Infectious diarrhea, dysentery and chronic diarrheas, and colic are severe, debilitating conditions presenting with abdominal pain and in some cases inflammation. Acute visceral pain involves the activation of high-threshold nociceptive fibers, while chronic visceral pain is thought to be due to sensitization of both extrinsic and intrinsic mechanoreceptors by conditions such as inflammation or ischemia [15,16,17]. Therefore, effective herbal remedies of pain and diarrheas are likely to contain neural active compounds and in the case of chronic pain remedies, may have anti-inflammatory components.

The need for medications that are used to treat patients with chronic gastrointestinal illnesses presenting with pain and inflammation is unmet and growing. For thousands of years, botanical medications have played a significant role in public health as treatments [1,2,9,14,18,19] and sources of new drugs and will continue to do so [20,21]. Therapeutic uses of about 80% of 122 plant-derived drugs correspond to their original ethnopharmacological role [20]. This suggests that careful screening of the diverse botanical preparations used in TAHM—or derivative fractions and compounds—have a potential for new therapies against painful, chronic gastrointestinal disorders, and integration into western medical treatment practices of veterinary and human patients. One example, and perhaps the best fit for this theme, is the root extract from Harpagophytum procumbens—a plant native to Saharan Africa—that has been accepted for use (together with acupuncture) as complementary treatments for osteoarthritis in western veterinary and human medicine. The basis for the acceptance of this plant product, and its effectiveness, is in containing components with analgesic and anti-inflammatory properties (such as triterpenoid glycoside beta-sitosterol) and the known side effects of lowering blood sugar, and increasing stomach acids and rhythmic cardiac activity [22]. Better complementary drugs are needed and African botanical folk therapies offer the most valuable resource. In the Table 1 and Table 2, plant species with the dagger sign after their names appear to be the most widely used in TAHM against painful gastrointestinal illnesses and diarrhea. Most of these plants are also used to treat several chronic illnesses (not included) suggesting that they should be given prioritized research to support and advance their therapeutic uses.

Medicinal plants used to treat human pain and diarrhea are covered here because plant species used to extract products for treating animal and human pain and diarrheas overlap. Roughly, over 150 medicinal plant species are used to treat painful gastrointestinal illnesses (58 families), diarrhea, and dysentery in animal patients in Africa (Table 1). By contrast, there are over 250 medicinal plant species (75 families) used for similar purposes in TAHM to treat human patients (Table 2). A summary of plant families in Table 3 indicate that leguminosae, compositae, lamiaceae, rubiciae, anacardiaceae, malvaceae, menispermaceae, and apocynaceae are the major medicinal plant families for both animal and human use in Africa, with over 70 plant species being used to treat both veterinary and human patients (Table 1; family name with asterisk sign). The overlap shown here emphasizes the need for veterinary investigators/practitioners to become familiar with the plant species used to treat similar or related human illnesses, whether it is in Africa or other parts in the world. Families that appear to be prominent sources of plant medications for humans but not animals are clusiaceae, aizoaceae, capparaceae, convolvulaceae, hypoxidaceae, lauraceae, and salicaceae. Compared with Africa (Table 1 and Table 2), the most common Chinese ethnoveterinary plant products are from the family ranunculaceae (Table 4), followed by papaveraceae and leguminosae (Table 3). Collectively, summary data supports the notion that herbal medications for human illnesses have been more extensively studied than botanical preparations used for treating similar conditions in veterinary patients. What is alarming is the lack of information found in the literature about the treatment of acute/chronic pain, diarrhea and dysentery in cats and dogs.

Although, the African Herbal Pharmacopoeia has been published [2], it is only covers a few selected plant species. The available databases on African medicinal plants, such as: http://www.ulb.ac.be/sciences/bota/pharmel.htm, http://www.prota.org/PROTAstartframes.htm and http://www.ippc.orst.edu/ipmafrica/db/index.html are not adequate. There is need for more TAHM electronic databases such as monographs of plants and plant derivatives used in veterinary and human alternative medicine practices in Africa. Such resources of summary data will be valuable to research, teaching TAHM, and public knowledge and could be made available through the Pan-African Natural Products Library.

