Piper Nigrum is known as black pepper

Piper Longum has a compound called piperine.

Testosterone 5alpha-reductase inhibitory active constituents of Piper nigrum leaf.
Biol Pharm Bull. 2007 December. Hirata N, Tokunaga M, Naruto S, Iinuma M, Matsuda H. School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan.
Previously we reported that Piper nigrum leaf extract showed a potent stimulation effect on melanogenesis and that (-)-cubebin (1) and (-)-3,4-dimethoxy-3,4-desmethylenedioxycubebin (2) were isolated as active constituents. As a part of our continuous studies on Piper species for the development of cosmetic hair-care agents, testosterone 5alpha-reductase inhibitory activity of aqueous ethanolic extracts obtained from several different parts of six Piper species, namely Piper nigrum, Piper methysticum, Piper betle, Piper kadsura, Piper longum, and Piper cubeba, were examined. Among them, the extracts of Piper nigrum leaf, Piper nigrum fruit and Piper cubeba fruit showed potent inhibitory activity. Activity-guided fractionation of Piper nigrum leaf extract led to the isolation of 1 and 2. Fruits of Piper cubeba contain 1 as a major lignan, thus inhibitory activity of the fruit may be attributable to 1. As a result of further assay on other known constituents of the cited Piper species, it was found that piperine, a major alkaloid amide of Piper nigrum fruit, showed potent inhibitory activity, thus a part of the inhibitory activity of Piper nigrum fruit may depend on piperine. The 5alpha-reductase inhibitory activities of 1 and piperine were found for the first time. In addition, the Piper nigrum leaf extract showed in vivo anti-androgenic activity using the hair regrowth assay in testosterone sensitive male C57Black/6CrSlc strain mice.

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