# Sphaeriaurantin A from soil bacteria blocks malaria parasite in lab cultures at low nanomolar doses

- Published: 2026-11-07 19:29 UTC
- Section: Life & Health › Medicine
- Tags: sphaeriaurantin A, malaria drug lead, Plasmodium falciparum, glycosylated polyketides, Sphaerisporangium, soil bacteria, liver stage malaria, antimalarial resistance, natural products, Actinomycetota
- URL: https://realtech.media/news/rt-eefe84e105268a77fec0cfee_sphaeriaurantin_a_from/

**Researchers described three new glycosylated polyketides from an Actinomycetota strain. The lead compound acts on P. falciparum in blood and liver stages, and no resistance appeared in tests.**

![Sphaeriaurantin A from soil bacteria blocks malaria parasite in lab cultures at low nanomolar doses](https://realtech.media/media/2026/11/9008081b54c37ec3.webp)
*science-et-vie.com*

A team led by Chantal D. Bader and Ben Shen of the Herbert Wertheim UF Scripps Institute in Florida, together with Jennifer E. Collins and Debopam Chakrabarti of the University of Central Florida, has described three previously unknown compounds called sphaeriaurantins (SPAs). The work was published in the Journal of the American Chemical Society. The compounds come from a soil bacterium of the genus Sphaerisporangium that had been kept cold in a strain collection for decades [1]. They are glycosylated type II polyketides, and the results come from laboratory experiments only.

## Screening and structure

The search was prompted by the spread of resistance in the malaria parasite Plasmodium falciparum. Actinomycetota evolved to make many structurally diverse natural products as defenses against soil-dwelling protozoa, which makes them a plausible source of antiplasmodial leads. The authors report selective inhibition of P. falciparum by five distinct natural product families, SPAs among them [1].

The researchers screened purified natural products and extracts from actinobacteria strains, then set aside those that damaged human cells. They re-cultured the producing bacterium, adjusted the growth medium to raise yield and purified the compounds as bright orange powders. Structures were established by mass spectrometry and NMR, derivatization of the deoxyhexose sugar units and comparison with authentic standards, and quantum chemical calculations of NMR shifts and electronic circular dichroism spectra [1]. Two other strains in the collection carry the same biosynthetic genes.

According to the authors, the pseudodimeric structure typical of SPAs, probably formed late in biosynthesis, is highly relevant for the low nanomolar activity [1].

## Activity and open questions

SPA A kills the parasite rapidly and acts at all intraerythrocytic stages. It is also effective against the liver stage, where infection begins without symptoms. It inhibited a strain already resistant to several drugs [1].

When parasites were kept under continuous exposure to the compound for a prolonged period, no regrowth was observed. The compound was also tested against lines carrying known resistance mutations, and none of them escaped its effect [1]. The authors conclude that the mode of action most likely differs from existing antimalarials such as chloroquine and artemisinin.

The molecular target of SPA A in the parasite is still unknown, and identifying it is the next step announced by the team. The authors describe SPA A as a promising antimalarial lead for further development, not as a treatment [1].

## Sources

1. [Journal of the American Chemical Society](https://doi.org/10.1021/jacs.6c11333)
2. [science-et-vie.com](https://www.science-et-vie.com/corps-et-sante/paludisme-alors-quelle-dormait-dans-le-congelateur-dun-laboratoire-depuis-des-decennies-cette-bacterie-est-capable-de-tuer-le-parasite-en-5-heures-et-offre-une-nouvelle-piste-de-traiteme-265293.html)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-eefe84e105268a77fec0cfee_sphaeriaurantin_a_from/