In the past two decades significant progress has been made in research on TAHM, as indicated by the number of publications with South African institutions taking a lead. Subsequently, the majority of plant species described here are from Southern Africa, Nigeria, Egypt and East Africa. This indicates that more work is needed to identify and/or document plant species used to treat veterinary and human pain, diarrhea from other areas of Africa to fully exploit the indigenous herbal medicine in Africa. We, and other scientists [23], have observed that there are several gaps and inconsistencies in gathering information about herbal African folklore medicine. Particularly interesting are inconsistencies found in the documentation of what parts and exact ratios of plants are suitable for a particular medication or, whether the plant preparation is used as an individual or in a mixture [4,24,25]. African governments and institutions such as the Natural Products Research Network for Eastern and Central Africa (NAPRECA; [12]) should establish standardized “guidelines” of gathering this data for all researchers in order to produce accurate documentation of indigenous plant use in Africa.

The advances associated with verification of efficacy, bioactive compounds, safety, and semi-processing to pack and preserve traditional Chinese medications have helped bolster the integration of Chinese medicine into western medicine. Traditional African herbal medicine (TAHM) utilizes organic botanical products, which could contribute to global improvement of animal health care and production, either as individual preparations or as adjunctive therapies to western medicine. However, this will require carefully guided strategic research. Pre-requisites for research priorities are identifying critical needs of global veterinary/human medicine for new or adjunctive therapies to improve health and wellness (in this case, treating pain and gastrointestinal disorders). As shown in this review, many natural medications against body pain and gastrointestinal conditions with symptoms of diarrheas and dysentery are available in Africa. Prioritized research is necessary in order to determine what plant species or derivertives should be analyzed fully. A careful and thorough literature review dealing with the described folklore is needed to identify and select plant species to be considered for research priority. Additional considerations include: comparison of existing information with literature about patient/farm-evidence based social studies, laboratory tests, and clinical/field trials across the world [11,26,27]. National and pan African advisory councils for complementary and alternative medicine in veterinary care should lead the prioritization and botanical drug development initiatives for integration or adjunctive therapy with acupuncture and western medicine.

Empirical approaches for scientific validation of the efficacy, safety, bioactive components, and mechanisms of action are necessary for the progress towards integration of TAHM into western medicine [7,26,27,28]. Systematic, prioritized research that provides irrefutable, proof-of-principle evidence for interventions against pain and gastrointestinal disorders described in folklore practices are necessary prerequisites to bolster the integration of TAHM into modern medicine. Strategic, basic research should focus on biological effects and mechanisms of action underlying the described folklore practices, and characterize the active components of the intervention. Verification of cellular mechanism should use in vivo and in vitro methods by means of simple methods for fast screening, if possible, accompanied by state-of-the-art techniques to demonstrate and quantify bioactivity. Most medicinal herbs/plants have several medicinal compounds (or compounds of similar classes) that exhibit similar medicinal effects. Determination of classes of compounds can be done using simple chemical tests and is useful to validate traditional use. These tests should not be employed as screens that provide justifications for traditional uses only [23]. Instead, testing should target the isolation, characterization, testing of bioactive components and establishing optimal doses, non-specific vs. specific effects, bioavailability, side effects, and toxicity levels.

Research should not be viewed as a means to discover new compounds, but rather, should be seen as an absolute need to develop the most promising plant therapies into either unmodified natural products (crude extracts), semi-refined products (fractions/sub-fractions or recombinants of fractions), and/or pure compounds and compound formulas [4,8,28,29,30]. Semi-processed products can be cheaper and have concentrated active components without constituents with adverse or toxic effects. They then become best suited in quality, efficiency, safety, and affordability for use as medications or diet supplements in the treatment of veterinary and human patients [8,29,31]. To achieve this goal, research should be prioritized toward selected plant species, and information about processing, packaging, stability, quality, dosing, preservation of natural habitats, and farming selected plants should be gathered though research.

