10 Pvalue less than 0.05 was considered statistically significant. 3. concentration in the rat penile cells were analyzed. The results showed the significant improved sexual motivation, copulatory overall performance, and ICP of aged rats treated with sildenafil citrate and all doses of EM extract as compared to control aged rats. Moreover, their serum testosterone levels were slightly improved and significant increase in penile cGMP concentration was observed in these aged rats treated with sildenafil citrate and EM draw out. The results suggest that treatment with EM could inhibit S186 activity of PDE5 in penile cells resulting in the improved cGMP level and bring to the improvement of erectile function and sexual performance. 1. Intro Erectile dysfunction (ED) refers to a man’s consistent inability to accomplish or preserve penile erection for adequate sexual activity . The prevalence and the severity of ED increase with advancing age; different pathogenetic factors could contribute to age-related ED [2, 3]. Phosphodiesterase 5 (PDE5) protein manifestation and enzyme activity were significantly elevated in penile cells of aged rats. Aged rats that received sildenafil citrate (a PDE5 inhibitor), an enzyme that promotes degradation of cGMP, showed a similar magnitude of intracavernosal pressure (ICP) as observed in the young group . PDE5 inhibitors, sildenafil (Viagra?), vardenafil (Levirate?), tadalafil (Cialis?), and Avanafil (Stendra?) are commonly used for the treatment of ED [5, 6]. The most common side effect of PDE5 inhibitors is definitely retinal defects through the inhibition of PDE6 [7, 8]. Consequently, the use of an natural medicine having high selectivity could be an alternative to the people synthetic PDE5 inhibitors.Eulophia macrobulbon(E.C. Parish & Rchb. f.) Hook. f. (EM) is definitely a plant belonging to the Orchidaceae family. In Thailand, tuber of EM has been traditionally used for a long time to relieve pain and fatigue . In previous study, it has been shown the separation of EM tuber components yielded four phenanthrene compounds which were (1) 9,10-dihydro-4-(4-hydroxybenzyl)-2,5-dimethoxyphenanthrene-1,7-diol, a new phenanthrene, (2) 1-(4-hydroxybenzyl)-4,8-dimethoxyphenanthrene-2,7-diol, (3) 9,10-dihydro-2,5-dimethoxyphenanthrene-1,7-diol, and (4) 1,5,7-trimethoxyphenanthrene-2,6-diol). These phenanthrenes from EM were reported to serve as novel phosphodiesterase-5 inhibitors, and the most potent inhibitor was 1-(4-hydroxybenzyl)-4,8-dimethoxyphenanthrene-2,7-diol which experienced IC50 value of 1 1.670.54 Eulophia macrobulbonExtraction EM was collected from Prachinburi Province, Thailand. The flower was recognized by Asst. Prof. Dr. Rabbit Polyclonal to PLA2G4C Anupan Kongbangkerd, Faculty of Sciences, Naresuan University or college. A voucher specimen (No. 002716) was deposited in the Biology Division, Faculty of Technology, Naresuan University or college, Thailand. Ethanol draw out of EM was prepared as explained previously . The draw out was stored at -20C until use. The ethanolic EM extract was standardized using 1-(4-hydroxybenzyl)-4,8-dimethoxyphenanthrene-2,7-diol, as the standard markers and analyzed from the HPLC-UV/Vis system. The content of standard marker in the ethanolic draw out S186 of EM used in this study yields as 0.52%. 2.2. Animals and Housing This study was carried out on adult (5-6-month-old) and naturally aged male rats (18-20-month-old). In addition, adult female (5-6-month-old) rats were used during sexual behavior screening. All animals were purchased from your National Laboratory Animal Center, Mahidol University or college, Salaya, Nakornpathom, Thailand. All experimental methods conformed to the guidelines established from the National Study Council of Thailand and were authorized by Naresuan University or college Animal S186 Care and Use Committee (NUACUC) (authorization no. 56 04 0064). Animals were housed in the standard animal housing conditions with managed at a temp of 221C, a relative moisture of 5510%, and a 12:12 h reversed light/dark cycle at Naresuan University or college Center for Animal Research (accreditation from the AAALAC International since 2014). Male Wistar rats were divided into 6 organizations, each group consisting of 10 animals as (1) young control, rats receiving the vehicle, propylene glycol (PG); (2) aged control, rats receiving PG; (3) aged + EM at 15 mg/kg BW; (4).