Purpose: In this study, the author conducted a search in literature for qualitative and quantitative analysis of alkaloids contained in Passiflora sp. (mainly P. incarnata). From this literature search, the author investigated the types (chemical profiles) and amounts of harmane alkaloids (beta-carboline alkaloids) contained in Passiflora sp. (mainly P. incarnata), and furthermore, their psychopharmacological activity. The author then considered the contribution of harmane alkaloids to the neuropsychiatric effects of Passiflora sp. Finally, the author compared the composition and amount of harmane alkaloids contained in Passiflora sp. (mainly P. incarnata) with those of Peganum harmala, a known hallucinogenic plant, and considered the possibility of
serious health hazards posed by harmane alkaloids.
Method: Among the several references the author has used in their historical research on Passiflora sp., the Costa, et al. (2016) paper was the only one that included a research report on alkaloid analysis. The author searched for information about alkaloids contained in Passiflora sp. in Costa, et al. (2016) and the references used therein. In connection with this, the author also searched the web for information about Peganum harmala and harmane alkaloids (beta-carboline alkaloids).
Results: Research reports on the harmane alkaloid content of Passiflora sp. since 1980 have shown that the concentrations are lower than those reported up until the 1970s. In comparison with Peganum harmala, the beta-carboline alkaloid content in Peganum harmala, the % w/w level is significantly higher than the parts-permillion (ppm) level in P. incarnata. The research results have also shown that beta-carboline alkaloids such as harmane alkaloids easily pass though the blood-brain barrier and bind to and interact with receptors for benzodiazepines, serotonin, and dopamine, and that they have a wide range of psychopharmacological effects, including antidepressant, central stimulant, and hallucinogenic effects, by regulating the metabolism and concentrations of monoamine neurotransmitters in the brain through their MAO-A inhibitory action. On the other hand, beta-carboline alkaloids such as harmane have been shown to bind to benzodiazepine receptors in the GABAA receptor-benzodiazepine receptor system, attenuating or reversing the inhibitory effects of GABA, including its anticonvulsant effect.
Conclusion: Harmane alkaloids (beta-carboline alkaloids), such as harmane contained in Passiflora sp., are present at very low concentrations, at the ppm level. However, at this concentration level, harmane and other harmane alkaloids may act as GABAA receptor inverse agonists (negative allosteric modulators) and induce effects opposite to the GABA inhibitory action, such as anxiogenesis and central nervous system excitation. Therefore, the authors speculate that the mild psychoneurotic effects of Passiflora sp. may be due to trace amounts of harmane alkaloids controlling the excessive GABAergic inhibitory effect of aglycones such as apigenin at GABAA receptors.
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