Exploring bixin from <i>Bixa orellana</i> L. seeds: quantification and <i>in silico</i> insights into its anti-cancer potential

Bixin, the key pigment of <i>Bixa orellana</i> L., is an apo-carotenoid found in the seed arils. The present study aimed to quantitatively determine the bixin content of seeds and explore its anti-cancer activity through <i>in silico</i> studies. The bixin content from the seeds of the local genotype, TNMTP8, quantified by RP-HPLC was 4.58 mg per gram. The prediction of pharmacological activity suggested that bixin may serve as a BRAF, MMP9, TNF expression inhibitors, and TP53 expression enhancer. According to molecular docking analysis, bixin interacted with eight different skin cancer targets and had the lowest binding energy compared to the standard drug, 5-fluorouracil. The binding score between bixin and the targets ranged from −4.7 to −8.7 kcal/mol. The targets BRAF and SIRT3 interacted well with bixin, with binding energies as low as −8.3 and −8.7 kcal/mol, respectively. Hence, the dynamic behavior of these two docked complexes throughout a 500 ns trajectory run was investigated further. The Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF) values, and total contacts as a function of time recorded during scrutiny suggest that both complexes were stable. This was validated by post-molecular dynamics analysis using Molecular Mechanics Generalized Born Surface Area (MM-GBSA). Principal component analysis (PCA) was used to analyze the significant differences in motion exhibited by BRAF-Bixin and SIRT3-Bixin. The results showed that bixin is a promising source for potential treatment interventions in skin cancer therapies. Communicated by Ramaswamy H. Sarma胭脂树橙（bixin）是红木（Bixa orellana L.）的核心色素，属于存在于种子假种皮中的脱辅基类胡萝卜素。本研究旨在定量测定种子中的胭脂树橙含量，并通过计算机模拟（in silico）研究探索其抗癌活性。采用反相高效液相色谱（RP-HPLC）对本地基因型TNMTP8的种子中胭脂树橙含量进行定量分析，结果为每克种子含4.58 mg胭脂树橙。药理活性预测结果显示，胭脂树橙可作为BRAF、MMP9、TNF的表达抑制剂，同时可增强TP53的表达。分子对接分析表明，胭脂树橙可与8种不同的皮肤癌靶点结合，且与对照药物5-氟尿嘧啶（5-fluorouracil）相比，其结合能最低。胭脂树橙与各靶点的结合得分介于-4.7至-8.7 kcal/mol之间。其中，BRAF与SIRT3与胭脂树橙的结合效果最佳，结合能分别低至-8.3和-8.7 kcal/mol。因此，本研究进一步考察了这两个对接复合物在500 ns轨迹运行过程中的动态行为。分析过程中记录的均方根偏差（RMSD）、均方根波动（RMSF）值以及随时间变化的总接触数均表明，两种复合物均保持稳定。这一结果通过分子动力学后分析的分子力学广义玻恩表面积法（MM-GBSA）得到了验证。本研究采用主成分分析（PCA）对BRAF-胭脂树橙与SIRT3-胭脂树橙复合物的运动差异进行了分析。结果表明，胭脂树橙是一种极具潜力的皮肤癌治疗候选药物来源。本文由Ramaswamy H. Sarma通讯。