The medicinal chemistry and neuropharmacology of kratom: A preliminary discussion of a promising medicinal plant and analysis of its potential for abuse

Mitragynine and morphine produce dose-dependent bimodal action on food but not water intake in rats

Kratom (Mitragyna speciosa), containing the primary alkaloid mitragynine, has emerged as an alternative self-treatment for opioid use disorder. Mitragynine binds numerous receptor types, including opioid receptors, which are known to modulate food consumption. However, the ability of acute mitragynine to modulate food consumption remains unknown. The current study assessed the effects of acute mitragynine or morphine administration on unconditioned food and water intake in 16 Sprague-Dawley rats. Food and water intake changes were monitored in response to morphine, mitragynine (1.78-56 mg/kg ip), saline, or vehicle controls for 12 h, starting at the onset of the dark cycle. Naltrexone pretreatment was used to examine pharmacological specificity. Both morphine and mitragynine demonstrated a biphasic food intake dose-effect, with low doses (5.6 mg/kg) increasing and high doses (56 mg/kg) decreasing food intake. All morphine doses reduced water intake; however, only the highest dose of mitragynine (56 mg/kg) reduced water intake. Naltrexone attenuated both stimulatory and inhibitory effects of morphine on food intake, but only the stimulatory effect of mitragynine. In conclusion, low doses of mitragynine stimulate food intake via opioid-related pathways, while high doses likely recruit other targets.NEW & NOTEWORTHY This study reveals that morphine and the kratom alkaloid mitragynine produce dose-dependent effects on feeding in rats. Low doses stimulate food intake via opioid pathways, while high doses decrease consumption through nonopioid mechanisms. Morphine potently suppresses water intake at all doses, whereas only high doses of mitragynine reduce drinking. These findings provide novel insights into the complex opioid and nonopioid mechanisms underlying the effects of mitragynine on ingestive behaviors.

Kratom (Mitragyna speciosa) use for self-management of pain: Insights from cross-sectional and ecological momentary assessment data

Kratom (Mitragyna speciosa) is increasingly used in the US for self-management of pain, despite limited research on its efficacy and safety. To better understand how and why people use kratom for pain self-management, we analyzed baseline survey data (N = 395) and 15-day ecological momentary assessment (EMA) data (N = 357) from kratom consumers across the US. Although we recruited participants based on their kratom use, not on whether they used it for pain management, nearly half (49.1 %) met criteria for chronic pain, with many reporting substantial pain relief and high effectiveness of kratom in managing pain. A majority (69.2 %) reported difficulties in obtaining adequate pain treatment, and most indicated that these challenges impacted their decision to try kratom. Most participants did not report concerns about overuse or significant side effects. EMA data showed that, regardless of chronic-pain status, pain relief was the most frequently endorsed primary motivation for daily kratom use. There were no significant association between daily pain levels and kratom use frequency, and no difference in the daily kratom use between those with vs. without chronic pain. Recent kratom use was associated with lower current pain levels. Stronger subjective effects of kratom were associated with lower pain levels. This effect was significantly moderated by chronic-pain status: those with chronic pain showed a stronger link between subjective kratom effects and pain reduction. These findings underscore the urgent need for systematic, rigorous research on long-term implications, efficacy, and safety of kratom in pain management to guide informed clinical practices and regulatory policies. PERSPECTIVE: This study reveals that chronic pain is common among kratom consumers, who frequently use it for pain self-management and report significant relief, as shown by ecological momentary assessment. There is an urgent need for research into kratom's safety, efficacy, and mechanisms to guide clinical practice and inform policies.

The effects of Mitragyna speciosa extracts on intestinal microbiota and their metabolites in vitro fecal fermentation

BACKGROUND

Kratom (Mitragyna speciosa) has a long history of traditional use. It contains various alkaloids and polyphenols. The properties of kratom's alkaloids have been well-documented. However, the property of kratom's polyphenols in water-soluble phase have been less frequently reported. This study assessed the effects of water-soluble Mitragyna speciosa (kratom) extract (MSE) on gut microbiota and their metabolite production in fecal batch culture.

RESULTS

The water-soluble kratom extract (MSE0) and the water-soluble kratom extract after partial sugar removal (MSE50) both contained polyphenols, with total phenolic levels of 2037.91 ± 51.13 and 3997.95 ± 27.90 mg GAE/g extract, respectively and total flavonoids of 81.10 ± 1.00 and 84.60 ± 1.43 mg CEQ/g extract. The gut microbiota in fecal batch culture was identified by 16S rRNA gene sequencing at 0 and 24 h of fermentation. After fermentation, MSE50 stimulated the growth of Bifidobacterium more than MSE0. MSE0 gave the highest total fatty acids level among the treatments. The phenolic metabolites produced by some intestinal microbiota during fecal fermentation at 24 h were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The major metabolite of biotransformation of both water-soluble MSEs by intestinal microbiota was pyrocatechol (9.85-11.53%).

CONCLUSION

The water-soluble MSEs and their produced metabolites could potentially be used as ingredients for functional and medicinal food production that supports specific gut microbiota. © 2024 Society of Chemical Industry.

Use of Cannabinoids by People Who Consume Kratom in the United States

OBJECTIVES

To estimate lifetime, past-year, and past-month prevalence of kratom, cannabis, and cannabidiol-only product use among adults 18 years and older in the United States, using 2 independent datasets.

METHODS

Utilizing ( a ) the 2022 National Survey on Drug Use and Health (NSDUH) and ( b ) a 2022 online national convenience sample of adults who use kratom regularly (from our research group at the National Institute on Drug Abuse [NIDA]), we examined key demographic information as well as lifetime, past-year, and past-month substance use and preferences.

RESULTS

Among the full sample of adults from the 2022 NSDUH, the prevalence of lifetime use was 49.69% for cannabis, 34.09% for cannabidiol-only products, and 1.93% for kratom. When solely examining participants who have used kratom, both independent datasets showed higher proportions of cannabis use over the lifetime-92.81% (95% confidence interval: 90.31-95.31) in the NSDUH subset and 92.16% (95% confidence interval: 89.37-94.95) in our NIDA sample.

CONCLUSIONS

Our study demonstrates that people are co-using kratom with cannabis and/or cannabidiol-only products at the same time or during the same time period, though more research is needed to understand people's motivations and practices for such co-use. Co-use might result in herb-herb interactions that may impact research findings and clinical outcomes for people who use kratom.

Metabolic engineering of yeast for de novo production of kratom monoterpene indole alkaloids

Monoterpene indole alkaloids (MIAs) from Mitragyna speciosa ("kratom"), such as mitragynine and speciogynine, are promising novel scaffolds for opioid receptor ligands for treatment of pain, addiction, and depression. While kratom leaves have been used for centuries in South-East Asia as stimulant and pain management substance, the biosynthetic pathway of these psychoactives have only recently been partially elucidated. Here, we demonstrate the de novo production of mitragynine and speciogynine in Saccharomyces cerevisiae through the reconstruction of a five-step synthetic pathway from common MIA precursor strictosidine comprising fungal tryptamine 4-monooxygenase to bypass an unknown kratom hydroxylase. Upon optimizing cultivation conditions, a titer of ∼290 μg/L kratom MIAs from glucose was achieved. Untargeted metabolomics analysis of lead production strains led to the identification of numerous shunt products derived from the activity of strictosidine synthase (STR) and dihydrocorynantheine synthase (DCS), highlighting them as candidates for enzyme engineering to further improve kratom MIAs production in yeast. Finally, by feeding fluorinated tryptamine and expressing a human tailoring enzyme, we further demonstrate production of fluorinated and hydroxylated mitragynine derivatives with potential applications in drug discovery campaigns. Altogether, this study introduces a yeast cell factory platform for the biomanufacturing of complex natural and new-to-nature kratom MIAs derivatives with therapeutic potential.

