The interweaving roles of mineral and microbiome in shaping the antibacterial activity of archaeological medicinal clays

Ethnopharmacological relevance: 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’. Aim of the study: 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. Materials and methods: 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 60) is tested against Gram-positive, S. aureus and Gram-negative, P. aeruginosa. Results: 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. Conclusions: 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

On metal and ‘spoiled’ wine: analysing psimythion (synthetic cerussite) pellets (5th-3rd centuries BCE) and hypothesising gas-metal reactions over a fermenting liquid within a Greek pot

A Pb-based synthetic mineral referred to as psimythion (pl. psimythia) was manufactured in the Greek world at least since the 6th c BCE and routinely by the 4th c BCE. Theophrastus (On Stones, 56) describes its preparation from metallic Pb suspended over a fermenting liquid. Psimythion is considered the precursor of one of western art’s most prominent white pigments, i.e. lead white (basic lead carbonate or synthetic hydrocerussite). However, so far, and for that early period, published analyses of psimythia suggest that they consisted primarily of synthetic cerussite. In this paper, we set out to investigate how it was possible to manufacture pure cerussite, to the near exclusion of other phases. We examined the chemical and mineralogical composition (pXRF/XRD) of a small number of psimythion pellets found within ceramic pots (pyxis) from Athens and Boeotia (5th–4th c BCE) in the collection of the National Archaeological Museum (NAM), Athens. Analyses showed that the NAM pellets consisted primarily of Pb/cerussite with small amounts of Ca (some samples) and a host of metallic trace elements. We highlight the reference in the Theophrastus text to ‘spoiled wine’ (oxos), rather than ‘vinegar’, as has been previously assumed, the former including a strong biotic component. We carried out DNA sequencing of the pellets in an attempt to establish presence of microorganisms (Acetic Acid Bacteria). None was found. Subsequently, and as a working hypothesis, we propose a series of (biotic/abiotic) reactions which were likely to have taken place in the liquid and vapour phases and on the metal surface. The hypothesis aims to demonstrate that CO2 would be microbially induced and would increase, as a function of time, resulting in cerussite forming over and above hydrocerussite/other Pb-rich phases. Psimythion has for long been valued as a white pigment. What has perhaps been not adequately appreciated is the depth of empirical understanding from the part of psimythion manufacturers of the reactions between abiotic and biotic components within ‘oxos’/pot, as key drivers of minerals synthesis. Ultimately, psimythion manufacture may rest in understanding the nature of ‘oxos’, antiquity’s relatively little researched strongest acid

Greco-Roman mineral (litho)therapeutics and their relationship to their microbiome : the case of the red pigment miltos

This paper introduces a holistic approach to the study of Greco-Roman (G-R) lithotherapeutics. These are the minerals or mineral combinations that appear in the medical and scientific literature of the G-R world. It argues that they can best be described not simply in terms of their bulk chemistry/mineralogy but also their ecological microbiology and nanofraction component. It suggests that each individual attribute may have underpinned the bioactivity of the lithotherapeutic as an antibacterial, antifungal or other. We focus on miltos, the highly prized, naturally fine, red iron oxide-based mineral used as a pigment, in boat maintenance, agriculture and medicine. Five samples (four geological (from Kea, N. Cyclades) and one archaeological (from Lemnos, NE Aegean)) of miltos were analyzed with physical and biological science techniques. We show that: a. Kean miltos and Lemnian earth/miltos must have been chemically and mineralogically different; b. Lemnian miltos must have been more effective as an antibacterial against specific pathogens (Gram + and Gram − bacteria) than its Kean counterpart; c. two samples of Kean miltos, although similar, chemically, mineralogically and eco-microbiologically (phylum/class level), nevertheless, displayed different antibacterial action. We suggest that this may constituteproof of microbial ecology playing an important role in effecting bioactivity and, interestingly, at the more specific genus/species level. From the perspective of the historian of G-R science, we suggest that it may have been on account of its bioactivity, rather than simply its 'red-staining' effect, that miltos gained prominent entry into the scientific and medical literature of the G-R world

Archaeological medicinal earths as antibacterial agents: the case of the Basel Lemnian sphragides.

This paper presents the scientific investigation of three Lemnian sphragides (terra sigillata), a famed medicinal clay (earth) of antiquity, dated to the 16th-17th century, and presently in the collection of the Museum for the History of Pharmacy of the University of Basel. The three specimens are examined here against the backdrop of samples of sedimentary clays from the purported locality of its extraction, at Kotsinas, NE Lemnos, Greece. The study demonstrates, for the first time, that the three Lemnian sphragides displayed antibacterial properties against gram positive pathogens (staphelococcus aureus); the modern clays displayed none. Subsequent analysis with DPLC-MS of one of the three sphragides and one sample of clay revealed the presence of organic constituents in the sphragis which were absent from a sample of the modern clay. A fungal secondary metabolite is proposed here as the molecule responsible but other factors may have a role to play. The ongoing investigation for the bioactivity od some medicinal clays might aid in the re-evaluation of Belon's statement included at the start of this paper, namely, that the Lemnian Earth worked only because people in the past wished it to work

Metallurgical waste

No abstract available

Technical studies of Aegean Bronze Age wall painting: methods, results and future prospects

No abstract available

The building and industrial remains at Agrileza, Laurion (fourth century BC) and their contribution to the workings at the site

A detailed programme of sample collection and laboratory analysis was undertaken at Agrileza, an ore-dressing installation in the Laurion. The site consists of three compounds with associated washeries (Agrileza A, B, and C), some excavated partially, others in full, in the late 1970s and early 1980s and dating to the last quarter of the 4th cent. BC. The particular functions of some of the rooms in compound C are tentatively put forward. The main part of the paper is concerned with the nature, composition, and particle size distribution of the tailings recovered both from washeries A and C and from elsewhere in compound C. The silver-to-lead ratios and particle size distribution of the tailings may suggest that the series of basins and channels making up each washery served not merely as a water purification device, but as a means of trapping ore that had escaped the first washing, for the purpose of dressing it further

"Harvesting" the Ore: The Use of Iron Seepages in the Early Bloomery Furnace in Ireland

In this paper we suggest that iron-seepages, a precursor form of bog iron ore, must have been among the earliest iron ores used in early bloomery furnaces in Ireland. This is because: of their bright orange colour; the dramatic red-staining of the associated water-red springs or meinn in Gaelic; their rapid regenerative nature which means that they would have been “harvested” on a cyclical basis rather than “mined”; and also because there is an absence of solid bog ore remains within the relict furnaces. Archaeological evidence for iron-seepage ore, consisting of fine powdery material, in early bloomery furnaces would be elusive on account of its clay-like pasty nature and the fact that it will easily merge into a background of soil and metallurgical waste. We assume that the original wet clay-like pasty mass would have been dried prior to charging in the furnace and purer than our modern sample; and also, possibly, but not necessarily, shaped into small lumps

The bloomery mounds of the Scottish Highlands. Part 2: a review of iron mineralization

No abstract available