Back to plants for drug discovery: from ethnomedicine to more conventional approaches

Over the last years, there is rekindling of interest in drug discovery from botanical resources. This thesis proposed two different approaches (from ethnomedicine to scholarly strategies) for drug discovery from medicinal plants, identifying the areas of knowledge involved and addressing the challenges encountered, with the aim of enhancing the chance of success of the overarching process. The first approach consists to review the literature to increase understanding of a plant of interest and generate strong hypotheses for future drug development research on this plant. Illustrating such an approach, we focused on Tithonia diversifolia (Hemsl.) A. Gray (TD). Knowledge about TD was collected from both online databases and non-electronic resources. Overall, a total of 1,804 reports have been collected. After subsequent duplicates removal and screening for relevant titles and abstracts, a total of 119 text articles were obtained and assessed for eligibility. Finally, 168 articles were selected, of which forty-nine were added after analyses of the reference lists of the included papers. We found that all parts of the plant are valued in several cultures for a wide scope of ailments ranging from topical issues \u2014wounds, skeleto-muscular disorders, abscesses, dermatological conditions, and stomach pains\u2014 to systemic disorders such as diabetes, malaria, fever, hepatitis and infectious diseases. Importantly, most of the ethnomedical claims of TD have been substantiated in several studies conducted in vitro and in vivo in animals. Sometimes, findings were conflicting and thanks to this review, we were able to assess the weight of evidence for each pharmacological effect of TD. The anti-inflammatory, antimalarial, antidiabetic, antioxidant and anticancer effects do stand out but there is also a stunning array of other relevant pharmacological effects. Chemically, a hundred of chemicals, mainly terpenoids and phenols, have been isolated from various TD extracts so far. Of these, some compounds including Tagitinin C have been linked to the pharmacology of TD. About the toxicological profile, we were able to conclude based on evidence that short-term oral administration of TD is relatively well-tolerated in animals when taken at doses less than 100 mg/kg. The second approach consists to screen the ethnomedical knowledge of indigenous people to select the best plant candidate to launch a drug discovery campaign. So, we carried out a 6-month cross-sectional questionnaire-based survey to explore the use of medicinal plants (MP) in People living with HIV (PLHIV) in the city of Dschang (West Region, Cameroon). Of the 247 HIV-infected respondents, 54.9% reported to use plants. MP users were then kindly invited to provide photographs and/or specimens of plants for botanical identification. A total of 70 MP, chiefly the herbs, were mentioned by informants (82.2% of total MP users, mean\ub1SEM: 2.2\ub10.2 MP/subject, min 1, max 11), of which forty-nine have been botanically identified. Commonly reported pathological conditions or symptoms treated with MP included malaria (n = 27, 18.4% of total citations), cough (n = 20, 13.6%) and abdominal pain (n = 16, 10.9%). The benefits of using MP reportedly ranged from moderate (n = 60, 57.7%) to complete (n = 35, 33.7%) relief, while only 8 subjects (7.7% of MP users) reported no change in their terms. Interestingly, 2 subjects (33.3 % of respondents) denounced fatigue and weight loss. We also observed that THPs were the main advisors of PLHIV on the use of MP. Thus, in the rest of our study, their knowledge and attitudes towards HIV/AIDS were surveyed aiming at understanding whether they may be an appropriate resource to assist in the scaling up of HIV prevention and treatment delivery services in Cameroon. 16 THPs were recruited by the chairperson of the Cooperative Society of Producers of Medicinal Plants of West Region based on their good reputation in traditional healing practice. Three of them acknowledged the use of MP to manage HIV diseases in their clients. All THPs who agreed to participate in the survey were also evaluated for their knowledge of HIV transmission, prevention and diagnosis. We found that their knowledge related to HIV was relatively low raising concern about their aptitude to effectively assist conventional health practitioners in fighting against HIV/AIDS. Resulting from literature mining and ethnomedical claims is the adoption of a relevant pharmacological testing system. In any case, the testing systems should represent the biological activities that best match the ethnomedical uses of the selected plant species. In addition, it is important to bear in mind that plant extracts are complex mixtures containing various components and, therefore, their overall activity results from interactions between their naturally occurring ingredients. It is with this background that we conducted a study of comparison of the effects of a whole extract of a particular strain of Cannabis sativa L. to that of cannabidiol (CBD). We knew cannabis is endowed with a potent anti-inflammatory effect attributable mainly to CBD, but also to its entourage. This mechanism by which other compounds occurring in cannabis may contribute to its clinical effects has been espoused as an \u201centourage effect\u201d. The concept of entourage effect was first introduced in 1998 by Ben-Shabat and Raphael Mechoulam but still, there was no hard evidence that the entourage effect is real. So, thanks to a collaboration with a pharmaceutical company, we grew a particular strain of cannabis deprived of THC and standardized in 5% CBD (CM5). Then, we tested the effects of an extract of CM5 in parallel to that of pure CBD at equimolar concentrations on neutrophil functions including oxidative metabolism, migration and production of proinflammatory cytokines. Results show that CM5 0.05-50 \u3bcg/mL and CBD 10-8-10-5 M inhibit the neutrophil functions including ROS production, cell migration, mRNA levels of proinflammatory cytokines (but at the protein level, only TNF-a was inhibited) to a comparable extent, indicating that CBD may be the main responsible of the anti-inflammatory effects of Cannabis. The effects of CBD and CM5 show however remarkable differences in terms of potency and efficacy, suggesting that beyond CBD, other components of cannabis may contribute to its biological effects. As a whole, such results support the use of cannabis and CBD to stem inflammation, however also warrant in-depth investigation of the underlying cellular and molecular mechanisms to better exploit their therapeutic potential