Kratom use and mental health: A systematic literature review and case example

OBJECTIVE

This review aims to synthesize and critically evaluate the existing literature on kratom use and its possible association with induction of psychotic and manic symptoms, in order to identify potential areas for future research that would improve our understanding of the risks of kratom consumption.

METHODS

An electronic search was performed using five major databases: including PubMed, Scopus, Google Scholar, Web of Science, and PsycINFO. keywords such as kratom, Mitragyna speciosa, mania, psychosis, bipolar disorder, schizophrenia, schizoaffective, case report, and case series. The retrieved articles on initial search were screened based on predefined inclusion and exclusion criteria for this study, and then data synthesis was performed to analyze relevant information from the included studies.

RESULTS

Six prior papers were found using (1 case series and 5 case reports). These included 10 cases, involving kratom use association with mania and psychosis. The ages of patients ranged from 28 to 55 years mean age was 38, and (SD 13.74), the majority were males (8 out of 11). Patients had durations of kratom use ranging from 2 wk to 15 years. Significant association was found between kratom use and the worsening of psychotic and manic symptoms in individuals with psychiatric conditions.

CONCLUSIONS

Our research highlights the possibility of worsening preexisting psychiatric conditions in the context of kratom use. This study emphasizes the need for clinical evaluation of patients for kratom use. Additional research is required to gain a deeper understanding of the potential mental health implications of kratom use, especially among vulnerable populations.

Kratom: a primer for pain physicians

PURPOSE OF REVIEW

Kratom is used commonly in the United States, usually to mitigate pain, opioid withdrawal, or fatigue. A comprehensive discussion on kratom, tailored to pain management physicians, is needed, given its associated risks and potential interactions.

RECENT FINDINGS

Kratom and its main metabolites, mitragynine and 7-OH-mitragynine, bind to a variety of receptors including mu opioid receptors. Still, kratom cannot be described as a classic opioid. Kratom has been utilized without FDA approval as an alternative to traditional medications for opioid use disorder and opioid withdrawal. Lower doses of kratom typically cause opioid-like effects while higher doses can have sedating effects. Tolerance, dependence and withdrawal still occur, although kratom withdrawal appears to be more moderate than opioid withdrawal. Contamination with heavy metals and biological toxins is concerning and there is potential for serious complications, including seizures and death.

SUMMARY

The use of kratom as an opioid-sparing alternative as a part of a multimodal pain regimen is not without significant risks. It is of utmost importance for pain physicians to be aware of the risks and adverse effects associated with kratom use.

Beneficial and adverse health effects of kratom (Mitragyna speciosa): A critical review of the literature

Used in Southeast Asia for generations, kratom gained popularity in the United States and elsewhere over the past several decades. Derived from Mitragyna speciosa, kratom preparations including leaves, teas, powders, capsules, and extracts may yield stimulant, analgesic, and opioid-like effects that occur dose-dependently based on concentrations of kratom's key alkaloids, mitragynine and 7-hydroxymitragynine. Such effects are responsible for kratom's potential as a reduced-harm alternative to opiates and as a withdrawal treatment. But these properties are also associated with tolerance development and addictive potential. Given mitragynine and 7-hydroxymitragynine activity on cytochrome P450 isoforms and opioid receptors, adverse effects among polysubstance users are a concern. Current literature on the toxicology of kratom is reviewed, including product alkaloid concentrations, in vitro and in vivo data, epidemiological evidence, and human case data. The potential harms and benefits of kratom products are discussed within an exposure assessment framework, and recommendations for industry are presented. Current evidence indicates that kratom may have therapeutic potential in some persons and that products present few risks with typical, non-polysubstance use. However, few studies identified alkaloid doses at which adverse effects were expected in humans or animals. Such research is needed to inform future assessments of kratom's risks and benefits.

A Preliminary Inventory of Kratom (Mitragyna Speciosa) Products and Vendors on the Darknet and Cryptomarkets

In recent years, the online sale of kratom (Mitragyna speciosa), a Southeast Asian plant with both medicinal and psychoactive properties, has raised health concerns mainly due to the uncontrolled diffusion of adulterated kratom-related products. This exploratory study provides, for the first time, a snapshot of the availability of kratom products on the darknet which has been further validated by data searches on the surface web. A total of 231 listings of kratom across 23 darknet marketplaces were identified between March 2020 and October 2021. Among these, 40 were found actively sold across five markets by thirteen vendors. Listed items were mainly advertised as "safe" substitutes for medicinal products for the self-management of pain and other health conditions and offered in various forms (e.g., dry leaf powder, pills, capsules). Purchases were made using cryptocurrencies, with some vendors offering Pretty Good Privacy, and were shipped from Europe, Australia, the United States, and the United Kingdom. Goods sold by the same sellers also included illicit drugs and fraud-related products. Our study discovered a previously unknown diffusion of kratom products on the darknet mainly for self-treating a variety of medical conditions, suggesting the need for further research and immediate interventions to safeguard the well-being and health of kratom consumers.

Controversies in Assessment, Diagnosis, and Treatment of Kratom Use Disorder

PURPOSE OF REVIEW

We apply the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) criteria for substance use disorders (SUDs) to the herbal product kratom. Similarities and differences between kratom use disorder (KUD) and other SUDs are explored, along with assessment, diagnostic, and therapeutic recommendations for KUD.

RECENT FINDINGS

Literature reports of "kratom addiction" or KUD rarely specify the criteria by which patients were diagnosed. Individuals meeting DSM-5 KUD criteria typically do so via tolerance and withdrawal, using more than intended, and craving, not functional or ​psychosocial disruption, which occur rarely. Most clinicians who use medication to treat patients with isolated KUD select buprenorphine formulations, although there are no controlled studies showing that buprenorphine is safe or efficacious in this patient population. Diagnosis and treatment decisions for KUD should be systematic. We propose an algorithm that takes into consideration whether KUD occurs with comorbid opioid use disorder.

Psychoactive plant derivatives (ayahuasca, ibogaine, kratom) and their application in opioid withdrawal and use disorder - a narrative review

The opioid epidemic and limited access to treatment for opioid withdrawal (OW) and opioid use disorder (OUD) has led individuals to seek alternative treatments. This narrative review aims to educate clinicians on the mechanisms of action, toxicity, and applications of psychoactive plant-based substances patients may be using to self-treat OUD and OW. We specifically discuss ayahuasca, ibogaine, and kratom as they have the most evidence for applications in OUD and OW from the last decade (2012-2022). Evidence suggests these substances may have efficacy in treating OW and OUD through several therapeutic mechanisms including their unique pharmacodynamic effects, rituals performed around ingestion, and increased neuroplasticity. The current evidence for their therapeutic application in OUD and OW is primarily based on small observational studies or animal studies. High-quality, longitudinal studies are needed to clarify safety and efficacy of these substances in treatment of OW and OUD.

Kratom (Mitragyna speciosa) Use and Mental Health: A Systematic Review and Multilevel Meta-Analysis

INTRODUCTION

Kratom (Mitragyna speciosa) is a medicinal tree native to Southeast Asia. The present multilevel meta-analysis describes the association between kratom use and the positive and negative indicators of mental health.

METHODS

A total of thirty-six articles were included in the meta-analysis to examine the associations, using a random-effects model.

