Laboratory of Cyanobacterial Biotechnology, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
J Photochem Photobiol B. 2014 Jan 5;130:287-92. doi: 10.1016/j.jphotobiol.2013.12.001. Epub 2013 Dec 12.
The biosynthesis of natural sunscreening compounds as influenced by ultraviolet radiation, their stability and antioxidant activity were studied in the cyanobacterium Gloeocapsa sp. CU-2556. An analysis by high-performance liquid chromatography (HPLC) with photodiode-array (PDA) detection revealed the biosynthesis of two MAAs, shinorine (UVλmax 333nm) and an unknown MAA designated as M-307 (UVλmax 307nm) with retention times of 5.9 and 6.4min, respectively. Induction of the synthesis of MAAs was studied under 395 (PAR), 320 (PAR+UV-A) and 295 (PAR+UV-A+UV-B) nm cut-off filters. MAAs induction was significantly increased with an increase in exposure time up to 72h in the samples covered with 295nm cut-off filters. Contrary to shinorine, the biosynthesis of M-307 was more dominant in this unicellular cyanobacterium. Both MAAs were highly stable to some physico-chemical stressors such as UV radiation, heat and a strong oxidizing agent. The MAA M-307 was more stable under strong oxidative stress than shinorine. Moreover, UV-C radiation drastically decreased the stability of both MAAs. The MAAs (shinorine+M-307) also exhibited efficient antioxidant activity which was dose-dependent. The results indicate that MAAs may perform a vital role in survival and sustainability of Gloeocapsa sp. CU-2556 in harsh environmental conditions by its ability to absorb/screen short wavelength UV radiation and antioxidant function.
研究了蓝细菌 Gloeocapsa sp. CU-2556 中天然防晒化合物的生物合成、紫外线辐射对其稳定性和抗氧化活性的影响。高效液相色谱（HPLC）与光电二极管阵列（PDA）检测分析表明，该蓝细菌合成了两种 MAAs，即 shinorine（UVλmax 333nm）和一种未知的 MAA，命名为 M-307（UVλmax 307nm），保留时间分别为 5.9 和 6.4min。研究了在 395nm（PAR）、320nm（PAR+UV-A）和 295nm（PAR+UV-A+UV-B）截止滤光片下 MAAs 的合成诱导情况。在覆盖有 295nm 截止滤光片的样品中，随着暴露时间的增加至 72h，MAAs 的合成显著增加。与 shinorine 不同，M-307 在这种单细胞蓝细菌中的生物合成更为突出。两种 MAAs 对一些物理化学胁迫因素如紫外线辐射、热和强氧化剂具有很高的稳定性。在强氧化应激条件下，M-307 比 shinorine 更稳定。此外，UV-C 辐射会大大降低两种 MAAs 的稳定性。MAAs（shinorine+M-307）还表现出有效的抗氧化活性，且具有剂量依赖性。研究结果表明，MAAs 可能通过吸收/屏蔽短波长紫外线辐射和抗氧化功能，在恶劣的环境条件下对 Gloeocapsa sp. CU-2556 的生存和可持续性发挥重要作用。