Nasal Accumulation and Metabolism of Δ9-Tetrahydrocannabinol Following Aerosol (‘Vaping’) Administration in an Adolescent Rat Model

Passive aerosol exposure to Δ9-tetrahydrocannabinol (THC) in laboratory animals results in faster onset of action and less extensive liver metabolism compared to most other administration routes and might thus provide an ecologically relevant model of human cannabis inhalation. Previous studies have, however, overlooked the possibility that rodents, as obligate nose breathers, may accumulate aerosolized THC in the nasal cavity, from where the drug might directly diffuse to the brain. To test this, we administered THC (ten 5-s puffs of 100 mg/mL of THC) to adolescent (31-day-old) Sprague-Dawley rats of both sexes. We used liquid chromatography/tandem mass spectrometry to quantify the drug and its first-pass metabolites – 11-hydroxy-Δ9-THC (11-OH-THC) and 11-nor-9-carboxy-Δ9-THC (11-COOH-THC) – in nasal mucosa, lungs, plasma, and brain (olfactory bulb and cerebellum) at various time points after exposure. Apparent maximal THC concentration and area under the curve were ∼5 times higher in nasal mucosa than in lungs and 50–80 times higher than in plasma. Concentrations of 11-OH-THC were also greater in nasal mucosa and lungs than other tissues, whereas 11-COOH-THC was consistently undetectable. Experiments with microsomal preparations confirmed local metabolism of THC into 11-OH-THC (not 11-COOH-THC) in nasal mucosa and lungs. Finally, whole-body exposure to THC deposited substantial amounts of THC (∼150 mg/g) on fur but suppressed post-exposure grooming in rats of both sexes. The results indicate that THC absorption and metabolism in nasal mucosa and lungs, but probably not gastrointestinal tract, contribute to the pharmacological effects of aerosolized THC in male and female rats

Back to plants for drug discovery: from ethnomedicine to more conventional approaches

