O extrato bruto (DCM:MeOH 2:1) das raízes de Piper crassinervium foi submetido a fracionamentos cromatográficos resultando no isolamento e identificação de oito substâncias, sendo estas uma flavanona (5,4'-diidroxi-7-metoxiflavanona [isosakuranetina]), duas hidroquinonas preniladas (1,4-diidroxi-2-[3',7'-dimetil-1'-oxo-2'-E-6'-octadienil]-benzeno e 1,4-diidroxi-2-[3',7'-dimetil-1'-oxo-2'-Z-6'-octadienil]-benzeno), um cromeno (ácido-2-metil-2-[4'-metil-3'-pentenil]2H-1-benzopirano-6-carboxílico), um derivado prenilado do ácido benzóico (ácido 4-hidroxi-3-[3',7'-dimetil-1'-oxo-octa-2'-E-6'-dienil]-benzóico), uma amida isobutílica (piperlonguminina) e duas amidas piperidínicas (piperina e diidropiperina). As substâncias isoladas tiveram suas estruturas químicas determinadas por experimentos de espectrometria de massas, RMN de ¹H e ¹³C e comparadas com os dados da literatura.

The crude extracts of the roots of Piper crassinervium was submitted to chromatographic steps yielding eight compounds including a flavanone (5,4'-dihydroxy-7-methoxyflavanone [isosakuranetin]), two prenylated hydroquinones (1,4-dihydroxy-2-[3',7'-dimethyl-1'-oxo-2'-E-6'-octadienyl]-benzene and 1,4-dihydroxy-2-[3',7'-dimethyl-1'-oxo-2'-Z-6'-octadienyl]-benzene), one chromene (2-methyl-2-[4'-methyl-3'-pentenyl]-2H-1-benzopyran-6-carboxylic acid), one prenylated derivative of benzoic acid (4-hydroxy-3-[3',7'-dimethil-1'-oxo]2'-E-6'-octadienyl-benzoic acid), one isobutyl amide (piperlonguminine) and two piperidine amides (piperine and dihydropiperine). The structures of the isolated compounds were determined by mass spectrometry, ¹H and ¹³C NMR data by comparison with the literature data.