Application to Butterbur Products of a Suggested Daily Intake-Based Safety Evaluation of Individual Herbal Supplements with Cytochrome P450 Expression as a Major Index.

The present paper first proposes a method for ensuring the safety of commercial herbal supplements, termed the suggested daily intake-based safety evaluation (SDI-based safety evaluation). This new method was inspired as a backward analog of the acceptable daily intake (ADI) derivation from the no observed adverse effect level (NOAEL), the basis of food additive risk analysis; namely, rats are dosed with individual herbal supplement products at the SDI for human use multiplied by 100 (the usual uncertainty factor value) per body weight for 8 d. The primary endpoint is the sign of adverse effects on liver, especially gene expression of cytochrome P450 (CYP) isoforms. The proposed method was then applied to three butterbur (Petasites hybridus) products without pyrrolizidine alkaloids but lacking clear safety information. Results showed that two oily products markedly enhanced the mRNA expression of CYP2B (>10-fold) and moderately enhanced that of CYP3A1 (<4-fold) with liver enlargement. These products also caused the renal accumulation of alpha 2-microglobulin. One powdery product showed no significant effect on liver and kidney. The large difference in effects of products was due to the difference in chemical composition revealed by liquid chromatography-mass spectroscopy. The oily and the powdery products required attention in terms of safety and effectiveness, respectively. Finally, the results from the SDI-based safety evaluation of butterbur and other herbal supplement products were grouped into four categories and cautionary notes were discussed. The SDI-based safety evaluation of their products by herbal supplement operators would contribute to safe and secure use by consumers.

Current status of platelet-rich plasma therapy under the act on the safety of regenerative medicine in Japan.

In Japan, a legal framework has been established for the safe and effective application of regenerative medicine. After eight years of the Act on the Safety of Regenerative Medicine (RM Act), discussions have been underway in the Ministry of Health, Labor and Welfare of Japan to revise the law owing to numerous novel technologies and inappropriate case reports not anticipated when the law was enacted. Therefore, in this review article, we have reviewed the regenerative medicine provision plans and the contribution of platelet-rich plasma (PRP) therapy, a regenerative medicine technique widely used in Japan post RM Act implementation, to these plans. As of January 2022, 97.2% of the regenerative medicine provided under the RM Act had been for private practice, and most of them were Class Ⅲ regenerative medicine. Notably, PRP was the most used processed cell under the RM Act. PRP therapy accounted for approximately 66% of the regenerative medicine provision plans in clinical research or private practice and was the most provided regenerative medicine technology in Japan. PRP therapy was primarily used in dentistry to regenerate periodontal tissue (approximately 50%), followed by orthopedics, where it is used to treat osteoarthritis. We suggest that further discussion is essential to determine the factors that should be addressed by the RM act to evaluate the efficacy and safety of PRP therapy.

Internalization and Decrease of Duodenal DMT1 Involved in Transient Suppression of Iron Uptake in Short-Acting Mucosal Block.

Mucosal block (MB) is induced by the oral administration of excess iron (10 mg) and suppresses intestinal iron absorption for 3-72 h. The inhibition of iron absorption is accompanied by the downregulation of molecules associated with intestinal iron absorption. Recently, we found that a smaller amount of iron (1 mg) also induced a transient suppression of iron uptake without affecting gene expression levels (short-acting mucosal block, SAMB), which is specific to iron-deficient rats. In this study, we investigated how the nonheme iron transporters divalent metal transporter 1 (DMT1) and ferroportin (FPN) are involved in the transient suppression of iron uptake in SAMB. To induce SAMB, a test solution containing 1 mg iron was infused into the duodenum loop in iron-sufficient and iron-deficient rats. Total duodenal DMT1 and DMT1-IRE expression were increased during iron deficiency. After 15 min of 1 mg iron loading, the fluorescence intensity of duodenal DMT1 in iron-deficient rats was decreased and was comparable to that in iron-sufficient rats. Internalized DMT1-IRE as puncta was observed at 15 and 60 min after 1 mg iron loading, and the number of punctas was significantly increased after 60 min compared with control. There was no effect of 1 mg iron loading on the intracellular distribution of duodenal FPN. Our results suggest that the decrease and internalization of DMT1-IRE protein may be related, at least in part, to iron uptake suppression in SAMB.

