Research Articles (Chemistry and Polymer Science)

Permanent URI for this collection

https://scholar.sun.ac.za/handle/10019.1/5701

Browse

Browsing Research Articles (Chemistry and Polymer Science) by Subject "Alkaloids"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Alkaloids with activity against the Zika virus vector Aedes aegypti (L.) - crinsarnine and sarniensinol, two new crinine and mesembrine type alkaloids isolated from the South African Plant Nerine sarniensis
    (MDPI, 2016-10-27) Masi, Marco; Cala, Antonio; Tabanca, Nurhayat; Cimmino, Alessio; Green, Ivan R.; Bloomquist, Jeffrey R.; Van Otterlo, Willem A. L.; Macias, Francisco A.; Evidente, Antonio
    Two new Amaryllidaceae alkaloids, belonging to the mesembrine- and crinine-types, named crinsarnine (1) and sarniensinol (2), were isolated from the dried bulbs of Nerine sarniensis together with bowdensine (3), sarniensine (4), hippadine (5) and 1-O-acetyl-lycorine (6). Crinsarnine (1) and sarniensinol (2) were characterized using spectroscopic and chiroptical methods as (1S,2S,4aR,10bS)-2,7-dimethoxy-1,2,3,4,4a,6-hexahydro-5,11b-ethano[1,3]dioxolo-[4,5-j]phenanthridin- 1-yl acetate and (6-(3aR,4Z,6S,7aS)-6-methoxy-1-methyl-2,3,3a,6,7,7a-hexa-hydro-1H-indol-3a-yl)benzo [d][1,3]dioxol-5-yl)methanol, respectively. Furthermore, the complete spectroscopic characterization of bowdensine (3) is reported for the first time. Compounds 1–6 were evaluated against the Orlando reference strain of Aedes aegypti. None of compounds showed mortality against 1st instar Ae. aegypti larvae at the concentrations tested. In adult topical bioassays, only 1 displayed adulticidal activity with an LD50 = 2.29 ± 0.049 µg/mosquito. As regards the structure-activity relationship, the pretazettine and crinine scaffold in 2 and 4 and in 1 and 3 respectively, proved to be important for their activity, while the pyrrole[de]phenanthridine scaffold present in 5 and 6 was important for their reactivity. Among the pretazettine group compounds, opening of the B ring or the presence of a B ring lactone as well as the trans-stereochemistry of the A/B ring junction, appears to be important for activity, while in crinine-type alkaloids, the substituent at C-2 seems to play a role in their activity
  • Thumbnail Image
    Item
    A review on recent syntheses of Amaryllidaceae alkaloids and isocarbostyrils (time period mid-2016 to 2017)
    (Sage Publishing, 2018) Van Otterlo, Willem A. L.; Green, Ivan R.
    Alkaloids from the Amaryllidaceae have become valuable targets for synthetic organic chemists, mainly due to their wide variety of bioactivities and potential for utilization in medicinal chemistry ventures. In addition, the structural complexity of a number of these alkaloids has also been a reason for the interest in these compounds. In this review, the last 18 months of literature was perused and synthetic highlights have been presented here, with the hope to further focus attention on this interesting class of compounds and to encourage others to synthesize these compounds and their derivatives and/or analogues. The review contains examples of syntheses from most of the important alkaloid scaffold classes previously isolated from the Amaryllidaceae, namely: lycorine, crinine, galanthamine, tazettine, montanine, phenanthridone, phenanthridine, plicamine, mesembrine and some minor scaffolds (like gracilamine).