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Monoamine oxidase (MAO) is capable of catalysing the oxidative deamination of amines and neurotransmitters. MAO plays a pivotal role in maintaining neurotransmitters linked to neurological disorders viz. Alzheimer's disease (AD), Parkinson's disease (PD) etc. Therefore, inhibition of MAO can be implicated to the cure of such diseases. Synthetic MAO inhibitors are known to inhibit MAO activity. However, there are safety issues with synthetic MAO inhibitors and many of their effects are non-selective and irreversible. Contrasting synthetic drugs, plant-derived natural products have been popularized globally owing to their extensive acceptability and applicability, therapeutic potency and minimum side effects which potentiated the possibility of developing reversible, promising MAO inhibitors based on natural products. The present review comprehensively elucidates plant -derived natural reversible MAO inhibitors using the literature from the popular databases such as Google Scholar, Scopus, PubMed and Web of Science. This literature review reports approximately 51 plants that have been evaluated for MAO inhibitory activity. In addition, 93 plant-derived natural compounds were retrieved as MAO inhibitors. Majority of these investigations predominantly utilized an in vitro approach to evaluate the MAO inhibitors in relation to the developing treatments of related neurological diseases. However, in vivo studies and clinical trials are still lacking in evaluating the botanical-based MAO inhibitors. The aim of this review is to retrieve the recent literature to explore the in vitro and in vivo studies of plant-based natural products as MAO inhibitors, their structure-activity relationship and relevant molecular docking analyses and their roles in the emerging therapy against disorders like AD, and PD. Further, the review also discusses the shortcomings in the existing research in order to generate more coordinated and focused research in future.

The present investigation was conducted to find out the influence of different polyamines (PAs) viz. spermine (spm), spermidine (spd) and putrescine (put) and plant growth regulators (PGRs) on multiplication, rooting, callusing and regeneration in Aristolochia indica L. in vitro. Firstly, the A. indica plants were collected, surface sterilized and cultured in Schenk and Hildebrandt (SH) media fortified with various PGRs and PAs in different concentrations and combinations. SH media fortified with benzylaminopurine (BAP) (2.0 mg/l)+put (0.5 mM) and in another experiment, BAP (2.0 mg/l)+spd (1 mM) produced best results with 41.00 and 39.2 axillary shoots/ nodal explant respectively. Following 4-6 weeks of incubation, explants propagated in SH media augmented with various combinations and concentrations of BAP and kinetin (kin) (0.5, 1, 1.5 and 2 mg/l), spm, spd and put (0.5 and 1 mM) generated white friable callus. SH media supplemented with BAP (2.0 mg/l)+spd (0.5 mM) displayed best response with an average number of 47.5 base callus derived shoots . Following 6 weeks of incubation, SH+ indole-3-acetic acid (IAA) (1.0 mg/l)+spd (0.5 mM) resulted maximum average number (7) of roots per shoot. The genetic homogeneity of the mother plant (MP), hardened plant (HP) and in vitro regenerated plants was ascertained employing random-amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers. In this present study, in randomly selected A. indica plants, by using 6 ISSR and 5 RAPD primers, 63 scorable bands were derived, 59 of which were recorded as monomorphic with a degree of monomorphism of 90%. High-performance thin layer chromatography (HPTLC) revealed aristolochic acid (AA) content in in vitro grown A. indica roots and the roots from the mother plant (MP) as 6074.54 µg/g and 5891.14 µg/g respectively.

