Biological Evaluation of Nepeta laevigata, Nepeta kurramensis and Rhynchosia reniformis

Abstract

The methanol extracts and solvent soluble fractions of three selected plant species [Nepeta laevigata, Nepeta kurramensis and Rhynchosia reniformis] were evaluated for their antimicrobial, antiglycation, antiplatelet aggregation, antioxidant, cytotoxicity, phytotoxic activities, proximate compositions and isolation of natural products, for the intention of standardization and proper manage of bioactive principles in such heterogonous botanicals and encourage drug finding work with plants. The antibacterial results of Nepeta laevigata showed that the n-butanol fraction exhibited potential activity (85 % inhibition) against Escherichia coli and Proteus morganii (83 % inhibition), while in Nepeta kurramensis chloroform fraction exhibited promising activity (89 % inhibition) against Streptococcus cricetus, and Micrococcus flavas (84 % inhibition). In Rhynchosia reniformis, only crude extract exhibited 100% inhibition against Streptococcus cricitus while ethyl acetate fraction showed (99 % inhibition) against Micrococcus flavas, Streptococcus cricitus (95 % inhibition), and Proteus morganii (90 % inhibition). In antifungal activities; chloroform and ethyl acetate fractions of Nepeta laevigata as well as chloroform fraction of Nepeta kurramensis were promising; while in Rhynchosia reniformis chloroform, n-hexane and methanolic extracts were significant inhibitors as compared to rest of fractions. The fractions n-hexane and ethyl acetate of Nepeta laevigata demonstrated significant antiglycation activity with 71.26 % and 74.02 % inhibition and for Nepeta kurramensis 67.24 % inhibition was shown only by the n-hexane fraction. Among Rhynchosia reniformis fractions, ethyl acetate and chloroform displayed a significant antiglycation profile with 70.27 % and 76.02 % inhibition against protein glycation, respectively, while n-hexane fraction illustrated a moderate 64.06 % inhibition. In antiplatelet actions of Rhynchosia reniformis the water fraction was only dynamic against platelet activating factor (PAF) stimulate human platelet aggregation. Methanolic and n-butanol fractions exhibited potential activities against arachidonic acid (AA) and PAF while other fractions were insignificant and in platelet aggregation activity ofNepeta plants crude extract, chloroform and n-hexane fractions showed significant activity. The antioxidant potential of the crude extract and various fractions of Rhynchosia was assessed by using free radicals such as hydroxyl ( • OH) radical, total reactive oxygen species (ROS) and to scavenge authentic nitric oxides (ONOO - ). The Chloroform-soluble fraction was noted to contain a maximum amount of poly phenolic compounds acting as antioxidants (with IC 50 values of 30.24±0.07, 93.89±0.09 and 23.50±0.02, for scavenge authentic ONOO - , total ROS and to • OH radical, respectively) and established to be more efficient than crude extract and the other successive fractions. The ethyl acetate fraction of Nepeta laevigata exhibited stronger antioxidative profile with IC 50 values of 88.37±0.05 and 30.42±0.04, 55.97±0.09 for total ROS, • OH radical and to scavenge authentic ONOO - , respectively. Similar antioxidant profile was observed in Nepeta kurramensis. The fraction n-butanol of Rhynchosia reniformis showed potential cytotoxic activities while rests of the fractions were found to be inactive. No lethal activities were exhibited by Nepeta plants fractions. Surprisingly none of the fraction of all three plants under investigation exhibited phytotoxic activities. The proximate composition of the selected medicinal plants was assessed and analyzed according to AOAC methods. All the selected species were found to be a good source of ash, proteins and fats which can contribute greatly towards nutritional requirements and adequate protection against microorganism and other diseases. As a result of phytochemical investigation of Nepeta kurramensis seven pure compounds (1-7) were isolated out of which compound (1) is a new isolate and is named as Kurramenate after the plant species name. Two known flavonoids (8 and 9) have been provided by Rhynchosia reniformis. The compounds structures were confirmed on the basis of preliminary chemical tests and nuclear magnetic resonance (NMR) studies.O 1 3 4 5 6 OH 32' 2 1' O 3' 1'' O 3'' 4' 5'' 4'' 32'' O 6' 5' 6'' 7' 7'' 10'-25' 26' 8' 9' 27' 26'' 9'' 8'' 27'' 28'' 29'' 23' 31' 29' 2 3 1 30'' 31'' 4 6 1' O 1'' O 3' 9'-18' 7' 5' 4' 6' 4'' 3'' 10''-25'' OH 24' O 30' 28' 5'' 8' 7'' 6'' 19'' 20'' 21'' 22'' 9''-18'' 23'' O 21' 19' 8'' 22' 20' 24'' bis(2-ethylicosyl) phthalate (2) Kurramenate (1) OH OH 1-nonacosanol (4) 1-dotriacontanol (3) COOH HO HO HO Ursolic acid (5) H 3 C 5 \ 6 \ O 8 H 3 C O 1 \ O 1 7 6 4 5 OH 2 3 O 4 \ H 3 C CH 3 2 O CH 3 5-hydroxy-3,6,8,4 -tetramethoxyflavon (8) 5 \ O 1 \ O 1 7 H 3 C 6 \ O 8 3 \ \ 6 O `  -sitosterol (7)  -amyrin (6) 4 5 OH 2 3 OH 4 \ 3 \ 2 \ OH O ` 3,5,4 -trihydroxy-6,8-dimethoxyflavone (9) Compounds 1, 2, 8 and 9 exhibited moderate antimicrobial and antioxidative activities. The biologically active crude extracts, fractions and pure compounds can be used for the curing of microbial diseases, glycation, artery and oxygen stress allied syndromes. However, further in vivo examination of crude extracts, fractions and pure compounds will discover its potential pharmaceutical actions.