Abstract

Context

Streptomyces species are prolific sources of bioactive secondary metabolites known especially for their antimicrobial and anticancer activities.

Objective

This study sought to isolate and characterize antioxidant molecules biosynthesized by Streptomyces sp. KTM18. The antioxidant potential of an isolated compound and its toxicity were accessed.

Materials and methods

The compound was purified using bioassay-guided chromatography techniques. Nuclear magnetic resonance (NMR) experiments were carried out for structure elucidation. The antioxidant potential of the isolated compound was determined using DPPH free radical scavenging assay. The toxicity of the isolated compound was measured using a brine shrimp lethality (BSL) assay.

Results

Ethyl acetate extract of Streptomyces sp. KTM18 showed more than 90% inhibition of DPPH free radical at 50 µg/mL of the test concentration. These data were the strongest among 13 Streptomyces isolates (KTM12–KTM24). The active molecule was isolated and characterized as maculosin (molecular formula, C₁₄H₁₆N₂O₃ as determined by the [M + H]⁺ peak at 261.1259). The DPPH free radical scavenging activity of pure maculosin was higher (IC₅₀, 2.16 ± 0.05 µg/mL) than that of commercial butylated hydroxyanisole (BHA) (IC₅₀, 4.8 ± 0.05 µg/mL). No toxicity was observed for maculosin (LD₅₀, <128 µg/mL) in brine shrimp lethality assay (BSLA) up to the compound’s antioxidant activity (IC₅₀) concentration range. The commercial standard, berberine chloride, showed toxicity in BSLA with an LD₅₀ value of 8.63 ± 0.15 µg/mL.

Conclusions

Maculosin may be a leading drug candidate in various cosmetic and therapeutic applications owing to its strong antioxidant and non-toxic properties.

中文翻译：

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Maculosin，一种从链霉菌属中分离的无毒抗氧化化合物。KTM18

摘要

语境

链霉菌属物种是生物活性次级代谢物的丰富来源，尤其以其抗菌和抗癌活性而闻名。

客观的

本研究试图分离和表征由链霉菌属生物合成的抗氧化分子。KTM18。获得了分离化合物的抗氧化潜力及其毒性。

材料和方法

使用生物测定引导的色谱技术纯化该化合物。进行核磁共振（NMR）实验以阐明结构。使用 DPPH 自由基清除试验测定分离化合物的抗氧化潜力。使用盐水虾致死率 (BSL) 测定法测量分离化合物的毒性。

结果

链霉菌属的乙酸乙酯提取物。KTM18 在 50 µg/mL 的测试浓度下显示出 90% 以上的 DPPH 自由基抑制作用。这些数据是 13 种链霉菌分离株（KTM12-KTM24）中最强的。活性分子被分离并表征为maculosin（分子式，C ₁₄ H ₁₆ N ₂ O ₃由261.1259处的[M + H] ⁺峰确定）。纯 maculosin 的 DPPH 自由基清除活性 (IC ₅₀ , 2.16 ± 0.05 µg/mL) 高于商业丁基羟基茴香醚 (BHA) (IC ₅₀ , 4.8 ± 0.05 µg/mL)。maculosin (LD ₅₀, <128 µg/mL) 在丰年虾致死试验 (BSLA) 中达到化合物的抗氧化活性 (IC ₅₀ ) 浓度范围。商业标准品氯化小檗碱在 BSLA 中显示出毒性，LD ₅₀值为 8.63 ± 0.15 µg/mL。

结论

由于其强大的抗氧化和无毒特性，Maculosin 可能是各种美容和治疗应用中的主要候选药物。