Plant-based indole alkaloids are very rich in pharmacological activities, and the indole nucleus is considered to contribute greatly to these activities. This review’s fundamental objective is to summarize the pharmacological potential of indole alkaloids that have been derived from plants and provide a detailed evaluation of their established pharmacological activities, which may contribute to identifying new lead compounds. The study was performed by searching various scientific databases, including Springer, Elsevier, ACS Publications, Taylor and Francis, Thieme, Wiley Online Library, ProQuest, MDPI, and online scientific books. A total of 100 indole compounds were identified and reviewed. The most active compounds possessed a variety of pharmacological activities, including anticancer, antibacterial, antiviral, antimalarial, antifungal, anti-inflammatory, antidepressant, analgesic, hypotensive, anticholinesterase, antiplatelet, antidiarrheal, spasmolytic, antileishmanial, lipid-lowering, antimycobacterial, and antidiabetic activities. Although some compounds have potent activity, some only have mild-to-moderate activity. The pharmacokinetic profiles of some of the identified compounds, such as brucine, mitragynine, 7-hydroxymitragynine, vindoline, and harmane, were also reviewed. Most of these compounds showed promising pharmacological activity. An in-depth pharmacological evaluation of these compounds should be performed to determine whether any of these indoles may serv
Mitragyna speciosa (K.) H. (Kratom) is a tree that possesses stimulant and opioid-like analgesic effects, and is indigenous to Southeast Asia and Indochina, where it has seen widespread use for hundreds of years. The principal pharmacologically active alkaloids in kratom leaves include mitragynine (MG), 7-hydroxymitragynine (HMG), speciociliatine (SC), speciogynine (SG) and paynantheine (P). The pharmacological effects induced and their potency can vary dramatically according to variations in the proportions of alkaloid compounds present, which are related to geographic origin, stage of maturity and ecotype. Much of the analgesic and opiate-like psychoactive effect of kratom has been associated with the MG and HMG detected in M. speciosa (K.). H. Five different strains of M. speciosa (K.) H., which present differing vein colours and geographic origin, have been studied herein; red vein strains from Thailand, Malaysia and Bali, named Red Thai, Red Malay and Red Bali, a white vein strain from Borneo (White Borneo) and a green vein strain from Malaysia (Green Malay) were included in the study. Plant leaves were extracted under magnetic stirring at room temperature in a MeOH/H 2 O 1:1 mixture. Purified alkaloids were isolated in a number of organic extraction steps, from either aqueous basic or acidic phases, that culminated in precipitation (yields between 0.94 and 1.43%). These samples have been analysed using HPLC-DAD, HPLC-MS, HPLC-MS/MS and GC-MS to optimize the identificati
The basic science and clinical use of morphine and other "opioid" drugs are based almost exclusively on the extracts or analogues of compounds isolated from a single source, the opium poppy (Papaver somniferum). However, it now appears that biological diversity has evolved an alternative source. Specifically, at least two alkaloids isolated from the plant Mitragyna speciosa, mitragynine ((E)-2-[(2S,3S)-3-ethyl-8-methoxy-1,2,3,4,6,7,12,12b-octahydroindolo[3,2-h]quinolizin-2-yl]-3-methoxyprop-2-enoic acid methyl ester; 9-methoxy coryantheidine; MG) and 7-hydroxymitragynine (7-OH-MG), and several synthetic analogues of these natural products display centrally mediated (supraspinal and spinal) antinociceptive (analgesic) activity in various pain models. Several characteristics of these compounds suggest a classic "opioid" mechanism of action: nanomolar affinity for opioid receptors, competitive interaction with the opioid receptor antagonist naloxone, and two-way analgesic cross-tolerance with morphine. However, other characteristics of the compounds suggest novelty, particularly chemical structure and possible greater separation from side effects. We review the chemical and pharmacological properties of these compounds.
Mitragynina speciosa , more commonly known as kratom, is a plant native to Southeast Asia, the leaves of which have been used traditionally as a stimulant, analgesic, and treatment for opioid addiction. Recently, growing use of the plant in the United States and concerns that kratom represents an uncontrolled drug with potential abuse liability, have highlighted the need for more careful study of its pharmacological activity. The major active alkaloid found in kratom, mitragynine, has been reported to have opioid agonist and analgesic activity in vitro and in animal models, consistent with the purported effects of kratom leaf in humans. However, preliminary research has provided some evidence that mitragynine and related compounds may act as atypical opioid agonists, inducing therapeutic effects such as analgesia, while limiting the negative side effects typical of classical opioids. Here we report evidence that an active metabolite plays an important role in mediating the analgesic effects of mitragynine. We find that mitragynine is converted in vitro in both mouse and human liver preparations to the much more potent mu-opioid receptor agonist 7-hydroxymitragynine, and that this conversion is mediated by cytochrome P450 3A isoforms. Further, we show that 7-hydroxymitragynine is formed from mitragynine in mice and that brain concentrations of this metabolite are sufficient to explain most or all of the opioid-receptor-mediated analgesic activity of mitragynine. At the same ti
Kratom (Mitragyna speciosa) is a tropical plant containing various bioactive alkaloids such as mitragynine, 7-hydroxymitragynine, speciogynine, and paynantheine, known for their analgesic and stimulant activities. Unlike classical opioids, kratom has been reported to possess a lower risk of dependence and may act through inhibition of non-opioid inflammatory pathways such as cyclooxygenase (COX) and Toll-like receptor 4 (TLR4). This study aimed to evaluate the inhibitory activity of kratom leaf ethanol extract on COX-1 and COX-2 enzymes, assess its acute toxicity in mice, and determine its central nervous system (CNS) stimulant potential through the natatory exhaust test. The 96% ethanol extract of kratom leaves was tested for COX-1 and COX-2 inhibition using the TMPD assay method. Acute toxicity was evaluated following OECD guideline 423 at doses ranging from 5 to 2000 mg/kg BW in female mice. The stimulant activity test was conducted using the natatory exhaust method in male mice at doses of 50, 100, and 150 mg/kg BW. Statistical analysis was performed using ANOVA followed by Tukey’s test with a 95% confidence level. The extract exhibited 74.38% inhibition of COX-2 and 2.47% inhibition of COX-1 at a concentration of 1000 ppm, yielding a selectivity ratio of 30:1. Acute toxicity testing showed an LD₅₀ > 2000 mg/kg BW, categorized as mildly toxic, with no significant organic alterations. CNS stimulant activity increased up to 280% at a dose of 150 mg/kg BW compared to the neg
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