Humans have used psychoactive and medicinal plants for therapeutic, spiritual, and cultural purposes. Their bioactive characteristics play an important role across various ancient cultures. However, much of this knowledge has been lost due to the reliance on oral transmission, particularly in regions like Arabia, where written records are sparse before the Classical period. The analysis of preserved plant materials revealed a potential method to gain more information about the ancient plants in archeological artifacts.
This study assessed the usage of plant-based substances in the Iron Age Arabia, mainly focused on the archeological site Qurayyah. About 25 % of the 2250 identified plant species found in Arabia are used as medicinal plants. This suggests that past cultures may have used these plants for psychoactive and therapeutic properties. This study uses high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) in the multiple reaction monitoring (MRM) mode to determine the source of these residues and investigate the significance. The first definitive evidence that the plant was utilised in fumigation devices was the finding of Peganum harmala, also known as Harmal, Syrian Rue or Esfand.
The study was mainly focused on the analysis and extraction of plant secondary metabolites and lipids from the ancient organic residues from the Qurayyah archaeological site in Saudi Arabia. The samples were collected from the incense burners in Area N and Area D. Samples were analyzed as per the protocols. The samples were obtained on sterile aluminum foil and transferred to pre-cleaned glass vials for analysis. The materials used in the extraction process were HPLC grade methanol and acetonitrile, Dichloromethane, formic acid, ultrapure water, and analytical standards.
The samples were mixed with the quartz sand after being homogenised to a consistent particle size. The extracts were collected in the glass vials and concentrated by rotary evaporation. A Shimadzu LCMS-8050 triple-quadrupole system with an electrospray ionization (ESI) source was used for the HPLC-MS/MS analysis. The samples were segregated into two columns employing multiple reaction monitoring (MRM) mode for compound-specific detection. LabSolutions software was used to collect the data and process it. Authentic analytical standards were used to improve MRM mode variables for targeted compounds, which is necessary to screen the particular compounds in the archeological samples.
The two tricyclic β-carboline alkaloids harmine and harmane were found in the samples DA-QU_N-1, DA-QU_D-2, and DA-QU_D-1 as per the HPLC-MS/MS findings. Species of the Peganum genus found in Central Asia, the Mediterranean, Western Asia, North Africa, and Saudi Arabia contain these alkaloids. P. harmala is determined as the most likely source. Harmala alkaloids are reversible inhibitors of the monoamine oxidase A (MAO-A), which temporarily inhibits the enzyme that is responsible for the breakdown of neurotransmitters in the brain. This can lead to health benefits because these neurotransmitters accumulate at high levels, stimulating the central nervous system (CNS).
Different psychopharmacological effects, such as stimulation, sedation, antiparasitic, antibacterial, and anti-inflammatory activities, are facilitated by broad receptor affinity. DA-QU_D-2 and DA-QU_D-1 samples contain increased levels of sterol molecules, phytosterols, and cholesterol. Studies have shown that P. harmala seed oil has anti-inflammatory properties. β-amyrin and α-amyrin, these two pentacyclic triterpenoids, indicate a potential combination of these compounds.
Reference: Huber B, Luciani M, Abualhassan AM, et al. Metabolic profiling reveals first evidence of fumigating drug plant Peganum harmala in Iron Age Arabia. Commun Biol. 2025;8:720. doi:10.1038/s42003-025-08096-7
