Inhibition of mitochondrial respiration by the flavone aglycone isovitexin causes aberrant petal and leaf morphology in Silene latifolia

Future antimalarials from Artemisia? A rationale for natural product mining against drug-refractory Plasmodium stages

Covering: up to 2023Infusions of the plants Artemisia annua and A. afra are gaining broad popularity to prevent or treat malaria. There is an urgent need to address this controversial public health question by providing solid scientific evidence in relation to these uses. Infusions of either species were shown to inhibit the asexual blood stages, the liver stages including the hypnozoites, but also the sexual stages, the gametocytes, of Plasmodium parasites. Elimination of hypnozoites and sterilization of mature gametocytes remain pivotal elements of the radical cure of P. vivax, and the blockage of P. vivax and P. falciparum transmission, respectively. Drugs active against these stages are restricted to the 8-aminoquinolines primaquine and tafenoquine, a paucity worsened by their double dependence on the host genetic to elicit clinical activity without severe toxicity. Besides artemisinin, these Artemisia spp. contain many natural products effective against Plasmodium asexual blood stages, but their activity against hypnozoites and gametocytes was never investigated. In the context of important therapeutic issues, we provide a review addressing (i) the role of artemisinin in the bioactivity of these Artemisia infusions against specific parasite stages, i.e., alone or in association with other phytochemicals; (ii) the mechanisms of action and biological targets in Plasmodium of ca. 60 infusion-specific Artemisia phytochemicals, with an emphasis on drug-refractory parasite stages (i.e., hypnozoites and gametocytes). Our objective is to guide the strategic prospecting of antiplasmodial natural products from these Artemisia spp., paving the way toward novel antimalarial "hit" compounds either naturally occurring or Artemisia-inspired.

Half-lives and field soil concentrations of Alliaria petiolata secondary metabolites

The allelopathic potential of Alliaria petiolata is well established in the lab, but questions remain about the importance of these processes in natural settings, partly because we know so little about the stability of the purported allelopathic compounds. We determined the half-lives of several flavonoid glycosides produced by A. petiolata in sterile and non-sterile soil at two temperatures. We also attempted to quantify the levels of the glucosinolates and flavonoid glycosides produced by A. petiolata, in field soils. The flavonoid glycosides had half-lives in non-sterile soil ranging from 3 to 12 h. Even in sterile soil the longest half-life was only 45.5 h. None of the glucosinolates or flavonoid glycosides produced by A. petiolata were detected in bulk soil extracts. Only one compound, isovitexin-6''-O-beta-D-glucopyranoside, was detected during nine months of biomimetic soil extraction. These very low field levels and short half-lives suggest that the allelopathic effects of A. petiolata are likely either due to degradates of the compounds produced by the plant, or to other unknown mechanisms.