Dioscorea deltoidea (Family: Dioscoreaceae) is a high value endangered medicinal plant and the source of pharmaceutically important bioactive compound diosgenin, which is used in the synthesis of steroidal drugs. Establishing an efficient reproducible regeneration system is necessary for its sustainable utilization and conservation. The purpose of this research was to establish an effective and efficient in vitro regeneration protocol for D. deltoidea and assess its genetic and biochemical fidelity. In this report, Murashige and Skoog (MS) medium fortified with different types and concentration of Plant Growth Regulators (PGRs) were studied. Maximum shoot regeneration frequency was achieved in MS medium supplemented with 2.0 mg L − 1 BA whereas higher shoot multiplication was observed in 2.0 mg L − 1 BA + 1.0 mg L − 1 IBA. Highest rooting was recovered on MS medium supplemented with 2.0 mg L − 1 NAA. In vitro rooted plantlets were acclimatized with a survival rate of 96%. The genetic fidelity of the mother plant (MP), acclimatized plant (AP) and in vitro regenerants were found to be clonally similar as examined through ISSR fingerprinting. Of 7 ISSR primers tested, 5 produced scorable amplified products. The High Performance Thin Layer Chromatography (HPTLC) based chemical assessment showed varied chemical profile. The developed protocol would be beneficial in providing a germplasm conservation system, isolation of secondary metabolites and production of high value clonal regenerants for commercial production.

Dioscorea deltoidea (Dioscoreaceae) is an endangered species having tubers that possess anextensive range of therapeutic and economic value due to presence of bioactive compound diosgenin. Several industries have various necessities for compounds of specific classes and therefore, choosy extraction strategies for segregation of these classes ought to be produced.The current study aimed to screen potent part, identify best drying process, efficient extraction methods with solvent selection and seasonal variations on diosgenin content in D. deltoidea. The tuber contained the highest diosgenin content (1.15% DW) compared to leaf and stem. The highest yield of diosgenin was obtained using microwave-assisted extraction (MAE) with 50% ethanol (0.99% DW) and minimum incold maceration with water (0.46% DW). Shade drying was found to be the best drying method as compared to others in terms of diosgenin yield (1.43% DW) whereas sun drying produced low yield (1.12% DW). Estimation of yield and enriched diosgenin (1.19% DW) specified that winter (December) is the perfect time to harvest D. deltoidea.

Genetic variation study in 11 populations of D. chrysotoxum was conducted using 20 different inter-simple sequence repeats (ISSR) and 9 start codon targeted (SCoT) primers. Out of 199 bands produced by ISSR markers, 196 bands were polymorphic, resulting in high polymorphism (98.49%). SCoT markers, however, produced 111 polymorphic fragments generating 100% polymorphism. The Nei's genetic diversity at the species level (H = 0.184±0.11 for ISSR; H = 0.236±0.12 for SCoT) was higher than the average value at the population level (H = 0.160±0.15 for ISSR; H = 0.174±0.15 for SCoT). Low genetic differentiation among the populations (Gst = 0.1566 for ISSR; Gst = 0.2677 for SCoT) was observed due to high estimate of gene flow (Nm = 2.6938 for ISSR; Nm = 1.3678 for SCoT). Mantel test revealed a non-significant correlation between the genetic and geographical distance (r = -0.62; p = 0.86 for ISSR; r = -0.68; p = 0.82 for SCoT). Two-dimensional principal coordinate analysis (PCoA) determined the contribution of the first two principal components to the total genetic variation for combined ISSR and SCoT data at 13.71%. The distribution of individuals in the PCoA plot was in accordance with the unweighted pair group method with arithmetic averages (UPGMA) cluster analysis. Bayesian model-based STRUCTURE determined three (K = 3) gene pools for both ISSR and SCoT markers with a high degree of admixture in the populations. GENELAND further assigned the 11 different populations into 7 genetic clusters. Based on the genetic information obtained from the present investigation, we recommended different conservation strategies suited for effectively managing the endangered orchid. To the best of our knowledge, this is the first report of estimating the genetic diversity and population genetic structure of D. chrysotoxum in Manipur, a north-eastern state of India bordering Myanmar.

The commercialization of medicinal plants as recognized in their uses by nutraceutical, cosmeceutical and pharmaceutical industries is gaining more popularity and interest around the globe. The plant family Amaryllidaceae has a long history in the traditional medicinal system and used to treat diverse diseases. It is well known for its structurally-diverse alkaloids which exhibit a wide range of pharmacological activities. Crinum, an important bulbous geophyte is well known for its ornamental and therapeutic properties. In India, Crinum is represented by 15 different species which contain several alkaloids with biological properties. However, some of the medicinal uses of Indian Crinum species still require pharmacological analysis. In addition, more extensive research including different biotechnological approaches is needed in order to guarantee its sustainable utilization and long-term conservation. Further research is essential to improve our current knowledge about the bioactive components, toxicity, clinical relevance as well as its conservation status. The present review summarizes the research that has been done on the phytochemistry, pharmacology and in vitro studies of the Indian Crinum. Potential toxicity aspects as well as knowledge gaps and future perspectives are also discussed.

