In vitro fungistatic activity of 36 traditional oriental medicines and their synergistic effect against Trichophyton rubrume

Objective: To investigate the fungistatic activity and synergistic effects of natural products and their constituents, including traditional oriental medicines(TOMs).Methods: Fungistatic activities of TOMs prepared by hot-water(115 ℃) or ethanol(70%; 40 ℃) extraction were determined by their minimum inhibitory concentration.To assess possible synergistic effects, minimum inhibitory concentrations of various combinations were evaluated.Results: By evaluating antifungal susceptibility of Trichophyton rubrum, which is a major causative fungus for several types of dermatophytosis, we confirmed that ethanol extracts were more active than hot-water extracts in 25 of the 36 TOMs, suggesting that the constituents with high hydrophobicity tend to contribute significantly to fungistatic activity.We selected four TOMs with high fungistatic activity, including Aucklandiae radix, Gentianae macrophyllae radix, Scutellariae radix, and Galla rhois, and their synergistic effects were investigated through the combination studies between TOMs or TOM-conventional drug terbinafine.In combinations between four TOMs, partial synergistic effects were observed in Aucklandiae radix–Galla rhois and Gentianae macrophyllae radix–Galla rhois combinations, as supported by the lowest fractional inhibitory concentration index value of 0.66 for both combinations.Furthermore, Galla rhois showed the strongest synergistic effect on growth inhibition of Trichophyton rubrumwith a fractional inhibitory concentration index value of 0.50 in combination with terbinafine.Conclusions: Our findings indicate that the combination of TOMs and TOM-terbinafine may be effective on treatment for chronic and recurrent dermatophytosis by improving fungistatic activity and led to decrease systemic toxicity in clinical practice.

In-vitro assessment for the control of Fusarium species using a lactic acid bacterium isolated from yellow pitahaya(Selenicereus megalanthus(K. Schum. Ex Vaupel Moran))

The fungistatic activity of a lactic acid bacterium, which had been isolated from yellow pitahaya cultures, against fungi associated with basal rot(Fusarium oxysporum and Fusarium fujikuroi) was measured in the present study. Its activity was assessed in three fractions: fermented(S1), metabolic products(S2), and biomass(S3), using two fermentation substrates: Man Rogosa Sharpe agar(MRS) and potato dextrose agar(PDA). The bacterium was molecularly identified as Lactobacillus plantarum. S3 reduced F. fujikuroi growth by 100% over 48 h of fermentation, which occurred during the stationary phase of bacterial growth. The three fractions' fungistatic activity against F. fujikuroi depended on the substrate employed. The fermentation kinetic parameters for L. plantarum indicated that its specific growth rate was 0.46 h^–1, with 93.63% substrate consumption, 0.045 kg kg^–1 cell yield, and 0.54 kg kg^–1 product yield. The kinetic parameters calculated will allow for bacteria production scaling. These in-vitro trials reveal L. plantarum's possible application as a biocontrol agent for diseases associated with Fusarium. However, further ex-vivo and in-vivo researches are required to demonstrate its behavior in crops.

Hyphal Morphology and Elongation Alterations in Aspergillus nidulans Provoked by the Diterpene Kaurenoic Acid

Kaurenoic acid (KA), a kaurane-type diterpene extracted from leaves of Mikania hirsutissima, was previously reported as an inhibitor of vascular contractility mainly by blocking extracellular Ca2+ influx. The compound is known for several other biological activities such as antiparasitic, antispasmodic and antibacterial activity. The aim of the present study was to investigate the effect of KA on Aspergillus nidulans. KA (0.3 mM) showed fungistatic activity against A. nidulans with visible hyphal elongation and morphology damage. These effects were reverted by CaCl2 addition showing that KA interferes with intracellular Ca2+ gradient in A. nidulans. This is the first report on the mechanism of action of KA involving calcium levels by altering the elongation of fungi hyphae.