School of Mineral Resources Engineering, Technical University of Crete, 73100, Chania, Greece.
Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XQ, UK.
J Ethnopharmacol. 2020 Oct 5;260:112894. doi: 10.1016/j.jep.2020.112894. Epub 2020 Apr 26.
Medicinal Earths (MEs), natural aluminosilicate-based substances (largely kaolinite and montmorillonite), have been part of the European pharmacopoeia for well over two millennia; they were used generically as antidotes to 'poison'.
To test the antibacterial activity of three Lemnian and three Silesian Earths, medicinal earths in the collection of the Pharmacy Museum of the University of Basel, dating to 16th-18th century and following the methodology outlined in the graphical abstract. To compare them with natural clays of the same composition (reference clays) and synthetic clays (natural clays spiked with elements such as B, Al, Ti and Fe); to assess the parameters which drive antibacterial activity, when present, in each group of samples.
a total of 31 samples are investigated chemically (ICP-MS), mineralogically (both bulk (XRD) and at the nano-sized level (TEM-EDAX)); their organic load (bacterial and fungal) is DNA-sequenced; their bioactivity (MIC) is tested against Gram-positive, S. aureus and Gram-negative, P. aeruginosa.
Reference smectites and kaolinites show no antibacterial activity against the above pathogens. However, the same clays when spiked with B or Al (but not with Ti or Fe) do show antibacterial activity. Of the six MEs, only two are antibacterial against both pathogens. Following DNA sequencing of the bioactive MEs, we show the presence within of a fungal component, Talaromyces sp, a fungus of the family of Trichocomaceae (order Eurotiales), historically associated with Penicillium. Talaromyces is a known producer of the exometabolite bioxanthracene B, and in an earlier publication we have already identified a closely related member of the bioxanthracene group, in association with one of the LE samples examined here. By linking fungus to its exometabolite we suggest that this fungal load may be the key parameter driving antibacterial activity of the MEs.
Antibacterial activity in kaolinite and smectite clays can arise either from spiking natural clays with elements like B and Al, or from an organic (fungal) load found only within some archaeological earths. It cannot be assumed, a priori, that this organic load was acquired randomly and as a result of long-term storage in museum collections. This is because, at least in the case of medicinal Lemnian Earth, there is historical evidence to suggest that the addition of a fungal component may have been deliberate.
药用土（MEs）是天然的铝硅酸盐物质（主要为高岭石和蒙脱石），在欧洲药典中已有两千多年的应用历史；它们被用作通用解毒剂来对抗“毒物”。
本研究旨在测试巴塞尔大学药学博物馆收藏的三种莱姆尼亚（Lemnian）和三种西里西亚（Silesian）药用土的抗菌活性，这些药用土可追溯到 16 至 18 世纪，其研究方法遵循图形摘要中概述的方法。将它们与具有相同成分的天然粘土（参考粘土）和合成粘土（天然粘土中添加了 B、Al、Ti 和 Fe 等元素）进行比较；评估每组样品中存在的抗菌活性的参数。
共对 31 个样本进行了化学分析（ICP-MS）、矿物学分析（包括体相（XRD）和纳米级（TEM-EDAX））；对其有机负荷（细菌和真菌）进行了 DNA 测序；并测试了它们对革兰氏阳性菌金黄色葡萄球菌和革兰氏阴性菌铜绿假单胞菌的生物活性（MIC）。
参考蒙脱石和高岭石对上述病原体均无抗菌活性。然而，当用 B 或 Al 掺杂时（但用 Ti 或 Fe 掺杂时没有），相同的粘土具有抗菌活性。在六种 MEs 中，只有两种对两种病原体都具有抗菌活性。在对具有生物活性的 MEs 进行 DNA 测序后，我们发现其中存在真菌成分塔玛氏菌（Talaromyces），塔玛氏菌属于毛霉科（Trichocomaceae）（欧陆霉目 Eurotiales），历史上与青霉属有关。塔玛氏菌是生物外代谢产物生物黄樟素 B 的已知产生者，在之前的一篇出版物中，我们已经在与在此处检查的 LE 样本之一相关的生物黄樟素组中鉴定出了一个密切相关的成员。通过将真菌与其生物外代谢产物联系起来，我们认为这种真菌负荷可能是驱动 MEs 抗菌活性的关键参数。
在高岭石和蒙脱石粘土中，抗菌活性可以来自于用 B 和 Al 等元素掺杂天然粘土，也可以来自于仅在某些考古土中发现的有机（真菌）负荷。不能假设这种有机负荷是随机获得的，并且是由于长期存放在博物馆收藏中造成的。这是因为，至少在莱姆尼亚药用土的情况下，有历史证据表明，添加真菌成分可能是有意的。
