| dc.description.abstract | Despiteefforts to eradicate malaria, it remains a deadly disease with severe pathophysiological
impacts, due to parasitic resistance to available drugs. The success of plant-based drugs
motivated a study aimed at evaluating anti plasmodial and other pharmacologically active
principles from the plants, Caesalpinia volkensii (Leguminocae) root- and stem-bark, Senna
didymobotrya (Leguminocae) roots and Vitex doniana (Lamiaceae) stem-bark, which have been
used to manage malaria and other ailments by different African communities. Antiplasmodial,
analgesic, anti-inflammatory, antidyslipidaemic, and antioxidants bioassay guided isolation and
spectroscopic characterization of compounds on the three plants were carried out by subjecting
their crude extracts, fractions, and pure isolates to: in vitro anti plasmodial assay, in vivo
antinociceptive and anti-inflammatory assay, in vivo hyperlipidaemic assays followed by in vitro
adipocyte differentiation inhibition, and in vitro antioxidant assays. Two new furanoditerpenes
[Ic.Su-dihydroxyvoucapane (400) and 1a,6~-dihydroxyvoucapane-19~-methyl ester (401)]
together with voucapan-5a-ol (19), caesaldekarin C (38), deoxycaesaldekarin C (95), voucapane
(398), 5-hydroxyvinhaticoic acid (399), triacontanyl-(E)-ferrulate (402), triacontanyl-(E)-
cafIaete (403) and 30'-hydroxytriacontanyl-(E)-ferulate (404) were isolated from the root bark of
C. volkensii. The furanoditerpenes 19, 38, 95, 401 at 100 mg/kg, showed significantly (P:S0.05)
high antinociceptive activities in the two chemical models of nociception, however, the
compounds showed low to moderate (25-50~ antiplasmodial activities. Triacontanyl-Ecinnamoates
(402, 403 and 404) exhibited significant (p:S0.05) superoxide (02) scavenging,
hydroxyl radical (OH·) and lipid peroxidation inhibitions. Three new cas sane diterpenes
[voulkensin A, (408), voulkensin B, (407), and voulkensin A, (406)] and one new steroidal
glycoside [3-0-[~-glucopyranosyl(l ~ 2)-O-~-xylopyranosyl]-stigmasterol (409)] together with
oleanolic acid (185), 3-~-acetoxyolean-12-en-28-methyl ester (406), stigmasterol (176) and ~-
sitosterol (177) were isolated from the stem bark of C. volkensii. The novel diterpenes [406-408]
and 409 exhibited moderate (2-22J.tM) antiplasmodial activities. Seven anthraquinones,
chrysophanol (269), physcion (273), natalo-emodin-8-methyl ether (279), obtusifolin (285),
chrysophanol-I 0, 10'-biathrone (295), physcion-l 0,10' -bianthrone (299), 1,6-0-dimethylemodin
(410), and 176 were isolated from the roots of S. didymobotrya. These anthraquinones showed
significant (P:SO.Ol) lipid lowering and significant (p:S0.05) antioxidant effects, with 299 (50~M)
exhibiting potent (P::;O.05) adipocytes growth inhibition. Four new phytoecdysteroids, 2,3-
acetonide-24-hydroxyecdysone (411), I I -hydroxy-20-deoxyshidasterone (412), 21-
hydroxyshidasterone (413) 2,3-acetonide-22-0-~-glucosyl-20-hydroxyecdysone (415) together
with a known 24-hydroxyecdysone (414) were isolated from V doniana stem bark. These
ecdysteroids (1Omglkg) displayed potent in vivo anti-inflammatory activities comparable
(P:::;O.05)to diclofenac (50mg/kg). Compound 415 showed appreciably dose-dependent
inhibition of adipocytes maturation by 29, 31 and 42% at 0.1, 10 and 50J.lM. These results
supported the applications of the investigated plants in management of malaria and the cited
pathophysiological conditions in ethnomedicine. | en_US |
