Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 17  |  Issue : 1  |  Page : 32-39

Antioxidant activity, phenol and flavonoid contents of plant and callus cultures of Plectranthus barbatus andrews


Department of Plant Biotechnology, Genetic Engineering and Biotechnology Division, National Research Center, Dokki, Giza, Egypt

Date of Web Publication4-May-2018

Correspondence Address:
Mona M Ibrahim
Department of Plant Biotechnology, Genetic Engineering and Biotechnology Division, National Research Center, Dokki 12311, Giza
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/epj.epj_38_17

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  Abstract 

Background and objective Plectranthus barbatus is cultivated in many parts of the world for healing and food tradition. This study describes a protocol for the establishment of callus cultures of P. barbatus and examines their content of active compounds as well as their effects as antioxidants compared with in-vitro plants.
Materials and methods For obtaining callus cultures, three different explants were tested on MS medium with different growth regulators. Growth index was calculated for the best explant which gave the highest percentage of callus induction. Two different solvents were used for extraction. 2,2′‐Diphenyl-1‐picrylhydrazyl-scavenging activity, total phenolic and flavonoid contents were determined. Gas chromatography–mass spectroscopy analysis was performed to detect the different components.
Results and conclusion Maximum callus induction (100%), fresh weight (3.5 g), and growth index (16.5) were obtained from cotyledon explants cultured on MS medium supplemented with 2.0 mg/l naphthalene acetic acid+2.5 mg/l benzyl adenine. Aqueous methanol extracts exhibited higher 2,2′‐diphenyl-1‐picrylhydrazyl radical scavenging activity than hexane extracts at all tested concentrations. Likewise, methanolic extract of in-vitro plant and callus cultures gave the highest values of total phenolic (1.39 and 1.19 mg/g dry weight, respectively) and total flavonoid contents (4.87 and 1.14 mg/g dry weight, respectively). Thirty-one bioactive ingredients have been identified in the hexane extract of in-vitro plant and callus cultures of P. barbatus by gas chromatography–mass spectroscopy analysis.

Keywords: 2,2′-diphenyl-1-picrylhydrazyl, gas chromatography–mass spectroscopy, in-vitro culture, Plectranthus barbatus


How to cite this article:
Ibrahim MM, Arafa NM, Aly UI. Antioxidant activity, phenol and flavonoid contents of plant and callus cultures of Plectranthus barbatus andrews. Egypt Pharmaceut J 2018;17:32-9

How to cite this URL:
Ibrahim MM, Arafa NM, Aly UI. Antioxidant activity, phenol and flavonoid contents of plant and callus cultures of Plectranthus barbatus andrews. Egypt Pharmaceut J [serial online] 2018 [cited 2018 Jul 20];17:32-9. Available from: http://www.epj.eg.net/text.asp?2018/17/1/32/231880


  Introduction Top


Plectranthus barbatus, also known as Coleus barbatus (Andr.), is a member of Lamiaceae family [1]. P. barbatus is a tropical perennial plant used medicinally in Africa, Arabia, and India and grows spontaneously throughout many countries around the world. It has a wide range of therapeutic applications and used for body weight control, heart failure, hypertension, eczema, colic, respiratory disorders, sore urination, insomnia, and convulsions [2]. Moreover, medical studies also indicated that it may have a therapeutic benefit in asthma, angina, and psoriasis [3]. The leaves of C. barbatus are used medicinally in Egypt and Africa as an expectorant, emmenagogue, and diuretic [4]. P. barbatus has a significant economic impact worldwide due to its nutritive and therapeutic values [5].

Scientists have become persuaded that the compounds of plant origin play an important role for healing as well as for curing of human diseases [6]. P. barbatus has been found to be a rich source of bioactive metabolites such as phenols, alkaloids, terpenoids, flavonoides, and antioxidants [7],[8],[9],[10],[11]. Nowadays it has been studied extensively for novel biologically active constituents.

