by GSH synthesis rates and concentrations as expressed by the content could act as a pro-oxidant causing oxidative damage in normal humans particularly at high dosages [28]. Such transition in chemical nature could generate pro-oxidant–antioxidant imbalance thereby produce undesirable toxins leading to oxidative stress [22, 25]. Hence, a long-term toxicological profile plus storage history has been recommended to ascertain PH safety.
4.3 Lethal dose estimation
The median lethal dose (LD50) is the statistically derived dose following the administration of any PH which is expected to produce death in 50% of the treated population [40]. The toxic effects of chemicals, food substances, pharmaceuticals, etc., have attained great significance in the 21st century [17]. Toxicity tests are mostly used to examine specific adverse events or specific endpoints in disease identifications. Toxicity testing also helps to calculate the No or Low Observed Adverse Effect Level (NOAEL/LOAEL) dose and is helpful for clinical studies [39]. However, the methods of determination of median lethal dose (LD50) may impact negatively on the information for the use of PH. Therefore exaggerated lipid peroxidation levels due to PH might be the results of poor safety methodology [23]. This however can be minimized by using several methods to ascertain the PH LD50 level. Studies have suggested that lack of expertise in this aspect of scientific investigation might influence judgment on the PH formula [24]. Inability to in-cooperate the knowledge of individual median lethal dose might create impurities in the constituent mixture. The five most commonly paraded bitters in Nigeria for type 2 diabetes are Yoyo bitters (YB), Oroki herbal mixture (OB), Ruzu Bitters (RB), Fijk flusher (FB), and Fidson Bitter (FB) respectively. Although, each of this preparation has claimed for several indications, however, scientific investigations for the mixture have reported weight trimming and blood sugar modulations (Kale et al., 2018). Since their constituents are known, their ability to act synergistically and the potential for precipitating adverse herb reaction of LPO have been ascertained [15]. These concerned mixtures have multifaceted constituents most of which have popular applications. Examples include ginseng,
4.4 Manufacturer Bias
In contrast to the general belief, medicinal plant preparations have been shown to pose serious health risks in a dose and time-dependent either alone or in combination with other agents [19, 38]. Reports have it that PH contain tightly bound bioactive compounds and have shown the possibilities of an indirect risk that can be independent of the active compound [16]. Countries are now examining national pharmacovigilance data using statistical tools to report population possible risks [24]. This is because, oftentimes, the species specification by manufacturers on PH constituents did not correlate most times with products packaging thereby altering scientific decision on toxicological evaluations [25]. The potential to generate lipid peroxidation by several PH are underestimated [14]. On the other hand, the latter creates a contrast in mind when a single compound has a toxicity level greater than the combined mixture. Additionally, erroneous claims of total cure and or weight supporting supplement some of these PH are marketed with approved consent from regulatory authorities [22]. There are also exaggerations of PH with conventional drugs which have been suggested to contribute in part to the unwanted adverse reaction of some PH [14, 20, 23]. Thus, this issue associated with production bias has raised concern about quality control, screening methods as well as toxicity scoring which most regulatory authorities however have not been able to properly address it. Bon-santé cleanser® (BS) is a popular PH comprising of anogeissus leiocarpus (DC., family Combretaceae),
