Enzyme Inhibitory Constituents from Duranta repens.

Abstract

The genus Duranta (Verbenaceae) comprises about 35 species which are distributed in tropical and sub-tropical regions. The literature survey revealed that very little phytochemical work has been carried out on the genus Duranta, and only some steroids, 1) triterpenes 2) and iridoids 3) have so far been reported. Duranta repens LINN. is widely distributed in northern parts of Pakistan and finds various medicinal uses in the indigenous system of medicine. The fruits of this plant afford a medicine for the treatment of malaria.4) The methanolic extract also shows insecticidal and antifeedant properties.5) Previously, diterpenoids and flavonoids have been reported. 6) Our preliminary pharmacological screening of the methanolic extract revealed inhibitory activity against both thrombin and prolyl endopeptidase enzymes. This prompted us to carry out the phytochemical studies on this plant. We now report the isolation and structure elucidation of the two new isoprenylated flavonoids 1 and 2, and of an isoprenylated acetophenone derivative 3, along with the known compounds, 5-hydroxy-3,6,7,4Ј-tetramethoxyflavone (4), 7) rosenonolactone (5), 8) 6,7-dimethoxycoumarin (6), 9) 5a,8a-epidioxyergosta-6,22-dien-3b-ol (7) 10) and 5a,8a-epidioxyergosta-6,9(11),22-trien-3b-ol (8) 11) isolated for the first time from this species.Prolyl endopeptidase (PEP, EC 3.4.21.26) is the only serine protease which is known to cleave a peptide substrate in the C-terminal side of a proline residue.12) Prolyl endopeptidase has been suggested to play an important role in the biological regulation of peptide hormones such as vasopresssin, oxytocin, substance P, angiotensin and others.13) Moreover alterations of PEP enzyme level and activity seems to be associated with several health disorders such as Alzheimer's disease, depression, mania, thrombosis, AIDS and cancer. 14)Specific inhibitors of PEP are expected to have anti-amnesic effects. Many PEP inhibitors have been synthesized as candidates for the treatment of neuropathological disorders. 15) In the course of this work we have evaluated compounds 1-5 for their enzyme inhibiting activity. The compounds 1 and 2 showed strong inhibitory activity against PEP while 3-5 showed moderate activity. Moreover 4 and 5 also showed strong inhibitory activity against thrombin. The compounds 6-8 did not show enzyme inhibiting activity. April 2002Chem. Pharm. Bull. 50(4) 515-518 (2002) 515 * To whom correspondence should be addressed. Karachi-75270, Pakistan. Received November 26, 2001; accepted January 22, 2002 Isoprenylated flavonoids 5,7-dihydroxy-3- (2-hydroxy-3-methyl-3-butenyl)-3,6,4-trimethoxyflavone (1), 3,7-dihydroxy-3-(2-hydroxy-3-methyl-3-butenyl)-5,6,4-trimethoxyflavone (2) and an isoprenylated acetophenone derivative (3) have been isolated from Duranta repens along with known compounds, 5-hydroxy-3,6,7,4-tetramethoxyflavone (4), rosenonolactone (5), 6,7-dimethoxycoumarin (6), 5a a,8a a-epidioxyergosta-6,22-dien-3b b-ol (7) and 5a a,8a a-epidioxyergosta-6,9(11),22-trien-3b b-ol (8), isolat...

Two new anti-plasmodial flavonoid glycosides from Duranta repens

“…The MeOH extract of the plant also shows insecticidal and antifeedant properties against Aedes aegypti and Attagenus piceus, respectively 4 . Previous studies on the genus Duranta have resulted in the isolation of various compounds, including coumarinolignoids 5 , (E)-cinnamic acid, (E)-p-methoxycinnamic acid 6 , diterpenoids 7,8 , flavonoids 7,8 , steroids 9 , glycosides of phenylpropanoids 10,11 , triterpenes 12 , and iridoids 6,13,14 . Malaria is one of the most common infectious diseases in tropical and subtropical countries, including parts of the Americas, Asia, and Africa.…”

“…The structures of the known compounds (3-7) were established by comparison of their spectral data with literature values 7,8,20 . The two new flavonoid glycosides (1, 2) and the known flavonoids (3-7) described in this study were tested for anti-plasmodial activities against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum.…”

Characterization of oils fromDuranta repensleaf and seed

“…Duranta repens also known as yellow bush (the leaves) or pigeon berry (the seeds) is a fast growing, large, spreading shrub with numerous stems that reaches a height of 1-3 m (Okunlola, 2013). It belongs to the Verbenaceae family with the genus Duranta made up of about 35 species (Anis et al, 2002). Rowezak (2001) suggested that the fragrant pale blue flowers coupled to the golden orange berries make the plant appear very attractive.…”

New Bioactive Diterpene Polyesters from Euphorbia decipiens

“…11 Low molecular weight inhibitors of PEP have been reported in the literature, but the majority of these are of synthetic origin. In turn most of the natural PEP inhibitors are of microbial origin.…”