For the production of bioactive plant ingredients, biotechnological approaches, mainly plant tissue culture tools, seem to be an important stride to illuminate the suitable morphogenetic structure for that purpose. In plant tissue culture, biosynthesis of bioactive ingredients is occasionally differentiation dependent [12] and thus linked with the types and concentrations of growth regulators added to the culture medium [13],[14],[15]. In view of that, fitting of the culture medium and growth circumstances is the key for the biosynthesis of plant metabolites [16],[17]. In the present research, the effect of different plant growth regulators on callus induction has been clarified. The ability of scavenging 2,2′‐diphenyl-1‐picrylhydrazyl (DPPH) radicals, total phenolic and flavonoid contents were also examined. Finally, the chemical composition of the hexane extract of in-vitro plant and callus cultures of P. barbatus was analyzed using gas chromatography–mass spectroscopy (GC-MS).


  Materials and methods Top


Plant material

Seeds of P. barbatus were supplied from SEKEM Company, Cairo, Egypt.

Sterilization and incubation conditions

Seeds of P. barbatus were washed in current tap water, then surface sterilized in 70% (v/v) ethanol for 30 s, and immersed in 50% Clorox solution of household bleach (5.25% sodium hypochlorite) with a drop of Tween-20 for 15 min. After thorough washing four times in sterile water, the seeds were cultured on basal MS medium [18] supplemented with 0.7% (w/v) agar and 3% (w/v) sucrose. The cultures were incubated under controlled light regime (16/8 h photoperiod and 2000 lux) at 25±1°C.

In-vitro plant formation

Shoot tip explants were excised from growing seedlings and cultured on a solidified MS basal nutrient medium supplemented with 0.5 mg/l kinetin, after one month, the formed shoots were subcultured on the same medium for multiple plant formation.

Callus induction and growth dynamics

Cotyledon, leaf, and root segments were excised from the in-vitro growing seedlings and cultured on solidified MS basal nutrient medium supplemented with 2.0 mg/l naphthalene acetic acid (NAA)+2.5 mg/l benzyl adenine (BA) and 2.0 mg/l dichlorophenoxy acetic acid (2,4-D)+2.5 mg/l BA. Cultures were kept under a controlled temperature of 26±1°C and light conditions of 16/8 h photoperiod. Data were recorded after 4 weeks of culture period; callus induction percentage and growth index [19] were calculated based on the following equations:



Preparation of extracts

Dried powdered samples of the in-vitro plants and callus culture of P. barbatus were extracted using methanol (85%) and hexane for 24 h at room temperature. The extracts were collected, filtered, and evaporated to dryness. Each residue was dissolved in the same extract solvent and stored at 4°C until further use.

Extraction yield (%) of the extract was calculated using the formula:



2,2′‐Diphenyl-1‐picrylhydrazyl radical scavenging capacity

Radical scavenging capacity of the extracts against stable DPPH was determined by a slightly modified method [20]. Different concentrations of each extract (2.0, 4.0, 6.0, 8.0, and 10 mg/ml) were used to evaluate the antioxidant capacity. 500 μl of each extract were added at 2.5 ml of methanolic solution of DPPH (0.3 mM). After 30 min at room temperature, the absorbance values were measured at 517 nm on the spectrophotometer. Radical scavenging capacity (%) was calculated by the following formula:



where As is the absorbance of solution with extract and ADPPH is the absorbance of DPPH solution.

Total phenolic and total flavonoid contents

The concentration of phenolic compounds was determined using Folin–Ciocalteu reagent according to Singleton et al. [21]. A calibration curve of gallic acid (20, 40, 60, 80, and 100 µg/ml) was prepared. The absorbance of the samples and standard solutions were determined against a reagent blank at 550 nm with an ultraviolet/visible spectrophotometer. Total phenolic content was expressed as milligram of gallic acid equivalent per gram of dry weight (DW).

Total flavonoid content was measured using a modified colorimetric method according to Vabkova and Neugebauerova [22]. The standard curve was prepared using different concentrations of quercetin. The flavonoid content was expressed as milligram quercetin equivalents per gram of DW.