RESULTS

The pooled effect size showed a very small positive association between kratom use and negative indicators of mental health {r = 0.092, 95% confidence interval (CI) = [0.020, 0.164], p < 0.05}, while no significant association was found with positive indicators of mental health (r = -0.031, 95% CI = [-0.149, 0.087], p > 0.05). Pooled effect sizes of specific mental health outcomes indicated that kratom use showed only a small positive correlation with externalizing disorders (r = 0.201, 95% CI = [0.107, 0.300], p < 0.001). No significant association was found between kratom use and quality of life (r = 0.069, 95% CI = [-0.104, 0.242], p > 0.05) and internalizing disorders (r = -0.001, 95% CI = [-0.115, 0.095], p > 0.05). Multilevel moderator analysis showed that the pooled effect size of the association between kratom use and substance use disorder was stronger in Malaysia (r = 0.347, 95% CI = [0.209, 0.516], p < 0.001), and with the mean age (β1 = -0.035, 95% CI = [-0.055, -0.014], p = 0.003), and the drug profile of those who were not co-using other drugs (r = 0.347, 95% CI = [0.209, 0.516], p < 0.001).

CONCLUSION

The meta-analysis supports the kratom instrumentalization concept, in that a positive gain from kratom consumption can be achieved without any significant adverse associations with mental health.

Molecular mechanisms of morphine tolerance and dependence; novel insights and future perspectives

Drug addiction is a devastating condition that poses a serious burden on the society. The use of some drugs like morphine for their tremendous analgesic properties is also accompanied with developing tolerance, dependence and the withdrawal symptoms. These symptoms are frequently severe enough to reinforce the person in recovery to start over the use of drug again and hinder the clinical use of drugs like morphine for chronic pain. Research into opioid receptors and related molecular pathways has seen resurgence in the wake of the growing opioid epidemic. The current study provides a comprehensive scientific exploration of the molecular mechanisms and underlying signalling in morphine tolerance and dependence. It also critically evaluates current therapeutic approaches, shedding light on their efficacy and limitations, and future prospects.

Kratom as a potential substance use disorder harm reduction agent

Substance use disorders contribute to considerable U.S. morbidity and mortality. While effective pharmacotherapy options are available to treat opioid and alcohol use disorders, for a variety of reasons, many patients lack access to treatment or may be reluctant to seek care due to concerns such as perceived stigma or a current lack of desire to completely curtail their substance use. Furthermore, treatment options are limited for patients with stimulant or polysubstance use disorders. Thus, there is considerable need to expand the substance use disorder harm reduction armamentarium. Kratom (Mitragyna speciosa Korth.) is an herbal substance that can produce both opioid and stimulant-like effects, and its use in the US is growing. Though there are concerns regarding adverse effects, dependence risk, and limited regulation of its manufacturing and sale, the pharmacology of kratom and early preclinical studies suggest a potential role as a harm reduction agent for various substance use disorders, and it has historically been used in Southeast Asia for such purposes. The goal of this review is to describe kratom's history of use, pharmacology, and early pre-clinical and observational research regarding its therapeutic potential in opioid use disorder, as well as alcohol, stimulant, and polysubstance use disorders, while also highlighting current concerns around its use, existing gaps in the literature, and directions for future research.

Screening and confirmation of psilocin, mitragynine, phencyclidine, ketamine and ketamine metabolites by liquid chromatography-tandem mass spectrometry

A safe and productive workplace requires a sober workforce, free from substances that impair judgment and concentration. Although drug monitoring programs already exist, the scope and loopholes of standard workplace testing panels are well known, allowing other substances to remain a source of risk. Therefore, a high-throughput urine screening method for psilocin, mitragynine, phencyclidine, ketamine, norketamine and dehydronorketamine was developed and validated in conjunction with a urine and blood confirmation method. There are analytical challenges to overcome with psilocin and mitragynine, particularly when it comes to drug stability and unambiguous identification in authentic specimens. Screening and confirmation methods were validated according to the American National Standards Institute/Academy Standards Board (ANSI/ASB) Standard 036, Standard Practices for Method Validation in Forensic Toxicology. An automated liquid handling system equipped with dispersive pipette extraction tips was utilized for preparing screening samples, whereas an offline solid-phase extraction method was used for confirmation sample preparation. Both methods utilized liquid chromatography-tandem mass spectrometry to achieve limits of detection between 1-5 ng/mL for the screening method and 1 ng/mL for the confirmation method. Automation allows for faster throughput and enhanced quality assurance, which improves turnaround time. Compared to previous in-house methods, specimen volumes were substantially decreased for both blood and urine, which is an advantage when volume is limited. This screening technique is well suited for evaluating large numbers of specimens from those employed in safety-sensitive workforce positions. This method can be utilized by workplace drug testing, human performance and postmortem laboratories seeking robust qualitative screening and confirmation methods for analytes that have traditionally been challenging to routinely analyze.

An insight review on the neuropharmacological effects, mechanisms of action, pharmacokinetics and toxicity of mitragynine

Mitragynine is one of the main psychoactive alkaloids in Mitragyna speciosa Korth. (kratom). It has opium-like effects by acting on μ-, δ-, and κ-opioid receptors in the brain. The compound also interacts with other receptors, such as adrenergic and serotonergic receptors and neuronal Ca2+ channels in the central nervous system to have its neuropharmacological effects. Mitragynine has the potential to treat diseases related to neurodegeneration such as Alzheimer's disease and Parkinson's disease, as its modulation on the opioid receptors has been reported extensively. This review aimed to provide an up-to-date and critical overview on the neuropharmacological effects, mechanisms of action, pharmacokinetics and safety of mitragynine as a prospective psychotropic agent. Its multiple neuropharmacological effects on the brain include antinociceptive, anti-inflammatory, antidepressant, sedative, stimulant, cognitive, and anxiolytic activities. The potential of mitragynine to manage opioid withdrawal symptoms related to opioid dependence, its pharmacokinetics and toxic effects were also discussed. The interaction of mitragynine with various receptors in the brain produce diverse neuropharmacological effects, which have beneficial properties in neurological disorders. However, further studies need to be carried out on mitragynine to uncover its complex mechanisms of action, pharmacokinetics, pharmacodynamic profiles, addictive potential, and safe dosage to prevent harmful side effects.

Endogenous Opioid Activity as the Mechanism of Action for Mitragyna speciosa (Kratom): The Current State of the Evidence

Kratom (Mitragyna speciosa) is a substance derived from botanical compounds native to Southeast Asia. This substance has been cultivated predominantly in Thailand, Malaysia, Vietnam, and Myanmar, where it has historically been used in traditional medicine as a near panacea for several health problems. Such ritualistic use of kratom has been present for centuries; however, recreational use appears to have increased globally, especially in the United States. Pharmacodynamic and pharmacokinetic studies have found that kratom demonstrates a unique parabolic, dose-dependent pattern of effects ranging from stimulation to opioid and analgesic effects. Pharmacological research indicates that kratom is both a mu opioid receptor (μ-OR; MOR) and a kappa opioid receptor (κ-OR; KOR) agonist, which mediates its analgesic effects. Other research suggests that kratom may simultaneously act on dopaminergic and serotonergic receptors, which mediate its stimulant effects. This chapter reviews the literature related to the structural, functional, and cultural characteristics of kratom use. We begin with an overview of current and historical patterns of kratom, followed by a review of data on the pharmacodynamics and pharmacokinetics of kratom thus far.

A case of fatal overdose involving both hydromorphone and kratom

Kratom is a plant originating in Southeast Asia that has been used for its dose-dependent stimulant and opioid effects. The main active compound in kratom is mitragynine, an alkaloid with affinity for the mu-opioid receptor. Toxicity and fatalities related to kratom use have increased substantially in recent years. In this case report, we describe a 44-year-old man who was found deceased in bed. The only significant finding at autopsy was abdominal distension with >4 L of ascites. Toxicology testing was performed on femoral blood which showed 79 ng/mL of hydromorphone, 560 ng/mL of mitragynine, and 240 ng/mL of olanzapine. In addition, creatinine and urea in vitreous humor were significantly elevated, consistent with renal impairment. Death was attributed to hydromorphone toxicity with mitragynine being a contributing factor.