Screening of bioactive ingredient/s from natural products such as plant materials is best achieved through bioassay-guided fractionation. Generally, a bioassay is any in vitro or/and in vivo or ex vivo system used to detect the biological activity (effects) of a crude extract, fraction, or a pure isolate/compound from a living organism. Biotesting might be done using isolated cells, organs, tissue preparations, animals or human subjects. Combining the separation/isolation and characterization of bioactive ingredients with bioassays is called bioassay-guided fractionation. The extract, fractions, subfractions, and recombinants of fractions and subfractions are screened and tested for bioactivity in natural concentrations within the initial crude extract for bioactivity that correspond to that of the initial crude extract using the same bioassay. The components showing high activity, or higher activity, than others are further bioactivity-guided fractionated until the bioactive compound/s is/are obtained in pure form. Chemical assays—like antioxidative assays (e.g., Oxygen Radical Absorbance Capacity (ORAC) [32] or hydrogen peroxide [33] scavenging assays—are not considered to be bioassays but antioxidative-guided, or in a more general sense, activity-guided fractionation [34].

It is absolutely essential to use the fractions and subfractions in their natural concentrations/ratios, to perform recombination and omission experiments for comparing their activity in relation to the activity of the crude extract described through folklore practices. The advantage of using this approach is that chemical changes that occur during extraction, fractionation and isolation, synergistic and/or antagonistic, as well as additive (or a combination of these effects), can be traced. The majority of botanical therapies are extracted using water. Depending on the bioassay and isolation methods, water extraction can be problematic. It requires powerful organic solvents—such as dimethylsulfoxide [35] to be used prior to a final dilution in a buffer in appropriate concentrations for the bioassay. There are other procedures to overcome solubility problems such as using polyvinylpyrrolidone to form soluble complexes [36]. However, compounds like polyphenols, could interfere with the corresponding bioassays (receptor binding and enzyme assays) through nonspecific binding to proteins. These compounds should be removed by appropriate techniques (e.g., pre-separation, precipitation, or adsorbents like XAD-2 resin) but must be developed and tested individually to determine how each impacts the extract and bioassays to ensure that the method itself does not affect the bioactivity, which is cumbersome. Control experiments using blanks, control solutions/samples, as well as positive controls are mandatory during bioactivity-guided screening.

In most cases, the bioactivities of the fractions, subfractions, and pure compounds are lower than that of the initially used extract. This might be the sum of—or individual influence of—losses during workup (e.g., solvent fractionation), different chromatography techniques (e.g., column chromatography), evaporation of fractions, freeze-drying, and photosensitivity. Another possibility is that separating the extract into different fractions or compounds disrupts synergistic and/or additive effects. For instance, we have found that thin layer chromatoghraphic separation of G. buchananii stem bark extract yields fractions with anti-motility and pro-motility effects in guinea pig colon [37], suggesting that the crude extract contains compounds with opposite/antagonistic biological effects. In some cases, fractions show greater activity than the crude extract, which might be explained by suppressive and disturbing effects by the other ingredients in the crude extract. However, it is also possible that breakdown products (artifacts) generated during work-up and isolation have stronger activity than the initial (precursor) compound. To overcome these problems light should be excluded during work-up/isolation (brown glass), and inert gas atmosphere (nitrogen or argon) and cooling (ice bath, fridge, freezer) should be used. One approach to prove if artifacts are generated is to use non-targeted nuclear magnetic resonance (NMR) spectroscopy or liquid chromatography mass spectrometry (LC-MS) based metabolomics. Comparing the crude extract with its subfractions could give hints of new compounds generated during isolation/fractionation process. Also, accurate quantitation of the pure bioactive compound by means of LC-MS/MS, NMR or LC-UV in the crude extract, and subfraction followed by comparing the concentrations, could give evidence on breakdown, formation and degradation.

