Search

Hyaluronidase (hyase) is a hyaluronic acid (HA) depolymerizing enzyme produced by many pathogenic bacteria as a virulence factor to establish and spread infections. Present studies established that a steroidal fraction (SF) isolated from leaves of Carissa carandas act as a strong hyase inhibitor. The kinetic parameters involved in the inhibition of hyase by purified SF were studied and compared with standard hyase inhibitor quercetin. The purified SF showed the highest inhibition with an IC50 of 5.19 mM in comparison with a standard inhibitor, quercetin (IC50 8.63 mM). The inhibition constant (Ki) of purified SF determined by Dixon plot was 8.32 mM, which was significantly lower than that of quercetin standard. The kinetic behavior of enzyme hyase revealed to be more complex than classical competitive and uncompetitive inhibition where inhibitor affects both Km and Vmax. The inhibitor (I) favored the binding to the enzyme-substrate (ES) complex where Km value appeared to decrease (Kmapp < Km). The inhibitor also leads to decrease in the apparent maximum velocity of the enzyme-substrate reaction (Vmaxapp < Vmax). These results signpost toward mixed nature of inhibition of enzyme hyase by purified SF. Anti-hyaluronidase activity by a bioactive metabolite from C. carandas has not been reported so far and has high therapeutic potential against spread of pathogen and its toxins in the host.

The present study evaluates porcine pancreatic lipase (PPL) inhibitory potential of a phenolic fraction from the fermentation extract of endophytic fungus D. arengae. In absence of inhibitor (phenolic fraction), the initial K m and V max of PPL were found to be 3.83±0.94 µM and 11.54±0.54 µmole/min, respectively. While, in its presence the K m app and V max app was recorded as 7.48 µM and 10.6 µmole/min, respectively and were comparable to those obtained with standard, orlistat. Increase in the K m app and no change in the V max app in the presence of inhibitor (phenolic fraction) resulted in decrease in the specificity constant ( K cat / K m ). The inhibition constant ( K i ) for the phenol-rich fraction was recorded as 13.47±5.01 µg/ml, compared to 10.65±3.81 µM obtained for Orlistat. Thus, the phenol-rich fraction from endophytic D. arengae is able to inhibit PPL competitively as like Orlistat and holds promise as the potential drug candidate.

Present study evaluates antioxidative and erythrocyte membrane stabilizing potential of methanol extract of Carissa carandas leaves Cc(L)M and its purified fraction CM 1. Phytochemically Cc(L)M revealed presence of alkaloid, steroids, saponins and tanins. The results of antioxidant assays of Cc(L)M and CM 1 found to be dose dependent. However, in TLC bioautography, CM 1 showed yellow coloured scavenged band of DPPH reagent. The results revealed that CM 1 has significant (p≤0.05) free radical scavenging potential compared to Cc(L)M. The purified fraction CM 1 was found to be most potent with lowest EC 50 values for DPPH (546.4 µg/ml), OH - (498.5 µg/ml) radical scavenging and 57.48 µg/ml for reducing power assay. It also erythrocytes membrane stabilization effect with lowest EC 50 1.31 mg/ml as compared to Cc(L)M (2.56 mg/ml) and standard diclofenac sodium (1.00 mg/ml). The FT-IR and GC-HRMS analysis of CM 1 reveal the presence of steroid derivative 20-hydroxypregnan 18-oic acid.

The free radicals and the reactive oxygen species (ROS) are known to induce oxidative stress and it has been implicated in the pathology of cardiovascular diseases, inflammatory conditions, cancer and ageing. The activities associated with ROS can bedelayed, prevented or removedby antioxidant compounds (natural or synthetic). The use of synthetic antioxidants restricted because of their known side effects such as liver damage and carcinogenesis. The aim of this study to evaluate in vitro antioxidant and acute oral toxicity of Terminalia arjuna extracts. The present finding reveals that the purified fraction at100 µg/ml, showed maximum (91.32 ± 0.10 %,) DPPH radical scavenging effect in comparison with standard ascorbic acid (79.46 ± 0.10%) at the 10 µg/ml concentration. The reducing power of the purified extract was found to be dose dependent. Food and water intake of the animals in test and control groups was found normal during the 14 day acute oral toxicity studies and no apparent changes were observed in the internal organs of both, the test and control groups, after gross necropsy. The preliminary phytochemical screening of the crude acetone extract revealed dominant presence steroids, terpenoids, polyphenols, alkaloids and tannins. TLC profile of the purified fraction revealed a single band of Rf 0.38, a characteristic feature of triterpenoids. The UV absorption maximum of the purified fraction was recorded at 194nm. The FT-IR spectrum indicated presence of aromatic rings 3421 (COOH), 2957 (alkanes, CH2 and CH3), 1726 (carbonyl), 1599 (carboxylic acid), and region between 1000-1300 stretching of C-O, ester and ether carboxylic group. Thus, the isolated bioactive phytoconstituents form the bark extract of Terminalia arjuna could be used as natural anti-oxidants..