Two tospovirus isolates collected from tomato and bell pepper in Thailand were studied. The isolates induced severe necrotic mottling and/or necrotic spots and rings on the leaves and fruits of the respective plants as confirmed by back-inoculation. A polyclonal antiserum raised against its nucleocapsid (N) protein reacted only with an extract from plants infected with the homologous virus. Analysis of the nucleocapsid (N) gene sequence and its deduced amino acid sequence (Mw ∼31 kDa) showed 99% amino acid sequence homology with that of Tomato necrotic ring virus (TNRV). The nucleotide sequence of the 5 untranslated region and intergenic region flanking the N gene revealed typical features of the S RNA segment of tospoviruses. Mechanical inoculation of the virus on some plant species showed that most of the tested solanaceous species were susceptible to this virus. The biological, serological and molecular data presented here indicate that both isolates are identical to TNRV, a recently described tospovirus species in Thailand.

Overall, 244 samples of cucurbit crops with yellowing symptoms and selected weed species, from 15 provinces in Thailand, were screened by RT-PCR using primers Polero-CP-F and Polero-CP-R. A total of 160 samples (~66%) were infected by poleroviruses. Analysis of a 1.4 kb region covering the 3' RNA-dependent RNA polymerase (RdRp) gene, the intergenic non-coding region (iNCR), and the coat protein (CP), showed that four poleroviruses, namely, cucurbit aphid-borne yellows virus (CABYV), luffa aphid-borne yellows virus (LABYV), melon aphid-borne yellows virus (MABYV) and suakwa aphid-borne yellows virus (SABYV) were associated with the yellowing symptoms in cucurbit crops. Further analyses indicated presence of putative recombinant viruses referred to as CABYV-R and SABYV-R. CABYV-R was derived from the recombination between MABYV and the common strain of CABYV (CABYV-C). SABYV-R was derived from the recombination of MABYV and SABYV.

This study was carried out to investigate the protective effect of standardized γ-oryzanol-rich extracts on oxidative DNA damage induced by Fenton reaction and antiproliferative activity against human cancer cells. Six cultivars of Thai purple rice were collected in northern Thailand. Rice bran was extracted with hexane/ethyl acetate mixture and the extract was evaporated to obtain crude rice bran oil. Each rice bran oil was further purified by column chromatography to obtain the γ-oryzanol-rich extract. The extracts contained γ-oryzanol in the range of 1.17 -7.54 % w/w, in which GAM THOR exhibited the highest γ-oryzanol content. The extr \acts containing more than 5.0 % w/w γ-oryzanol (GAM THOR, GAM DOI MUSUR and GAM SUKHOTHAI-2) were selected to be standardized with γ-oryzanol and then the protective effect on oxidative DNA damage and antiproliferative activity against four human cancer cell lines (HT-29, HCT 116, MDA-MB-468 and PC3) were investigated. The extracts (10 µg/ml) exhibited a protective effect on oxidative DNA damage induced by Fenton reaction as compared with standard quercetin (lower than 5 µg/ml). Furthermore, all of the extracts exerted antiproliferative activity against human cancer cell lines in a dose-dependent manner. GAM THOR exhibited the highest antiproliferative activity against HT-29, HCT 116, MDA-MB-468 and PC3 with an 50% inhibition concentration value of 52.18 ± 1.21, 40.58 ± 5.69, 48.59 ± 2.40 and 51.61 ± 1.30 µg/ml, respectively. From these findings, γ-oryzanolrich extracts from Thai purple rice bran show potential as chemopreventive supplements or in nutraceuticals.