Studies in the Chemical Constituents of the Seeds of Pegnum harmala: Isolation and Structure Elucidation of Two b-Carboline Lactams - Harmalanine and Harmalacidine

Two 8-carboline lactams harmalanine and harmalacidine have been isolated from the seeds of Peganum harmala and their structures were elucidated as I and I1 respectively through chemical and spectroscopic studies.In the case of I, which is the simplest tetracyclic B-carboline lactam from any source, detailed nmr ('H and 13C) investigations including noe difference.2D nmr (cosy-45, noesy, 3-resolved) double resonance ex- periments and l H -' 3 ~-h e t e r o -~~~~ measurements have been used.Peganum harmala (Zygophylaceae) known in vernacular as harmala, is commonly found in Indo-Pakistan subcontinent and other parts of ~sia.'-~Its seeds are narcotic, anthelmintic, antispasmodic and employed in cases of asthma and rheumatism in the indigenous system of medicine.lj5Recent investigations have revealed that its main alkaloids, harmine, harmaline and tetrahydroharmine which belong to the category of hallucinogenics, are also potent reversible inhibitors of monoamine oxidase.6 Further, alkaloids of Peganum harmala were found to possess antimicrobial a c t i ~i t ~. ~' ~ More recent studies undertaken by Siddiqui et al. in the seed of Peganum harmala resulted in the isolation and structure elucidation of two new simple 8-carhaline alkaloids harmalldine7 and harmallcine.'The present paper deals with the isolation of two 8-carboline lactams harmalanine and harmalacidine from the seed and with their structure elucidation through chemical and spectral studies.