Microbial transformation of the anti-diabetic agent corosolic acid by Cunninghamella echinulata.

The pentacyclic triterpenoid corosolic acid was metabolized by Cunninghamella echinulata CGMCC 3.2000 to its C-24 aldehyde group metabolite and five other hydroxylated metabolites: madasiatic acid (2), 2α, 3ß, 7ß-trihydroxyurs-12-en-28-oic acid (3), 2α, 3ß, 15α-trihydroxyurs-12-en-28-oic acid (4), 2α, 3ß, 6ß, 7ß-tetrahydroxyurs-12-en-28-oic acid (5), 2α, 3ß, 7ß, 15α-tetrahydroxyurs-12-en-28-oic acid (6), and 2α, 3ß,7ß-trihydroxy-24-al-urs-12-en-28-oic acid (7); compounds 3, 5, and 7 were new compounds. The α-glucosidase inhibitory effects of the metabolites were also evaluated.

Microbial transformation of asiatic acid.

Asiatic acid (1), a major pentacyclic triterpene of Centella asiatica, was subjected to transformation by Penicillium lilacinum ACCC 31890, Fusarium equiseti CGMCC 3.3658, and Streptomyces griseus CGMCC 4.18 strains. Incubation of asiatic acid with P. lilacinum ACCC 31890 and F. equiseti CGMCC 3.3658 gave an identical product: 2α,3ß,15α,23-tetrahydroxyurs-12-en-28-oic acid (2). Biotransformation of asiatic acid by S. griseus CGMCC 4.18 resulted in three derivatives: 2α,3ß,21ß,23-tetrahydroxyurs-12-en-28-oic acid (3), 2α,3ß,23-trihydroxyurs-12-en-28, 30-dioic acid (4), and 2α,3ß,23,30-tetrahydroxyurs-12-en-28-oic acid (5). The structures of those derivatives were deduced from their spectral data. Products (2), (3), and (4) were new compounds. In addition, the in vitro cytotoxicities of those derivatives along with 1 were evaluated with several human cancer cell lines.

miR-140 Attenuates the Progression of Early-Stage Osteoarthritis by Retarding Chondrocyte Senescence.

Osteoarthritis (OA) is a major cause of joint pain and disability, and chondrocyte senescence is a key pathological process in OA and may be a target of new therapeutics. MicroRNA-140 (miR-140) plays a protective role in OA, but little is known about its epigenetic effect on chondrocyte senescence. In this study, we first validated the features of chondrocyte senescence characterized by increased cell cycle arrest in the G0/G1 phase and the expression of senescence-associated ß-galactosidase (SA-ßGal), p16INK4a, p21, p53, and γH2AX in human knee OA. Then, we revealed in interleukin 1ß (IL-1ß)-induced OA chondrocytes in vitro that pretransfection with miR-140 effectively inhibited the expression of SA-ßGal, p16INK4a, p21, p53, and γH2AX. Furthermore, in vivo results from trauma-induced early-stage OA rats showed that intra-articularly injected miR-140 could rapidly reach the chondrocyte cytoplasm and induce molecular changes similar to the in vitro results, resulting in a noticeable alleviation of OA progression. Finally, bioinformatics analysis predicted the potential targets of miR-140 and a mechanistic network by which miR-140 regulates chondrocyte senescence. Collectively, miR-140 can effectively attenuate the progression of early-stage OA by retarding chondrocyte senescence, contributing new evidence of the involvement of miR-mediated epigenetic regulation of chondrocyte senescence in OA pathogenesis.

Microbial transformation of the anti-diabetic agent corosolic acid.

Biotransformation of corosolic acid (1) by Cochliobolus lunatus and Streptomyces asparaginoviolaceus afforded four metabolites, which were identified by using (1)H NMR, (13)C NMR, DEPT, HSQC, HMBC and NOESY spectral data. Biotransformation of corosolic acid by C. lunatus R.R. Nelson & Haasis CGMCC 3.4381 produced three metabolites: 2α,3ß,21ß-trihydroxyurs-12-en-28-oic acid (2), 2α,3ß,7ß,21ß-tetrahydroxy-urs-12-en-28-oic acid (3) and 2α,3ß-dihydroxy-21-oxours-12-en-28-oic acid (4). Incubation of corosolic acid with growing cultures of S. asparaginoviolaceus CGMCC 4.0175 afforded metabolite 2α,3ß,30-trihydroxyurs-12-en-28-oic acid (5). All the metabolites were reported for the first time. The substrate and four metabolites, along with four products obtained previously, were evaluated for their inhibitory effects on α-glucosidase; all the triterpenes tested showed potent inhibitory effects.