**5. Biological activity of medicinal plants**

Due to the presence of bioactive molecules plants are used as phytomedicine to cure many complaints. *Catharanthus roseus* has 'vinblastine' and 'vincristine' and used in cancer. *Rauwolfia serpentina* is hypotensive due to presence of 'serpentine', 'reserpine' and 'ajmalicine'. *Papaver somniferum* contains 'morphine' and 'codeine' and is analgesic and sedative. 'Artemisinin' is effective against malaria derived from *A. annua*. Similarly, the bioactive components of plants 'Withanaloides' reported from *Withania somnifera* useful in treatment of arthritis. 'Charantin' a steroidal saponin, isolated from *Momordica charantia* reported for anti-diabetic activity. 'Diospyrin' reported from *Diosyros species* acts as antileishmanial agent. 'Tephdidoside' is a flavanol glycoside derived from *Tephorsea candida* found to be active against human cancer [16]. 'Berberine' derived from *Berberis vulgaris* reported for antidiabetic, hepatoprotective, antimicrobial activity. 'Digoxin'obtained from *Digitalis lanata* used in heart diseases. Similarly, 'Quinine' isolated from *Cinchona robusta* acts as antimalerial, antiparasitic agent. Another compound 'Allicin' isolated from *A. sativum* reported for its cardioprotective, antiinflammatory activity [17].

More than 35,000 plant species have been investigated and resulted in the discovery of anticancer drugs such as 'Vincristine', 'Vinblastine', 'Taxol', 'Etoposide analogs', 'Camptothecin' etc. Many number of effective drugs derived from higher plants were alkaloid 'Paclitaxol', isolated from *Taxus brevifolia* used in treatment of ovarian and breast cancers [18]. 'Andrographolide', active diterpine derived from *A. paniculata* acts as a noble anticancer agent against cancers of breast, ovary, stomach, colon, prostate, kidney, nasopharynx malignant melanoma and leukemia. 'Thymoquinone' and 'dithymoquinone' of *Nigella sativa* shows anticancer activity against different types of cancers such as colon, prostate, pancreas, uterus, malignant ascites, malignant lymphoma, malignant melanoma, sarcomas and leukemia. However, 'Plumbagin' isolated from *Plumbago zeylanica* hinders growth and spread of breast cancer, liver cancer, fibro-sarcoma, malignant ascites and leukemia by cell proliferation [19].

A wide range of reports are available on phytochemicals and pharmacological activity of medicinal plants. Several workers have reported biological activity of medicinal plants. Pharmacognostic and preliminary phytochemical analysis of *Colocasia esculenta* dried tubers were calculated. The tubers are good source of carbohydrate, protein and starch. Nutritional analysis showed moisture content (56.8%), ash content (1.22%), carbohydrate (3000 mg/100gm), protein (824 mg/100gm)

#### *Medicinal Plants and Its Pharmacological Values DOI: http://dx.doi.org/10.5772/intechopen.99848*

and starch (2700 mg/100gm) in dry tubers. Phytochemical analysis revealed the presence of alkaloids, glycosides, flavonoids, terpenoids, saponins and phenols [20]. *A. aspera* important medicinal plants reported in Ayurvedic literature with number of medicinal property. Phytochemical investigation of plant extracts were subjected to qualitative screening test for various constituents. This revealed the presence protein, glycosides, alkaloids, tannins and phenolic compound, steroid reducing sugars and saponin glycosides [21]. Pharmacognostic and phytochemical evaluation of *Tridax procumbens* were studied. The quantitative microscopical and histological study is done revealed the presence of Tricomes, palisade tissue, trachieds and vessels in powder microscopy. Phytochemical analysis of the whole plant is done and the presence of carbohydrates, sterioids, phenols and tannins were reported and quercitin is confirmed using HPTLC [22].

In parallel, phytochemical screening of *Cinnamomum zeylanicum* shows the presence of carbohydrate, glycoside, protein, tannins, saponins, flavonoids and terpenoids. The proximate analysis revealed that water soluble extractive values of leaves was 29.75, total ash value was 9.75, acid insoluble ash was found to be 2.50 and sulphated ash was 37.35. Anti- microbial activity of the disk diffusion method showed that chloroform and hydro-ethanol extracts of leaf were more effective against Gram–positive bacteria in vitro [23].

Antimicrobial activity of different extract of *Cynodon dactylon* was tested against disease causing bacterial pathogens using the agar well diffusion method. Areal parts of ethanol extract show more activity against *Pseudomonas aeruginosa* and *Staphylococcus aureus* with zone of inhibition 13.83 ± 0.29 mm and 2.0 ± 0.10 mm respectively. A total 20 compounds were identified from the hydroalcoholic extract of the whole parts through GC–MS analysis. Among all, hexadecanoic acid, ethyl ester inolenic acid, ethyl ester was the major components of the hydroalcoholic extract and hexadecanoic acid ethyl ester was abundant. The antioxidant activity of the hydro-alcoholic extract of aerial parts was studied *in vitro* by different methods. Of this superoxide radical scavenging assay revealed a maximum inhibition of 93.33%. Total antioxidant capacity equivalent of ascorbic acid was 172.39 mg/g of extract. Similaly, anticancer activity of methanolic extracts of leaves was studied in ascitic lymphoma (ELA) in Swiss albino mice. Results demonstrate that methanolic extract was found to be antiproliferative at lower concentrations and induced apoptotic cell death in COLO 320 DM cells [24].

*Pothos scandens* another medicinally important plant screened for its various biological activity. At lower concentration of ethanol extract was found to have more antimicrobial activity compare to other. The ethanol extract of root showed significant free radical scavenging activity with DPPH and superoxide radical scavenging activity (IC50 0.284 mg/mL and 70.84%). The active compounds of ethanol extract of aerial parts investigated through GC–MS analysis. This depicts that Dodecanoic acid, tetra decanoicacid and n- hexadecanoic acid acts as antioxidant. Similarly cytotoxicity of same plant was evaluated against MCF-7 (breast cancer) cell lines by MTT assay and results revealed that the extract has significant cytotoxic activity with an IC50 of 90.18 ± 5.20 μg/ml and also cell death of MCF-7 treated with the extract was due to the induction of apoptosis, which was confirmed by comet assay [25].

The in vitro cytotoxic activity of *Colocasia gigantea* extract on cervical cancer (Hela) and human white blood cells (WBC) was conducted. Bioassay-guided fractionation method showed that not all parts promote cytotoxic activity. The leaf fraction of dichloromethane showed significant cell proliferation effect on Hela cells, but not on WBCs. The n-hexane tuber fraction only exhibited significant cytotoxicity on Hela cells (IC50 585 μg/ml) and encouraged WBC cell proliferation. From the GC–MS spectrometry it was found the 4, 22-Stigmastadiene-3-one,

Diazoprogesterone, 9-Octadecenoic acid (Z)-, hexyl ester, and Oleic Acid were the components of n- hexane tuber fraction which had cytotoxic potential. Tuber fraction of n- hexane shows potential for cervical cancer treatment [26].