Over the last years, there is rekindling of interest in drug discovery from botanical resources. This thesis proposed two different approaches (from ethnomedicine to scholarly strategies) for drug discovery from medicinal plants, identifying the areas of knowledge involved and addressing the challenges encountered, with the aim of enhancing the chance of success of the overarching process. The first approach consists to review the literature to increase understanding of a plant of interest and generate strong hypotheses for future drug development research on this plant. Illustrating such an approach, we focused on Tithonia diversifolia (Hemsl.) A. Gray (TD). Knowledge about TD was collected from both online databases and non-electronic resources. Overall, a total of 1,804 reports have been collected. After subsequent duplicates removal and screening for relevant titles and abstracts, a total of 119 text articles were obtained and assessed for eligibility. Finally, 168 articles were selected, of which forty-nine were added after analyses of the reference lists of the included papers. We found that all parts of the plant are valued in several cultures for a wide scope of ailments ranging from topical issues —wounds, skeleto-muscular disorders, abscesses, dermatological conditions, and stomach pains— to systemic disorders such as diabetes, malaria, fever, hepatitis and infectious diseases. Importantly, most of the ethnomedical claims of TD have been substantiated in several studies conducted in vitro and in vivo in animals. Sometimes, findings were conflicting and thanks to this review, we were able to assess the weight of evidence for each pharmacological effect of TD. The anti-inflammatory, antimalarial, antidiabetic, antioxidant and anticancer effects do stand out but there is also a stunning array of other relevant pharmacological effects. Chemically, a hundred of chemicals, mainly terpenoids and phenols, have been isolated from various TD extracts so far. Of these, some compounds including Tagitinin C have been linked to the pharmacology of TD. About the toxicological profile, we were able to conclude based on evidence that short-term oral administration of TD is relatively well-tolerated in animals when taken at doses less than 100 mg/kg. The second approach consists to screen the ethnomedical knowledge of indigenous people to select the best plant candidate to launch a drug discovery campaign. So, we carried out a 6-month cross-sectional questionnaire-based survey to explore the use of medicinal plants (MP) in People living with HIV (PLHIV) in the city of Dschang (West Region, Cameroon). Of the 247 HIV-infected respondents, 54.9% reported to use plants. MP users were then kindly invited to provide photographs and/or specimens of plants for botanical identification. A total of 70 MP, chiefly the herbs, were mentioned by informants (82.2% of total MP users, mean±SEM: 2.2±0.2 MP/subject, min 1, max 11), of which forty-nine have been botanically identified. Commonly reported pathological conditions or symptoms treated with MP included malaria (n = 27, 18.4% of total citations), cough (n = 20, 13.6%) and abdominal pain (n = 16, 10.9%). The benefits of using MP reportedly ranged from moderate (n = 60, 57.7%) to complete (n = 35, 33.7%) relief, while only 8 subjects (7.7% of MP users) reported no change in their terms. Interestingly, 2 subjects (33.3 % of respondents) denounced fatigue and weight loss. We also observed that THPs were the main advisors of PLHIV on the use of MP. Thus, in the rest of our study, their knowledge and attitudes towards HIV/AIDS were surveyed aiming at understanding whether they may be an appropriate resource to assist in the scaling up of HIV prevention and treatment delivery services in Cameroon. 16 THPs were recruited by the chairperson of the Cooperative Society of Producers of Medicinal Plants of West Region based on their good reputation in traditional healing practice. Three of them acknowledged the use of MP to manage HIV diseases in their clients. All THPs who agreed to participate in the survey were also evaluated for their knowledge of HIV transmission, prevention and diagnosis. We found that their knowledge related to HIV was relatively low raising concern about their aptitude to effectively assist conventional health practitioners in fighting against HIV/AIDS. Resulting from literature mining and ethnomedical claims is the adoption of a relevant pharmacological testing system. In any case, the testing systems should represent the biological activities that best match the ethnomedical uses of the selected plant species. In addition, it is important to bear in mind that plant extracts are complex mixtures containing various components and, therefore, their overall activity results from interactions between their naturally occurring ingredients. It is with this background that we conducted a study of comparison of the effects of a whole extract of a particular strain of Cannabis sativa L. to that of cannabidiol (CBD). We knew cannabis is endowed with a potent anti-inflammatory effect attributable mainly to CBD, but also to its entourage. This mechanism by which other compounds occurring in cannabis may contribute to its clinical effects has been espoused as an “entourage effect”. The concept of entourage effect was first introduced in 1998 by Ben-Shabat and Raphael Mechoulam but still, there was no hard evidence that the entourage effect is real. So, thanks to a collaboration with a pharmaceutical company, we grew a particular strain of cannabis deprived of THC and standardized in 5% CBD (CM5). Then, we tested the effects of an extract of CM5 in parallel to that of pure CBD at equimolar concentrations on neutrophil functions including oxidative metabolism, migration and production of proinflammatory cytokines. Results show that CM5 0.05-50 μg/mL and CBD 10-8-10-5 M inhibit the neutrophil functions including ROS production, cell migration, mRNA levels of proinflammatory cytokines (but at the protein level, only TNF-a was inhibited) to a comparable extent, indicating that CBD may be the main responsible of the anti-inflammatory effects of Cannabis. The effects of CBD and CM5 show however remarkable differences in terms of potency and efficacy, suggesting that beyond CBD, other components of cannabis may contribute to its biological effects. As a whole, such results support the use of cannabis and CBD to stem inflammation, however also warrant in-depth investigation of the underlying cellular and molecular mechanisms to better exploit their therapeutic potential