In the present report, the effect of methyl jasmonate (MJ) and salicyclic acid (SA) elicitation, on the indole alkaloid production from micropropagated culture of the endangered Ayurvedic medicinal plant Rauvolfia serpentina Benth. ex Kurz, was investigated. The highest shoot multiplication was found in Murashige and Skoog (MS) media augmented with BAP (2.0 mg/l) following 4 weeks of culture. MS media fortified with cytokinins produced nodal explant-derived nodular base callus (NBC)/ nodular meristemoids (NMs) following 6 weeks. Maximum root length was found in half strength MS basal (½ MSO) media and maximum number of roots per shoot was noted in ½ MS media augmented with indole-3-butyric acid (IBA) (1.5 mg/l). Clonal fidelity of the in vitro plants was assessed by 10 inter-simple sequence repeat (ISSR) primers of which only 3 primers (UBC-810, UBC-820, and UBC-827) produced clear and reproducible bands. The content wise variation of indole alkaloids (reserpine and ajmalicine), post elicitor (MJ and SA) treatment (0.5-2 mg/l) was quantified via high-performance thin layer chromatography (HPTLC). In vitro raised R. serpentina root accumulated highest amount of reserpine (0.456% and 0.440%) followed by 1.5 mg/l MJ and SA mediated elicitation respectively. Ajmalicine content of in vitro root, grown on culture elicitated with MJ (1.5 mg/l and 2 mg/l), was 0.261%. The ascorbate peroxidase (APX) activity was the highest in MJ (1.5 mg/l) treated micropropagated plantlets (0.86 EU/min/mg protein) and comparatively lesser in root samples (0.77 EU/min/mg protein) following 9 days of treatment. In all tested concentrations, SA treated plant sample exhibited strong superoxide dismutase (SOD) activity but the MJ and SA mediated elicitation caused sharp decrease in catalase (CAT) activity in all plant samples. In elicitor treated plant samples, the 1,1-diphenyl2-picrylhydrazyl (DPPH) radical scavenging activity (%) as well as total phenolics and flavonoids contents were marginally higher than the untreated ones. In vivo and in vitro grown R. serpentina root extracts showed best response against the four evaluated ATCC strains of bacteria.

Medicinally important steroid-based compound diosgenin is usually obtained from the secondary metabolic products of several plant species. Diosgenin has been proven as a prospective bioactive drug lead to the pharmaceutical industries as having anti-cancer activity, anti-microbial activity, anti-thrombic activity, anti-diabetic activity, cardioprotective activity, anti-inflammatory activity, osteoarthritis protective activity etc. Observing the multiple therapeutic values of this compound, scientists and chemists have become interested to discover alternative sources. Endophytic microorganisms possess the potentials producing prospective secondary metabolites. Some diosgenin producing endophytic fungi and bacteria are detected and reported by authors. Extraction and quantification of the respective secondary metabolite in a proper way is required initially for its large scale production. Regular involvement of advance biotechnological approaches plus industrial fermentation technology along with proper funding following government policy is necessary for further progress in this field. Exploration of a higher number of diosgenin producing endophytic strains will definitely increase the supply for social requisition in a cost-effective and environment-friendly manner as limiting the excessive exploitation of plant sources.

