Medicinal & Aromatic Plant Division, Regional Plant Resource Centre, Forest & Environment Department, Govt. of Odisha, Nayapalli, Bhubaneswar 751015, India.
Institute of Life Sciences (ILS), NALCO Square, Bhubaneswar-751023, Odisha, India.
Bioorg Chem. 2019 Jul;88:102947. doi: 10.1016/j.bioorg.2019.102947. Epub 2019 Apr 22.
The aerial part of Geophila repens (L.) I.M. Johnst (Rubiaceae) has been used in India to improve intelligence and memory for a long time. As part of our ongoing efforts in discovering potential bioactive compounds from G. repens, we have studied the isolation, identification, and quantification of a new class of cholinesterase inhibitor from G. repens for Alzheimer's disease (AD). Terpene was isolated from hydroalcohol extract of G. repens (GRHA) and its structure was identified "Pentylcurcumene" by spectroscopic data. HPTLC fingerprint analysis was performed and good separation was achieved in mobile phase (benzene:methanol; 7.5:2.5, v/v, 254 and 366 nm; R 0.51). The method was validated using ICH guidelines in terms of linearity, specificity, sensitivity, accuracy, precision, robustness and stability. In cellular antioxidant studies e.g. DPPH, oxygen-radical-absorbance-capacity (ORAC) and cell-based-antioxidant-protection-in-erythrocytes (CAP-e) assays showed that, Pentylcurcumene showed remarkably different degrees of antioxidant activities in dose-dependent manner. Pentylcurcumene demonstrated anticholinesterase activities e.g. IC of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition were 73.12 ± 0.56 and 97.65 ± 0.46 μg/ml, respectively. To better understand enzyme kinetics, Lineweaver-Burk plot of Pentylcurcumene displayed the highest affinity with competitive inhibition (reversible) towards both AChE (V 0.8) and BChE (V 0.6). An improved and advanced HPTLC tool of bioautography detection of Pentylcurcumene has been successfully demonstrated its anticholinesterase activities. Molecular docking simulations of Pentylcurcumene (ligand) and enzymes (proteins) exhibited the binding of ligand at active sites of AChE (human/rat) and BChE (human/homology) efficiently and also predicted the hydrophobic interaction of drug towards different amino acid residue within proteins. As per the results of antioxidant study and with the support of molecular docking analysis, it is concluded that Pentylcurcumene could be a potential first-line cholinesterase-inhibitor for AD.
地锦草（Geophila repens（L.）I.M. Johnst）的地上部分在印度长期以来一直被用于提高智力和记忆力。作为我们从地锦草中发现潜在生物活性化合物的持续努力的一部分，我们研究了从地锦草中分离、鉴定和定量一种新的胆碱酯酶抑制剂，用于治疗阿尔茨海默病（AD）。萜烯从地锦草的水醇提取物（GRHA）中分离出来，其结构通过光谱数据鉴定为“戊基姜烯”。进行了 HPTLC 指纹分析，并在流动相（苯：甲醇；7.5：2.5，v/v，254 和 366nm；R 0.51）中实现了良好的分离。该方法根据 ICH 指南进行了线性、特异性、灵敏度、准确性、精密度、稳健性和稳定性验证。在细胞抗氧化研究中，例如 DPPH、氧自由基吸收能力（ORAC）和基于细胞的红细胞抗氧化保护（CAP-e）测定表明，戊基姜烯以剂量依赖的方式表现出显著不同程度的抗氧化活性。戊基姜烯表现出抗胆碱酯酶活性，例如乙酰胆碱酯酶（AChE）和丁酰胆碱酯酶（BChE）的抑制 IC 分别为 73.12±0.56 和 97.65±0.46μg/ml。为了更好地了解酶动力学，戊基姜烯的 Lineweaver-Burk 图显示出与 AChE（V 0.8）和 BChE（V 0.6）的竞争性抑制（可逆）具有最高亲和力。已经成功地证明了改进和先进的 HPTLC 生物自显影工具可检测戊基姜烯的抗胆碱酯酶活性。戊基姜烯（配体）和酶（蛋白质）的分子对接模拟显示，配体有效地结合到 AChE（人/大鼠）和 BChE（人/同源）的活性部位，并且还预测了药物与蛋白质内不同氨基酸残基的疏水相互作用。根据抗氧化研究的结果，并得到分子对接分析的支持，可以得出结论，戊基姜烯可能是治疗 AD 的潜在一线胆碱酯酶抑制剂。