[Kratom (Mitragyna Speciosa): a Psychoactive Plant with Opportunities and Risks]

Kratom is an evergreen tree that is native to Southeast Asia. Its leafs are traditionally used as a stimulant, a remedy for various health problems and for religious purposes. Especially in the US (in a lesser extent also in Europe) kratom use is significantly prevalent. In Western countries, kratom is used predominantly as an analgesic and stimulant, for the treatment of opioid use disorders, and for improving mental health (e. g., in depression, anxiety disorders). Main molecular constituents of kratom are alkaloids of which mitragynine and 7-hydroxymitragynine appear to be most important. Pharmacodynamics and -kinetics of kratom are complex and insufficiently studied. It is known that mitragynine and 7-hydroxymitragynine are partial agonist at human μ-opioid receptors and antagonists at κ- and δ-opioid receptors with additional effects at other central receptors. Tolerability of kratom is presumably better than that of classical opioids; this is probably due to missing effects of kratom on β-arrestin and discussed as a starting point for the development of opioids with improved tolerability. Some alkaloids of kratom are inhibitors of CYP26 and to a somewhat lesser degree of CYP2C19 and CYP3A4. The addictive potential of kratom appears to be lower than that of classical opioids; however, corresponding data is limited and kratom use disorders appear to occur primarily in Western countries. Several cases of severe health-related problems and deaths are known in the US; in these cases, however, polysubstance use was usually present. Kratom use is likely associated with hepatotoxicity and cardiotoxicity. Kratom-associated mortality and morbidity in Western countries are quantitatively significantly different from Southeast Asia, where kratom use is no public health problem. The reasons for this may be the combined use of substances (which is more prevalent in Western countries), higher dosages of consumed kratom, adulterations and contaminations of commercially available kratom in Western countries, pharmacokinetic interactions, and higher concentrations of 7-hydroxymitragynine in dried kratom leafs (that are typically consumed in Western countries) in comparison to fresh leafs (that are typically consumed in Southeast Asia).

A Critical Review of the Neuropharmacological Effects of Kratom: An Insight from the Functional Array of Identified Natural Compounds

Kratom (Mitragyna speciosa Korth. Havil) has been considered a narcotic drug for years, barred by the law in many parts of the world, while extensive research over the past few decades proves its several beneficial effects, some of which are still in ambiguity. In many countries, including Thailand, the indiscriminate use and abuse of kratom have led to the loss of life. Nonetheless, researchers have isolated almost fifty pure compounds from kratom, most of which are alkaloids. The most prevalent compounds, mitragynine and 7-hydroxy mitragynine, are reported to display agonist morphine-like effects on human μ-opioid receptors and antagonists at κ- and δ-opioid receptors with multimodal effects at other central receptors. Mitragynine is also credited to be one of the modulatory molecules for the Keap1-Nrf2 pathway and SOD, CAT, GST, and associated genes' upregulatory cascades, leading it to play a pivotal role in neuroprotective actions while evidently causing neuronal disorders at high doses. Additionally, its anti-inflammatory, antioxidative, antibacterial, and gastroprotective effects are well-cited. In this context, this review focuses on the research gap to resolve ambiguities about the neuronal effects of kratom and demonstrate its prospects as a therapeutic target for neurological disorders associated with other pharmacological effects.

Evaluation of toxicity profile of kratom (Mitragyna speciosa Korth) decoction in rats

Mitragyna speciosa Korth also known as kratom, is an herbal drug preparation for its therapeutic properties and opioid-replacement therapy. Kratom is consumed in a brewed decoction form in Malaysia and to date, no studies have characterized its chemical and toxicity profile. Thus, this study aims to evaluate kratom decoction's safety and toxicity profile after 28 days of treatment. Mitragynine content was quantified in kratom decoction and used as a marker to determine the concentration. Male and female Sprague Dawley rats were orally treated with vehicle or kratom decoction (10, 50 or 150 mg/kg) and two satellite groups were treated with vehicle and kratom decoction (150 mg/kg). Blood and organs were collected for hematology, biochemical and histopathology analysis at the end of treatment. No mortality was found after 28 days of treatment and no significant changes in body weight and hematology profile, except for low platelet count. High amounts of uric acid, AST, ALT and alkaline phosphatase were found in the biochemical analysis. Histological investigation of the heart and lungs detected no alterations except for the kidney, liver and brain tissues. In conclusion, repeated administration of kratom decoction provided some evidence of toxicity in the kidney and liver with no occurrence of mortality.

Cannabinoid mechanisms contribute to the therapeutic efficacy of the kratom alkaloid mitragynine against neuropathic, but not inflammatory pain

AIMS

Mitragynine (MG) is an alkaloid found in Mitragyna speciosa (kratom), a plant used to self-treat symptoms of opioid withdrawal and pain. Kratom products are commonly used in combination with cannabis, with the self-treatment of pain being a primary motivator of use. Both cannabinoids and kratom alkaloids have been characterized to alleviate symptoms in preclinical models of neuropathic pain such as chemotherapy-induced peripheral neuropathy (CIPN). However, the potential involvement of cannabinoid mechanisms in MG's efficacy in a rodent model of CIPN have yet to be explored.

MAIN METHODS

Prevention of oxaliplatin-induced mechanical hypersensitivity and formalin-induced nociception were assessed following intraperitoneal administration of MG and CB1, CB2, or TRPV1 antagonists in wildtype and cannabinoid receptor knockout mice. The effects of oxaliplatin and MG exposure on the spinal cord endocannabinoid lipidome was assessed by HPLC-MS/MS.

KEY FINDINGS

The efficacy of MG on oxaliplatin-induced mechanical hypersensitivity was partially attenuated upon genetic deletion of cannabinoid receptors, and completely blocked upon pharmacological inhibition of CB1, CB2, and TRPV1 channels. This cannabinoid involvement was found to be selective to a model of neuropathic pain, with minimal effects on MG-induced antinociception in a model of formalin-induced pain. Oxaliplatin was found to selectively disrupt the endocannabinoid lipidome in the spinal cord, which was prevented by repeated MG exposure.

SIGNIFICANCE

Our findings suggest that cannabinoid mechanisms contribute to the therapeutic efficacy of the kratom alkaloid MG in a model of CIPN, which may result in increased therapeutic efficacy when co-administered with cannabinoids.

Kratom Alkaloids, Cannabinoids, and Chronic Pain: Basis of Potential Utility and Role in Therapy

Introduction: Chronic neuropathic pain is as a severe detriment to overall quality of life for millions of Americans. Current pharmacological treatment options for chronic neuropathic pain are generally limited in efficacy and may pose serious adverse effects such as risk of abuse, nausea, dizziness, and cardiovascular events. Therefore, many individuals have resorted to methods of pharmacological self-treatment. This narrative review summarizes the existing literature on the utilization of two novel approaches for the treatment of chronic pain, cannabinoid constituents of Cannabis sativa and alkaloid constituents of Mitragyna speciosa (kratom), and speculates on the potential therapeutic benefits of co-administration of these two classes of compounds. Methods: We conducted a narrative review summarizing the primary motivations for use of both kratom and cannabis products based on epidemiological data and summarize the pre-clinical evidence supporting the application of both kratom alkaloids and cannabinoids for the treatment of chronic pain. Data collection was performed using the PubMed electronic database. The following word combinations were used: kratom and cannabis, kratom and pain, cannabis and pain, kratom and chronic pain, and cannabis and chronic pain. Results: Epidemiological evidence reports that the self-treatment of pain is a primary motivator for use of both kratom and cannabinoid products among adult Americans. Further evidence shows that use of cannabinoid products may precede kratom use, and that a subset of individuals concurrently uses both kratom and cannabinoid products. Despite its growing popularity as a form of self-treatment of pain, there remains an immense gap in knowledge of the therapeutic efficacy of kratom alkaloids for chronic pain in comparison to that of cannabis-based products, with only three pre-clinical studies having been conducted to date. Conclusion: There is sufficient epidemiological evidence to suggest that both kratom and cannabis products are used to self-treat pain, and that some individuals actively use both drugs, which may produce potential additive or synergistic therapeutic benefits that have not yet been characterized. Given the lack of pre-clinical investigation into the potential therapeutic benefits of kratom alkaloids against forms of chronic pain, further research is warranted to better understand its application as a treatment alternative.

