From the mother liquor after removal of piperine by crystallisation, Spring and Stark (1950) obtained an amorphous powder which on crystallisation from ethyl acetate gave two different types of crystalline aggregates, leaf like clusters and opaque wart like deposits. They were mechanically separated and further purified by crystallisation from ethyl acetate. The leaf shaped material yielded piperine and the opaque solid gave highly refractive yellow rods with green sheen. It had a melting point of 146-149°C and analysed for C19H21O3N and it was named piperettine. On hydrolysis with alcoholic potash piperettine gave piperidine and an acid piperettic acid as yellow needles having a m.p. 223-224°C. The acid gave a positive Labat test for a methylene dioxy group and an absorption maximum at 360 nm indicating it could be an analogue of piperic acid and that piperettine is the corresponding piperidide. The structure of piperettine was confirmed as 7-(3,4-methylenedioxy phenyl) hepta 2,4,6-trienoic acid piperidide by synthesis (7). They also analysed black pepper samples from different sources and found piperettine in all the samples ranging from 0.23 per cent in an Indian sample to 1.56 per cent in a sample from Sri Lanka.
By elaborate column chromatography of the residue after removal of piperine by repeated crystallisation, Traxler et al. (1971) obtained a viscous colourless liquid having pungency. It was named piperanine. Based on UV, IR and NMR spectra, its structure was proposed as 5-(3,4-Methylenedioxy phenyl)-2-trans pentenoic acid (8). The structure was confirmed by synthesis. The natural concentrate which could not be crystallised earlier, was crystallised by seeding with the synthetic product. The identity of synthetic piperanine with the natural isolate was established by mixed m.p., UV, IR and NMR spectra.
Grewe et al. (1970) on repeated column chromatography of a methylene chloride extract of black pepper, isolated a new alkaloid named as piperylin, crystallising as colourless needles melting at 142°C. UV and IR spectra resembled that of piperine. The mass spectral fragments were same as those produced in the acid part of piperine, but had a molecular ion at m/z 271. It showed an ion fragment at m/z 70 instead of m/ z 84 for piperidine. The base was suspected to be pyrrolidine and was confirmed by NMR. The structure was confirmed by synthesis of piperylin from piperic acid chloride and pyrrolidine. Piperylin (9) was found to be same as trichostachine isolated from Piper trichostachyon by Singh et al. (1969) Mori et al. (1974) also isolated by preparative thin layer chromatography a compound identified as 1-piperoyl pyrollidide and named it pyrroperine. This compound appears to be same as piperylin isolated by Grewe et al. (1970).
They could also isolate three other alkaloids, oily in nature and highly sensitive to light, by repeated preparative thin layer chromatography and named them piperoleins A, B and C. Piperolein B was obtained almost pure by this method. Based on UV, IR and NMR spectra it was proposed as the piperidide of 9-(3,4-methylene dioxy phenyl) non 8-enoic acid (10). Mass spectrum of the compound confirmed this structure. This was further confirmed by synthesis of piperolein B. Piperolein A and C could not be purified completely. Based on mass spectra, piperolein A appeared to have shorter aliphatic side chain while piperolein C appeared to have a longer aliphatic side chain compared to piperolein B.
10 Piperolein B
Su and Horvat (1981) isolated three insecticidally active compounds present in trace amounts from black pepper. They have been identified as (E,E)-N-(2-methyl propyl)-2,4-decadienamide, (E,E,E)-13-(1,3-benzodioxol-5-yl)-N-(2 methyl propyl)-2,4,12-trideca trienamide and (E,E,E)-11-(1,3-benzodioxol-5-yl)-N-(2-methyl propyl)-2,4,10-undecatrienamide. These compounds have earlier been isolated from various other species of Piper and named as peepuloidin, guineesine and pipericide. Atal et al. (1975) has reported isolation of minor amounts of highly pungent dihydro and tetrahydro piperine from black pepper.
Siddiqui et al. (1997) has recently isolated a new amide named pipericine, and based on spectral data it was identified as the N-butylamide of octadeca-trans-2-cis-4 dienoic acid (11).
Parmar et al. (1997) listed the following alkaloids in addition to those discussed above: brachymide B, guineesine, retrofractamide A, sarmentine, sarmentosine and tricholein.
Was this article helpful?
Acai, Maqui And Many Other Popular Berries That Will Change Your Life And Health. Berries have been demonstrated to be some of the healthiest foods on the planet. Each month or so it seems fresh research is being brought out and new berries are being exposed and analyzed for their health giving attributes.