Council for Scientific and Industrial Research, Pretoria, South Africa; University of Pretoria, Department of Chemistry, Pretoria, South Africa.
Council for Scientific and Industrial Research, Pretoria, South Africa.
J Ethnopharmacol. 2021 Sep 15;277:114222. doi: 10.1016/j.jep.2021.114222. Epub 2021 May 24.
There have been different methods proposed to prevent the sexual transmission of HIV-1 and many of them have centered on the use of anti-retrovirals as microbicides. Given that a large section of the African population still relies on herbal medicine, Lobostemon trigonus (L. trigonus), a traditionally used medicinal plant in South Africa to treat HIV-1 was further investigated for its potential as a natural microbicide to prevent the sexual transmission of HIV-1.
The aerial parts of L. trigonus were oven-dried at 80 °C, ground, extracted with boiling water for 30 min and then filtered. The aqueous extract produced was then bioassayed using different HIV-1 inhibition assays. The active components were purified and chemically profiled using ultra-performance liquid chromatography/quadrupole time-of flight mass spectrometry (UPLC-qTOF-MS). The mechanism of HIV-1 inhibition was determined by fusion arrest assay and time of addition assay. Molecular modelling and molecular dynamic simulations, using Schrödinger, were used to better understand the molecule's mechanism of entry inhibition by evaluating their docking affinity and stability against the gp120 of HIV-1.
The aqueous extract of this plant had a broad spectrum of activity against different subtypes of the virus; neutralizing subtype A, B and C in the TZM-bl cells, with IC values ranging from 0.10 to 7.21 μg/mL. The extract was also inhibitory to the virus induced cytopathic effects in CEM-SS cells with an EC of 8.9 μg/mL. In addition, it inhibited infection in peripheral blood mononuclear cells (PBMC) and macrophages with IC values of 0.97 and 4.4 μg/mL, respectively. In the presence of vaginal and seminal simulants, and in human semen it retained its inhibitory activity albeit with a decrease in efficiency, by about 3-fold. Studies of the mode of action suggested that the extract blocked HIV-1 attachment to target cells. No toxicity was observed when the Lactobacilli strains, L. acidophilus, L. jensenii, and L. crispatus that populate the female genital tract were cultured in the presence of L. trigonus extract. UPLC-qTOF-MS analyses of the purified fraction of the extract, confirmed the presence of six compounds of which four were identified as rosmarinic acid, salvianolic acids B and C and lithospermic acid. The additional molecular dynamic simulations provided further insight into the entry inhibitory characteristics of salvianolic acid B against the HIV-1 gp120, with a stable pose being found within the CD4 binding site.
The data suggests that the inhibitory effect of L. trigonus may be due to the presence of organic acids which are known to possess anti-HIV-1 properties. The molecules salvianolic acids B and C have been identified for the first time in L. trigonus species. Our study also showed that the L. trigonus extract blocked HIV-1 attachment to target cells, and that it has a broad spectrum of activity against different subtypes of the virus; thus, justifying further investigation as a HIV-1 microbicide.
已经提出了不同的方法来预防 HIV-1 的性传播，其中许多方法都集中在使用抗逆转录病毒作为杀微生物剂上。鉴于很大一部分非洲人口仍然依赖草药，因此进一步研究了南非传统上用于治疗 HIV-1 的 Lobostemon trigonus（L. trigonus）作为天然杀微生物剂的潜力，以预防 HIV-1 的性传播。
将 L. trigonus 的地上部分在 80°C 下进行烘箱干燥，研磨，用沸水提取 30 分钟，然后过滤。然后使用不同的 HIV-1 抑制测定法对产生的水提取物进行生物测定。使用超高效液相色谱/四极杆飞行时间质谱法（UPLC-qTOF-MS）对活性成分进行纯化和化学分析。通过融合抑制试验和添加时间试验确定 HIV-1 抑制的机制。使用 Schrödinger 进行分子建模和分子动力学模拟，以通过评估其对接亲和力和对 HIV-1 gp120 的稳定性来更好地了解该分子的进入抑制机制。
该植物的水提取物对不同亚型的病毒均具有广谱活性；在 TZM-bl 细胞中中和亚型 A、B 和 C，IC 值范围为 0.10 至 7.21μg/mL。该提取物还对 CEM-SS 细胞中的病毒诱导的细胞病变效应具有抑制作用，EC 值为 8.9μg/mL。此外，它还抑制外周血单核细胞（PBMC）和巨噬细胞的感染，IC 值分别为 0.97 和 4.4μg/mL。在存在阴道和精液模拟物以及人类精液的情况下，其抑制活性保持不变，但效率降低了约 3 倍。作用方式的研究表明，该提取物阻止了 HIV-1 附着在靶细胞上。当培养存在 L. trigonus 提取物时，定殖于女性生殖道的乳杆菌菌株嗜酸乳杆菌、詹森乳杆菌和卷曲乳杆菌没有观察到毒性。提取物的纯化部分的 UPLC-qTOF-MS 分析证实了六种化合物的存在，其中四种被鉴定为迷迭香酸、丹参酸 B 和 C 以及丹参素酸。额外的分子动力学模拟提供了对丹参酸 B 对 HIV-1 gp120 的进入抑制特性的进一步见解，发现其在 CD4 结合位点内具有稳定的构象。
数据表明，L. trigonus 的抑制作用可能是由于存在已知具有抗 HIV-1 特性的有机酸。首次在 L. trigonus 种中鉴定出丹参酸 B 和 C 分子。我们的研究还表明，L. trigonus 提取物阻止了 HIV-1 附着在靶细胞上，并且对不同亚型的病毒均具有广谱活性；因此，有理由进一步将其作为 HIV-1 杀微生物剂进行研究。