5. Molecular mechanisms of PH-induced LPO
Control | HAS1 (250 mg/kg) | HAS2 (500 mg/kg) | HAS3 (1000 mg/kg) | |
---|---|---|---|---|
Testosteronex | 3.56 ± 0.09 | 4.53 ± 0.04* | 4.84 ± 0.06* | 6.48 ± 0.13* |
PSAx | 1.83 ± 0.01 | 1.89 ± 0.01 | 1.81 ± 0.01 | 0.69 ± 0.02* |
Nitric Oxidex | 0.65 ± 0.10 | 0.85 ± 0.10 | 1.28 ± 0.10* | 1.83 ± 0.20* |
TNF-αx | 3.19 ± 0.19 | 2.72 ± 0.19 | 4.09 ± 0.18 | 4.46 ± 0.20* |
NF-kBx | 1.03 ± 0.14 | 1.64 ± 0.16 | 2.02 ± 0.13* | 2.83 ± 0.12* |
Oestrogeny | 51.72 ± 1.43 | 63.81 ± 2.26 | 51.44 ± 1.38 | 40.55 ± 2.13* |
Progesteroney | 43.91 ± 0.39 | 125.03 ± 0.58* | 143.91 ± 0.29** | 168.60 ± 0.38** |
Nitric Oxidey | 1.40 ± 0.01 | 1.38 ± 0.01 | 2.50 ± 0.02* | 2.40 ± 0.02* |
TNF-αy | 5.12 ± 0.19 | 6.90 ± 0.18 | 6.79 ± 0.19 | 8.44 ± 0.18* |
NF-kBy | 1.25 ± 0.11 | 1.32 ± 0.14 | 3.23 ± 0.12* | 4.11 ± 0.16* |
5.1 MDA levels
HAS1 lowered MDA level in the stomach by 32.2% in normal male rats (Figure 1). However, HAS2 produces an increased (p < 0.05) MDA levels in pancreas, heart, and brain by 113.64%, 70.37%, and 36% respectively. Additionally, HAS3 elevated MDA levels in testis (79.41%), kidney (52.38%), pancreas (104.55%), heart (88.89%), and brain (96%) respectively in rats. on the other hand, in the female rats, HAS1 caused an increase in MDA level in lung (57.69%) and pancreas (88%) respectively. Similarly, HAS2 produce elevated MDA levels in the lung and pancreas by 80.77% and 44% in the treated rats, whereas, HAS3 further increased (p < 0.05) MDA levels in the lung (50%), brain (82.14%), and pancreas (24%) respectively in the treated animals.
5.2 Reproductive hormones and molecular biomarkers
HAS3, HAS2 and HAS1 showed a dose-dependently decrease (p < 0.05) testosterone levels by 82.02%, 36.01% and 27.25% respectively (Table 2). Additionally, the PSA level was lowered in rats that received HAS3 by 62.44%. On the other hand, in female rats, HAS1 and HAS2 administration elevated serum oestrogen levels by 23.38%, whereas HAS2 and HAS3 lowered oestrogen levels by 0.54% and 21.60% when compared with control. Further, progesterone was increased in all the treated female rats by 283.97% (HAS3), 227.74% (HAS2), and 184.74% (HAS1) respectively. In male rats, serum NO levels were elevated (p < 0.05) following HAS2 and HAS3 administrations. Also, HAS3 increased (p < 0.05) TNF-α level by 39.99% in rats. In the female rats, however, both HAS2 and HAS3 elevated (p < 0.05) serum NO levels by 78.57% and 71.43% respectively. Further, TNF-α and NF-kB were increased in rats serum of HAS3 by 64.84% and 228.8% when compared with control.
6. Conclusions
The evidence that complementary and alternative therapy plays a crucial role in the management of health is indisputable. However, because of the complexity of the phytocompound present in PH, they may act as pro-oxidants as well as antioxidants. Therefore, as pro-oxidants, they generate lipid peroxidation products which are an important risk factors for tissue damage.
Acknowledgments
The kind leadership of my teachers and mentors, Dr. Awodele O. and Dr. Akindele A. J., of Department of Pharmacology, Therapeutics and Toxicology, College of Medicine, University of Lagos, Lagos Nigeria are gratefully acknowledged.
Conflict of interest
Authors declare that they have no competing interests. No specific grant received from any agency in the public, commercial, or not-for-profit sectors.
Acronyms and abbreviations
LPO | Lipid Peroxidation |
MDA | Malondialdehyde |
PH | Polyherbal |
TNF-α | Tumor Necrosis Factor-alpha |
HAS | Hydroethanolic extract of Acridocarpus smeathmannii root |
iNOS | Inducible nitric oxide synthase |
LD50 | Median lethal dose |
ROS/RNS | Reactive Oxygen/Nitrogen Species |
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