easyPACId, a Simple Method for Induced Production, Isolation, Identification, and Testing of Natural Products from Proteobacteria.

The easyPACId (easy Promoter Activation and Compound Identification) approach is focused on the targeted activation of natural product biosynthetic gene clusters (BGCs) encoding non-ribosomal peptide synthetases (NRPS), polyketide synthases (PKS), NRPS-PKS hybrids, or other BGC classes. It was applied to entomopathogenic bacteria of the genera Xenorhabdus and Photorhabdus by exchanging the natural promoter of desired BGCs against the L-arabinose inducible PBAD promoter in ∆hfq mutants of the respective strains. The crude (culture) extracts of the cultivated easyPACId mutants are enriched with the single compound or compound class and can be tested directly against various target organisms without further purification of the produced natural products. Furthermore, isolation and identification of compounds from these mutants is simplified due to the reduced background in the ∆hfq strains. The approach avoids problems often encountered in heterologous expression hosts, chemical synthesis, or tedious extraction of desired compounds from wild-type crude extracts. This protocol describes easyPACId for Xenorhabdus and Photorhabdus, but it was also successfully adapted to Pseudomonas entomophila and might be suitable for other proteobacteria that carry hfq.

Antispasmodic activity from Serjania caracasana fractions and their safety

Abstract In a previous study, we reported the antispasmodic and gastroprotective effects of the Serjania caracasana (Jacq.) Willd., Sapindaceae, extract. In the present study, we evaluated the LD50, hemolytic and antispasmodic activities of its fractions and characterized its major constituents by isolation and GC-MS. The animals showed non-toxic symptoms with oral doses up to 2000 mg/kg, suggesting a safe oral administration. Furthermore, a low hemolytic activity was detected for the saponin fraction. Antispasmodic activity of the fractions was evaluated through carbachol-induced contractions in rat ileum. The hexane fraction was the most potent (IC50 68.4 ± 5.9 µg/ml) followed by the dichloromethane fraction (IC50 161.3.4 ± 40.7 µg/ml). Butanol fraction was the less effective (IC50 219.8 ± 60.3 µg/ml). The phytochemical study of the S. caracasana fractions afforded the isolation of friedelin, β-amyrin, allantoin and quercitrin. This is the first time that the presence of allantoin and quercitrin in the Serjania genus has been reported. Among the isolated compounds and those characterized by GC-MS, β-amyrin and β-sitosterol were present in the most active fractions, hexane and dichloromethane, and they may be related to its antispasmodic activity. In addition, spathulenol was only found in the hexane fraction and its presence might justify the highest antispasmodic activity observed for this fraction.