310
zy
zyxw
zyxw
zyx
zyxwv
zyxwv
Journal of Natural Products
Vol. 49, No. 2,pp. 310-312, Mar-Apr 1986 zyxwvu
NAPHTHOQUINOIDS FROM LIPPIA SIDOZDES
L.M.A. MACAMBIRA’,
C.H.S. ANDRADE,F.J . A . MATOS, A.A. CRAVEIRO,
Laboratdrio de Produtos Naturais Associado ao CNPq, Departamto de Quimica Orgrinica e lnwgrinira,
Centro de Ciinrias da UFC, Caixa Postal, 301 0, Fwtaleza, Ceura, Brazil
and R. BRAZ FILHO
Universiahk F e h a l Rural ah Rio deJaneiro, Institute de Ciinrias Exatas,
Departamento de Quimica, 23460, Sercipedica, Rio deJaneiro, Brazil
Lippia sidoides Cham. (Verbenaceae) is
an aromatic shrub, widespread in occurrence in the deciduous vegetation
“caatinga” of Northeastern Brazil. Our
specimen was collected near Mossoro in
the state of Rio Grande do Norte. Observations of the use of an aqueous extract of
leaves by rural populations verified the
presence of healing and antiseptic effects. Some chemical and pharmacological studies of this plant were made previously, including chemical analysis of the
essential oils of the leaves, which contain
thymol and carvacrol as major constituents ( 2 ) . The essential oil shows
bactericidal, bacteriostatic, fungicidal,
and fungistatic activities against
Staphylococcus aureus and other microorganisms (3). The residual water resulting from the steam distillation process
presented several pharmacological effects on isolated organs and promoted
arterial hypotension on rats (4).
Interesting naphthoquinoids have
been reported in plants of the genus Lippia (5,6),but no mention is made of
their occurrence in L. sidoides. These observations and demonstration of several
biological activities in preparations of
this plant stimulated us to reexamine the
chemical constituents of the species,
especially the nature of the nonvolatile
components.
The following substances were identified in the methanolic extract of leaves
and branches: palmitic acid, stearic acid,
behenic acid, arachidic acid, lignoceric
‘This work is part of the M.S. thesis submitted
by L.M.A. Macarnbira to Universidade Federal
do Ceara.
acid, thymol, carvacrol, p-sitosterol,
lapachenol, isocatalponol, and a new
substance, 6-oxo-3,4,4a,5-tetrahydro3-hydroxy-2,2-dimethylnaphtho-1,2pirane (1). All substances but the last
were reported previously in plants of the
genus Lippia but not in this species.
1
zy
The ir spectrum of the new substance
(1) presented an absorption at 3530
cm-’ assignable to a nonassociated OH
group as well as absorptions for an
aromatic ketone (1670 cm-’), an
aromatic double bond (1580 cm- ’), for
four adjacent hydrogens in an aromatic
ring (775 cm-’), and an indication of a
cyclic ether (1280 crn-’) (7). Absorption at 256 nm in the uv spectrum confirmed the presence of a carbonyl group
conjugated with the aromatic ring (8).
The presence of this carbonyl group is
also supported by an absorption at S196.7 in the 13C-nmr spectrum (9).The
ms of 1 presented a significant peak at
246 daltons assignable to a molecular
ion of C15H1803as a molecular formula.
The ‘H-nrnr spectrum of 1 taken at 60
MHz in CDCI, contained the following
signals: (a) a multiplet from 7.3 to 8.0
8, corresponding to four aromatic protons; (b) a one hydrogen doublet at 4.56
(J=9.0Hz) in agreement with absorp-
zyxw
zyxwvuts
zyxw
zyxwv
zyxwvuts
zyxwvu
Mar-Apr 19861
Macambira et a / .: Naphthoquinoids
tion due to a proton on a benzylic carbon
bonded to oxygen; (c) a one hydrogen
quartet centered at 3.6 SY=5.0 and
12.0 Hz) attributed to a carbinolic proton; (d) a broad absorption at 2.5 6 corresponding to one hydrogen assignable
to an axial methynic proton; (e) a two hydrogen multiplet from 2.4 to 2.7 6 corresponding to the methylene protons of
carbon five; (0 a multiplet from 1.9 to
2 . 2 6 attributed to two aliphatic protons
of carbon four; (g) two 3-hydrogen
singlets at 1.3 and 1.4 corresponding to
the two gem methyl groups.
