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230 results on '"Thawai, Chitti"'

33. Biological insights into the piericidin family of microbial metabolites.

Author

Azad, Sepideh. M., Jin, Yu, Ser, Hooi‐Leng, Goh, Bey‐Hing, Lee, Learn‐Han, Thawai, Chitti, and He, Ya‐Wen

Subjects
UBIQUINONES, NADH dehydrogenase, ANTIBIOTICS, MICROBIAL metabolites, GENE clusters, CHEMICAL structure, STREPTOMYCES
Abstract

Extensively produced by members of the genus Streptomyces, piericidins are a large family of microbial metabolites, which consist of main skeleton of 4‐pyridinol with methylated polyketide side chain. Nonetheless, these metabolites show differences in their bioactive potentials against micro‐organisms, insects and tumour cells. Due to its close structural similarity with coenzyme Q, piericidins also possess an inhibitory activity against NADH dehydrogenase as well as Photosystem II. This review studied the latest research progress of piericidins, covering the chemical structure and physical properties of newly identified members, bioactivities, biosynthetic pathway with gene clusters and future prospect. With the increasing incidence of drug‐resistant human pathogen strains and cancers, this review aimed to provide clues for the development of either new potential antibiotics or anti‐tumour agents. [ABSTRACT FROM AUTHOR]

Published
2022
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34. Characterization of the multiple molecular mechanisms underlying RsaL control of phenazine-1-carboxylic acid biosynthesis in the rhizosphere bacterium Pseudomonas aeruginosa PA1201

Author

Sun, Shuang, Chen, Bo, Jin, Zi Jing, Zhou, Lian, Fang, Yun Ling, Thawai, Chitti, He, Ya Wen, RAMPIONI, Giordano, Sun, Shuang, Chen, Bo, Jin, Zi Jing, Zhou, Lian, Fang, Yun Ling, Thawai, Chitti, Rampioni, Giordano, and He, Ya Wen

Subjects
Pseudomonas, phenazine-1-carboxylic acid (PCA) biosynthesis, quorum sensing, gene regulation, RsaL
Abstract

Phenazines are important secondary metabolites that have been found to affect a broad spectrum of organisms. Two almost identical gene clusters phz1 and phz2 are responsible for phenazines biosynthesis in the rhizobacterium Pseudomonas aeruginosa PA1201. Here, we show that the transcriptional regulator RsaL is a potent repressor of phenazine-1-carboxylic acid (PCA) biosynthesis. RsaL negatively regulates phz1 expression and positively regulates phz2 expression via multiple mechanisms. First, RsaL binds to a 25-bp DNA region within the phz1 promoter to directly repress phz1 expression. Second, RsaL indirectly regulates the expression of both phz clusters by decreasing the activity of the las and pqs quorum sensing (QS) systems, and by promoting the rhl QS system. Finally, RsaL represses phz1 expression through the downstream transcriptional regulator CdpR. RsaL directly binds to the promoter region of cdpR to positively regulate its expression, and subsequently CdpR regulates phz1 expression in a negative manner. We also show that RsaL represents a new mechanism for the turnover of the QS signal molecule N-3-oxododecanoyl-homoserine lactone (3-oxo-C12-HSL). Overall, this study elucidates RsaL control of phenazines biosynthesis and indicates that a PA1201 strain harboring deletions in both the rsaL and cdpR genes could be used to improve the industrial production of PCA.

Published
2017

35. Neuroprotective potential of new chromones isolated from the soil actinomycete Microbispora sp. TBRC6027.

Author

Kittisrisopit, Suchada, Bunbamrung, Nantiya, Thawai, Chitti, Tadtong, Sarin, Niemhom, Nantawan, Komwijit, Somjit, Rachtawee, Pranee, and Pittayakhajonwut, Pattama

Subjects
NEUROPROTECTIVE agents, CHROMONES, BREAST cancer, ANTIBACTERIAL agents, SOILS
Abstract

Nine new chromone analogs (1–9) were isolated from the soil actinomycete Microbispora sp. TBRC6027. The chemical structures were determined based upon NMR spectroscopic methods. These compounds were evaluated in vitro by using P19-derived neurons for neuroprotective activity against oxidative stress induced by serum deprivation and showed % viability of neurons at the concentration of 1 ng/mL varied from 43.51% to 52.99% without significant neurotoxicity for P19-derived neurons at the same concentration. Moreover, all tested compounds were inactive for antibacterial activity against both Gram-positive and Gram-negative bacteria and for cytotoxicity against MCF-7 (human breast cancer) and Vero cells at maximum tested concentration 50 μg/mL. However, compounds 4, 6, and 7 displayed weak cytotoxicity against NCI-H187 (human small-cell lung cancer) cells with IC50 in a range of 87.99–91.57 μM. [ABSTRACT FROM AUTHOR]

Published
2021
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41. Allocation of trisoxazole macrolides in the sponge Penares cf. nux and the impact on epiphytic bacterial cohabitants.

Author

Olatunji, Oyenike O., Petchoubon, Aekaphon, Thawai, Chitti, and Plubrukarn, Anuchit

Subjects
MACROLIDE antibiotics, METABOLITES
Abstract

The correlation between the allocation of trisoxazole macrolides in the capitums, appendages, and bases of the sponge Penares cf. nux and the surface-attached bacteria on the corresponding parts was examined. The kabiramide contents were highest in the capitums, followed by the appendages and bases. Conversely, direct counts of cultivable surface-attached bacteria showed that the bacteria aggregate more densely on the surfaces of the bases. This suggested the repelling effects of the kabiramides against the fouling bacteria, particularly on the capitums and appendages. Twenty-two bacterial strains were isolated and identified to 15 species; however, none has shown the potentials as a producer of any secondary metabolites in the sponge P. nux. [ABSTRACT FROM AUTHOR]

Published
2020
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