In this study, lyophilized and methanolic extracts of aloe gel from different germplasms were evaluated for their potential to inhibit mushroom tyrosinase activity. The results showed potent inhibitory effect of Aloe vera gel extracts on L-dihydroxyphenylalanine (L-DOPA) oxidation catalyzed by tyrosinase in a dose-dependent manner. Significant differences in % inhibition of tyrosinase among the extraction methods and the germplasms were observed. The relative performance of the germplasms was evaluated with the help of posthoc multicomparison test. The methanolic extract was more effective than the lyophilized crude gel in all the germplasms. The inhibitory effect of the lyophilized gel and methanolic extract tested from five germplasms followed the order: RM > TN > S24 > OR > RJN. The germplasm RM showed the highest tyrosinase inhibition, and the maximum % inhibition noted was 26.04% and 41.18%, respectively for the lyophilized and methanolic extracts at 6 mg · mL(-1) concentration. Lineweaver-Burk plots of the different concentrations of L-DOPA in the absence and presence of lyophilized gel extract showed competitive inhibition of mushroom tyrosinase in all the germplasms. This study suggests that the germplasm RM could potentially be used for the isolation and identification of the effective tyrosinase inhibitory component, and ascertains the critical role of selecting the best source of germplasm for natural product isolation and characterization.
Agaricales ; enzymology ; Aloe ; chemistry ; Enzyme Inhibitors ; chemistry ; Fungal Proteins ; antagonists & inhibitors ; chemistry ; Gels ; chemistry ; Kinetics ; Monophenol Monooxygenase ; antagonists & inhibitors ; chemistry ; Plant Extracts ; chemistry

Background/Aims: Association of sarcopenia with disease severity in ulcerative colitis (UC) is not clearly defined. We planned to estimate the prevalence of sarcopenia in patients with UC as per the revised definition and its relation with the disease severity. Methods: A cross-sectional assessment of sarcopenia in patients with UC was performed. Disease activity was graded according to complete Mayo score. Hand grip strength was assessed with Jamar hand dynamometer, muscle mass using a dual energy X-ray absorptiometry scan, and physical performance with 4-m walk test. Sarcopenia was defined as a reduction of both muscle mass and strength. Severe sarcopenia was defined as reduced gait speed in presence of sarcopenia. Results: Of 114 patients (62 males, mean age: 36.49±12.41 years), 32 (28%) were in remission, 46 (40.4%) had mild-moderate activity, and 36 (31.6%) had severe UC. Forty-three patients (37.7%) had probable sarcopenia, 25 (21.9%) had sarcopenia, and 14 (12.2%) had severe sarcopenia. Prevalence of sarcopenia was higher in active disease (2 in remission, 6 in active, and 17 in severe, P<0.001). Of 14 with severe sarcopenia, 13 had severe UC while 1 had moderate UC. On multivariate analysis, lower body mass index and higher Mayo score were associated with sarcopenia. Of 37 patients with acute severe colitis, 16 had sarcopenia. Requirement of second-line therapy was similar between patients with and without sarcopenia. On follow-up (median: 18 months), there was a non-significant higher rate of major adverse events in those with sarcopenia (47.4% vs. 33.8%, P=0.273). Conclusions Sarcopenia and severe sarcopenia in UC correlate with the disease activity.