The PND 13C-nmrspectrum showed
the presence of 15 spectral lines in agreement with the proposed molecular formula. In addition to the carbonyl (196.7
6), six aromatic carbons are clearly present (131.0, 144.6, 125.0, 127.4,
126.8, and 134.0 6). Three carbons are
bonded tooxygen(76.5,73.4, and70.8
6), one carbon is in the vicinity of a carbonyl (43.1 6), and four aliphatic carbons (16.2, 28.1, 39.8, and 35.0 6) are
observed. Specific assignments are given
in the Experimental section. The placement of the hydroxyl group at carbon 3
instead of carbon 4 was possible from
analysis of 13C-nmrspectrum where the
difference in absorptions of the gem
methyl groups (28.1 and 16.2 6) can be
attributed to the y-effect of the hydroxyl
in the vicinity. Furthermore, it is
reasonable to propose isocatalponol (2)
as the biosynthetic precursor which, by
cyclization, produces 1. In fact, treatment of isocaltalponol (2) with mchloroperbenzoic acid in CHCI, followed by reaction with BF,. Et,O gave
1, identical, by tlc in three systems of
solvent and 'H-nmr spectrum, with the
natural product. The same argument
311
also favors positioning the hydroxyl at
position 3. Acetylation of 1 gave a
monoacetyl derivative, confirming the
presence of a secondary aliphatic hydroxyl.
The proposed structure (1)for this
naphthoquinoid has no parallel in the
literature. as far as we know.
EXPERIMENTAL
GENERALEXPERIMENTAL PROCEDURES.Mps were determined on a Mettler FP-5/52 and
are uncorrected. Spectral data were obtained on
the following instruments: ir, Perkin-Elmer
Model 283-B; 'H nmr, Varian EM-360; I3C
nmr; Varian XL-100; ms, Hewlett, Packard H P
5995A; gc/ms, HP-5933 equipped with datasystem; uv, Varian Model 634-S. Adsorbents for cc
and tlc, silicagel 60, 230-400 mesh and silica gel
60 tlc plates 250 mesh were purchased from
Merck and Co.
zyxwv
PLANT MATERIAL.-haves
and branches of
L. sidoiah were collected around Mossoro, Rio
Grande do Norte, in the semiarid area of the
Brazilian Northeast in June 1981. Voucher specimens are deposited in the "Herbario Prisco Bezerra" of the Universidade Federal do Ceara, Fortaleza-Cad, Brazil.
EXTRACTIONAND PURIFICATION.-Dried
parts (23 g) were extracted with MeOH in a
Sohxlet apparatus, giving 760 g of a resinous extract. This material (250 g) was adsorbed on silica
gel (500 g) and eluted with CHCI,, Me,CO, and
MeOH successively to give fractions of 41.9 g,
107.6 g , and 80.6 g. These fractions were submitted to fractionation by repetitive cc to give a
fixed oil, an aromatic volatile oil, four known
solid substances, and the new naphthoquinone
zyxw
zyxw
2
(1).
The fixed oil was treated with BF,-MeOH
complex, and the product was extracted with
hexane. Gdms analysis of the hexane extractives
gave five peaks which were compared with ms
spectra and retention times of standard methyl
esters of fatty acids and identified as the methyl
esters ofpalmitic, stearic, arachidic, behenic, and
lignoceric acids.
The volatile oil was obtained by further cc of
the Me,CO eluate and is showed by gc/ms analysis two major components that were identified as
thymol and carvacrol by comparison of their ms
and Kovat's indices with standards.
6,7-Dimethoxy-5,4'dihydroxyflavone
was isolated by silica gel cc of the Me,CO eluate and recrystallized from CHCI3-Me,CO to give an
amorphous yellow solid, 50 mg, with mp 285288" (10.11). p-Sitosterol was isolated (970 mg)
from the CHCI, eluate by further cc and purified
zyxwvutsrq
zyz
3 12
Journal of Natural Products
P o l . 49, No. 2
lowed by workup produced 1(0.0235 g) identical
by repetitive precipitations with MeOH until
with natural naphthoquinoid (1). ‘H nmr 7.9pure, mp 136-139”. Lapachenol was isolated
7.1 (m, 4, ArH), 4.5 (d, 1.10 Hz, H-la), 3.6
(100.0 mg) from the CHCI, eluate by repetitive
(dd,]=5.0 Hz and]=12.0 Hz, 1, H-3), 2.3cc. Recrystallization of the main fraction gave a
2.7 (m, 3, H-4 and H-5), 1.7-2.2 (m, 2, H - 4 ,
yellow solid, mp 57-60”. Its ir, ’H nrnr, and
1.45 (s, 3, CH,), 1.35 (s, 3, CH3).
mass spectra were identical to those obtained
from an authentic sample (5). Isocatalponol was
ACKNOWLEDGMENTS
isolated by cc of the CHCI, eluate followed by deThis
work
was supported by grants from the
colorizing with charcoal and a new cc to give neeBrazilian
institutions
CNPq and FINEP. We
dles (150.0 mg), mp 78-79’, Its mp, ir, ‘H nmr,
would like to thank Prisco Bezetra and Afdnio G.
and mass spectra were in agreement with those of
Fernandes from the Herbarium of Universidade
isocatalponol(6,12). zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
Federal do Cead for collection and botanical iden6-OXO-3,4,4A-5-TETRAHYDRO-3-HYDROXY- tification of the plants.
2,2-DIMETHYLNAPHTHO C1,21 P Y R A N (I).LITERATURE CITED
Obtained by cc of the Me,CO eluate. Recrystal1. A.A. Craveiro, J.W. Alencar, F.J.A.
lized from C6H6, mp 148-149’, M+ 246.
Matos, C.H. S. Andrade, and M. I.L.