Gas chromatography–mass spectrometric analysis

The hexane extract of plants and callus cultures of P. barbatus were analyzed in National Research Center, using Gas Chromatography–Mass Spectrometry with the following specifications; a TRACE GC Ultra Gas Chromatographs (THERMO Scientific Corp., USA), coupled with a THERMO mass spectrometer detector (ISQ Single Quadrupole Mass Spectrometer). TG-5MS-fused silica capillary column (30 m, 0.251 mm, 0.1 mm film thickness). For GC-MS detection, an electron ionization system with an ionization energy of 70 eV was used. Helium gas was used as the carrier gas at a constant flow rate of 1 ml/min. The injector and MS transfer line temperature was set at 280°C. The quantification of all the identified components was investigated using a percent relative peak area. A tentative identification of the compounds was performed based on the comparison of their relative retention time and mass spectra with those of the NIST, WILLY library data of the GC-MS system.


  Results and discussion Top


Seeds germination of Plectranthus barbatus

The sterilized seeds of P. barbatus were grown on basal MS medium. Seedlings were fully germinated in a range of 3–4 weeks ([Figure 1]).
Figure 1 Germination of Plectranthus barbatus seedlings on basal MS medium after four weeks of cultivation.

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In-vitro plant formation

Shoot tip explants cultured on MS medium containing 0.5 mg/l kinetin succeeded in shoot and root formation after 1 month. Formed shoots were subcultured on the same medium, after 3 months the formation of new shoots with rooting was observed (in-vitro plants, [Figure 2]).
Figure 2 Multiple plants formation of Plectranthus barbatus from shoot tip explant after sub-cultured on MS-medium containing 0.5 mg/l kinetin.

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Callus induction and growth dynamics

Callus cultures were initiated form cotyledon, leaf, and root explants. Data presented in [Table 1] observed that callus have been formed from all tested explants (cotyledon, leaf and root). Maximum callus induction percentage observed with cotyledon explants in the media containing NAA+BA and 2,4-D+BA (100 and 80%, respectively) was notably higher than that of the root explants (50 and 40%, respectively), whereas the leaf explants were shown to have the least response in the two used media (30 and 20%, respectively).
Table 1 Effect of different growth regulators and explant types on callus induction percentage of Plectranthus barbatus

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The copious callus induction was obtained with the MS medium containing 2.0 mg/l NAA+2.5 mg/l BA followed by the MS medium containing 2.0 mg/l 2,4-D+2.5 mg/l BA. The callus nature was compacted and yellow to green in color ([Figure 3]).
Figure 3 Callus induction of Plectranthus barbatus on MS-medium containing 2.0 mg/l NAA+2.5 mg/l BA from cotyledon (A), leaf (B) and root (C) explants.

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Callus induction percentages in P. barbatus were 100, 50, and 30% with cotyledon, root, and leaf explants, respectively, in an MS medium containing 2.0 mg/l NAA+2.5 mg/l BA, whereas the MS medium containing 2.0 mg/l 2,4-D+2.5 mg/l BA was shown the lower response with cotyledon, root, and leaf explants (80, 40, and 20%, respectively; [Table 1]). Initiated calli derived from different explants (cotyledon, leaf, and root) were subcultured on the best combination medium which contains 2.0 mg/l NAA+2.5 mg/l BA for callus fresh weights and growth index evaluation. Browning of initiated callus was detected with leaf and root calli during the second subculture. Therefore, the callus derived from the cotyledon explant was relied on in the rest of the trials.

Callus fresh weight as well as callus growth index increased gradually until the maximum values of 3.5 g and 16.5, respectively, were recorded at the fifth week and then declined at sixth week of cultivation ([Figure 4]). So it needs to be subcultured every 5-week intervals. After three subcultures (with 5-week intervals), the calli resulted from the cotyledon explant were proliferated and enlarged ([Figure 5]) and were used in chemical composition evaluation compared with the in-vitro plants.
Figure 4 Growth dynamics of Plectranthus barbatus callus obtained from cotyledon explants for six weeks.

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Figure 5 Callus culture of Plectranthus barbatus from cotyledon explant after three sub-cultures.

