Plant-derived natural products for drug discovery: current approaches and prospects.

Nature has abundant source of drugs that need to be identified/purified for use as essential biologics, either individually or in combination in the modern medical field. These drugs are divided into small bio-molecules, plant-made biologics, and a recently introduced third category known as phytopharmaceutical drugs. The development of phytopharmaceutical medicines is based on the ethnopharmacological approach, which relies on the traditional medicine system. The concept of 'one-disease one-target drug' is becoming less popular, and the use of plant extracts, fractions, and molecules is the new paradigm that holds promising scope to formulate appropriate drugs. This led to discovering a new concept known as polypharmacology, where natural products from varying sources can engage with multiple human physiology targets. This article summarizes different approaches for phytopharmaceutical drug development and discusses the progress in systems biology and computational tools for identifying drug targets. We review the existing drug delivery methods to facilitate the efficient delivery of drugs to the targets. In addition, we describe different analytical techniques for the authentication and fingerprinting of plant materials. Finally, we highlight the role of biopharming in developing plant-based biologics.

Effect of different extraction techniques on total phenolic and flavonoid contents, and antioxidant activity of betelvine and quantification of its phenolic constituents by validated HPTLC method.

The objective of the study is to analyze the effect of different extracting methods on the polyphenolic content and antioxidant activities in Piper betle leaves. In the present research, P. betle leaf extract was prepared by sonication, Soxhlet and maceration methods using acetone (100%, v/v). The efficiency of the extraction methods was estimated by quantifying the total phenolic content (TPC) by the Folin-Ciocalteu method and total flavonoid content (TFC) by AlCl3 colorometric methods, and antioxidant power of the various extracts was determined by DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical scavenging assay. Thin-layer chromatography (TLC) bioautography was carried out to identify antioxidants, and their amount was determined by the newly developed high-performance thin-layer chromatography (HPTLC) method. DPPH free radical scavenging capacity of the different extracts from strongest to weakest was as follows: ascorbic acid (4.27 µg/mL) > sonication (5.35 µg/mL) >, maceration (5.53 µg/mL)>, soxhlet extraction (5.83 µg/mL). Same trend was also observed for the ABTS radical scavenging capacity. Similarly, findings of this study also showed that sonication extract possessed highest phenolic and flavonoid contents followed by maceration and Soxhlet extraction. In addition, important bioactive phenolic constituents which contribute largely towards antioxidant potential such as eugenol and eugenol acetate were quantified using HPTLC (high-performance thin-layer chromatography) method. The average percent recovery of eugenol and eugenol acetate was found to be 97.28% and 98.04%, respectively. The LOD (limit of detection) and LOQ (limit of quantification) for eugenol were 5 and 15 ng/spot, whereas that of eugenol acetate were 10 and 30 ng/spot. The HPTLC densitometric determination also supported the results of antioxidant assays by revealing the presence of higher amount of identified antioxidants in sonication followed by maceration and Soxhlet extraction. The developed HPTLC chromatogram profile may be used as a reference for the standardization of P. betle leaf extracts.

Phytochemical analysis of flower from Pandanus odorifer (Forssk.) Kuntze for industrial application.

Pandanus odorifer (Forssk.) Kuntze is an economically important aromatic plant. The essential oil from male flowers is widely used in aromatherapy, cosmetics and as food flavouring agent. Phenylethyl methyl ether (PEME), the major constituent of essential oil, gives the chief characteristic fragrance to the oil. In the present study, 180 samples from 12 different regions were collected and hydrodistilled for essential oil isolation. The oil was then subjected to GC and GC-MS analysis to find out the percentage of the constituents. The results revealed PEME as the major constituent ranging from 58.03 to 81.86% and terpinen-4-ol, the second major constituent ranging from 7.81 to 21.46%. Soil nitrogen was found to be the most influential factor for oil yield and PEME content. The flowers containing high essential oil yield and PEME content could be used as elite chemotypes with enough potential for large-scale commercial cultivation to meet the demand of kewda industries.

Differential expression of CURS gene during various growth stages, climatic condition and soil nutrients in turmeric (Curcuma longa): Towards site specific cultivation for high curcumin yield.

Curcuma longa L., accumulates substantial amount of curcumin and essential oil. Little is known about the differential expression of curcumin synthase (CURS) gene and consequent curcumin content variations at different agroclimatic zones. The present study aimed to evaluate the effect of climate, soil and harvesting phase on expression of CURS gene for curcumin yield in two high yielding turmeric cultivars. Expression of CURS gene at different experimental zones as well as at different harvesting phase was studied through transcriptional analysis by qRT-PCR. Curcumin varied from 1.5 to 5% and 1.4-5% in Surama and Roma respectively. The expression of CURS also varied from 0.402 to 5.584 fold in Surama and 0.856-5.217 fold in Roma. Difference in curcumin content at a particular zone varied among different harvesting period from 3.95 to 4.31% in Surama and 3.57-3.83% in Roma. Expression of CURS gene was also effected by harvesting time of the rhizome which varied from 7.389 to 16.882 fold in Surama and 4.41-8.342 fold in Roma. The CURS gene expression was found regardless of variations in curcumin content at different experimental zones. This may be due to the effects of soil and environmental variables. Expression was positively correlated with curcumin content with different harvesting time at a particular zone. This find indicates effect of soil and environment on molecular and biochemical dynamics of curcumin biosynthesis and could be useful in genetic improvement of turmeric.

Chemical composition and antioxidant activity of essential oil from leaves and rhizomes of Curcuma angustifolia Roxb.

The essential oil extracted from rhizome and leaf of Curcuma angustifolia Roxb. (Zingiberaceae) was characterised by gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis revealed the presence of 32 and 35 identified constituents, comprising 92.6% and 92% of total leaf and rhizome oil, respectively. Curzerenone (33.2%), 14-hydroxy-δ-cadinene (18.6%) and γ-eudesmol acetate (7.3%) were the main components in leaf oil. In rhizome oil, curzerenone (72.6%), camphor (3.3%) and germacrone (3.3%) were found to be the major constituents. Antioxidant capacities of oil were assessed by various methods, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and reducing power ability (RPA). Based on the results, the leaf oil showed more antioxidant potential as compared to rhizome oil and reference standards (ascorbic acid and butylated hydroxytoluene (BHT)). Thus, the leaf essential oil of C. angustifolia can be used as an alternative source of natural antioxidant.

Characterization of Kewda volatile components by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry.

Kewda (Pandanus fascicularis Lam.) is a well known medicinal and aromatic plant. The paper aims to precisely characterize volatile constituents present in Kewda flower oil using comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GCxGC-TOFMS). A total of 159 components were identified due to enhanced chromatographic separation and mass spectral deconvolution of GCxGC-TOFMS. On the basis of its chemical structure, the identified compounds were grouped into hydrocarbons, alcohols, ethers, ketones, esters, nitrogen compounds, aldehydes, acids, lactones, halides and sulfur containing compounds. Ethers were the major components. The predominant compounds identified by GCxGC-TOFMS were kewda ether, ortho-cymene and terpinen-4-ol. A database containing retention indices of compounds was created for the bi-dimensional column, thus proving to be a remarkable step for analysis of constituents using a GCxGC system. GCxGC-TOFMS separated a number of co-eluting components which were unresolved on a single GC column.