Targeting Opioid Receptors in Addiction and Drug Withdrawal: Where Are We Going?

This review article offers an outlook on the use of opioids as therapeutics for treating several diseases, including cancer and non-cancer pain, and focuses the analysis on the opportunity to target opioid receptors for treating opioid use disorder (OUD), drug withdrawal, and addiction. Unfortunately, as has been well established, the use of opioids presents a plethora of side effects, such as tolerance and physical and physiological dependence. Accordingly, considering the great pharmacological potential in targeting opioid receptors, the identification of opioid receptor ligands devoid of most of the adverse effects exhibited by current therapeutic agents is highly necessary. To this end, herein, we analyze some interesting molecules that could potentially be useful for treating OUD, with an in-depth analysis regarding in vivo studies and clinical trials.

Precipitated withdrawal with kratom use following naltrexone administration

Kratom is an herbal supplement with reports of use for natural pain relief or treatment of opioid withdrawal symptoms. Kratom has metabolites that bind to and agonize mu-opioid receptors similar to opiate medications. There have been reports of serious adverse reactions, with a potential for dependence with long-term use and withdrawal that may occur upon discontinuation. Naltrexone can result in abrupt withdrawal symptoms when used with opioids or opioid-like supplements such as kratom. This case report describes withdrawal precipitated by naltrexone administration in a patient with undisclosed chronic kratom use. This case highlights the importance of thorough assessment of all self-administered herbal and over-the-counter supplements as they may have serious interactions with other prescribed medications and affect therapeutic outcomes.

Clinical Implications of Kratom (Mitragyna speciosa) Use: a Literature Review

Purpose of Review

This work aims to provide an up-to-date review of the preclinical and clinical scientific literature on the therapeutic value of kratom to better understand the underlying mechanisms related to its use and inform future therapeutic applications.

Recent Findings

A growing number of studies, mainly of cross-sectional nature, describe the widespread use of kratom by individuals to self-treat pain, psychiatric symptoms, and substance use disorders (SUD) outside a controlled clinical setting. Preclinical evidence suggests kratom is effective as an analgesic agent and might decrease the self-administration of other drugs. A randomized controlled trial has further supported kratom's therapeutic value as an analgesic. Investigations in nonclinical samples of long-term kratom users also indicate its therapeutic benefit in managing SUD symptoms (e.g., craving) and long-term or acute symptoms (e.g., withdrawal) for alcohol, opioids, and other illicit drugs. However, episodes of kratom-related intoxications have also been reported, often due to the adulteration and the contamination of kratom products mainly sold online or mixed toxicities when consumed outside clinical and traditional settings.

Summary

Evidence on the clinical implications of kratom use is still limited and uncertain, with kratom research constantly evolving. Therefore, further randomized trials are needed.

Modified Akuamma Alkaloids with Increased Potency at the Mu-opioid Receptor

Akuammine (1) and pseudoakuammigine (2) are indole alkaloids found in the seeds of the akuamma tree (Picralima nitida). Both alkaloids are weak agonists of the mu opioid receptor (μOR); however, they produce minimal effects in animal models of antinociception. To probe the interactions of 1 and 2 at the opioid receptors, we have prepared a collection of 22 semisynthetic derivatives. Evaluation of this collection at the μOR and kappa opioid receptor (κOR) revealed structural-activity relationship trends and derivatives with improved potency at the μOR. Most notably, the introduction of a phenethyl moiety to the N1 of 2 produces a 70-fold increase in potency and a 7-fold increase in selectivity for the μOR. The in vitro potency of this compound resulted in increased efficacy in the tail-flick and hot-plate assays of antinociception. The improved potency of these derivatives highlights the promise of exploring natural product scaffolds to probe the opioid receptors.

Comparative metabolomics analysis reveals alkaloid repertoires in young and mature Mitragyna speciosa (Korth.) Havil. Leaves

The fresh leaves of Mitragyna speciosa (Korth.) Havil. have been traditionally consumed for centuries in Southeast Asia for its healing properties. Although the alkaloids of M. speciosa have been studied since the 1920s, comparative and systematic studies of metabolite composition based on different leaf maturity levels are still lacking. This study assessed the secondary metabolite composition in two different leaf stages (young and mature) of M. speciosa, using an untargeted liquid chromatography-electrospray ionisation-time-of-flight-mass spectrometry (LC-ESI-TOF-MS) metabolite profiling. The results revealed 86 putatively annotated metabolite features (RT:m/z value) comprising 63 alkaloids, 10 flavonoids, 6 terpenoids, 3 phenylpropanoids, and 1 of each carboxylic acid, glucoside, phenol, and phenolic aldehyde. The alkaloid features were further categorised into 14 subclasses, i.e., the most abundant class of secondary metabolites identified. As per previous reports, indole alkaloids are the most abundant alkaloid subclass in M. speciosa. The result of multivariate analysis (MVA) using principal component analysis (PCA) showed a clear separation of 92.8% between the young and mature leaf samples, indicating a high variance in metabolite levels between them. Akuammidine, alstonine, tryptamine, and yohimbine were tentatively identified among the many new alkaloids reported in this study, depicting the diverse biological activities of M. speciosa. Besides delving into the knowledge of metabolite distribution in different leaf stages, these findings have extended the current alkaloid repository of M. speciosa for a better understanding of its pharmaceutical potential.

Controversial usages of kratom (Mitragyna speciosa): For good or for evil

Kratom (Mitragyna speciosa) is a plant that grows well in tropical climates such as in Southeast Asia. Traditionally, people discovered it possessed a stimulating effect that relieved tiredness. Furthermore, it contains analgesic and medicinal properties for the treatment of pain, diarrhea, muscle discomfort, and blood pressure and to enhance stamina. Nevertheless, long term or regular consumption of kratom leads to addiction. This is because the main alkaloid of kratom, mitragynine, binds to opioid receptors and exerts a euphoric effect similar to that of morphine, which may lead to death. Due to this reason, kratom has been listed as a regulated substance in many countries including the United States, Thailand, Malaysia, Bhutan, Finland, Lithuania, Denmark, Poland, Sweden, Australia, and Myanmar. Usages of kratom carry two pharmacological effects depending on dosage. Low-dose kratom exerts a stimulating effect that refreshes the user. High-dose kratom exerts sedative effects that can lead to addiction similar to that of morphine. Despite the euphoric effect of kratom, the beneficial values of kratom to human health is indisputable. Therefore, a complete banning of kratom may cause a loss to pharmaceutical industry. Rather, a controlled or selective usage of kratom will be a better choice.