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The change in cell metabolism from a stationary state to one of active cell division is required for callus induction, which often means the reverse of cell differentiation and specialization [23]. To induce callus from explants owing to its effect on cell growth, auxin is usually required to achieve this, whereas cytokinins stimulate cell division [24]. The capacity for callus induction seems to be highly dependent on the explant nature and the type of growth regulators. A seedling was found to be the optimal source for plant segments used in callus induction [25]. The use of 2,4-D has been notarized in various Plectranthus species, and was used in P. barbatus by the studies of Tripathi et al. [26].

2,2′‐Diphenyl-1‐picrylhydrazyl radical scavenging capacity and extraction yield

The accumulation of active ingredients in cell cultures at a higher level than those in native plants has been observed in Panax ginseng through optimization of cultural conditions [27], rosmarinic acid in Coleus blumei [28], shikonin in Lithospermum erythrorhizon [29], diosgenin in Dioscorea spp. [30], and ubiquinone-10 in Nicotiana tabacum [31], whereas plant cell cultures sometime produce lower quantities of secondary metabolites with different profiles when compared with the intact plant [32].

Bioactive compounds extracted using two different solvents are methanol (85%) and hexane. [Table 2] shows the highest extraction yield with in-vitro grown plants (38.5%) followed by callus cultures (13.2%) with methanolic extract. Likewise, the same trend was observed with hexane extraction but with a lower extraction outcome with both plant and callus (8.1 and 4.8%, respectively). The difference in extraction yield may be attributed either to the solvent used for extraction and/or to the source of the plant part. To develop the production of plant metabolites, a lot of organic compounds were included to the culture medium [33]. The concept is that an intermediate compound of a metabolic route is expected to raise the yield of final products [34].
Table 2 Extraction yield of plants and callus cultures of Plectranthus barbatus extracted with methanol (85%) and hexane solvents

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The free radical scavenging method explains and evaluates the antioxidant potential of a compound, an extract, or other biological sources. [Table 3] shows the activity of free radical scavenging of different concentrations of P. barbatus extracts. Except with hexane extract from callus cultures, radical scavenging activity increases with increasing the concentration of the extract. It is important to mention that methanol extracts exhibited higher activity than hexane at all tested concentrations.
Table 3 2,2′‐Diphenyl-1‐picrylhydrazyl antioxidant capacity (%) in vitro plant and callus extracts of Plectranthus barbatus using methanol (85%) and hexane solvents

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Methanol extract of the callus showed the highest DPPH radical scavenging activity (94.5%) among all tested extracts, followed by methanol extract of the in-vitro plant (92%) at the maximum used concentration of the extract (10 mg/ml). While the highest DPPH radical scavenging activity with hexane extracts was recorded with the in-vitro plant (64%) at 10 mg/ml of the extract concentration, the lowest value was observed with callus culture extracts (44.4%) ([Table 3]).

The model of scavenging the stable DPPH radical is a method used extensively to evaluate the antioxidant activity in a comparatively short time [35]. Antioxidant activity from different parts of C. forskohlii has been studied [36]. Ethanolic extract of P. barbatus is being widely used in African countries as a herbal treatment to reduce oxidative stress [37]. The extract represented significant free radical scavenging activity [38]. A comparative study has been made between the callus extract and leaf extract of C. forskohlii and found that the antioxidant activity of the callus extract was more compared with the leaf extract, they showed that this result may be due to more accumulation of active phenolic compounds in the callus [39].

Total phenolic and total flavonoid contents

[Table 4] declares that methanolic extract of in-vitro plant and callus cultures gave the highest values of total phenolic (1.39 and 1.19 mg/g DW, respectively) and total flavonoid contents (4.87 and 1.14 mg/g DW, respectively) compared with hexane extracts. Also, the plant extract shows higher total phenolic (0.25 mg/g DW) and total flavonoid (0.31 mg/g DW) compared with callus which recorded 0.09 and 0.06 mg/g DW, respectively, with hexane solvent.
Table 4 Total phenolic and total flavonoid contents of aqueous methanol and hexane extracts of Plectranthus barbatus

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Seeking of healthy food and dynamic medication were pressed on scientists for searching natural antioxidants from different plants. Phenolic and flavonoid compounds were known to have potential antioxidant properties [40],[41],[42],[43]. Phenolic compounds represent one of the major classes of plant-active metabolites, broadly scattered among the plant kingdom, and an essential part of the human diet. Flavonoids comprise the most studied group of plant phenolic that are effective scavengers of hydroxyl and peroxyl radicals, and of the superoxide anion [44]. Moreover, the presence of flavonoid indicates the natural occurring phenolic compound, with beneficial effects in the human diet as antioxidants and as neutralizing free radicals [45].