Back to plants for drug discovery: from ethnomedicine to more conventional approaches

Over the last years, there is rekindling of interest in drug discovery from botanical resources. This thesis proposed two different approaches (from ethnomedicine to scholarly strategies) for drug discovery from medicinal plants, identifying the areas of knowledge involved and addressing the challenges encountered, with the aim of enhancing the chance of success of the overarching process. The first approach consists to review the literature to increase understanding of a plant of interest and generate strong hypotheses for future drug development research on this plant. Illustrating such an approach, we focused on Tithonia diversifolia (Hemsl.) A. Gray (TD). Knowledge about TD was collected from both online databases and non-electronic resources. Overall, a total of 1,804 reports have been collected. After subsequent duplicates removal and screening for relevant titles and abstracts, a total of 119 text articles were obtained and assessed for eligibility. Finally, 168 articles were selected, of which forty-nine were added after analyses of the reference lists of the included papers. We found that all parts of the plant are valued in several cultures for a wide scope of ailments ranging from topical issues —wounds, skeleto-muscular disorders, abscesses, dermatological conditions, and stomach pains— to systemic disorders such as diabetes, malaria, fever, hepatitis and infectious diseases. Importantly, most of the ethnomedical claims of TD have been substantiated in several studies conducted in vitro and in vivo in animals. Sometimes, findings were conflicting and thanks to this review, we were able to assess the weight of evidence for each pharmacological effect of TD. The anti-inflammatory, antimalarial, antidiabetic, antioxidant and anticancer effects do stand out but there is also a stunning array of other relevant pharmacological effects. Chemically, a hundred of chemicals, mainly terpenoids and phenols, have been isolated from various TD extracts so far. Of these, some compounds including Tagitinin C have been linked to the pharmacology of TD. About the toxicological profile, we were able to conclude based on evidence that short-term oral administration of TD is relatively well-tolerated in animals when taken at doses less than 100 mg/kg. The second approach consists to screen the ethnomedical knowledge of indigenous people to select the best plant candidate to launch a drug discovery campaign. So, we carried out a 6-month cross-sectional questionnaire-based survey to explore the use of medicinal plants (MP) in People living with HIV (PLHIV) in the city of Dschang (West Region, Cameroon). Of the 247 HIV-infected respondents, 54.9% reported to use plants. MP users were then kindly invited to provide photographs and/or specimens of plants for botanical identification. A total of 70 MP, chiefly the herbs, were mentioned by informants (82.2% of total MP users, mean±SEM: 2.2±0.2 MP/subject, min 1, max 11), of which forty-nine have been botanically identified. Commonly reported pathological conditions or symptoms treated with MP included malaria (n = 27, 18.4% of total citations), cough (n = 20, 13.6%) and abdominal pain (n = 16, 10.9%). The benefits of using MP reportedly ranged from moderate (n = 60, 57.7%) to complete (n = 35, 33.7%) relief, while only 8 subjects (7.7% of MP users) reported no change in their terms. Interestingly, 2 subjects (33.3 % of respondents) denounced fatigue and weight loss. We also observed that THPs were the main advisors of PLHIV on the use of MP. Thus, in the rest of our study, their knowledge and attitudes towards HIV/AIDS were surveyed aiming at understanding whether they may be an appropriate resource to assist in the scaling up of HIV prevention and treatment delivery services in Cameroon. 16 THPs were recruited by the chairperson of the Cooperative Society of Producers of Medicinal Plants of West Region based on their good reputation in traditional healing practice. Three of them acknowledged the use of MP to manage HIV diseases in their clients. All THPs who agreed to participate in the survey were also evaluated for their knowledge of HIV transmission, prevention and diagnosis. We found that their knowledge related to HIV was relatively low raising concern about their aptitude to effectively assist conventional health practitioners in fighting against HIV/AIDS. Resulting from literature mining and ethnomedical claims is the adoption of a relevant pharmacological testing system. In any case, the testing systems should represent the biological activities that best match the ethnomedical uses of the selected plant species. In addition, it is important to bear in mind that plant extracts are complex mixtures containing various components and, therefore, their overall activity results from interactions between their naturally occurring ingredients. It is with this background that we conducted a study of comparison of the effects of a whole extract of a particular strain of Cannabis sativa L. to that of cannabidiol (CBD). We knew cannabis is endowed with a potent anti-inflammatory effect attributable mainly to CBD, but also to its entourage. This mechanism by which other compounds occurring in cannabis may contribute to its clinical effects has been espoused as an “entourage effect”. The concept of entourage effect was first introduced in 1998 by Ben-Shabat and Raphael Mechoulam but still, there was no hard evidence that the entourage effect is real. So, thanks to a collaboration with a pharmaceutical company, we grew a particular strain of cannabis deprived of THC and standardized in 5% CBD (CM5). Then, we tested the effects of an extract of CM5 in parallel to that of pure CBD at equimolar concentrations on neutrophil functions including oxidative metabolism, migration and production of proinflammatory cytokines. Results show that CM5 0.05-50 μg/mL and CBD 10-8-10-5 M inhibit the neutrophil functions including ROS production, cell migration, mRNA levels of proinflammatory cytokines (but at the protein level, only TNF-a was inhibited) to a comparable extent, indicating that CBD may be the main responsible of the anti-inflammatory effects of Cannabis. The effects of CBD and CM5 show however remarkable differences in terms of potency and efficacy, suggesting that beyond CBD, other components of cannabis may contribute to its biological effects. As a whole, such results support the use of cannabis and CBD to stem inflammation, however also warrant in-depth investigation of the underlying cellular and molecular mechanisms to better exploit their therapeutic potential