Kratom use as more than a "self-treatment"

Background: Mitragyna speciosa (kratom) is increasingly used in the United States for its pharmacological effects. Kratom's relative novelty makes for a dynamic situation, such that use motivations are not firmly established and may be changing. Investigators and clinicians require frequent updates on kratom trends.Objectives: To assess the current state of kratom-use initiation, sourcing, motivations, preference, conceptualizations, and perceived stigma, using survey responses from current and former users.Methods: Between April-May 2021 we recontacted 289 respondents who reported lifetime kratom use (on an unrelated survey) to answer kratom-specific questions.Results: The sample (N=129) was majority female (51.9%) and white (71.9%). Most (69.0%) reported first trying kratom after 2015. Mean age of use initiation (29.9 years) was older than for other substances, including opioids. Kratom ranked as a preferred substance by 48.5%. The strongest drug association with past-year kratom use was vaped nicotine (OR=3.31,95% CI 1.23-8.88). Use was less likely among those prescribed buprenorphine in the past year (OR=0.03, CI 0.01-0.28). Past-month cannabis use (OR=4.18,CI 1.80-9.72) had the strongest association with past-month kratom use. Over 40 use motivations were endorsed, many (but not all) supporting the "self-treatment" narrative of kratom use, including use as an opioid, alcohol, or stimulant substitute. Treatment shortfalls were associated with decisions to try kratom.Conclusions: Kratom use motivations are diversifying, with multiple factors driving use. As sales continue to increase, the public-health, clinical, and policy responses to kratom should be grounded in rigorous bench-to-bedside scientific research. Comprehensive study of kratom is currently lacking.

Associations of Lifetime Nonmedical Opioid, Methamphetamine, and Kratom Use within a Nationally Representative US Sample

Co-use of non-medical opioids (NMO) and methamphetamine is increasing. So too is the use of the psychoactive botanical "kratom," including among people with NMO and methamphetamine use histories. We assessed characteristics associated with respondent groups who reported lifetime methamphetamine and/or kratom use within a nationally representative US sample using 2019 National Survey on Drug Use and Health data from respondents reporting lifetime NMO use (diverted prescription opioids, heroin). Weighted prevalence estimates for demographic, mental health, and substance use outcomes were determined. Logistic regression examined associations between group membership and outcomes. Among this sample of respondents with lifetime NMO use, 67.6% (95% CI = 65.6-69.4%) reported only NMO use; 4.6% (3.9-5.4%) reported NMO+Kratom; 24.7% (22.7-26.7%) reported NMO+Methamphetamine; and 3.2% (2.5-3.9%) reported NMO+Methamphetamine+Kratom. Compared to those in the NMO-only group, the NMO+Kratom group was more likely to report past-year serious mental illness (SMI; OR = 2.27), suicidality (OR = 1.89), and past-month psychological distress (OR = 1.88). The NMO+Methamphetamine+Kratom group was more likely to report past-year SMI (OR = 2.65), past-month psychological distress (OR = 2.06), and unmet mental health needs (OR = 2.03); increased odds for drug injection, opioid withdrawal, and perceived treatment need also emerged. Risk factors were observed for all groups but were greatest among those reporting use of all three substances.

Variations in mitragynine content in the naturally growing Kratom (Mitragyna speciosa) population of Thailand

We analyzed the content of mitragynine (MG) found in kratom leaves (Mitragyna speciosa) and the influence of different environmental conditions (air and soil variables) on the yield in various regions of Thailand. The content of MG in kratom leaves ranged from 7.5 - 26.6 mg g^-1 of dry leaf weight. Canonical correspondence analysis showed that the most significant environmental variables affecting the MG content among the various regions were light intensity, relative humidity, soil volumetric water content (VW), soil pH, and calcium. This study is a first step towards providing information about environmental conditions suitable to maximize the quality and quantity of bioactive alkaloids in kratom. Future studies should focus on leaf collection and the post-harvest processes in order to assure the desired alkaloidal content in finished products, when produced under suitable environmental conditions identified in this study.

Kratom: Substance of Abuse or Therapeutic Plant?

Kratom is the common term for Mitragyna speciosa and its products. Its major active compounds are mitragynine and 7-hydroxymitragynine. An estimated 2.1 million US residents used kratom in 2020, as a "legal high" and self-medication for pain, opioid withdrawal, and other conditions. Up to 20% of US kratom users report symptoms consistent with kratom use disorder. Kratom use is associated with medical toxicity and death. Causality is difficult to prove as almost all cases involve other psychoactive substances. Daily, high-dose use may result in kratom use disorder and opioid-like withdrawal on cessation of use. These are best treated with buprenorphine.

Development and validation of ELISA for screening of Kratom (Mitragyna speciosa) habitual users using urinary AZ122 biomarker

Background Kratom (Mitragyna speciosa korth), has been used traditionally in Southeast Asia for its therapeutic properties. The major alkaloid of kratom, mitragynine binds to opioid receptors to give opioid-like effects that causes addiction. In our previous study, we have identified AZ122 as a unique biomarker in habitual or regular kratom users through analysis of their urinary protein profiles. We aimed to develop and validate a screening method by means of ELISA for detection of kratom habitual users. Methods An ELISA approach was applied for the development of a screening method using urinary AZ122 as biomarker. Method validation was carried out using 3 QC materials at different concentration of AZ122. The data was analyzed statistically using SPSS (Version 25). Results The ELISA was presented with Pearson correlation coefficient of 0.9993. The repeatability and reproducibility were presented at CV <7%, while the accuracy ranged from 78% to 96% at various AZ112 concentrations. Upon testing on 176 male respondents (n = 88 regular kratom users, and n = 88 healthy controls), the specificity and sensitivity of the assay were both 100%. Conclusions The ELISA has been validated and can be potentially used as a reliable screening test for detection of kratom habitual users.

Public Health Implications and Possible Sources of Lead (Pb) as a Contaminant of Poorly Regulated Kratom Products in the United States

Kratom (Mitragyna speciosa) is a tropical tree that is indigenous to Southeast Asia. Kratom leaf products have been used in traditional folk medicine for their unique combination of stimulant and opioid-like effects. Kratom is being increasingly used in the West for its reputed benefits in the treatment of pain, depression, and opioid use disorder (OUD). Recent studies from the United States Food and Drug Administration (FDA, Silver Spring, MD, USA) and our laboratory have shown that many kratom products being sold in the United States are contaminated with potentially hazardous levels of lead (Pb). In this commentary, we discuss the public health implications of the presence of Pb in kratom products, particularly as they relate to the predicted levels of Pb exposure among kratom users. We also considered the specific toxic effects of Pb and how they might relate to the known physiologic and toxicologic effects of kratom. Finally, we consider the possible sources of Pb in kratom products and suggest several areas for research on this issue.

Metabolism of Speciociliatine, an Overlooked Kratom Alkaloid for its Potential Pharmacological Effects

Speciociliatine, a diastereomer of mitragynine, is an indole-based alkaloid found in kratom (Mitragyna speciosa). Kratom has been widely used for the mitigation of pain and opioid dependence, as a mood enhancer, and/or as an energy booster. Speciociliatine is a partial µ-opioid agonist with a 3-fold higher binding affinity than mitragynine. Speciociliatine has been found to be a major circulating alkaloid in humans following oral administration of a kratom product. In this report, we have characterized the metabolism of speciociliatine in human and preclinical species (mouse, rat, dog, and cynomolgus monkey) liver microsomes and hepatocytes. Speciociliatine metabolized rapidly in monkey, rat, and mouse hepatocytes (in vitro half-life was 6.6 ± 0.2, 8.3 ± 1.1, 11.2 ± 0.7 min, respectively), while a slower metabolism was observed in human and dog hepatocytes (91.7 ± 12.8 and > 120 min, respectively). Speciociliatine underwent extensive metabolism, primarily through monooxidation and O-demethylation metabolic pathways in liver microsomes and hepatocytes across species. No human-specific or disproportionate metabolites of speciociliatine were found in human liver microsomes. The metabolism of speciociliatine was predominantly mediated by CYP3A4 with minor contributions by CYP2D6.

