Comparative HPTLC analysis of bioactive marker barbaloin from in vitro and naturally grown Aloe vera

Spectroscopic characterization of different protonation/deprotonation states of Barbaloin in aqueous solution

Barbaloin (10-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthraquinone: aloin A), present in Aloe species, is widely used in food, cosmetic and pharmaceutical industries. Here we characterize its optical absorption and emission spectra in aqueous solution at different pH values. Through pH titration, using both absorption and fluorescence spectroscopy, two pK_a values for Barbaloin were determined: pK_a1=9.6±0.6 and pK_a2=12.6±0.8. These acidity constants were found to be higher than those found for Emodin, a similar molecule which lacks the sugar moiety present in Barbaloin. Performing quantum mechanical calculations for non-ionized, singly, doubly, and triply deprotonated forms of Barbaloin in vacuum and in water, we assigned the positions of the site for the first and third deprotonation in the anthraquinone group, and the second deprotonation in the glucose group. The instability of Barbaloin in high pH solutions is discussed here, and the optical absorption and fluorescence spectra due to products resulted from Barbaloin degradation at high pH is well separated from the Barbaloin original spectra. Biological fluids have specific pH values to maintain homeostasis, hence determining the pK_a of Barbaloin is important to evaluate the mechanism of action of this drug in different parts of an organism as well as to predict pharmacological relevant parameters, such as absorption, distribution, metabolism, and excretion.

Biotechnology for micropropagation and camptothecin production in Ophiorrhiza sp

Camptothecin (CPT) is a monoterpenoid-alkaloid, an anticancer compound from plant. Ever since its discovery in 1996 from the bark of Camptotheca acuminata, various researches have been conducted for enhancing its production. CPT has also been reported in several other species belonging to the plant families Icacinaceae, Rubiaceae, Apocynaceae, Nyssaceae, Betulaceae, Violaceae, Meliaceae, and Gelseminaceae. Out of these, Ophiorrhiza sp. (Rubiaceae) is the next possible candidate for sustainable CPT production after C. acuminata and Nothapodytes nimoonia. Various biotechnological-studies have been conducted on Ophiorrhiza sp. for searching the elite species and the most optimal strategies for CPT production. The genus Ophiorrhiza has been used as medicines for antiviral, antifungal, antimalarial, and anticancer activities. Phytochemical analysis has revealed the presence of alkaloids, flavonoids, triterpenes, and CPT from the plant. Because of the presence of CPT and its herbaceous habit, Ophiorrhiza sp. has now become a hot topic in research area. Currently, for mass production of the elite spp., tissue culture techniques have been implemented. In the past decades, several researchers have contributed on the diversity assessment, phytochemical analysis, mass production, and in vitro production of CPT in Ophiorrhiza sp. In this paper, we review the on the biotechnological strategies, optimal culture medium, micropropagation of Ophiorrhiza sp., effect of PGR on shoot formation, rhizogenesis, callus formation, and enhanced production of CPT for commercial use. KEY POINTS: • Latest literature on in vitro propagation of Ophiorrhiza sp. • Biotechnological production of camptothecin and related compounds • Optimization, elicitation, and transgenic studies in Ophiorrhiza sp.

Colchicine (a high-priced alkaloid) accumulation and HPTLC quantification in different stages of in vitro developed tuber of Gloriosa superba L

Background

Gloriosa superba L. belongs to Colchicaceae, which is an important medicinal plant containing high-priced alkaloid colchicines and other potent phytochemicals. Due to its extensive importance at the industrial level, this plant is overexploited. Moreover, indiscriminate harvesting for raw material leads to a decline in the population of this plant in the natural environment. Thus, the present study deals with the optimization of colchicine accumulation from the different intervals of in vitro and in vivo tubers of Gloriosa.

Result

To obtain in vitro tuberization, shoot tip explants were inoculated on Murashige and Skoog medium prepared with 3 mg/l BA and 0.5 mg/l Kn + 1 mg/l 2, 4-D followed by 2 mg/l BA + 0.2 mg/l NAA. In the high-performance thin-layer chromatography study (HPTLC), the linearity range of colchicine was set at a concentration range of 100–1000 ng/spot with a regression value (r) of 0.99. Its Rf value (0.25) was recorded at 254 nm. The colchicine amount in the in vivo tuber was 7.75 ± 0.25% dry weight, while the nearby amount of 7.7 ± 0.40% dry weight of colchicine was produced from 2 weeks in vitro old tuber. This value was followed by the 4th-week old tuber with 6.35 ± 0.17% dry weight and then a gradual decrease in its accumulation.

Conclusion

The significant results for the accumulation of colchicine at different stages were observed. Hence, this strategy of colchicine production creates a new possibility for improved production of colchicine under in vitro conditions which will be helpful to various pharmaceutical industries without damaging the plants from the natural environment.

Graphical abstract

Concurrent production and relative quantification of vasicinone from in vivo and in vitro plant parts of Malabar nut (Adhatoda vasica Nees)

The present study documents a simultaneous production and comparative assessment of extracted vasicinone from in vivo (leaves and stems) and in vitro (leaves, stems and calli) plant parts of Adhatoda vasica Nees, a well-known medicinal plant. High-performance thin layer chromatography (HPTLC) analysis of the above-mentioned plant parts, collected at their 60-day-old growth stage, was performed via methanolic extraction and with the aid of toluene:butanol:butyl acetate (9:0.5:0.5; v/v/v) solvent system. The method was validated with the help of aluminium sheet precoated with silica gel 60 F₂₅₄ TLC plates, following the ICH guidelines in order to maintain accuracy, precision and repeatability. Correlation coefficient, limit of detection and limit of quantification values were found to be reasonable. The outcome revealed a linearity that ranged between 2 and 6 µg/spot. During the comparison of estimated vasicinone quantity from in vivo and in vitro plant parts, it was evident that in vitro samples produced relatively higher vasicinone than that of the in vivo counterparts. Maximum vasicinone (6.402 ± 0.010% of dry weight) production was quantified from in vitro leaves followed by calli (5.222 ± 0.092% of dry weight) and in vitro stems (2.007 ± 0.041% of dry weight). On the other hand, in vivo leaves and stems produced comparatively lower quantities of vasicinone (2.412 ± 0.139 and 1.933 ± 0.046% of dry weight, respectively) suggesting the in vitro clonal propagation as a superior approach in comparison to in vivo propagation. Nonetheless, simultaneous production from both the sources (in vivo and in vitro plant parts) provides a new avenue for augmented production of vasicinone.