WAKUI, V. G. Alcaloides de Psychotria capitata Ruiz & Pav. (Rubiaceae): determinação estrutural e atividade biológica. 2014. 91 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Goiânia, 2015
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Abstract
Typos corrected by ChatGPT
Considering that Psychotria species are described as sources of alkaloids, mainly of the β-carboline type with potential biological activity, this work focused on the phytochemical study of Psychotria capitata Ruiz & Pav. (Rubiaceae) leaves, which are widely found in the Cerrado biome.
The study of this species led to the isolation and structural elucidation of the alkaloids bufotenine, bufotenine-N-oxide, and the coumarin iso-scopoletin. These alkaloids were found in most of the studied fractions. Furthermore, two additional alkaloids were identified in a mixture: 6-hydroxy-2-methyl-1,2,3,4-tetrahydro-β-carboline and 7-carboxyl-2-methyl-3,4-dihydro-β-carbolinium. The latter is a novel alkaloid, still undergoing structural elucidation.
Additionally, considering the great bioactive potential of indole alkaloids, particularly those found in Psychotria species with respect to central nervous system biological activity, we submitted fractions and isolated compounds of P. capitata to in vitro evaluation with monoamine oxidases (MAO-A and MAO-B) as biological targets.
These biological assays were conducted in collaboration with a research group from FF/UFRGS that develops studies to identify enzymatic inhibitors involved in neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease. Thus, the search for compounds that interact with cholinesterases (AChE and BChE) and monoamine oxidases (MAO-A and MAO-B) is important for understanding the neurochemical basis of these diseases.
The alkaloidal fractions of P. capitata (10 mg/mL) showed inhibition rates between 60% and 89%, demonstrating the potential of these fractions. Bufotenine showed selective inhibition of MAO-A (IC₅₀ ~89 μM), while bufotenine-N-oxide showed no inhibition of either enzyme.
Therefore, this work contributes to the study of species in the Rubiaceae family, confirming the great potential of this family as a source of indole alkaloids with a β-carboline nucleus, which exhibit biological activity of significant interest.
Comments from ChatGPT:
Summary of Findings on Beta-Carbolines and Bufotenine from Psychotria capitata
• Psychotria capitata leaves were found to contain significant amounts of bufotenine (5-HO-DMT), its N-oxide derivative, and two beta-carboline alkaloids: 6-hydroxy-2-methyl-1,2,3,4-tetrahydro-β-carboline and 7-carboxyl-2-methyl-3,4-dihydro-β-carbolinium (the latter a novel compound still under study).
• These alkaloids were present across nearly all extracted fractions of the plant, suggesting they are major chemical constituents.
• Biological testing revealed that the alkaloid-rich fractions (10 µg/mL) inhibited MAO-A and MAO-B by 60–89%, indicating potential neurological activity.
• Bufotenine itself showed selective inhibition of MAO-A, with an IC₅₀ of ~86–89 µM.
• Although bufotenine acts as an MAOI, it is orders of magnitude weaker than harmine (a classic beta-carboline MAOI found in Banisteriopsis caapi), which has an IC₅₀ near 0.007 µM. This makes harmine roughly 8,000–15,000 times more potent than bufotenine as an MAOI.
• The pronounced MAO inhibition observed in the plant extracts is therefore more likely attributed to the beta-carboline alkaloids rather than bufotenine itself.
Full version available in link.
Abstract
Typos corrected by ChatGPT
Considering that Psychotria species are described as sources of alkaloids, mainly of the β-carboline type with potential biological activity, this work focused on the phytochemical study of Psychotria capitata Ruiz & Pav. (Rubiaceae) leaves, which are widely found in the Cerrado biome.
The study of this species led to the isolation and structural elucidation of the alkaloids bufotenine, bufotenine-N-oxide, and the coumarin iso-scopoletin. These alkaloids were found in most of the studied fractions. Furthermore, two additional alkaloids were identified in a mixture: 6-hydroxy-2-methyl-1,2,3,4-tetrahydro-β-carboline and 7-carboxyl-2-methyl-3,4-dihydro-β-carbolinium. The latter is a novel alkaloid, still undergoing structural elucidation.
Additionally, considering the great bioactive potential of indole alkaloids, particularly those found in Psychotria species with respect to central nervous system biological activity, we submitted fractions and isolated compounds of P. capitata to in vitro evaluation with monoamine oxidases (MAO-A and MAO-B) as biological targets.
These biological assays were conducted in collaboration with a research group from FF/UFRGS that develops studies to identify enzymatic inhibitors involved in neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease. Thus, the search for compounds that interact with cholinesterases (AChE and BChE) and monoamine oxidases (MAO-A and MAO-B) is important for understanding the neurochemical basis of these diseases.
The alkaloidal fractions of P. capitata (10 mg/mL) showed inhibition rates between 60% and 89%, demonstrating the potential of these fractions. Bufotenine showed selective inhibition of MAO-A (IC₅₀ ~89 μM), while bufotenine-N-oxide showed no inhibition of either enzyme.
Therefore, this work contributes to the study of species in the Rubiaceae family, confirming the great potential of this family as a source of indole alkaloids with a β-carboline nucleus, which exhibit biological activity of significant interest.
Comments from ChatGPT:
Summary of Findings on Beta-Carbolines and Bufotenine from Psychotria capitata
• Psychotria capitata leaves were found to contain significant amounts of bufotenine (5-HO-DMT), its N-oxide derivative, and two beta-carboline alkaloids: 6-hydroxy-2-methyl-1,2,3,4-tetrahydro-β-carboline and 7-carboxyl-2-methyl-3,4-dihydro-β-carbolinium (the latter a novel compound still under study).
• These alkaloids were present across nearly all extracted fractions of the plant, suggesting they are major chemical constituents.
• Biological testing revealed that the alkaloid-rich fractions (10 µg/mL) inhibited MAO-A and MAO-B by 60–89%, indicating potential neurological activity.
• Bufotenine itself showed selective inhibition of MAO-A, with an IC₅₀ of ~86–89 µM.
• Although bufotenine acts as an MAOI, it is orders of magnitude weaker than harmine (a classic beta-carboline MAOI found in Banisteriopsis caapi), which has an IC₅₀ near 0.007 µM. This makes harmine roughly 8,000–15,000 times more potent than bufotenine as an MAOI.
• The pronounced MAO inhibition observed in the plant extracts is therefore more likely attributed to the beta-carboline alkaloids rather than bufotenine itself.