Correspondingly, C. forskohlii extracts also tested positive for phenolic compounds. The phenolic compounds are aromatic secondary metabolites that impart color, flavor, and are associated with health benefits such as reduced risk of heart and cardiovascular diseases [46],[47]. Phenolic compounds account for most of the antioxidant activities in plants [48].

Gas chromatography–mass spectrometric analysis

A total of 31 bioactive ingredients have been identified in the hexane extract of in-vitro plant and callus cultures of P. barbatus by GC-MS analysis. [Table 5] shows the constituents of the bioactive ingredients. Seven compounds representing 67.42% of the bioactive ingredients in plant cultures were identified, namely: heptadecane (19.65%), p-Toluic acid 2-ethylhexyl ester (9.48%), dotriacontane (9.40%), tricosane (8.95%), hexadecane (7.41%), 9, 12, 15-octadecatrienoic acid (2-phenyl-1,3-dioxolan-4-yl) methyl ester (6.39%), and 1,1-diethyl-2,2-bis(phenyl sulfonyl) hydrazine (6.14%). On the other hand, only five compounds representing 53.01% of the bioactive compounds were detected in callus culture extracts, namely 2, 6, 10-trimethyltetradecane (16.89%), di-(2-ethylhexyl) phthalate (14.11%), limonene (10.73%), 12,15-octadecadiynoic acid methyl ester (5.82%), and (4-bromophenyl) bis (2,4-dibromophenyl) amine (5.46%) as shown in [Table 5]. Other major and minor residual compounds in both Plectranthus barbatus extracts ranged from 0.87 to 6.39% in plant extracts and from 1.72 to 4.48% in callus extracts. Nonidentified compounds (21.77%) were detected in GS-MS analysis of callus cultures. Eighteen essential compounds from C. forskohlii was detected which were hydrocarbons and oxygenated compounds in the percentage of 22 and 69%, respectively, with α-fenchyl acetate and α-pinene as the major components [49]. Four Plectranthus species (P. amboinicus, P. neochilus, P. grandis, and P. barbatus) were analyzed by GC/MS, they detected 14 compounds, the most common compound was sesquiterpenes, also transcaryophyllene was found in high concentrations in the extract of four species; some compounds were distinctive for each species and the others were common in the four species [50]. Also, six major components were identified in the root hexane extract of C. forskohlii (α-cedrene, β-cadinene, citronellal, two labdane derivatives, and β-citronellol) [51]. In this area as well, the aerial parts of six Plectranthus species were analyzed by GC/MS and showed that the essential oil consists mostly of monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, and oxygenated sesquiterpenes [52].
Table 5 Gas chromatography–mass spectrometry analysis for hexane extract of in-vitro plant and callus cultures of Plectranthus barbatus

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  Conclusion Top


P. barbatus is a prosperous plant with bioactive metabolites. True to its folk nutritive and therapeutic values, the current research has shown that the solvent extraction of the in-vitro plant and callus cultures of P. barbatus has lots of bioactive ingredients. More experimentation should be done for isolation and characterization of new antioxidant compounds.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Lukhoba CW, Simmonds MSJ, Paton AJ. Plectranthus: a review of ethnobotanical uses. J Ethnopharmacol 2006; 103:1–24.  Back to cited text no. 1
    
2.
Ammon HP, Kemper FH. Ayurveda: 300 years of Indian traditional medicine. Med Welt 1982; 33:148–153.  Back to cited text no. 2
    
3.
Ammon HP, Muller AB. Forskolin: from an ayurvedic remedy to a modern agent. Planta Med 1985; 6:473–477.  Back to cited text no. 3
    