Another necessary step, after the identification of the bioactive component, is the accurate quantitation, especially if more than one compound was identified, and rating them for their bioactivity on the basis of activity-over-threshold (AoT) (threshold = EC₅₀, IC₅₀, activity equivalent…) in order to bridge the gap between pure structural chemistry and bioactivity. AoT-factors could be seen as a model approach and representing the individual contribution of each single compound to the activity of the crude extract. The higher the AoT-factor, the higher the contribution a single bioactive molecule has on the bioactivity of the whole extract. With the quantified bioactives the proof-of-principle in form of reconstitution (recombination) and omission experiments should be performed. A reconstitute should be prepared by blending solutions of the individual bioactive compounds in their “natural” concentrations and comparing the bioactivity of this mixture with the crude extract. The goal of such experiments is to prove whether the isolation, purification process, and quantitation steps alter bioactivity. Discrepancy between recombinants (the “cocktail”) and the crude extract suggests bad quantitation during preparation of recombinants, or synergistic compounds are not present in the mixture, and/or important bioactive compounds were altered during separation as mentioned above.

Finally, omission experiments should be performed to demonstrate the importance of the bioactivity of compound classes, or single compounds, in comparison to the whole recombinant in their “natural” concentrations. With this strategy additive, antagonistic, and synergistic effects can be demonstrated. An example for the whole work-flow, bioassay-guided separation and beyond was demonstrated by [38], in which taste-active compounds in roasted cocoa nibs were identified by means of bioassay-guided fractionation. In this context, sequential application of solvent extraction, gel permeation chromatography, and RP-HPLC in combination with taste dilution analyses [39], followed by LC-MS and 1D/2D-NMR experiments, ultraviolet/visible (UV/Vis), circular dichroism (CD) spectroscopy, and polarimetry, as well as independent enantiopure synthesis revealed a family of previously unidentified amino acid amides. Accurate quantitation of N-phenylpropenoyl-L-amino acids was performed by stable isotope dilution analysis (SIDA) using LC-MS/MS. A total of 84 putative taste compounds were quantified in roasted cocoa beans, and then rated for taste contribution on the basis of dose-over-threshold (DoT)-factors in order to bridge the gap between pure structural chemistry and human taste perception. To verify these quantitative results, an aqueous taste reconstitute was prepared by blending aqueous solutions of the individual taste compounds in their “natural” concentrations. Sensory analyses revealed that the taste profile of this artificial cocktail was very close to the taste profile of an aqueous suspension of roasted cocoa nibs. To further narrow down the number of key taste compounds, taste omission experiments and human dose/response functions were performed demonstrating the key organoleptics of the roasted cocoa nibs [38,40,41,42]. Additional bioactivity screening of selected isolated or synthesized N-phenylpropenoyl-L-amino acids from cocoa revealed induction of mitochondrial activity and proliferation rate in human liver cell lines as well as human keratinocytes [43], and potent inhibition of the adhesion of Helicobacter pylori to human stomach tissue [43,44].

Bioactivity-guided separation/isolation of already known bioactive compounds should be avoided. This process is called dereplication. Dereplication strategies generally involve a combination of bioassay, separation science, spectroscopic methods, and database searching and can be regarded as chemical or biological screening processes [45]. The identification of known compounds that could be responsible for the bioactivity of an extract under investigation is the first critical step prior to bioactivity-guided isolation. This can mean either full identification of a compound after only partial purification, or partial identification to the level of a class of compounds. Full identification in these cases relies on comparison with a characterized reference compound. Partial identification serves to: (a) identify undesirable compounds, such as tannins, polyphenols, and fatty acids; (b) prioritize samples for extraction; and (c) gather information on the type of compound to facilitate subsequent isolation [45]. If the dereplication process reveals that the bioactive component of an extract or subfraction is already known and has the same, or similar, bioactivity as the whole extract how does one then proceed? Is this a reason for excluding further bioactivity-guided separation of this extract? How does the activity of your extract compare with that of the single known compound? Even when the same bioassay is used for a certain extract, and a known or exactly this identified bioactive used as control, could you be really sure that this is the only one bioactive constituent in your extract or not?

To avoid replication the following four points should be considered.