Basolateral amygdala cannabinoid CB1 receptors mediate the antinociceptive activity of harmaline in adolescent male mice

Evidence suggests a clear role for the amygdala endocannabinoid system in pain processing. Harmaline has been also known as the main nociceptive agent extracted from the Peganum harmala plant. In this study, the role of basolateral amygdala (BLA) cannabinoid CB1 receptors in pain sensitivity of harmaline-treated mice were assessed using tail-flick and hot plate methods in adolescent male NMRI mice. Intraperitoneal administration of two higher doses of harmaline (6 and 8 mg/kg) increased tail-flick latency, suggesting an antinociceptive activity. The same result was observed for the higher dose of harmaline in the hot plate test. Intra-BLA microinjection of CB1 receptor agonist ACPA (1 and 1.5 ng/mouse) or (1.5 ng/mouse) enhanced the ineffective dose-response of harmaline on pain threshold in the tail-flick or hot plate tests, respectively. Microinjection of two higher doses of CB1 receptor antagonist AM251 (0.5 and 1 ng/mouse) attenuated the antinociceptive activity of harmaline (8 ng/mouse) in both tail-flick and hot plate tests. Meanwhile, ACPA and AM251 did not alter latency to withdraw from the noxious stimulus in both tests, by themselves. It should be noted that the analgesic dose of the drugs alone or in combination did not affect locomotor activity. The obtained results highlight that BLA CB1 receptors mediate the antinociceptive activity of harmaline.

Need for clarity and context in case reports on kratom use, assessment, and intervention

This Letter to the Editor is a response to Broyan and colleagues who recently published a Case Report presenting data on 28 patients in the United States who identified kratom as their primary substance of use and who were subsequently induced on buprenorphine/naloxone for a reported diagnosis of kratom use disorder. We applaud the authors for helping to advance the science on kratom and recognize the difficulties in conducting kratom-related clinical assessment and research. However, a number of inconsistences and generalizations were identified in this Case Report, which also lacked some critical context. Importantly, such inconsistencies and generalizations can be observed throughout kratom-specific case reports. We feel this is now an important opportunity to highlight these issues that are present in the Broyan and colleagues Case report but emphasize that they are not unique to it. We do this with the hope that by acknowledging these issues it can help inform editors, clinicians, and researchers who may not be familiar with kratom and, as a result of this unfamiliarity, may inadvertently present findings in a manner that could confuse readers and even misinform clinical researchers and practitioners.

Acute, Sublethal, and Developmental Toxicity of Kratom (Mitragyna speciosa Korth.) Leaf Preparations on Caenorhabditis elegans as an Invertebrate Model for Human Exposure

Kratom (Mitragyna speciosa Korth.) is a tree native to Southeast Asia with stimulant and opioid-like effects which has seen increased use in Europe and North America in recent years. Its safety and pharmacological effects remain under investigation, especially in regard to developmental and generational toxicity. In the current study, we investigated commercial kratom preparations using the nematode Caenorhabditis elegans as a translational model for toxicity and pharmacological effects. The pure alkaloids mitragynine and 7-hydroxymitragynine as well as aqueous, ethanolic, and methanolic extracts of three commercial kratom products were evaluated using a battery of developmental, genotoxic, and opioid-related experiments. As determined previously, the mitragynine and 7-hydroxymitragynine content in kratom samples was higher in the alcoholic extracts than the aqueous extracts. Above the human consumption range equivalent of 15-70 µg/mL, kratom dose-dependently reduced brood size and health of parent worms and their progeny. 7-hydroxymitragynine, but not mitragynine, presented with toxic and developmental effects at very high concentrations, while the positive control, morphine, displayed toxic effects at 0.5 mM. Kratom and its alkaloids did not affect pumping rate or interpump interval in the same way as morphine, suggesting that kratom is unlikely to act primarily via the opioid-signalling pathway. Only at very high doses did kratom cause developmental and genotoxic effects in nematodes, indicating its relative safety.

Plant growth and phytoactive alkaloid synthesis in kratom [Mitragyna speciosa (Korth.)] in response to varying radiance

Leaves harvested from kratom [Mitragyna speciosa (Korth.)] have a history of use as a traditional ethnobotanical medicine to combat fatigue and improve work productivity in Southeast Asia. In recent years, increased interest in the application and use of kratom has emerged globally, including North America, for its potential application as an alternative source of medicine for pain management and opioid withdrawal syndrome mitigation. Although the chemistry and pharmacology of major kratom alkaloids, mitragynine and 7-hydroxymitragynine, are well documented, foundational information on the impact of plant production environment on growth and kratom alkaloids synthesis is unavailable. To directly address this need, kratom plant growth, leaf chlorophyll content, and alkaloid concentration were evaluated under three lighting conditions: field full sun (FLD-Sun), greenhouse unshaded (GH-Unshaded), and greenhouse shaded (GH-Shaded). Nine kratom alkaloids were quantified using an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. Greenhouse cultivation generally promoted kratom height and width extension by 93-114% and 53-57%, respectively, compared to FLD-Sun. Similarly, total leaf area and leaf number were increased by 118-160% and 54-80% under such conditions. Average leaf size of plants grown under GH-Shaded was 41 and 69% greater than GH-Unshaded and FLD-Sun, respectively; however, no differences were observed between GH-Unshaded and FLD-Sun treatments. At the termination of the study, total leaf chlorophyll a+b content of FLD-Sun was 17-23% less than those grown in the greenhouse. Total leaf dry mass was maximized when cultivated in the greenhouse and was 89-91% greater than in the field. Leaf content of four alkaloids to include speciociliatine, mitraphylline, corynantheidine, and isocorynantheidine were not significantly impacted by lighting conditions, whereas 7-hydroxymitragynine was below the lower limit of quantification across all treatments. However, mitragynine, paynantheine, and corynoxine concentration per leaf dry mass were increased by 40%, 35%, and 111%, respectively, when cultivated under GH-Shaded compared to FLD-Sun. Additionally, total alkaloid yield per plant was maximized and nearly tripled for several alkaloids when plants were cultivated under such conditions. Furthermore, rapid, non-destructive chlorophyll evaluation correlated well (r2 = 0.68) with extracted chlorophyll concentrations. Given these findings, production efforts where low-light conditions can be implemented are likely to maximize plant biomass and total leaf alkaloid production.

Kratom Use Among U.S. Adolescents: Analyses of the 2019 National Survey on Drug Use and Health

BACKGROUND

Kratom (Mitragyna speciosa) is an opioid-like psychoactive substance not approved by the U.S. Food and Drug Administration that could be used due to its euphoric, stimulant, and analgesic effects. Kratom is gaining popularity in the U.S. and becoming a reason of concern among pediatricians.

METHODS

Data from the 2019 National Survey on Drug Use and Health were analyzed to estimate the prevalence and identify correlates of lifetime and past 12-month kratom use among 13,397 U.S. adolescents. Multivariable logistic regression models were conducted to assess the associations of interest.

RESULTS

Lifetime and past 12-month prevalence of kratom use was .44% (95% confidence interval [CI] .32-.60) and .27% (95% CI .18-.40), respectively. Past 12-month cigarette use was associated with lifetime kratom use (adjusted odds ratio 2.60, 95% CI 1.07-6.35). Past 12-month cannabis use was associated with past 12-month kratom use (adjusted odds ratio 2.48, 95% CI 1.15-5.35).

CONCLUSIONS

This first report on the epidemiology of adolescent kratom use provides a baseline to assess kratom use trends in future years and identify potential correlates of use among adolescents.