4.
Dragendorff G. In Die Heilpflanzen der verscheidenen V61ker und Zeiten. Stuttgart: Ferdinand Enke 1898. 585–586.  Back to cited text no. 4
    
5.
Shivaprasad HN, Pandit S, Bhanumathy M, Manohar D, Vishal J, Shariq AT, Xiao S. Ethnopharmacological and phytomedical knowledge of Coleus forskohlii: an approach towards its safety and therapeutic value. Orient Pharm Exp Med 2014; 14:301–312.  Back to cited text no. 5
    
6.
Balandrin MJ, Klocke JA. Medicinal, aromatic and industrial materials from plants. In: Bajaj YPS, editor. Biotechnology in agriculture and forestry. Berlin, Heidelberg: Medicinal and Aromatic Plant, Springer-Verlag 1988. 1–36  Back to cited text no. 6
    
7.
Dubey MP, Srimal RC, Nityanand S, Dhawan BN. Pharmacological studies on coleonol, a hypotensive diterpene from Coleus forskohlii. J Ethnopharmacol 1981; 3:1–13.  Back to cited text no. 7
    
8.
Warrier PK, Nambiar VPK, Ramankutty C. Indian medicinal plants. Madras: Orient Longman Ltd; 1995. 1–5  Back to cited text no. 8
    
9.
Alasbahi RH, Melzig MF. Plectranthus barbatus: a review of phytochemistry, ethnobotanical uses and pharmacology − part 1. Planta Med 2010; 76:653–661.  Back to cited text no. 9
    
10.
Jagtap M, Chandola HM, Ravishankar B. Clinical efficacy of Coleus forskohlii (Willd.) Briq. (Makandi) in hypertension of geriatric population. Ayu 2011; 32:59–65.  Back to cited text no. 10
    
11.
Uma-Maheswari R, Selvamurugan C, Lakshmi JJ, Prabha A. Hairy root culture of an important medicinal plant: Coleus Forskohlii. Int J of Agri Sci 2011; 3:82–89.  Back to cited text no. 11
    
12.
Yeoman MM, Yeoman CL. Manipulating secondary metabolism in cultured plant cells. New Phytol 1996; 134:553–569.  Back to cited text no. 12
    
13.
Zhang ZJ, Zhou WJ, Li HZ. The role of GA, IAA and BAP in the regulation of in vitro shoot growth and microtuberization in potato. Acta Physiol Plant 2005; 27:363–369.  Back to cited text no. 13
    
14.
Avilés F, Ríos D, González R, Sánchez-Olate M. Effect of culture medium in callogenesis from adult walnut leaves (Juglans regia L.). Chil J Agric Res 2009; 69:460–467.  Back to cited text no. 14
    
15.
Baque MA, Hahn EJ, Paek KY. Induction mechanism of adventitious root from leaves explants of Morinda citrifolia as affected by auxin and light quality. In Vitro Cell Dev Biol Plant 2010; 46:71–80.  Back to cited text no. 15
    
16.
Ramanchandra-Rao S, Ravishankar GA. Plant cell cultures: chemical factories for secondary metabolites. Biotechnol Adv 2002; 20:101–153.  Back to cited text no. 16
    
17.
Chan LK, Lim PS, Choo ML, Boey PL. Establishment of Cyperus aromaticus cell suspension cultures for the production of juvenile hormone 3. In Vitro Cell Dev Biol Plant 2010; 46:8–12.  Back to cited text no. 17
    
18.
Murashige T, Skoog FA. Revised medium for rapid growth and bio assays with tobacco tissue cultures. Physiol Plant 1962; 15:473–497.  Back to cited text no. 18
    
19.
Dung NN, Szoki E, Verzar-Petri G. The growth dynamics of callus tissue of root and leaf origin in Datura innoxia Mill. Acta Bot Acad Sci Hung 1981; 27:325–333.  Back to cited text no. 19
    
20.
Brand-Williams W, Cuvelier ME, Berset C. Use of a free radical method to evaluate antioxidant activity. Lebenson Wiss Technol 1995; 28:25–30.  Back to cited text no. 20
    