A Novel Standardized <i>Cannabis sativa</i> L. Extract and Its Constituent Cannabidiol Inhibit Human Polymorphonuclear Leukocyte Functions

Cannabis and cannabinoids offer significant therapeutic benefits for a wide scope of pathological conditions. Among them, the clinical issues rooted in inflammation stand out, nonetheless, the underlying mechanisms are not yet plainly understood. Circumstantial evidence points to polymorphonuclear leukocytes (PMN) as targets for the anti-inflammatory effects of cannabis. Therefore, we conducted this study to assess the effects of CM5, a novel Cannabis sativa L. extract standardized in 5% cannabidiol (CBD), on human PMN functions, including cell migration, oxidative metabolism and production of tumour necrosis factor (TNF)-&#945;. We then sought to investigate whether such effects could be ascribed to its content in CBD. Cell migration was assessed by the Boyden chamber assay, oxidative metabolism by means of spectrofluorimetric measurement of reactive oxygen species (ROS) production, and TNF-&#945; was measured by real time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Results show that both CM5 and CBD inhibit PMN migration, ROS and TNF-&#945; production, indicating that CBD may be the main item responsible for the effects of CM5. CM5 is however more potent than CBD on cell migration and TNF-&#945; production, and less effective on ROS production, suggesting that beyond CBD, other components of the cannabis plant may contribute to the biological effects of the extract. As a whole, such results support the use of cannabis standardized extract and CBD to stem inflammation; however, they also warrant in-depth investigation of the underlying cellular and molecular mechanisms to better exploit their therapeutic potential

Cannabinoids, inner ear, hearing and tinnitus: a neuroimmunological perspective

Cannabis has been used for centuries for recreational and therapeutic purposes. Whereas, the recreative uses are based on the psychotropic effect of some of its compounds, its therapeutic effects range over a wide spectrum of actions, most of which target the brain or the immune system. Several studies have found cannabinoid receptors in the auditory system, both at peripheral and central levels, thus raising the interest in cannabinoid signaling in hearing, and especially in tinnitus, which is affected also by anxiety, memory, and attention circuits where cannabinoid effects are well described. Available studies on animal models of tinnitus suggest that cannabinoids are not likely to be helpful in tinnitus treatment and could even be harmful. However, the pharmacology of cannabinoids is very complex, and most studies focused on neural CB1R-based responses. Cannabinoid effects on the immune system (where CB2Rs predominate) are increasingly recognized as essential in understanding nervous system pathological responses, and data on immune cannabinoid targets have emerged in the auditory system as well. In addition, nonclassical cannabinoid targets (such as TRP channels) appear to play an important role in the auditory system as well. This review will focus on neuroimmunological mechanisms for cannabinoid effects and their possible use as protective and therapeutic agents in the ear and auditory system, especially in tinnitus

