Om Dutt Tyagi

Phytochemistry of the genus Piper

Abstract The secondary metabolites isolated from Piper species for the period 1907 to June 1996 have been reviewed. Nearly six hundred chemical constituents belonging to different classes of bioactive compounds are listed together with their source(s) and references.

Polyphenols and alkaloids from piper species

Abstract Thirty eight compounds of different types have been isolated from twelve Piper species. The ether extract of the leaves of P. aduncum yielded eleven compounds, out of which 2,6-dimethoxy-4-(2-propenyl)phenol was isolated for the first time from the genus Piper and 2-acetoxy-1,3-dimethoxy-5-(2-propenyl)benzene is a new compound. The petrol extract of the stems and leaves of P. attenuatum furnished a novel long chain alcohol, 14-benzo 1 , 3 dioxol-5-yl-tetradecan-2-ol. From P. betle, β-sitosteryl palmitate was isolated for the first time from the genus Piper. A novel amide, 3-(3,4-dimethoxyphenyl)propanoyl pyrrole has been obtained from P. brachystachyum. Nerolidol was isolated for the first time from P. falconeri. From the methanol extract of the stems and leaves of P. khasiana, piperlonguminine, piperine, apigenin dimethyl ether and β-sitosterol were obtained. Retrofractamide A was obtained for the first time from P. longum; the structure of (+)-asarinin, isolated from P. longum, was confirmed by X-ray crystallographic studies. Retrofractamide A, apigenin dimethyl ether, tetratriacontanol and tectochrysin were isolated from P. manii. P. pedicellosum furnished β-sitosterol, pellitorine, piperlonguminine, cepharadione A and furacridone, the last compound being isolated for the first time from the genus Piper.

Lignans and neolignans from Piper schmidtii

Abstract The unknown enantiomeric lignan (−)-machilin G and the known lignans (+)-calopiptin, (−)-zuionin A as well as a new neolignan kadsurin A and known neolignans futoquinol, isodihydrofutoquinol A, isodihydrofutoquinol B, along with parsley apiole, have been isolated from the leaves and stem of Piper schmidtii . The unpublished 13 C NMR data of the above known neolignans and the reassignment of the 1 H NMR spectrum of isodihydrofutoquinol B are also reported.

An aristolactam from Piper acutisleginum and revision of the structures of piperolactam B and D

Abstract A new aristolactam, 10-amino-4-hydroxy-2,3-dimethoxyphenanthrene-1-carboxylic acid lactam, was isolated from the stem of Piper acutisleginum . The structures of two related alkaloids, piperolactam B and D, have been revised.

Neolignans and a lignan from Piper clarkii

Abstract Four new compounds, a lignan and three neolignans, together with one known neolignan have been isolated from the leaves and stems of Piper clarkii . Their structures were established on the basis of 1 H, 13 C and 1 H 1 H COSY NMR, NOE and mass spectral data and CD curves. The novel lignan was identified as (2 S ,5 S )-diveratryl-(3 R ,4 S )-dimethyltetrahdrofuran. The structures of the new neolignans were established as (7 R ,8 R ,1′ S )- Δ 8′ -1′-methoxy-3,4-methylenedioxy-1′,6′-dihydro-6′-oxo-7.0.4′,8.3′-lignan[2 R ,3 R ,5 S )-2-(1,3-benzodioxol-5-yl)-3,5-dihydro-5-methoxy-3-methyl-5-(2-propenyl)-6(2H)-benzofuranone], (7 S ,8 S ,3′ R )- Δ 8′ -3,3′,4-trimethoxy-3′,6′-dihydro-6′-oxo-7.0.4′,8.3′-lignan[2 S ,3 S ,3 aR )-2-(3,4-dimethoxyphenyl)-3,3a-dihydro-3a-methoxy-3-methyl-5-(2-propenyl)-6(2H)-benzo-furanone] and rel-(7 S ,8 S ,1′ R ,3′ R )- Δ 8′ -5′-methoxy-3,4-methylenedioxy-1′,2′,3′,4′-tetrahydro-2′,4′-dioxo-7.3′,8.1′- lignan[(7 S ,6 S ,5 R ,1 R )-7-(1,3-benzodioxol-5-yl)-3-methoxy-6-methyl-5-(2-propenyl)bicyclo[3.2.1]oct-3-ene-2,8-dione]. The known neolignan has been identified as denudatin B.

Biotransformations in the regioselective deacetylation of polyphenolic peracetates in organic solvents

Regioselectivity has been observed in the deacetylation of peracetates of polyphenolic aromatic ketones by lipases from porcine pancreas (PPL) and Candida cyclindracea (CCL) suspended in organic solvents. The deacetylation of acetoxyl groups at positions para and meta to the carbonyl (ketonic) group is favoured over the one at the ortho position.

A wax ester from Piper clarkii

Abstract A novel type of wax ester has been isolated from a petrol extract of stems and leaves of Piper clarkii and its structure established as 3-(4-hydroxyphenyl)propyl tetracosanoate. The structure was verified by synthesis. The oxygenated cyclohexane (+)-crotepoxide and β-sitosterol were also isolated.

Neolignans and an isoprenylated phenol from Piper clarkii

Abstract The stems and leaves of Piper clarkii have yielded two new neolignans [nomenclature follows Gottlieb, O. R. (1978) Prog. Chem. Org. Nat. Prod. 35 , 1], rel-(7R,8R,1′S,3Ŕ,4′S)-Δ 8′ -1′,2′,3′,4′-tetrahydro-4′-hydroxy-5′- methoxy-3,4-methylenedioxy-2′-oxo-7.3′,8. 1′-lignan (clarkinol) and (7R,8R, 1′S)-Δ 8′ - 1′,6′-dihydro- 1′,3,4-trimethoxy-6′- oxo-7.0.4′,8.3′-lignan, as well as the new isoprenylated phenol, 2-(3-methyl-2-butenyl)-3,4,5-trimethoxyphenol. In addition, velutin (3′,7-dimethoxy-4′,5-dihydroxyflavone) and a known neolignan (7R,8S,l′S)-Δ 8′ -1′,4′-dihydro-5′- methoxy-3,4-methylenedioxy-4′-oxo-8. 1′,7.0.2′-lignan, are reported and the 1 H NMR data of the latter are reassigned.

New antibacterial tetratriacontanol derivatives from Agave americana L.

Abstract Three biogenetically related compounds have been isolated from Agave americana L. namely 5-hydroxy-7-methoxy-2-tritriacontyl-4H-1-benzopyran-4-one, tetratriacontyl hexadecanoate and tetratriacontanol. Two of them exhibited significant antibacterial activity.

A benzoic acid ester from Uvaria narum

Abstract A new benzoic acid ester, 2-E-[2″-oxo-cyclopent-3″-en-1″-ylidene]ethyl benzoate, together with tritriacontane, tetratriacontanol and β-sitosterol have been isolated from a petrol extract of the leaves of Uvaria narum. The structure of the new ester has been established on the basis of spectral data and finally confirmed by X-ray crystallography. Glut-5(6)-en-3-ol and betulapren-11-ol have also been isolated from a petrol extract of the leaves and stems of U. hookeri; this is the first report of the isolation of the latter compound from the genus Uvaria.