21.
Singleton VL, Orthofer R, Lamuela-Raventos RM. Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Methods Enzymol 1999; 299:152–178.  Back to cited text no. 21
    
22.
Vabkova J, Neugebauerova J. Determination of total phenolic content, total flavonoid content and frap in culinary herbs in relation to harvest time. Acta Univ Agric et Silvic Mendel Brun 2012; LX:167–172.  Back to cited text no. 22
    
23.
Phillips GC. In vitro morphogenesis in plants-recent advances. In Vitro Cell Dev Biol Plant 2004; 40:342–345.  Back to cited text no. 23
    
24.
Gamborg OL, Shyluk JP. Nutrition, media and characteristics of plant cell and tissue cultures. In: Thorp TA, editor. Plant tissue culture: methods and applications in agriculture. New York: Academic Press 1981. 21–44  Back to cited text no. 24
    
25.
Nayak NR, Chand PK, Rath SP, Patnaik SN. Influence of some plant growth regulators on the growth and organogenesis of Cymbidium aloifolium (L.) Sw. Seed-derived rhizomes in vitro. In Vitro Cell Dev Biol Plant 1998; 34:185–188.  Back to cited text no. 25
    
26.
Tripathi CKM, Basu SK, Jain S, Tandon JS. Production of coleonol (forskolin) by root callus cells of plant Coleus forskohlii. Biotechnol Lett 1995; 17:423–426.  Back to cited text no. 26
    
27.
Kim DS, Song M, Kim S, Jang D, Kim J, Ha B et al. The improvement of ginsenoside accumulation in Panx ginseng as a result of ƴ-irradiation. J Ginseng Res 2013; 37:332–340.  Back to cited text no. 27
    
28.
Ulbrich B, Weisner W, Arens H. In: Neumann KH, Reinhard E editors. Primary and secondary metabolism of plant cell cultures. Berlin: Springer-Verlag 1985. 293–303  Back to cited text no. 28
    
29.
Kim DJ, Chang HN. Enhanced shikonin production from Lithospermum erythrorhizonby in situ extraction and calcium alginate immobilization.Biotechnol Bioeng 36:460–466.  Back to cited text no. 29
    
30.
Rokem JS, Tal B, Goldberg I. Methods for increasing diosgenin production by Dioscorea cells in suspension cultures. J Nat Prod 1985; 48:210–220.  Back to cited text no. 30
    
31.
Matsumoto T, Kanno N, Ikeda T, Obi Y, Kisaki T, Noguchi M. Selection of cultured tobacco cell strains producing high levels of ubiquinone 10 by a cell cloning technique. Agric Biol Chem 1981; 45:1627–1633.  Back to cited text no. 31
    
32.
Whitaker RJ. Am Chem Soc Symp Ser 1986; 317:347–362.  Back to cited text no. 32
    
33.
Namdeo AG, Jadhav TS, Rai PK, Gavali S, Mahadik KR. Precursor feeding for enhanced production of secondary metabolites. Pharmacogn Rev 2007; 1:227–231.  Back to cited text no. 33
    
34.
Rao SR, Ravishankar GA. Plant cell cultures: chemical factories of secondary metabolites. Biotechnol Adv 2002; 20:101–153.  Back to cited text no. 34
    
35.
Gulcin I, Sat IG, Beydemir S, Elmastas M, Kufrevioglu OI. Comparison of antioxidant activity of clove (Eugenia caryophylata Thunb) buds and lavender (Lavandula stoechas L.). Food Chem 2004; 87:393–400.  Back to cited text no. 35
    
36.
Khatun S, Chatterjee NC, Cakilcioglu U. The strategies for production of forskolin vis-a-vis protection against soil borne diseases of the potential herb coleus forskohlii briq. Eur J Med Plants 2011; 1:1–9.  Back to cited text no. 36
    
37.
Kapewangolo P, Hussein AA, Meyer D. Inhibition of HIV-1 enzymes, antioxidant and anti-inflammatory activities of Plectranthus barbatus. J Ethnopharmacol 2013; 149:184–190.  Back to cited text no. 37
    
