Eco-geographical Influence on β-Carboline Alkaloid Accumulation in Peganum Harmala L. Seeds: A Comparative Study Between Naâma (Algeria) and Selected Regions Using HPLC and GC-MS

Abstract

Background: Peganum harmala L. (Zygophyllaceae) is a perennial herbaceous plant widely distributed across arid and semi-arid ecosystems of the Mediterranean basin and Central Asia. Its seeds are exceptionally rich in β-carboline alkaloids, particularly harmine and harmaline, which are of considerable pharmacological interest. Environmental stress conditions typical of steppe ecosystems including drought, extreme temperatures, and poor soils are known to influence secondary metabolite biosynthesis in plants, yet the quantitative impact of eco-geographical factors on alkaloid accumulation in this species remains incompletely understood.

Objectives: This study aimed to quantify the major β-carboline alkaloids (harmine and harmaline) in seeds of Peganum harmala collected from the El Kasdir region (Province of Naâma, Algeria), and to assess how eco-geographical and climatic factors influence alkaloid accumulation through a comparative multi-regional analysis. This interdisciplinary approach combining plant ecology and analytical chemistry constitutes the original contribution of this work.

Methods: Seeds were harvested in July 2018 from the El Kasdir region, which is characterized by a steppe climate with cold, arid winters and sandy soils of basic pH (8.4). Alkaloid extraction was performed following the protocol of Herraiz and al. (2010)[1], using a perchloric acid/methanol solution (1:1). The resulting extracts were analyzed by High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD) and Gas Chromatography coupled with Mass Spectrometry (GC/MS). The quantitative results obtained from five samples were then compared with six published studies covering six geographical regions: Setif and Djelfa (Algeria), Toledo (Spain), Agadir (Morocco), Tehran (Iran), and Xinjiang (China).

Results: HPLC-DAD and GC/MS analyses identified harmaline (retention time: 19.29 min; 44.39%) and harmine (retention time: 19.71 min; 46.05%) as the two dominant alkaloids, together representing more than 90% of the total alkaloid fraction. Mean concentrations were 32.7 ± 1.7 mg/g for harmaline and 20.96 ± 1.18 mg/g for harmine. A minor alkaloid, tetrahydroharmine (THH), was also detected at 0.5%. The comparative analysis revealed marked interregional variability: the highest concentrations were recorded in Xinjiang, China (58.46 mg/g harmaline; 40.77 mg/g harmine) and Toledo, Spain (56.0 mg/g; 43.2 mg/g), Agadir, Morocco (0.874 mg/g; 8.514 mg/g). Tehran, Iran (0.25%; 1, 84%), Setif, Algeria (3,8 % ; 2,9 % ) and Djelfa, Algeria (48.009%; 38.44 %)

Conclusion: This study demonstrates that β-carboline alkaloid biosynthesis in Peganum harmala is strongly modulated by eco-geographical factors, including climate (aridity, precipitation, temperature), edaphic conditions (soil type, organic matter content), and altitude. Arid continental climates appear to favor higher alkaloid accumulation, while milder, ocean-influenced conditions are associated with lower concentrations. These findings highlight the importance of considering geographical origin and environmental context in the standardization of medicinal plant products derived from Peganum harmala.