Pannipa Prompiboon. Study of secondary metabolite(s) produced by Nomuraea Rileyi and entomopathogenic fungus. Doctoral Degree(Biopharmaceutical Sciences). Mahidol University. : Mahidol University, 2008.
Study of secondary metabolite(s) produced by Nomuraea Rileyi and entomopathogenic fungus
Abstract:
This study searches for potential cytotoxic substances produced by Nomuraea
rileyi, an active compound was isolated from mycosed Spodoptera litura through an
activity guided fractionation process. The compound, cytotoxic against the Sf9 insect
cell line, was identified to be ergosterol peroxide (5α, 8α-epidioxy-24(R)-
methylcholesta-6, 22-dien-3β-ol) using nuclear magnetic resonance techniques,
infrared spectrometry, and mass spectroscopy. Anticancer screens demonstrated that
ergosterol peroxide inhibited the growth of hormone-dependent breast cancer cell
line (T47D), hormone-independent breast cancer cell line (MDA-MB-231), human
epidermoid carcinoma in mouth cell line (KB), human cervical carcinoma cell line
(HeLa), lung cancer cell line (H69AR) and human cholangiocarcinoma cell line
(HuCCA-1) at IC50 of 5.8, 28.0, 46.7, 58.4, 65.4 and 105.1 μM, respectively. Anti
HIV-1 activity of ergosterol peroxide was determined by syncytium reduction assay.
The HIV-1 inhibitory activity and cytotoxicity toward host cells were evaluated as
EC50 of 15.96 μg/ml and IC50 of 150.77 μg/ml, respectively. The therapeutic index
(IC50/EC50) of 9.45 was calculated for ergosterol peroxide.
In respect of in vivo toxic activity, ergosterol peroxide showed moderate
effects against S. litura larvae-46.7 % mortality via topical application after 7 day
post-treatment whereas the per os application had no effect on insect survival. No
significant mortality was observed by injecting ergosterol peroxide into Heliothis
virescens. The amounts of ergosterol peroxide produced by N. rileyi cultures under in
vitro and in vivo were quantified. The physiological levels of ergosterol peroxide
detected in mycosed and mummified cadavers were at 0.40 and 5.94 μg/ g dried
weight, respectively. The mycelia and hyphal bodies cultures contained ergosterol
peroxide at levels of 3.93 and 5.14 μg/g dried weight, respectively. These amounts
were less than those needed to cause cytotoxicity response.