Heike Franke

Bromelain, a proteolytic enzyme complex from Ananas comosus (pineapple), is used in foods, food supplements, and medicinal products, yet its oral safety remains insufficiently characterized. Pharmacological, toxicological, clinical, and regulatory evidence was reviewed in a weight-of-evidence approach complemented by a market survey of bromelain supplements in Germany and an exploratory dose–response analysis. Acute oral lethality was very low (LD₅₀ > 10,000 mg/kg bw). A more sensitive endpoint, transient heart-rate increase after single oral doses in humans, yielded an exploratory acute reference value (0.7 mg/kg bw); surveyed single dosage units exceeded it 2- to 15-fold. Exploratory benchmark-dose modeling of the heart-rate data placed the threshold for pharmacological action at approximately 400 mg per single dose. Given statistically significant clinical effects from about 100 mg/day, all surveyed products fell within the reported pharmacologically active dose range. For chronic intake, no adequate oral repeated-dose study was available, so a provisional, screening-level health-based guidance value of 0.18 mg/kg bw/day was derived from a 28-day human no observed adverse effect level of 53.4 mg/kg bw/day and an uncertainty factor of 300; recommended intakes exceeded it about 8- to 78-fold. These exceedances indicate insufficient data to establish the safety of supplement doses, especially for long-term use, not demonstrated harm. Adequate repeated-dose data are needed, and products at pharmacologically active doses require case-by-case regulatory evaluation.

Background: Glioblastomas (GBMs) are highly invasive and heterogeneous in nature which strongly contributes to poor survival of patients, averaging 15 months after diagnosis. With little treatment options being available in particular for addressing GBM invasiveness, there is a high need for supplementary therapies in addition to classical cytostatics like Temozolomide (TMZ). Methods: The aim of this study was to examine promising compounds, the natural indole scaffold RAD114 and three semisynthetic analogs (RAD118, RAD119, RAD120) as well as the aryl sulfonamide AqB011, for their inhibitory potential specifically on tumor cell invasion. For this, GBM xenograft tissue slice tandem co-culture (XTCC) models were employed, closely reflecting the in vivo patient situation. In particular, these ex vivo tissue slice air-liquid interface (ALI) models also allow for distinguishing between inhibitory effects on bulk tumor growth vs tumor cell invasion into the normal brain tissue. Results: Profound anti-invasive effects of the natural indole scaffold RAD114, three semisynthetic analogs (RAD118, RAD119, RAD120), and the aryl sulfonamide AqB011 were observed in XTCC models based on G55T2 and U87-MG GBM xenografts co-cultured with mouse brain slices in ALI tandem co-culture. While effects on bulk tumor growth were rather moderate, profound inhibition or even abolishment of tumor invasion was observed, dependent on the compound, its dosage and the model. At a non-toxic concentration (10 µM), RAD118 and AqB011 showed the highest effectiveness in reducing tumor invasion. Combination effects at sub-optimal compound dosages were observed as well. Conclusions: Both compound classes - the tested semisynthetic indole analogs and the sulfonamide derivative – may be promising lead candidates for drugs useful to specifically address the issue of GBM invasiveness. They strongly restrained GBM cell invasion, alone and in combination. Rather than acting through cytotoxic effects, they specifically inhibit cell migration into native brain tissue.

Bromelain, a proteolytic enzyme complex from Ananas comosus (pineapple), is used in foods, food supplements, and medicinal products, yet its oral safety remains insufficiently characterized. Pharmacological, toxicological, clinical, and regulatory evidence was reviewed in a weight-of-evidence approach, and exposure was estimated from bromelain supplements marketed in Germany. Acute oral lethality was very low (LD₅₀ >10,000 mg/kg bw), with large margins of exposure. A more sensitive endpoint, a transient heart-rate increase after single oral doses in humans, yielded an exploratory acute reference value (0.7 mg/kg bw) that the surveyed single doses exceeded 2- to 15-fold. Benchmark-dose (BMD) modeling of the same heart-rate data placed the threshold for pharmacological action at approximately 390 mg per single dose; with statistically significant clinical effects from about 100 mg/day, all surveyed products were in the pharmacologically active range. For chronic intake, no adequate oral repeated-dose study was available. A preliminary health-based guidance value (HBGV) of 0.18 mg/kg bw/day was therefore derived from a 28-day human no-observed-adverse-effect level (NOAEL) of 53.4 mg/kg bw/day and a composite uncertainty factor of 300; recommended intakes exceeded it about 8- to 78-fold. Both exceedances indicate uncertainty rather than demonstrated risk; pending adequate long-term data, a precautionary approach appears warranted, and products at pharmacologically active doses may qualify as function-based medicinal products.

Coffee oil derived from spent coffee grounds of Coffea arabica is considered a novel food in the European Union (EU), requiring pre-market approval supported by comprehensive toxicological data. The effects of coffee oil on human health, particularly on blood parameters and liver enzymes, have been investigated in several studies. This review article summarizes the available toxicological literature on coffee oil, including its bioactive diterpenes cafestol and kahweol, which are known for their potential health effects. Considering the different modes of action of these two diterpenes, moderate consumption of coffee oil may be considered safe for healthy adults. Based on the changes in serum values in humans, this review provides initial estimations of LOAEL, NOAEL, and ADI for these diterpenes. The findings suggest that an intake of 225 mg of coffee oil per day might be considered safe assuming that coffee oil contains about 0.4% diterpenes. In summary, the assessment based on the published data indicates that (i) the consumption of coffee oil contained in any type of prepared coffee appears to be safe because the homeostasis of lipid levels in the blood is not significantly affected, and (ii) a low consumption of coffee oil as such might be acceptable but would require a refined risk assessment considering the exposure levels of the intended food product, which must be provided for novel food approval procedures.