Marginally excessive iron loading transiently blocks mucosal iron uptake in iron-deficient rats.

Regular "mucosal block" is characterized by decreased uptake of a normal iron load 3-72 h after the administration of excess iron (generally 10 mg) to iron-deficient animals. We found that short-acting mucosal block could be induced by much lower iron concentration and much shorter induction time than previously reported, without affecting levels of gene expression. A rapid endocytic mechanism was reported to decrease intestinal iron absorption after a high iron load, but the activating iron load and the time to decreased absorption were undetermined. We assessed the effects of 30-2,000 µg iron load on iron uptake in the duodenal loop of iron-deficient and iron-sufficient rats under anesthesia. One hour later, mucosal cellular iron uptake in iron-deficient rats administered 30 µg iron was 76.1%, decreasing 25% to 50.7% in rats administered 2,000 µg iron. In contrast, iron uptake by iron-sufficient rats was 63% (range 60.3-65.5%) regardless of iron load. Duodenal mucosal iron concentration was significantly lower in iron-deficient than in iron-sufficient rats. Iron levels in portal blood were consistently higher in iron-deficient rats regardless of iron load, in contrast to the decreased iron uptake on the luminal side. Iron loading blocked mucosal uptake of marginally excess iron (1,000 µg), with a greater effect at 15 min than at 30 min. The rapid induction of short-acting mucosal block only in iron-deficient rats suggests DMT1 internalization.

Rapid regulation of intestinal divalent metal (cation) transporter 1 (DMT1/DCT1) and ferritin mRNA expression in response to excess iron loading in iron-deficient rats.

We determined the effects of excess iron on the expression of duodenal divalent metal transporter 1 (DMT1) and ferritin (Ft) in iron-deficient rats which had increased iron absorption. DMT1 mRNA was down-regulated and Ft mRNA was up-regulated 2 h after administering the iron. However, more than 2 h was needed for Ft protein synthesis to occur in the duodenal mucosa.

High dose of commercial products of kava (Piper methysticum) markedly enhanced hepatic cytochrome P450 1A1 mRNA expression with liver enlargement in rats.

Commercial products containing the kava plant (Piper methysticum), known to have the anxiolytic activity, are banned in several European countries and Canada because of the suspicion of a potential liver toxicity. In some reports, kava and kavalactones (major constituents of kava) inhibited activities of cytochrome P450 (CYP) isoforms including CYP1A2. On the other hand, a few studies showed that administration of kava to rats moderately increased CYP1A2 proteins in the liver. CYP1A isoforms are likely responsible for the metabolic activation of potent carcinogenic environmental toxins such as aflatoxins, benzo[a]pyrene, and others. On these bases, we have investigated the effects of administration of commercial kava products on gene expression of hepatic CYP1A isoforms in rats. A high dose (equivalent to approximately 380mg kavalactones/kg/day; 100 times of the suggested dosage for human use) of two different types of kava products for 8 days significantly increased liver weights. CYP1A2 mRNA expression was moderately increased (2.8-7.3 fold). More importantly, the high dose of kava markedly enhanced CYP1A1 mRNA expression (75-220 fold) as well as ethoxyresorufin O-deethylase activities and CYP1A1 immunoreactivities. Thus, no observed adverse effect levels of kavalactones would be lower than 380mg/kg/day. When the safety factor of kavalactones is assumed to be 100, a value most often used upon the risk analysis of chemicals and designed to account for interspecies and intraspecies variations, a number of kava product users likely ingest more kavalactones than acceptable daily intakes. Based on overall evidence, we should pay considerable attention to the possibility that kava products induce hepatic CYP1A1 expression in human especially in sensitive individuals.