The horrifying impact of emergence of cancer as an endemic disease worldwide associated with accelerated mortality rate caused significant boost in anticancer drug discovery. The most successful broad spectrum anti-neoplastic monoterpene indole alkaloid camptothecin (CPT) is the product of such natural product based therapeutic approach. This promising anticancer compound, currently approved against cancer, was first isolated from Camptotheca acuminata of Nyssaceae family and was reported as a potent inhibitor of eukaryotic topoisomerase I. Despite its continuous success under clinical studies, low accumulation, slow growth and over-exploitation of Camptotheca acuminata, high extraction cost, complex nature of total, semi and chemical synthesis has failed to meet the industrial demand. As an alternative bio-prospecting route, fermentation of endophytic microbial culture and co-culture of CPT producing plant cell suspension with endophytes have evolved. Endophytes are reported for their contribution in plant growth, disease resistance, stress tolerance and agricultural productivity which may have contributed to scale up the CPT production. This review sums up the current trend in endophytic microbes-based CPT biosynthesis and biotechnological strategies for optimization of CPT yield. Moreover, interaction of endophytic fungi with different host plants under experimental variables, their mode of elicitation, possibility of microbial strain improvement via application of biotechnological strategies and respective lacunas are also being elucidated.

Frequent use of medicinal plants is common in healthcare needs of mankind since ancient ages. Among these Moringa oleifera Lam. is one of the vastly used plant whose various parts (leaf, fruit, seeds etc.) are included in regular diet for their multiple ability of combating several health issues. WHO has highlighted on the proper utilization of natural products and marked plant-based medicines as prime study candidates. Taking initiative to explore bioactive leads other than conventional chemotherapeutic agents (with undesirable side effects) have drawn attention of the scientists involved in viral research due to the lack of effective vaccines and insufficient supply of existing costly drugs to socio-economic demands. Several studies were reported regarding the antiviral activity of M. oleifera plant, a pronounced bioprospective aspirant. The plant is known to be used in many traditional medicines and pharmacopeias against an array of medical conditions that include malaria, diabetes, skin infection, tuberculosis, anemia, headaches, epilepsy, sexually transmitted diseases and so on. In African traditional medicine, the plant is popularly used against AIDS and related secondary infections associated with HIV. It showed significant activities against viruses like HIV, HSV, HBV, EBV, FMDV and NDV. In some cases active molecules with mode of actions were documented by authors. On the other hand, there is a number of reports where neither lead compounds nor the relevant mechanisms were clarified regarding the viral inhibitory activities of crude plant extract. Immense studies should be going on to resolve those unanswered motifs along with the well planned trials of clinical application of already discovered potent phytochemicals. For conducting the continuous investigational groundwork in this field, the respective plant should be preserved with proper maintenance, necessarily.

The study was designed to evaluate the role of various plant polyamines (PAs) on in-vitro multiplication and regeneration in the Ayurvedic memory enhancer Bacopa monnieri (L.) Wettst. Natural populations of B. monnieri were collected, sterilized and micropropagated in Murashige and Skoog (MS) media supplemented with different concentration and combination of plant growth regulators (PGRs) and PAs. MS media supplemented with 6-benzylaminopurine (BAP) (2.0 mg/l) + spermidine (spd) (1 mM) and in another set, kinetin (kin) (2.0 mg/l) + spd (1 mM) were found to be the best multiplication media whereas MS + indole-3-butyric acid (IBA) (1.0 mg/l) + spermine (spm) (1.0 mM) produced highest average number of roots per shoot. After 4–6 weeks of incubation, nodal explants cultured in MS media supplemented with various PGRs and PAs produced green compact or white friable nodular base calli (NBC). The NBC showed organogenic potential when subjected to MS media supplemented with cytokinins and PAs. Clonal fidelity of the regenerated plants was assessed using inter-simple sequence repeat (ISSR) and random-amplified polymorphic DNA (RAPD) markers. Out of the 60 clear and reproducible bands recorded, 54 were found to be monomorphic displaying high degree of monomorphism (90%) and lower polymorphic level (10%) between the mother plant and in-vitro regenerants. High-performance liquid chromatography (HPLC) revealed total bacoside content in B. monnieri grown in-vitro (PA-treated) and the mother plant (MP) grown in nature to be 27.89 and 25.46 mg/g respectively. The phytochemical analysis of the PA-treated micropropagated plants also revealed significantly higher levels of phenolics and flavonoids with comprehensively higher antioxidant potentials in PA-treated in-vitro grown plants (PATP) and the subsequently acclimatized plants (PATP-A) over the PA-untreated in-vitro grown plants (with/no PGR) (PAUP) and the mother plant (MP).