Abstract
As part of our efforts towards identifying and subsequently developing lead compounds from medicinal plants of Cameroon to combat neglected tropical diseases, we embarked to phytochemically investigate Enantia chlorantha (Syn. Annickia chlorantha). The rationale for choosing this plant is its numerous uses in folk medicine in Cameroon and other parts of Africa. In Cameroon the quaternary protoberberine alkaloids, columbamine (2), palmatine (3) and jatrorrizine (4) have been isolated from the stem back and combined to produce a phytomedicine (HEPAZOR®) used in the treatment of viral hepatitis. An alkaloidal extraction of the methanolic extract of the stem bark of the plant was carried-out and this afforded yellow amorphous solids whose structure was obtained using routine nuclear magnetic resonance spectroscopy (NMR), high pressure liquid chromatography coupled to an electrospray mass spectrometer (HPLC-ESI-MS) and comparison with literature. The compound was identified as pseudopalmatine (1), a quaternary protoberberine alkaloid. Preliminary screening of the compound on both adult and juvenile worms of Onchocerca ochengi, a close relative of Onchocerca volvulus, the parasite responsible for human onchocerciasis (river blindness), showed that compound (1) was inactive at a concentration of 500 μg/mL on the adult worms, but inhibited microfilariae motility completely at this same concentration and by 50 % at 250 μg/mL and was thus considered active. While this work to the best of our knowledge constitutes the first report on the anti-onchocercal activity of quaternary protoberberine alkaloids in general and pseudopalmatine (1) in particular isolated from E. Chlorantha, it has however opened a window for further investigation of the anti-onchoceral activity of this class of compounds. Key words: anti-onchocercal, pseudopalmatine, alkaloid, Enantia chlorantha
Highlights
While human onchocerciasis is a neglected tropical disease (NTD), it remains the world’s second most leading infectious cause of blindness, with over 37 million patients and a risk population of over 120 million Samje et al (2014)
Annickia chlorantha), a medicinal plant of Cameroon whose bark is used in folk medicine for the treatment of malaria and jaundice (Ajanohoun et al.,1996), HEPAZOR®, a phytomedicine developed by the Laboratoire Santé Nature (PHYTORICA) in Douala, Cameroun, comprising the quaternary protoberberine alakaloids columbamine (2), 15%, palmatine (3), 65% and jatrorrhizine (4), 20%, (Labothera, (2005) is used for the treatment of viral hepatitis
We report the isolation and identification of pseudopalmatine (1), a diisoquinoline quaternary protoberberine alkaloid and its preliminary screening in vitro against adult and juvenile worms of Onchocerca ochengi, a close relative of Onchocerca volvulus, the parasite responsible for human onchocerciasis
Summary
While human onchocerciasis (river blindness) is a neglected tropical disease (NTD), it remains the world’s second most leading infectious cause of blindness, with over 37 million patients and a risk population of over 120 million Samje et al (2014). We report the isolation and identification of pseudopalmatine (1), a diisoquinoline quaternary protoberberine alkaloid and its preliminary screening in vitro against adult and juvenile worms of Onchocerca ochengi, a close relative of Onchocerca volvulus, the parasite responsible for human onchocerciasis (river blindness). While this is the first report on the anti-onchocercal screening of quatenary protoberberine alkaloids in general and pseudopalmatine (1) in particular, it has opened a window for further investigation of anti-onchocercal activity of these class of compounds
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