C,,H1,O3; ir Y max (IU3r) 3530, 3050, 1670,
Machado,]. Nat. Prod., 44, 679 (1980).
1580, 1450, 1280, 1250, 1110, 1070, 1050,
2. A.A. Craveiro, A.G. Fernandes, C.H.S.
1020, 775, 640 cm-’; ms m/z (96)246 (M+, l),
Andrade, F.J.A. Matos, J.W. Alencar,
228 (l), 188 (lo), 157 (3), 145 (26), 144 (loo),
and M.I.L. Machado, “Oleos Essenciais de
129 (4), 116 (23), 115 (28), 105 (2,2), and 91
Plantas do Nordeste,” ed. UFC, 1980, p.
(3); ‘H nmr (60 MHz, CDCI,) 6 8.02-7.30 (m,
110.
4,ArH),4.5(d,]=9.0Hz, l,H-la),3.63(dd,
3. M.L.B.A. Aguiar, F.J.A. Matos, and
]=5.0; 12.0 Hz, 1, H-3), 2.50 (m, 1, H-4a),
V.L.A. Moura, CiEncia e Cultura, 36 (7),
2.40-2.70 (m, 2, H-5), 1.99-2.20 (m, 2, H-4),
Suplemento, 547 (1984).
1.41 (s, 3, CH,), 1.30(s, 3, CH,); 13Cnmr(25.2
4. F.F. Matos, “Efeitosfarmacologicos de LipMHz, CDCI, 6 196.7 (s, C-6), 144.6(s, C-loa),
pia sihides Cham.” Disset-racio de Mes134.0 (d, C-9), 131.0 (s, C-7a), 127.4 (d, C-7),
trado, Universidade Federal do Ceara, For126.8 (d, C-8), 125.0 (d, C- lo), 76.5 (s, C-2),
taleza-ce., 1980.
73.4 (d, C-la), 70.8 (d, C-3), 43.1 (t, C-5), 39.8
5. A.R. Burnett and R.H. Thomson, /.
(d, C-4a), 35.0 (t, C 4 ) , 28.1 (q, CH, eq.), and
Chem. Soc. (C), 2100 (1967).
16.2 (9, CH, ax.);{CX]*’D +22.46.
6. K. Inowe, H . Inone, T. Taga, R. Fugita,
6-oX0-3,4,4A,
5-TETRAHYDRO-3-HYDROXYK. Osaki, and K. Kukiyama, Chem.
2,2-DIMETHYL-NAPHTHOC1,21PYRAN ACETATE.
Phann. Bull., 28, 1224 (1980).
-To pyridine (1.0 ml) and Ac20 (2.0 ml) was
7. R.M. Silverstein, G.C. Bassler, and T.C.
added l ( 2 5 0 mg). The reaction mixture was kept
Morril, “SpectrometryIdentification of Orfor 24 h at room temperature. Usual workup gave
ganic Compounds,” 3rd ed.,John Wiley &
an oil. ‘H nmr (60 MHz, CDCI,) 6 8.02-7.3 (m,
Sons Inc., NewYork, 1974, pp. 73-117.
4, ArH), 4.6 (d, /= 10.0 Hz, H- la), 4.7 (dd,
8. E.M. Peixoto, R. Pinchin, and A.C.
]=5.0 and 12.0 Hz, 1, H-3), 2.5 (m, 3, H-4a
Pinto, Citncia e Cultura, Suplemento, 125
and H-5), 2.2-1.8 (m, 2, H-4), 2.08 (s, 3, CH3(1978).
C=O), 1.43 (s, 3, CH,), 1.36 (s, 3, CH,); 13C
9. F.W. Wehrli and T . Nishida, “Progress in
nrnr (25.2 MHz, CDCI,) 6 195.9(s, C-6), 170.2
the Chemistry of Organic Natural Prod(5, CH,-C=O), 133.8 (d, C-9), 130.8 (s, C-7a),
ucts.” Ed. by L. Zechmeister, Springer
127.4 (d, C-7), 126.9 (d, C-8), 124.7 (d, C-lo),
Verlag, Vienna, Vol. 36, 1979, p. 125.
74.6 (s, C-2), 74.5 (d, C-la), 70.7 (d, C-3). 42.7
10. C.H. Brieskokn and W . Biechele, Tet(t, C-5), 39.0 (d, C-4a), 31.4 (t, C-4), 27.9 (9,
rahedron Letterr, 31,2603 (1969).
CH, ax), 2 1.1 (9, CH,-C=O), 17.6 (q, CH, eq.).
11. J . W . Wallace, Phytochemistry, 10, 452
(1971).
SYNTHESISOF l.-Isocatalponol(O.304 g) in
C.H. Brieskorn and R. Pohlmann, Arch.
12.
CHCI, (5.0 ml) was treated with m-chloroperPharm., 309,829 (1976).
benzoic acid (0.226 g) in CHCI,. Treatment of
Rereived 22 May I985
the reaction mixture with BF3*Et20(traces) fol-
zyxw
zyxwvut
zyxwvuts
zyx
zy
zyx