Cannabidiol (CBD), a non-psychotropic main component of the Cannabis plant, has been approved as a drug in the European Union (EU) under the name “Epidyolex”. However, its approval process as a food ingredient under the Novel Food Regulation was paused by the European Food Safety Authority (EFSA) due to a lack of safety data. Nevertheless, there is a growing, unregulated market in which CBD is advertised with various health claims and dosage instructions. Of particular concern is its toxic effect on the liver and possible reproductive toxicity in humans. Studies suitable for calculating the benchmark dose were identified from the available data. Animal studies yielded a benchmark dose lower confidence limit (BMDL) of 43 mg/kg bw/day, which translates into a safe human dose of approximately 15 mg/day. Only the Lowest-Observed-Adverse-Effect Level (LOAEL) of 4.3 mg/kg bw/day could be identified from the human data. This updated risk assessment confirmed a health-based guidance value (HBGV) of 10 mg/day based on human LOAEL. Despite the existing data gaps, preliminary regulation appears advisable because the current form of the gray CBD market is unacceptable from the standpoint of consumer safety and protection.

This study presents a new risk assessment of pulegone, a substance classified as possibly carcinogenic to humans (Group 2B) by the WHO International Agency for Research on Cancer (IARC). The analysis used data from a two-year carcinogenicity studies in rats and mice conducted by the National Toxicology Program (NTP) in 2011. Because of the absence of a no-observed adverse effect level (NOAEL) in these studies, the benchmark dose (BMD) approach was employed as an alternative risk assessment method. The lowest BMD lower confidence level (BMDL) of 4.8 mg/kg b.w./day among the eight endpoints served as the point of departure for calculating an acceptable daily intake (ADI) of 48 μg/kg b.w./day. This new ADI is significantly lower than the previously established tolerable daily intake of 0.1 mg/kg b.w./day set in 1997. The analysis also considered various genotoxicity studies, which indicate that pulegone’s effects follow a nongenotoxic, thresholded mechanism. The estimated intake levels of pulegone in the European Union and USA were below the newly calculated ADI, suggesting a low health risk based on current consumption patterns.

Cannabidiol (CBD), a non-psychotropic main component of the Cannabis plant, is approved as a drug in the European Union (EU) under the name “Epidyolex”. However, the approval process as a food ingredient under the Novel Food Regulation was paused by the European Food Safety Authority (EFSA) due to a lack of safety data. Nevertheless, there is a growing, unregulated market in which CBD is advertised with various health claims and different dosage instructions. Of particular concern is its toxic effect on the liver and possible reproductive toxicity in humans. Studies suitable for calculating a benchmark dose were identified from the available data. Animal studies yielded a Benchmark Dose Lower Confidence Limit (BMDL) of 43 mg/kg bw/day, which translates into a safe human dose of approximately 15 mg/day. Only a Lowest Observed Adverse Effect Level (LOAEL) of 4.3 mg/kg bw/day could be identified from the human data. This updated risk assessment confirmed the Health-based Guidance Value (HBGV) of 10 mg/day based on human LOAEL. Despite existing data gaps, preliminary regulation appears advisable as the current form of the gray CBD market is unacceptable from the standpoint of consumer safety and protection.

Approximately 8 million tons of dates (Phoenix dactylifera) are produced globally each year. The seeds of the fruit, which make up 10–15% of its weight, are typically discarded. Date seed coffee is a sustainable food system innovation rooted in the traditions of high date-producing regions. Dating back to the late 19th century, date seed coffee has evolved from a historical coffee substitute to a modern caffeine-free alternative. Date seed coffee has a long history of consumption in the European Union (EU). This indicates that it may not require novel food authorization. The composition of date seeds is evaluated in this review and a toxicological risk assessment for date seed coffee is conducted. Subchronic studies show that consuming date seed or date seed coffee has no adverse effects. Therefore, currently unavailable chronic toxicity, carcinogenicity, and reproductive toxicity studies may be unnecessary. However, for a comprehensive evaluation, it is recommended to conduct an in vitro mutagenicity test. This review provides information on the safety of date seed coffee and highlights the need for further research.

Isoeugenol has recently been evaluated as possibly carcinogenic (Group 2B) by the WHO International Agency for Research on Cancer (IARC). In light of this evaluation, an updated risk assessment of this common food constituent was conducted using the benchmark dose (BMD) approach as recommended by the European Food Safety Authority (EFSA) for point of departure (POD) determination, as an alternative to the no observed adverse effect level (NOAEL). This approach was specifically chosen, as for the relevant neoplastic endpoints only lowest observed adverse effect level (LOAEL) values are available. The toxicological endpoint from the animal studies with the most conservative BMD lower confidence limit (BMDL) value was identified. Using the obtained BMDL value of 8 mg/kg body weight/day as POD, an acceptable daily intake (ADI) of 16 µg/kg body weight/day was obtained, which—despite being more conservative than previous approaches—is still clearly above the estimated daily exposure level to isoeugenol in the USA and in Europe. These results confirm a low risk of the estimated daily exposure levels of isoeugenol.