Understanding Kratom Use: A Guide for Healthcare Providers

Kratom (Mitragyna speciosa Korth., Rubiaceae) is a plant native to Southeast Asia, where it has been used for centuries as a mild stimulant and as medicine for various ailments. More recently, as kratom has gained popularity in the West, United States federal agencies have raised concerns over its safety leading to criminalization in some states and cities. Some of these safety concerns have echoed across media and broad-based health websites and, in the absence of clinical trials to test kratom’s efficacy and safety, considerable confusion has arisen among healthcare providers. There is, however, a growing literature of peer-reviewed science that can inform healthcare providers so that they are better equipped to discuss kratom use with consumers and people considering kratom use within the context of their overall health and safety, while recognizing that neither kratom nor any of its constituent substances or metabolites have been approved as safe and effective for any disease. An especially important gap in safety-related science is the use of kratom in combination with physiologically active substances and medicines. With these caveats in mind we provide a comprehensive overview of the available science on kratom that has the potential to i clarity for healthcare providers and patients. We conclude by making recommendations for best practices in working with people who use kratom.

Searching for a Signal: Self-Reported Kratom Dose-Effect Relationships Among a Sample of US Adults With Regular Kratom Use Histories

There is limited understanding regarding kratom use among US adults. Although motivations for use are increasingly understood, typical kratom doses, threshold of (low and high) doses for perceived effectiveness, and effects produced during cessation are not well documented. We aimed to extend prior survey work by recruiting adults with current and past kratom exposure. Our goal was to better understand kratom dosing, changes in routines, and perception of effects, including time to onset, duration, and variability of beneficial and adverse outcomes from use and cessation. Among respondents who reported experiencing acute kratom effects, we also sought to determine if effects were perceived as helpful or unhelpful in meeting daily obligations. Finally, we attempted to detect any signal of a relationship between the amount of kratom consumed weekly and weeks of regular use with ratings of beneficial effects from use and ratings of adverse effects from cessation. We conducted an online survey between April-May 2021 by re-recruiting participants from a separate study who reported lifetime kratom use. A total of 129 evaluable surveys were collected. Most (59.7%) had used kratom >100 times and reported currently or having previously used kratom >4 times per week (62 weeks on average). Under half (41.9%) reported that they considered themselves to be a current "regular kratom user." A majority (79.8%) reported experiencing acute effects from their typical kratom dose and that onset of effects began in minutes but dissipated within hours. Over a quarter reported that they had increased their kratom dose since use initiation, whereas 18.6% had decreased. Greater severity of unwanted effects from ≥1 day of kratom cessation was predicted by more weeks of regular kratom use (β = 6.74, p = 0.02). Acute kratom effects were largely reported as compatible with, and sometimes helpful in, meeting daily obligations. In the absence of human laboratory studies, survey methods must be refined to more precisely assess dose-effect relationships. These can help inform the development of controlled observational and experimental studies needed to advance the public health understanding of kratom product use.

Physiological dependence to mitragynine indicated by a rapid cross-dependence procedure with heroin-dependent mice

The potential of mitragynine to produce physiological dependence (withdrawal) was assessed using a rapid assessment procedure with male ICR mice exposed to heroin-admixed food followed by naloxone (subcutaneously, s.c.) precipitation of withdrawal. Initial studies indicated that 3 days of exposure to 3.0 mg/g of heroin-admixed food followed by naloxone (0.6 mg/kg) reliably precipitated withdrawal jumping and weight loss. Lower concentrations of heroin-admixed food and lower doses of naloxone produced fewer withdrawal signs. A longer exposure to heroin-admixed food did not produce significantly greater amounts of jumping or weight loss. Further, these withdrawal signs were dose-dependently reversed by s.c. administration of heroin immediately following naloxone administration. Mitragynine (s.c.) also dose-dependently suppressed naloxone-precipitated withdrawal signs. Additionally, both jumping and weight loss were suppressed over a comparable range of mitragynine doses when administered by gavage with a noticeably, but not significantly, higher potency than with s.c. administration. The ED₅₀ values for mitragynine for the suppression of withdrawal by any route (354-911 μmol/kg) were greater than the minimally effective dose that decreased locomotor activity (251 μmol/kg) and from 40- to 104-fold greater than those for heroin. The results suggest inherent opioid dependence liability of mitragynine. The in vivo potency relations between mitragynine and heroin are consistent with a conclusion of dependence-producing effects, indicated by the suppression of withdrawal, comparable to standard opioid μ-receptor agonists, differing primarily in terms of potency. The present paper provides a method for the rapid assessment of physiological dependence liability applicable to other kratom plant constituents or any potential opioid dependence-producing agents.

The Chemical and Pharmacological Properties of Mitragynine and Its Diastereomers: An Insight Review

Mitragynine, is a naturally occurring indole alkaloid that can be isolated from the leaves of a psychoactive medicinal plant. Mitragyna speciosa, also known as kratom, is found to possess promising analgesic effects on mediating the opioid receptors such as µ (MOR), δ (DOR), and κ (KOR). This alkaloid has therapeutic potential for pain management as it has limited adverse effect compared to a classical opioid, morphine. Mitragynine is frequently regarded to behave like an opioid but possesses milder withdrawal symptoms. The use of this alkaloid as the source of an analgesic candidate has been proven through comprehensive preclinical and clinical studies. The present data have shown that mitragynine is able to bind to opioid receptors, particularly MOR, to exhibit the analgesic effect. Moreover, the chemical and pharmacological aspects of mitragynine and its diastereomers, speciogynine, speciociliatine, and mitraciliatine, are discussed. It is interesting to know how the difference in stereochemical configuration could lead to the difference in the bioactivity of the respective compounds. Hence, in this review, the updated pharmacological and toxicological properties of mitragynine and its diastereomers are discussed to render a comprehensive understanding of the pharmacological properties of mitragynine and its diastereomers based on their structure-activity relationship study.

Ameliorative effects of alkaloid extract from Mitragyna speciosa (Korth.) Havil. Leaves on methamphetamine conditioned place preference in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Mitragyna speciosa (Korth.) Havil., popularly known as Kratom (KT), is a medicinal plant used for pain suppression in Southeast Asia. It has been claimed to assist drug users withdraw from methamphetamine (METH) dependence. However, its use was controversial and not approved yet.

AIM OF THE STUDY

This study was conducted to characterize local field potential (LFP) patterns in the nucleus accumbens (NAc) and the hippocampus (HP) in mice with METH conditioned place preference (CPP) that were treated with KT alkaloid extract.

MATERIALS AND METHODS

Male Swiss albino ICR mice were implanted with intracraneal electrodes into the NAc and HP. To induce METH CPP, animals were injected intraperitoneally once a day with METH (1 mg/kg) and saline (0.9% w/v) alternately and put into METH/saline compartments to experience the associations between drug/saline injection and the unique environmental contexts for 10 sessions. Control group received saline injection paired with both saline/saline compartments. On post-conditioning day, effects of 40 (KT40), 80 (KT80) mg/kg KT alkaloid extract and 20 mg/kg bupropion (BP) on CPP scores and LFP powers and NAc-HP coherence were tested.

RESULTS

Two-way ANOVA revealed significant induction of CPP by METH sessions (P < 0.01). Multiple comparisons indicated that METH CPP was completely abolished by KT80 (P < 0.001). NAc gamma I (30.0-44.9 Hz) and HP delta (1.0-3.9 Hz) powers were significantly increased in mice with METH CPP (P < 0.01). The elevated NAc gamma I was significantly suppressed by KT80 (P < 0.05) and the increased HP delta was significantly reversed by KT40 (P < 0.01) and KT80 (P < 0.001). In addition, NAc-HP coherence was also significantly increased in gamma I (30.0-44.9 Hz) frequency range (P < 0.05) but it was reversed by KT80 (P < 0.05). Treatment with BP did not produce significant effect on these parameters.

CONCLUSIONS

These findings demonstrated that KT alkaloid extract significantly reversed CPP scores and LFP patterns induced by METH administration. The ameliorative effects of the extract might be beneficial for treatment of METH craving and addiction.