Grossowicz N, Waxman S
Chemotherapy. 1983;29(6):436-41. doi: 10.1159/000238232.
Homofolic acid (HF) was found to inhibit the growth of Lactobacillus casei ATCC 7469 in 100 ng/ml or higher concentrations in the presence of folic acid (PGA) on short (24-48 h) incubation. HF blocked the uptake of 3HPGA into L. casei cell suspensions. On prolonged (3-5 days) incubation HF (greater than 10 ng/ml) promoted growth of L. casei both in the presence and absence of PGA. No growth was obtained when both PGA and HF were omitted. Thus, HF was apparently biotransformed from an inhibitory analog into a growth-promoting HF derivative. Indeed, sterile filtrates from HF-grown cultures supported growth of L. casei in a folate-free medium on short incubation, supporting the notion that a folate-like active compound was formed from HF on prolonged incubation with L. casei. In the presence of homopteorate (10-60 micrograms/ml) no transformation of HF into folate-active compounds took place.
在存在叶酸（PGA）的情况下，发现高叶酸（HF）在短时间（24 - 48小时）孵育时，浓度为100 ng/ml或更高时可抑制干酪乳杆菌ATCC 7469的生长。HF阻止了3HPGA进入干酪乳杆菌细胞悬液。在长时间（3 - 5天）孵育时，HF（大于10 ng/ml）在有和没有PGA的情况下均促进了干酪乳杆菌的生长。当同时省略PGA和HF时则没有生长。因此，HF显然从一种抑制性类似物生物转化为一种促进生长的HF衍生物。实际上，来自HF培养物的无菌滤液在短时间孵育时能支持干酪乳杆菌在无叶酸培养基中的生长，这支持了在与干酪乳杆菌长时间孵育时从HF形成一种类似叶酸的活性化合物的观点。在存在高蝶呤（10 - 60微克/毫升）的情况下，未发生HF向叶酸活性化合物的转化。
