Semisynthesis of Antitrypanosomal p-Quinone Analog Possesing the Komaroviquinone Pharmacophore.

A p-quinone analog having the komaroviquinone pharmacophore fused with a more conformationally flexible cycloheptane ring, was semisynthesized from natural demethlsalvicanol isolated from Perovskia abrotanoides via four steps in 26% overall yield. The IC50 for the antitrypanosomal activity of the analog was 0.55 µM.

Panowamycins A and B, new antitrypanosomal isochromans produced by Streptomyces sp. K07-0010.

Two new isochromans, panowamycins A and B, were purified by solvent extraction, silica gel and octadecylsilyl silica gel (ODS) column chromatography followed by preparative HPLC, from a culture broth of Streptomyces sp. K07-0010, together with the known compounds NFAT-133, conglobatin, piericidin C series and dinactin. Structures of panowamycins were elucidated as new analogs of NFAT-133 by spectroscopic studies including various NMR experiments. Panowamycins A and B showed moderate antitrypanosomal activity, with IC(50) values of 0.40 and 3.30 µg ml(-1), respectively.

In vitro antitrypanosomal activity of some phenolic compounds from propolis and lactones from Fijian Kawa (Piper methysticum).

During our search to discover new antitrypanosomal compounds, eight known plant compounds (three phenolic compounds and five kawa lactones) were evaluated for in vitro activity against Trypanosoma brucei brucei. Among them, we found two phenolic compounds and three kawa lactones possessing an α-pyrone influenced antitrypanosomal property. In particular, ß-phenethyl caffeate, farnesyl caffeate and dihydrokawain exhibited high or moderate selective and potent antitrypanosomal activity in vitro. We detail here the antitrypanosomal activity and cytotoxicities of the compounds, in comparison with two commonly used antitrypanosomal drugs (eflornithine and suramin). Our findings represent the first report of the promising trypanocidal activity of these compounds.

Spoxazomicins A-C, novel antitrypanosomal alkaloids produced by an endophytic actinomycete, Streptosporangium oxazolinicum K07-0460(T).

Three novel antitrypanosomal alkaloids, named spoxazomicins A-C, were isolated by silica gel column chromatography and HPLC from the culture broth of a new endophytic actinomycete species, Streptosporangium oxazolinicum K07-0460(T). The structures of the spoxazomicins were elucidated by NMR and X-ray crystal analyses and shown to be new types of pyochelin family antibiotic. Spoxazomicin A showed potent and selective antitrypanosomal activity with an IC50 value of 0.11 µg ml⁻¹ in vitro without cytotoxicity against MRC-5 cells (IC50=27.8 µg ml⁻¹).

In vitro and in vivo antimalarial activity of puberulic acid and its new analogs, viticolins A-C, produced by Penicillium sp. FKI-4410.

In the course of screening for antimalarial agents, five tropolone compounds were isolated from the culture broth of Penicillium sp. FKI-4410. Two were known compounds, puberulic acid and stipitatic acid. Three were new analogs of puberulic acid, designated viticolins A-C. Among them, puberulic acid exhibited potent antimalarial inhibition, with IC(50) values of 0.01 µg ml(-1) against chloroquine-sensitive and -resistant Plasmodium falciparum strains in vitro. Furthermore, puberulic acid showed weak cytotoxicity against human MRC-5 cells, with an IC(50) value of 57.2 µg ml(-1). The compound also demonstrated a therapeutic effect in vivo, which compared well against the currently used antimalarial drugs, and thus shows promise as a leading candidate for development into a new antimalarial compound.

Sinefungin VA and dehydrosinefungin V, new antitrypanosomal antibiotics produced by Streptomyces sp. K05-0178.

Two new nucleotide antibiotics, named sinefungin VA and dehydrosinefungin V, were separated by cation exchange column chromatography and purified by HPLC from the culture broth of Streptomyces sp. K05-0178, together with the known antibiotics, sinefungin, dehydrosinefungin and KSA-9342. The structures of the two novel sinefungin analogs were elucidated by spectroscopic studies, including various NMR and advanced peptide chemical methods. Sinefungin VA consists of adenosine and ornithylvalylalanine, whereas dehydrosinefungin V consists of 4',5'-dehydroadenosine and ornithylvaline. Sinefungin VA showed potent antitrypanosomal activity with an IC(50) value of 0.0026 µg ml(-1) in vitro without cytotoxicity against MRC-5 cells. Dehydrosinefungin V showed moderate antitrypanosomal activity (IC(50)=0.15 µg ml(-1)).