The wide-ranging medicinal uses attributed to genus Mangifera indica and Azarirachta indica led to carry out bioassay guided phytochemical studies. Leaves of M. indica and A. indica were ground and extracted with methanol. After solvent evaporation, a dark green residue was obtained. It was dissolved in water and successively partitioned with n-hexane, CHCl3, EtOAc and butanol. All the fractions except n-hexane showed remarkable inhibitory activities of both exo and endoglucanase, the chloroform and butanol fractions also showed significant herbicidal potential. Repeated chromatographic resolution of all these fractions and sub-fractions M. indica and only butanol fraction of A.indica using silica gel column and subsequent elution of different combination of solvent systems resulted the isolation of thirteen compounds from Mangifera indica and seven compounds from Azadirachta indica, which includ four new compounds 1, 2, 4, and 18. along with the compounds 1,2,3,4,5,6,7,9,10,11 and 14, 16, 17 reported for the first time from M. indica and A.indica respectively. The compounds 8, 12, 13 and 15, 19, 20 were already reported from A. indica and M.indica respectively. All the compounds were tested against cellulases (both exo and endoglucanase) enzymes of Melanoplus sanguinipes (a worldwide problematic insect), compounds 2,3,4,5,6,9,10 and 11 for their herbicidal potential against Parthenium hysterophorus(a worldwide notorious weed) and 2,3,4,5 10and 11 for their antimicrobial activity against five fungal (Macrophamina phaseolena, alternaria alternaria, Penicilium citrii, Aspergillous fumigatous and Aspergillous niger) and four bacterial strains (Lactobacillus sp., Escherichiacoli, Azospirillium lipoferum and Bacillus sp.). The results of the present study indicate that the medicinal plants M.indica and A.indica possess substantial pesticidal, herbicidal, antifungal and antibacterial properties. Especially the pesticidal and herbicidal constituents of M. indica leaves can be exploited for the management of Melanoplus sanguinipes and Parthenium hysterophorus L. The compound 10 exhibited significant inhibition of both enzymes and the growth of parthenium to a large extent.Structure of this compound can be used as an analogue for the preparation of a nature friendly biopesticides and herbicides for the control of one of the most destructive pest Melanoplus sanguinipes and most noxious weed Parthenium hysterophorus to protect the major cash crops of Pakistan.