Observational and Clinical Research is fundamental to validate treatment methods, safety, estimate efficacy and doses, and demonstrate and document medicinal effects of crude extracts, fractions, sub-fractions, and isolated compounds prior to using them to improve the health and wellness of veterinary patients in real practice settings. This research assures the removal of toxic and inhibitory components, while leaving those with synergistic or additive beneficial effects allowing the production of refined products with concentrated active constituents in the mixture of extracts or composite formula drugs. This research is needed to shift TAHM towards “evidence-based traditional African medicine” hence, make way for the acceptance of extracts and isolated compounds in medical practices in Africa and integration into western medicine. Chinese traditional medicine has advanced using varying proportions (combinations) of different plant parts/plant species packaged as tablets or capsules [29,48,49]. Standardized, formulated plant extracts for adjunctive treatment with acupuncture and western medicine are needed to treat gastrointestinal illnesses with chronic pain and inflammation in veterinary patients. New products should be formulated using efficacious and proven natural remedies with the goal of reducing hospitalization time, treatment time, and cost.

Traditional healing methods are integral components of health care in Africa and China [1,2,3,9,14,48,49,50,51,52,53,54]. Historically, traditional treatments of veterinary patients rely on extracts (90%) of plant origin and there is overlap of plant species used in these practices (Table 1, Table 3 and Table 4). African and Chinese ethnoveterinary practices are not widely accepted in the western world, nor are they fully exploited internally by medical professionals [1,2,3,7,9,14,48,49,50,51]. Veterinary health care professionals need to be pro-active in translational research with the goal of better understanding and higher integration of traditional healing with western practices. The key barriers hampering the integration into western medicine are similar [2,3,7,9,12,48,49,50,51].

African countries have much to learn from the milestones made in traditional Chinese medicine and Chinese ethnoveterinary medicine. Several themes emerge in support of this idea: African countries should support and promote basic and clinical research in TAHM to define evidence for efficacy, safety, quality, and mechanisms of action for plant-based traditional therapies. Research needs to be aimed at developing medications for companion and pet animals, which appear to be less documented but much needed in western medicine. Documentation of plant species versus diseases conditions, safety, dose toxicity, bioactive compounds and their chemical structures, and mechanisms of action are all essential for product development, academic and prescriptions purposes. This data should be compiled in electronic databases to ease accessibility, and compiling TAHM pharmacopoe should be done at national and continental levels.

Compound formulas (herbal mixtures) constitute the majority of TCVM prescriptions containing principal herbs, associate herbs, adjuvant, and messenger herbs. Processed formulations have reduced toxicity and concentrated bioactive ingredients [31,48,50]. There are indications that some parts of Africa have begun manufacturing natural extracts and semi-purified formulations [12,28] and this should be a pan African goal. However, the efficacy, safety, quality and advantages of these products should be established, and processing must be adequately regulated [27,28,51]. Traditional Chinese medicine is taught in traditional medical and veterinary schools [27,52]. Incorporating ethnomedicine in traditional veterinary medicine curricula is much needed in Africa. This will increase the awareness of folk medicine amongst veterinary healthcare and animal production professionals, and have a positive impact on future research and development strategies. China has established a TCM regulatory institution to ensure the quality and safety of patients [14,26,29,48] and this must be done in African countries.

Solvent fractionation, in combination with different chromatography techniques, can lead to separating the extract into a large number of fractions for bioassays. For example, with the Sepbox 2D HPLC [163] up to 576 fractions with a very high yield of pure compounds can be collected for subsequent biological screening. The Sepbox concept is based on a patented combination of HPLC and SPE (Solid Phase Extraction), using two-dimensional separation, one extract can be completely separated in vials or microtiter plates per day [163]. The production of such a large number of fractions makes it possible to screen a lot of different plant materials via high throughput screening (HTS), because many samples can be assayed in a short period of time. The basis of high throughput screening includes: reduction in size of test volumes, employment of high-density microwell plates, and automated processing. All of which make biotesting less labor-intensive, more reproducible, and less expensive as many routine tasks are performed by robots [45]. In essence, this strategy operates on detecting a specialized effect of a test compound or extract on receptors or enzymes (single-target specific bioassay) or on intact cells, isolated organs, or whole animals (multitarget functional bioassay) [45]. Conversely, HTS is based on a large number of samples, and researchers all over the world using ethnopharmacological approaches or chemical libraries build by elicitation of plant culture, combinatorial chemistry, combinatorial biosynthesis, engineering of biosynthetic pathways, induction of microbial secondary metabolism, and biotransformation [164].

