Cysteine proteases from the Asclepiadaceae plants latex exhibited thrombin and plasmin like activities.

In the present study we evaluated the presence of cysteine protease from the latex of four plants Asclepias curassavica L., Calotropis gigantea R.Br., Pergularia extensa R.Br. and Cynanchum puciflorum R.Br. belongs to the family Asclepiadaceae. Cysteine proteases from these plants latex exhibited both thrombin and plasmin like activities. Latex enzyme fraction in a concentration dependent manner induced the formation of clot in citrated blood plasma. Direct incubation of fibrinogen with latex enzyme fraction resulted in the formation of fibrin clot similar to thrombin enzyme. However prolonged incubation resulted in degradation of the formed fibrin clot suggesting plasmin like activity. Latex enzyme fraction preferentially hydrolyzed Aalpha and Bbeta chains of fibrinogen to form fibrin clot. Latex enzyme fraction also hydrolyzed the subunits of fully cross linked fibrin efficiently, the order of hydrolysis was alpha-polymer > alpha-chains > beta-chain and gamma-gamma dimer. Cysteine proteases from all the four Asclepiadaceae plants latex exhibited similar action on fibrinogen and fibrin. This study scientifically validate the use of plant latex in stop bleeding and wound healing by traditional healers all over the world.

Topical application of serine proteases from Wrightia tinctoria R. Br. (Apocyanaceae) latex augments healing of experimentally induced excision wound in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Wrightia tinctoria R. Br. (Apocyanaceae) is a folk medicinal plant known to have immunomodulatory, anti-inflammatory and antihemorrhagic potential. Wrightia tinctoria latex is used for treatment of various clinical conditions including psoriasis, blisters, mouth ulcers, and extensively for topical application on fresh wounds to promote accelerated healing. AIMS OF THE STUDY: To investigate the wound healing potential of Wrightia tinctoria latex proteases using a mouse model. MATERIALS AND METHODS: Proteolytic activity of Wrightia tinctoria latex proteases (WTLP) was determined on various substrates (casein, gelatin and collagen (type-I and IV)). The thermal stability and the class of proteases present in WTLP were determined using heat treatment and specific protease inhibitors, respectively. Excision wound model in mice was used to evaluate the healing potential of WTLP application (twice daily, 10mg/kg). Neosporin, a standard drug, was used for comparison. The progression of healing was monitored using physical (wound contraction), biochemical (collagen content, catalase and MMP activity) and histological examinations. RESULTS: WTLP contains thermostable serine proteases, which are completely inhibited by PMSF. WTLP showed strong caseinolytic, gelatinolytic and collagenolytic activity. The excision wound healing rate upon WTLP treatment was significantly higher than (>2-fold) the control group (49% vs. 18%, (**)p<0.01) on day 3 and throughout the study. PMSF pre-treated and heat denatured WTLP failed to promote wound healing. In addition, serial biochemical analysis of the granulation tissue demonstrated 1.5-fold more (2444 ± 100 vs. 1579 ± 121 µg/100mg tissue) hydroxyproline content and 5.6-fold higher catalase activity (16.7 ± 1.3 vs. 3 ± 0.3 units/mg) compared to controls. Further, the enhanced collagen content and matrix metalloproteinase activity correlated with wound contraction rate following WTLP and Neosporin treatment. Histological analysis on day 9 confirmed complete epithelialization, re-establishment of skin structure and accelerated wound healing following WTLP treatment. CONCLUSIONS: The thermostable serine proteases of Wrightia tinctoria latex are directly involved in the wound healing process. Our findings provide a biochemical basis for the role of WTLP in the enhancement of wound healing. The study supports traditional topical application of Wrightia tinctoria latex on fresh wounds to promote accelerated healing.

Characterization of major zinc containing myonecrotic and procoagulant metalloprotease 'malabarin' from non lethal trimeresurus malabaricus snake venom with thrombin like activity: its neutralization by chelating agents.

A major myonecrotic zinc containing metalloprotease 'malabarin' with thrombin like activity was purified by the combination of gel permeation and anion exchange chromatography from T. malabaricus snake venom. MALDI-TOF analysis of malabarin indicated a molecular mass of 45.76 kDa and its N-terminal sequence was found to be Ile-Ile-Leu- Pro(Leu)-Ile-Gly-Val-Ile-Leu(Glu)-Thr-Thr. Atomic absorption spectral analysis of malabarin raveled the association of zinc metal ion. Malabarin is not lethal when injected i.p. or i.m. but causes extensive hemorrhage and degradation of muscle tissue within 24 hours. Sections of muscle tissue under light microscope revealed hemorrhage and congestion of blood vessel during initial stage followed by extensive muscle fiber necrosis with elevated levels of serum creatine kinase and lactate dehydrogenase activity. Malabarin also exhibited strong procoagulant action and its procoagulant action is due to thrombin like activity; it hydrolyzes fibrinogen to form fibrin clot. The enzyme preferentially hydrolyzes Aα followed by B subunits of fibrinogen from the N-terminal region and the released products were identified as fibrinopeptide A and fibrinopeptide B by MALDI. The myonecrotic, fibrinogenolytic and subsequent procoagulant activities of malabarin was neutralized by specific metalloprotease inhibitors such as EDTA, EGTA and 1, 10-phenanthroline but not by PMSF a specific serine protease inhibitor. Since there is no antivenom available to neutralize local toxicity caused by T. malabaricus snakebite, EDTA chelation therapy may have more clinical relevance over conventional treatment.

Thrombin like activity of Asclepias curassavica L. latex: action of cysteine proteases.

AIM OF THE STUDY: To validate the scientific basis of plant latex to stop bleeding on fresh cuts. Cysteine protease(s) from Asclepias curassavica (Asclepiadaceae) plant latex was assessed for pro-coagulant and thrombin like activities. MATERIALS AND METHODS: A waxy material from the latex of Asclepias curassavica latex was removed by freezing and thawing. The resulted latex enzyme fraction was assayed for proteolytic activity using denatured casein as substrate. Its coagulant activity and thrombin like activity were determined using citrated plasma and pure fibrinogen, respectively. Inhibition studies were performed using specific protease inhibitors to know the type of protease. RESULTS: The latex enzyme fraction exhibited strong proteolytic activity when compared to trypsin and exerted pro-coagulant action by reducing plasma clotting time from 195 to 58 s whereas trypsin reduced clotting time marginally from 195 to 155 s. The pro-coagulant activity of this enzyme fraction was exerted by selectively hydrolyzing A alpha and B beta subunits of fibrinogen to form fibrin clot when pure fibrinogen was used as substrate as assessed by fibrinogen-agarose plate method and fibrinogen polymerization assay. Trypsin failed to induce any fibrin clot under similar conditions. The electrophoretic pattern of latex enzyme fraction-induced fibrin clot was very much similar to that of thrombin-induced fibrin clot and mimic thrombin like action. The proteolytic activity including thrombin like activity of Asclepias curassavica latex enzyme fraction was completely inhibited by iodoaceticacid (IAA). CONCLUSION: Cysteine proteases from Asclepias curassavica latex exhibited strong pro-coagulant action and were found to be specific in its action (Thrombin like). This could be the basis for the use of plant latex in pharmacological applications that justify their use as folk medicine.