J Ethnopharmacol. 2016 Sep 16. pii: S0378-8741(16)30876-5. doi: 10.1016/j.jep.2016.09.035. [Epub ahead of print]
- 1Department
of Pharmaceutical Chemistry, Section Pharmacognosy, School of Pharmacy,
University of Oslo. P. O. Box 1068 Blindern, N-0316 Oslo, Norway.
- 2Department of Traditional Medicine, BP 1746, Bamako, Mali.
- 3Department
of Pharmaceutical Chemistry, Section Pharmacognosy, School of Pharmacy,
University of Oslo. P. O. Box 1068 Blindern, N-0316 Oslo, Norway.
Electronic address: helle.wangensteen@farmasi.uio.no.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE:
Syzygium
guineense has been traditionally used in Mali in West Africa for the
treatment of different diseases such as stomach problems, wounds,
inflammations and various female disorders.
AIMS OF THE STUDY:
1)
To perform an ethnopharmacological survey on the traditional use of S.
guineense among Malian healers. 2) To isolate and identify chemical
constituents from S. guineense leaves and to study their radical
scavenging and enzyme inhibitory effects.
MATERIALS AND METHODS:
In
four different districts in Mali, 44 healers were interviewed about
their medicinal use of S. guineense. A methanol extract of the leaves of
this tree was prepared and further fractionated using different
chromatographic methods. Isolated compounds were identified by 1D and 2D
NMR spectroscopy. Extracts and isolated compounds were investigated as
DPPH radical scavengers and as inhibitors of xanthine oxidase and
15-lipoxygenase, and the methanol extract was tested for toxicity
towards Artemia salina nauplii.
RESULTS:
Major
uses by Malian healers were against dermatosis, pain, malaria/fever and
for wound healing. There was little consensus about the use in the
different districts. Leaves were most commonly used. From the methanol
leaf extract, the flavonoids gallocatechin (1), myricetin (2),
myricetin-3-O-glucoside (3), myricetin-3-O-rhamnoside (4),
myricetin-3-O-glucuronide (5) and
myricetin-3-O-β-d-(6"-galloyl)galactoside (6), the gallotannins
1,2,3,6-tetra-O-galloyl-β-d-glucose (7) and
1,2,3,4,6-penta-O-galloyl-β-d-glucose (8), and the ellagitannins
casuarictin (9) and casuarinin (10) were isolated. These ten polyphenols
are all new for the species. The crude methanol extract was active as a
radical scavenger and as an inhibitor of xanthine oxidase and
15-lipoxygenase. Among the isolated compounds, pentagalloylglucose was
the best enzyme inhibitor (IC50 25 ± 4 μM for 15-lipoxygenase, 8 ± 1 μM for xanthine oxidase), while casuarictin (IC50 3.9 ± 0.1 μM), casuarinin (IC50 4.5 ± 0.3 μM) and pentagalloylglucose (IC50 5 ± 1 μM) showed the highest radical scavenging activity. The methanol extract was non-toxic to Artemia salina nauplii.
CONCLUSION:
S.
guineense leaves are commonly used among Malian healers, however the
traditional practice varies a lot between different regions. The leaves
of S. guineense are rich in polyphenols; several are galloylated, either
as galloylated flavonoids, gallotannins or ellagitannins. The high
content of biologically active polyphenols might be important for
medicinal effects of this plant and might give a rationale for the
widespread usage of S. guineense in Mali.
Copyright © 2016. Published by Elsevier Ireland Ltd.
KEYWORDS:
15-lipoxygenase; DPPH; Syzygium guineense; antioxidants; ethnopharmacology; xanthine oxidase