38.
Maioli MA, Alves LC, Campanini AL, Lima MC, Dorta DJ, Groppo M et al. Iron chelating mediated antioxidant activity of Plectranthus barbatus extract on mitochondria. Food Chem 2010; 122:203–208.  Back to cited text no. 38
    
39.
Sunitha K, Chary KB, Nimgulkar CC, Kumar BD, Manohar-Rao D. Identification, quantification and antioxidant activity of secondary metabolites in leaf and callus extracts of Coleus forskohlii. Int J Pharm Bio Sci 2013; 4:1139–1149.  Back to cited text no. 39
    
40.
Aehle E, Grandic SRL, Ralainirina R, Baltora-Rosset S, Mesnard F, Prouillet C et al. Development and evaluation of an enriched natural antioxidant preparation obtained from aqueous Spinach (Spinacia oleracea) extracts by an adsorption procedure. Food Chem 2004; 86:579–585.  Back to cited text no. 40
    
41.
Del-Bano MJ, Lorente J, Castillo J, Benavente-García O, Del-Río JA, Ortuno A et al. Phenolic, diterpenes, flavones, and rosmarinic acid distribution during the development of leaves, flowers, stems, and roots of Rosmarinus officinalis, antioxidant activity. J Agric Food Chem 2003; 51:4247–4253.  Back to cited text no. 41
    
42.
Sastre J, Millan A, de la Asuncion JG, Pla R, Juan G, Pallardo FV et al. A Ginkgo Biloba extract (EGb 761) prevents mitochondrial aging by protecting against oxidative stress. Free Radic Biol Med 1998; 24:298–304.  Back to cited text no. 42
    
43.
Van Beek TA. Chemical analysis of Ginkgo biloba leaves and extracts. J Chromatogr A 2002; 967:21–55.  Back to cited text no. 43
    
44.
Heim KE, Tagliaferro AR, Bobilya DJ. Flavonoids antioxidants, chemistry, metabolism and structure-activity relationships. J Nutr Biochem 2002; 13:572–584.  Back to cited text no. 44
    
45.
Del-Ri A, Obdululio BG, Casfillio J, Marin FG, Ortuno A. Uses and properties of citrus flavonoids. J Agric Food Chem 1997; 45:4505–4515.  Back to cited text no. 45
    
46.
Alothman M, Bhat R, Karim AA. Effects of radiation processing on phytochemicals and antioxidants in plant produce. Trends Food Sci Technol 2009; 5:201–212.  Back to cited text no. 46
    
47.
Bhat R, Ameran SB, Karim AA, Liong MT. Quality attributes of star fruit (Averrhoa carambola L.) juice treated with ultraviolet radiation. Food Chem 2011; 127:641–644.  Back to cited text no. 47
    
48.
Aliyu AB, Musa AM, Sallau MS, Oyewale AO. Proximate composition, mineral elements and anti-nutritional factors of Anisopus mannii N.E. Br. (Asclepiadaceae). Trends Appl Sci Res 2009; 4:68–71.  Back to cited text no. 48
    
49.
Chowdhary AR, Sharma ML. GC-MS investigations on the essential oil from Coleus forskohlii Briq. Indian Perfumer 1998; 42:15–16.  Back to cited text no. 49
    
50.
Bandeira JM, Barbosa FF, Barbosa LMP, Rodrigues ICS, Bacarin MA, Peters JA, Braga EJB. Composition of essential oil of four species of Plectranthus genus. Rev bras plantas med 2011; 13:157–164.  Back to cited text no. 50
    
51.
Murugesan S, Rajeshkannan C, Sumathi R, Manivachakam P, Suresh-Babu D. Bioactivity of root hexane extract of Coleus forskohlii Briq. Labiatae: GC/MS characterization and identification. European J Exp Bio 2012; 2:1469–1473.  Back to cited text no. 51
    
52.
Shaheen U, Khalik KA, Abdelhady IA, Howladar S, Alarjah M, Abourehab MA. HPLC profile of phenolic constituents, essential oil analysis and antioxidant activity of six Plectranthus species growing in Saudi Arabia. J Chem Pharm Res 2017; 9:345–354.  Back to cited text no. 52
    


    Figures

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    Tables

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