In the past, lack of bioassays, time-consumption, and instability of bioassays hampered the search for “hits”. Recombinant DNA technologies have facilitated the development of cell-based assays. Eukaryotic cells can be engineered to produce a specific gene product in response to a stimulus, and reporter genes are frequently used as indicators of transcriptional activity or activation of particular signaling pathways within the cell [45]. These techniques are needed to screen and test bioactive components from African botanical extracts that have been documented or shown to have therapeutic effects against pain and gastrointestinal disorders.

Validation of preliminary hits by mammalian animal models is slow and expensive. The use of the zebrafish-based assays combine the advantage of HTS assays, compared to mammalian models, with the outcome being greater relevance to humans. The primary advantages of zebrafish for drug discovery include their high genetic, physiologic, and pharmacologic similarity with humans, as well as their small size, optical transparency, rapid development, and large numbers of embryos and larvae (which are the primary system for experimental analysis). Because of their small size (1 to 5 mm), zebrafish embryos and larvae are compatible with microtiter plates for screening, thereby requiring only microgram amounts of each extract, fraction, or compound to be tested. Because of the high fecundity of zebrafish, large numbers of embryos and larvae can be produced and analyzed in a more cost-effective manner than, for example, mice and rats. Combined, these features define zebrafish as an ideal in vivo model for the systematic identification of bioactive natural products with therapeutic potential [165]).

Bioactivity screening in zebrafish embryos of over 80 east African medicinal plants yielded two methanolic extracts from Oxygonum sinuatum (Meisn.) Dammer (Polygonaceae) and Plectranthus barbatus Andrews (Lamiaceae), which inhibited intersegmental vessel (ISV) outgrowth in fli-1: enhanced green fluorescent protein (EGFP) embryos in a dose-dependent manner. Zebrafish bioassay-guided fractionation identified the active components of these plants as emodin (an inhibitor of the protein kinase CK2) and coleon A lactone (a rare abietane diterpenoid with no previously described bioactivity). Both emodin and coleon A lactone inhibited mammalian endothelial cell proliferation, migration, and tube formation in vitro, as well as angiogenesis in the chick chorioallantoic membrane (CAM) assay [166]. Few studies indicate zebra fish can be employed in studies of pain [167] and gastrointestinal disorders [168]. Clearly zebra fish should be considered when choosing models for testing the bioactivity of extracts from African botanical remedies of pain and gastrointestinal disorders.

Whether natural product drug discovery programs should rely on wild plants collected “randomly” from the natural environment, or whether they should also include plants collected on the basis of use in traditional medicine, remains an open question. However, in this review, we emphasize the need to use TAHM documented practices for choosing plant species for screening. As indicated earlier, this view is supported by the analysis conducted by [20] showing that therapeutic uses of about 80% of 122 plant-derived drugs correspond to their original ethnopharmacological role. Similarly, a study conducted in Vietnam and Laos by Gyllenhaal and colleagues [169] suggests that ethnomedical uses may contribute to a higher rate of activity in drug discovery screening. A random bioassay-guided fractionation of 7,500 traditional medicinal plant extracts from South Africa to identify fractions with anticancer activity and active constituents showed that 68% of these plant species—which were hits in the screening program—were reported to be used medicinally. Based on this data, it appears that unrelated medicinal use of the source plants may serve as an initial guide to selection of plants for anticancer screening [117]. This supports the indigenous knowledge of using an individual extract for treating more than one illness.

Bioassay-guided fractionation of the dichloromethane root bark extract of Entada abyssinica A.Rich., a plant used by traditional healers in Uganda for the treatment of sleeping sickness, led to the isolation of a diastereoisomer of the clerodane type diterpene kolavenol. It showed a trypanocidal activity with an IC₅₀ value of 2.5 µg/mL (8.6 µM) against Trypanosoma brucei rhodesiense, the causative agent of the acute form of human African trypanosomiasis [170]. In this case, a dereplication process or a partially performed dereplication process might have excluded the extract from further investigation, but as reported, a diastereomer of the already described kolavenol was identified.