Determinants, prevalence and trend of use of medicinal plants among people living with HIV: a cross‑sectional survey in Dschang, Cameroon

People living with HIV (PLHIV) in Cameroon often seek care from traditional health practitioners (THPs) and use medicinal plants (MP). Most MP, however, still lacks evidence for their efficacy and safety, and their use, often undisclosed to referring physicians, may interfere with standard therapies. Therefore, we conducted a survey of 247 PLHIV in Dschang to assess the determinants, prevalence and trend of MP use. Besides, we surveyed 16 THPs about the use of MP in PLHIV and HIV-related knowledge. 54.9% PLHIV declared using in total 70 plants, 91.3% users were satisfied with MP, and unwanted effects were reported in 2 cases. MP users were less educated than nonusers, had longer disease duration and were more often unemployed. Only 3 THPs used MP in PLHIV, and most of them had insufficient knowledge of HIV. Results may be useful for education on HIV and integration of traditional medicines with conventional therapeutics

Determinants, Prevalence and Trend of Use of Medicinal Plants Among People Living with HIV: A Cross-Sectional Survey in Dschang, Cameroon

8nonePeople living with HIV (PLHIV) in Cameroon often seek care from traditional health practitioners (THPs) and use medicinal plants (MP). Most MP, however, still lacks evidence for their efficacy and safety, and their use, often undisclosed to referring physicians, may interfere with standard therapies. Therefore, we conducted a survey of 247 PLHIV in Dschang to assess the determinants, prevalence and trend of MP use. Besides, we surveyed 16 THPs about the use of MP in PLHIV and HIV-related knowledge. 54.9% PLHIV declared using in total 70 plants, 91.3% users were satisfied with MP, and unwanted effects were reported in 2 cases. MP users were less educated than nonusers, had longer disease duration and were more often unemployed. Only 3 THPs used MP in PLHIV, and most of them had insufficient knowledge of HIV. Results may be useful for education on HIV and integration of traditional medicines with conventional therapeutics.noneMabou Tagne, Alex*; Biapa Nya, Prosper Cabral; Tiotsia Tsapi, Armand; Edingue Essoh, Annick Kevin; Pembouong, Gynette; Ngouadjeu Ngnintedem, Michael Alliance; Marino, Franca; Cosentino, MarcoMabou Tagne, Alex; Biapa Nya, Prosper Cabral; Tiotsia Tsapi, Armand; Edingue Essoh, Annick Kevin; Pembouong, Gynette; Ngouadjeu Ngnintedem, Michael Alliance; Marino, Franca; Cosentino, Marc

NAAA-regulated lipid signaling governs the transition from acute to chronic pain.

Chronic pain affects 1.5 billion people worldwide but remains woefully undertreated. Understanding the molecular events leading to its emergence is necessary to discover disease-modifying therapies. Here we show that N-acylethanolamine acid amidase (NAAA) is a critical control point in the progression to pain chronicity, which can be effectively targeted by small-molecule therapeutics that inhibit this enzyme. NAAA catalyzes the deactivating hydrolysis of palmitoylethanolamide, a lipid-derived agonist of the transcriptional regulator of cellular metabolism, peroxisome proliferator-activated receptor-α (PPAR-α). Our results show that disabling NAAA in spinal cord during a 72-h time window following peripheral tissue injury halts chronic pain development in male and female mice by triggering a PPAR-α-dependent reprogramming of local core metabolism from aerobic glycolysis, which is transiently enhanced after end-organ damage, to mitochondrial respiration. The results identify NAAA as a crucial control node in the transition to chronic pain and a molecular target for disease-modifying medicines