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Further flavonoids from Piscidia erythrina
Phyrochcmitrry, Vol. 25, No. 6. pi. 1505-1506.1986. Printedin Oreat Britain.
FURTHER
0031~9422/86f3.00 + 0.00 Q 1986Pwgmorl PrcmLtd.
FLAVONOIDS L. LABBIENTO, F.
Cmtro Chimica dci Rcxxttori de1 C. N. R.. c/o
lDipartimento
MENICHINP
PISCIDIA
ERYTHRINA
and F. DELLEMONAcHEt
Istitutodi Chimia, Universitl Cattolica,Vii Pineta%a%etti,644.00168 ROM, My;
di Chimica, Univeniti (Rccebed
Key Word Idex-Piscidia
FROM
erythrtnq Lcguminosae;
della Calabr&
Arcavacata di Rcnde (Ca), Italy
19 Sepoem&r1985) roots; llavanone; irotlavone.
Abtract-Wrenylpinocembrin and 5,7,4’-trihydroxy-3’,5’-di-(A2-isopentenyl) isollavone were isolated and identified from the roots of Piscidia erythrina.
ExPEPlMEMAL
INTRODUCITON We early reported [l] on the isolation from Piscidiu erythrina (Leguminosae) of two new prenyhited isoand 6’-(A’flavones, namely 2’deoxypiscerythrone __. . . . isopentenyl) piscerythrone in addition to pmviously known compounds [2]. This paper deals with the stn~ ture determination of two further minor components which we have now obtained in a pure state.
Em& and isohtfm Forextrrtion ~~~YxI~Iwsee ref.[ 11. Part (14 g) of the re&luc (25 g) from the CHCl, extractof the root bark (3 kg) was chromatographed on silica gel (CIiCl,-MeOH, 19 : 1) yielding roten0id.q fraction C3 and isotlavoncs [ 1J. FractionC3 (1.5g) by CC (C&-EtOAc, 19 : 1) gaveflavanonel(l24 mg)and a mixture(160mg)whichon silica gel (CH,Cl,) affordedfurther quantities of flavanone l(63 mg)
RESULTSAND DISCUSStON The first component, mp 169-170” (M, 324) was a 5,7dihydroxyllavanone substituted by a y,ydimethylallyl chain in the A-ring (spectral evidence) and was assigned structure 1 (&prenylpinocembrin). The location of the chain was supported by the ‘H NMR data in pyridine-& vs deuterochloroform [3] for the H-6 (AS + 0.40 ppm) and for the methylene of the chain (As + 0.25 ppm). Acidcatal@ cyclization of 1 yielded 2 which showed the expected Ad values for H-6 and for the methylene of the chroman ring (+ 0.16 and 0 ppm, respectively). Finally, the natural product with 6_prenylpinocembrin, mp 210“ [4] gave a depressed mp. Structure 1 has been previously assigned by Bohlmann and Abraham [S] to an oily product isolated from Hefichrysum hypouphalwn (Compositae) and the only available data @rtic&rly the broad singlet in the ‘HNMR spectrum for the two methyls of 1 with respect to two broad singlets for the 6isomer) were in accordance with our findings. This is the first report of a tlavanone from P. erythrina, which is nevertheless a known source of isotlavones and rotenoids I?, a 5.6dihydroxy isofiavone containing hydroxyl group in the B-ring It was assigned 3 on of the chemical of the equivalent B aromatic protons in the ‘H NMR spectrum and of to (hf, 424).
tTo whom correspondence
4
HO
should be addressed. 1505
Cl01 /\ OH
0”
-
0
3
\
/ OH
HO
FURTHER
0031~9422/86f3.00 + 0.00 Q 1986Pwgmorl PrcmLtd.
FLAVONOIDS L. LABBIENTO, F.
Cmtro Chimica dci Rcxxttori de1 C. N. R.. c/o
lDipartimento
MENICHINP
PISCIDIA
ERYTHRINA
and F. DELLEMONAcHEt
Istitutodi Chimia, Universitl Cattolica,Vii Pineta%a%etti,644.00168 ROM, My;
di Chimica, Univeniti (Rccebed
Key Word Idex-Piscidia
FROM
erythrtnq Lcguminosae;
della Calabr&
Arcavacata di Rcnde (Ca), Italy
19 Sepoem&r1985) roots; llavanone; irotlavone.
Abtract-Wrenylpinocembrin and 5,7,4’-trihydroxy-3’,5’-di-(A2-isopentenyl) isollavone were isolated and identified from the roots of Piscidia erythrina.
ExPEPlMEMAL
INTRODUCITON We early reported [l] on the isolation from Piscidiu erythrina (Leguminosae) of two new prenyhited isoand 6’-(A’flavones, namely 2’deoxypiscerythrone __. . . . isopentenyl) piscerythrone in addition to pmviously known compounds [2]. This paper deals with the stn~ ture determination of two further minor components which we have now obtained in a pure state.
Em& and isohtfm Forextrrtion ~~~YxI~Iwsee ref.[ 11. Part (14 g) of the re&luc (25 g) from the CHCl, extractof the root bark (3 kg) was chromatographed on silica gel (CIiCl,-MeOH, 19 : 1) yielding roten0id.q fraction C3 and isotlavoncs [ 1J. FractionC3 (1.5g) by CC (C&-EtOAc, 19 : 1) gaveflavanonel(l24 mg)and a mixture(160mg)whichon silica gel (CH,Cl,) affordedfurther quantities of flavanone l(63 mg)
RESULTSAND DISCUSStON The first component, mp 169-170” (M, 324) was a 5,7dihydroxyllavanone substituted by a y,ydimethylallyl chain in the A-ring (spectral evidence) and was assigned structure 1 (&prenylpinocembrin). The location of the chain was supported by the ‘H NMR data in pyridine-& vs deuterochloroform [3] for the H-6 (AS + 0.40 ppm) and for the methylene of the chain (As + 0.25 ppm). Acidcatal@ cyclization of 1 yielded 2 which showed the expected Ad values for H-6 and for the methylene of the chroman ring (+ 0.16 and 0 ppm, respectively). Finally, the natural product with 6_prenylpinocembrin, mp 210“ [4] gave a depressed mp. Structure 1 has been previously assigned by Bohlmann and Abraham [S] to an oily product isolated from Hefichrysum hypouphalwn (Compositae) and the only available data @rtic&rly the broad singlet in the ‘HNMR spectrum for the two methyls of 1 with respect to two broad singlets for the 6isomer) were in accordance with our findings. This is the first report of a tlavanone from P. erythrina, which is nevertheless a known source of isotlavones and rotenoids I?, a 5.6dihydroxy isofiavone containing hydroxyl group in the B-ring It was assigned 3 on of the chemical of the equivalent B aromatic protons in the ‘H NMR spectrum and of to (hf, 424).
tTo whom correspondence
4
HO
should be addressed. 1505
Cl01 /\ OH
0”
-
0
3
\
/ OH
HO