Extracts from 11 West African plants traditionally used to treat malaria in Ghana were tested against both the chloroquine-sensitive strain (PoW) and the chloroquine-resistant clone Dd2 of Plasmodium falciparum. Due to the promising in vitro activity of the lipophilic extract [IC₅₀: 10.5 μg/mL (PoW); 13.1 μg/mL (Dd2)], Microglossa pyrifolia (Lam.) Kuntze was chosen for further phytochemical investigation. Bioassay-guided fractionation of the aerial parts of M. pyrifolia revealed the fractions eluting from a RP-18 column with 80% to 100% MeOH to be most active with IC₅₀ values ranging from 2.5 to 18.7 μg/mL against PoW and a Dd2 starins of Plasmodium falciparum. From active fractions, 13 compounds were isolated and their structures were established on the basis of spectroscopic methods. The two diterpenes E-phytol [IC₅₀: 8.5 μm (PoW); 11.5 μm (Dd2)], and 6E-geranylgeraniol-19-oic acid [IC₅₀: 12.9 μm (PoW); 15.6 μm (Dd2)] proved to be the most active constituents [171]. Normally, fractions showing high activity (or higher activity than others) are further bioactivity-guided fractionated until the bioactive compound/s is/are obtained in pure form. In cases in which—from a bioactive fraction—the major components were isolated and afterwards the single compounds were measured, the major bioactive compound could be overseen. This is explainable, if the major bioactive compound is not the most abundant in the chromatogram (perhaps not UV active), or no quantitation of the isolated compounds is performed, or no recombination of the isolated compounds is performed.

The temporary immersion system (TIS) for the in vitro production of bioactive compounds (e.g., in Harpagophytum (Devil’s Claw)), might be an option for fast and easier production of bioactive lead compounds [172]. Harpagophytum procumbens DC. is a perennial herbaceous plant growing in South and Tropical Africa, especially in the Kalahari Desert and in the Namibian steppes. The dried aqueous extract is known for its anti-inflammatory effects [173]. In this study, the immersion time of TIS cultures (200 mL) was 1 h per day over 4 months. The biomass produced consisted mainly of normal plants with rooted leafy shoots, together with some partially differentiated callus. The total iridoid levels in root, stem, and leaf tissues of TIS grown plants were similar to that of two-year old glasshouse grown whole plants [172].

To summarize, research suggests that botanical remedies used in TAHM have components with medicinal activities. Apparently, plant species used in TAHM to treat pain, inflammation, and gastrointestinal disorders shown here have never been subjected to HTS screening. Based on folklore description and scant evidence to support to the presence of components with analgesic and anti-motility effects, there is the need to use HTS to screen and identify neuroactive compounds as well as anti-inflammatory compounds. Although high throughput screening requires a state-of-the art infrastructure (which is not available in many African institutions) it is still possible through collaborative research partnerships between African and western countries and China.

The majority of studies done to verify analgesic and anti-inflammatory effects of extracts used in TAHM use chemical and thermal agents to induce pain and inflammation [95,129,174,175]. The presence of anti-diarrheal agents is determined using anti-motility and anti-secretory assays in intact animals, isolated tissues, and cells [114,115,153,176]. The goal of the vast majority of these studies is to determine the basis for supporting folklore practices [23]. There is a critical need to investigate the analgesic potential of plant extracts through identification of bioactive compounds, their mechanisms of action, efficacy, and toxicity in search for new pain-relievers [19,173,175,177,178,179] and anti-diarrheal drugs [114,115,136,176,178,180]. This is necessary to verify the effectiveness of botanical therapies and to provide solid evidence for safety. In addition, contemporary analgesics, such as opiates and nonsteroidal anti-inflammatory drugs, are often not suitable in all cases, particularly chronic pain due potency, side effects, and tolerance (e.g., opiates and cannabinoids) [181,182,183]. Medicinal plants are known to be an important source of new chemical substances with potential therapeutic effects [2,18,19,20,178,184,185]. Based on the advances being made in pain research, determination of antinociceptive profiles of crude extracts and semipurified extracts should be done as means for rapid screening specific tests as highlighted below: