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At least 19 recordsLinked to original sources
PubMed2025

Indel mutation in transcription factor PabHLH2 regulates amygdalin accumulation and kernel bitterness in apricot.

Amygdalin, the phytochemical responsible for the characteristic bitterness of apricot (Prunus armeniaca L.) kernels, also exhibits significant bioactive properties and therapeutic potential. Genetic regulation of amygdalin content is therefore a key objective in apricot breeding programs aimed at quality improvement. In this study, we conducted quantitative trait loci (QTL) mapping to uncover the genetic basis of sweet-bitter differentiation in apricot kernels. We identified a 15-bp insertion/deletion (indel) polymorphism strongly related to kernel bitterness, with marker validation achieving 100% concordance across 601 apricot germplasm accessions. Notably, this polymorphic site is located within the helix-loop-helix (HLH) domain of the basic HLH (bHLH) transcription factor PabHLH2. Protein interaction analyses revealed that the 15-bp deletion variant impaired dimerization capacity, reducing transcriptional activation of downstream targets. Using yeast one-hybrid screening and dual-luciferase reporter assays, we identified PaCYP71AN24 and PaCYP79D16 as direct transcriptional targets of PabHLH2. Functional characterization further indicated that the PabHLH2a variant (harboring the 15-bp insertion) significantly enhanced the promoter activity of these cytochrome P450 genes compared with the deletion variant. Transient overexpression and silencing experiments in apricot kernels further confirmed that the 15-bp insertion positively regulates both PaCYP71AN24/PaCYP79D16 expression and prunasin accumulation, the immediate biosynthetic precursor of amygdalin. Overall, these findings provide mechanistic insights into the allelic variation underlying kernel bitterness and delineate the molecular cascade of amygdalin biosynthesis. The identified molecular markers and functional characterization establish a basis for marker-assisted breeding of low-amygdalin apricot cultivars, supporting the dual-purpose utilization of kernels in food and pharmaceutical industries.

Amygdalin↗
PubMedDate not supplied

Experimental studies of the antitumor activity of amygdalin MF (NSC-15780) alone and in combination with beta-glucosidase (NSC-128056).

Amygdalin MF was evaluated alone and in combination with an activating agent, beta-glucosidase, against three transplantable rodent tumors; Ridgway osteogenic sarcoma, Lewis lung carcinoma, and P388 leukemia. In dose-response studies up to the LD20 in normal mice, amygdalin MF alone did not demonstrate significant antitumor activity against any of these three tumor systems. Similarly, at doses not exceeding the LD10 in normal mice, amygdalin MF plus beta-glucosidase did not demonstrate antitumour activity against any of these three tumor systems. Potentiation of the lethal toxicity of amygdalin MF by beta-glucosidase was observed in all studies where the two agents were given in simultaneous combination.

Amygdalin↗
PubMedDate not supplied

Antitumor activity of amygdalin MF (NSC-15780) as a single agent and with beta-glucosidase (NSC-128056) on a spectrum of transplantable rodent tumors.

Experiments are described in which four transplantable rodent tumors (L1210 lymphoid leukemia, P388 lymphocytic leukemia, B16 melanoma, and Walker 256 carcinosarcoma) were used to investigate the antitumor activity of amygdalin MF. Amygdalin MF was given alone and in combination with beta-glucosidase which was administered 1/2 hour prior to amygdalin MF, starting 24 hours after tumor implantation. No antitumor activity was observed in any of the four tumor systems tested with the drug alone or in combined therapy. The combined therapy showed potentiation of toxicity with doses of amygdalin MF greater than or equal to 100 mg/kg.

Amygdalin↗
PubMed1978

A simple method for the estimation of amygdalin in the urine.

A procedure for the estimation of D- and D,L-amygdalin in urine is described. Amygdalin is hydrolyzed by beta-glucosidase and base to benzaldehyde, glucose and cyanide. Benzaldehyde is extracted with methylene chloride and the ultraviolet (UV) absorbence determined at 243 nm. The response of human urine "spiked" with amygdalin was linear between 10 and 75 microgram/ml. Mice administered 100 mg/kg of amygdalin intravenously or orally excreted about 70 and 20% of the administered dose, respectively, over 96 hours. In each instance more than 96% of excreted drug equivalents were obtained within the first 24 hours.

Administration, Oral↗
PubMed1978

Antitumor tests of amygdalin in spontaneous animal tumor systems.

In a series of 6 experiments with CD8F1 mice with spontaneous mammary adenocarcinomas Sugiura noted by macrovisual observation with some histology an overall average of 21% of mice with lung metastases when treated with 1,000--2,000 mg/kg/day of amygdalin compared with 90% of the control mice. The significance attributed to those early observations is seriously challenged by the negative findings of 3 independent investigators, by 2 out of 3 negative cooperative experiments in which Sugiura participated, and particularly by the blind experiment in which he and others under blind readings found no anticancer activity. Treatment of Swiss albino mice showed no destructive effect upon their spontaneous mammary adenocarcinomas. Of the treated mice, 22% were found by macrovisual observation to have lung metastases while 91% were noted among the controls. The results are subject to questions raised in the discussion. Amygdalin at 2,000 mg/kg/day was ineffective both in treating and preventing the development of spontaneous leukemia in AKR mice. At 1,000 mg/kg/day it was not found effective in preventing or significantly delaying the development of spontaneous mammary tumors in CD8F1 mice. In summary, we do not have evidence to support taking amygdalin to clinical trial, although other considerations may require that one be conducted.

Adenocarcinoma↗
PubMed1979

Screening test for amygdalin in tablets, solutions, powders, and seeds.

A rapid screening test for detecting amygdalin in tablets, solutions, powders, and seeds, based on the liberation of both hydrogen cyanide and benzaldehyde as a result of enzymatic decomposition, is described. The procedure can be easily performed outside the laboratory with small amounts of sample; the samples require no special preparation or pretreatment. The test can be performed in less than or equal to 60 min and is sensitive to at least 0.2 mg amygdalin. Vicianin, lucumin, prunasin, and sambunigrin would also given positive tests, but instrumental analysis can be used to distinguish amygdalin from these compounds.

Amygdalin↗
PubMed1978

Pharmaceutical assessment of amygdalin (Laetrile) products.

The National Cancer Institute (NCI) recently acquired a large supply of formulated products of amygdalin manufactured by Cyto Pharma of Mexico, for possible use in a clinical trial in the US. Tablets for oral administration and ampules of the injectable produce were obtained. Both forms were extensively analyzed and evaluated by several analytic and pharmaceutical laboratories under contract with the NCI. Analytic test procedures were developed to determine the chemical integrity and quantitative composition of the formulated products. Routine physical and biologic tests were also performed to evaluate the manufacturing quality of both dosage forms. The results indicate that both the oral and injectable forms of amygdalin were substandard by US criteria for manufactured pharmaceutical products. All samples were determined to be chemically subpotent, mislabeled, and of poor manufacturing quality. More than 20 samples of the ampules were found by visual inspection to contain microbial contamination. Other samples were found to be pyrogenic. Based on the results of the testing performed, both tablet and ampule forms of amygdalin manufactured by Cyto Pharma of Mexico are considered unfit for use in man.

Administration, Oral↗
PubMed1978

Initial pharmacologic studies of amygdalin (laetrile) in man.

A simple enzymatic assay has been applied to the determination of amygdalin in urine and plasma of patients taking laetrile on their own initiative. Following parenteral administration of laetrile, amygdalin is excreted primarily as the unchanged molecule and urinary recoveries may approach 100 percent. Peak plasma levels after a 6 gm intramuscular dose were 180 microgram/ml. The ratio of amygdalin epimers was unchanged in the urine following parenteral injection.

Amygdalin↗
PubMed1978

Antitumor tests of amygdalin in transplantable animal tumor systems.

Except for oral administration, there was no grossly observed toxicity from carefully administered high doses of amygdalin in the experimental systems used. The compound in high doses was ineffective against the DMBA-induced rat mammary carcinoma and the following transplanted experimental tumors: Sarcoma 180, plasma cell tumor LPC-1, leukemia L1210, Mecca lymphosarcoma, Ridgway osteogenic sarcoma, sarcoma T241, mammary carcinoma E0771, Taper liver tumor, Ehrlich carcinoma (solid and ascites), and Walker carcinosarcoma 256. Amygdalin did not noticeably influence the toxicity or impair the efficacy of these chemotherapeutic agents in their respective systems: Cytosine arabinoside, methotrexate, cytoxan, or 5-fluorouracil in L1210; the latter two in LPC-1; 6-mercaptopurine in Ridgway osteogenic sarcoma; estradiol-17beta or 2alpha-methyldihydrotestosterone propionate in the DMBA-induced rat mammary carcinoma.

Amygdalin↗
PubMed1978

Liberation of cyanide from alpha-aminonitriles relative to amygdalin.

A series of aminoitriles have been synthesized and studied whose nonenzymatic dissociation with release of cyanide may be varied by modest alteration of their molecular structure from that obtained with nonenzymatic dissociation of amygdalin to that obtained from enzymatic dissociation of amygdalin by substantial quantities of beta-glucosidase. The relationship between such alterations in molecular structure and nonenzymatic dissociation is discussed. A combination of the results of these studies and studies relating molecular structure to physical localization propensity in tumors has potential in the design of chemotherapeutic agents.

Amygdalin↗
PubMed1979

Studies of amygdalin (laetrile) toxicity in rodents.

Amygdalin (laetrile), given to Fischer 344 rats in doses of 250, 500, and 750 mg/kg intraperitoneally daily for five days, caused mortalities of 30.8% 44.1%, and 56.8%, respectively. The mode of death and the elevated serum cyanide levels in the dying animals strongly suggested cyanide poisoning as the cause of death. These findings seriously question the use of amygdalin in clinical medicine under any circumstances.

Amygdalin↗
PubMed1975

[Tumour hyperacidulation through intravenous glucose infusion enhanced by amygdalin and beta-glucosidase application (author's transl)].

Tumour peracidity in otherwise moderately hyperacidulated tumours or tumour regions of DS carcinosarcoma-bearing Wistar rats attained by glucose infusion was substantially increased by simultaneous infusion of amygdalin and intratumoral i.m. or i.v. application of beta-glucosidase. Here the pH value of healthy tissue, measured at the sceletal muscle, remained unchanged. By means of the said process, tumour hyperacidulation has been raised to a level of deltapH =0.97; attaining a pH difference between tumourous and normal tissue of up to deltapH = 1.6. In one case, the slope of pH reduction in the tumour increased to 870%. Moreover, combined administration of glucose, amygdalin and beta-glucosidase evoked a significant cancerostatic effect hypogenesis, tumour regression) being comparable with the action of an Ifosfamid dosage of 150 mg-kg-1. However, i.m. and i.v. application of beta-glucosidase under narcosis results in an overall process that still remains somewhat too toxic. Hence optimizing studies are intended with the particular aim to further improve the comparability of this process.

Acids↗
PubMed1979

Effects of cyanate, thiocyanate, and amygdalin on metabolite uptake in normal and neoplastic tissues of the rat.

Thiocyanate was found to resemble cyanate in its inhibitory effects on [3H]thymidine incorporation and the uptake of [32P]phosphate and [3H]amino acids in transplanted tumors of the BUF rat. The capacity to inhibit metabolite uptake in hepatomas and a colon tumor under conditions in which uptake was unchanged or increased in host liver was concluded to be a common feature of the action of cyanate and thiocyanate. Inhibition of [32P]phosphate uptake and [3H]thymidine incorporation into DNA of tumors was also observed after treatment of rats with amygdalin. With this drug, however, the action on tumors and livers of host rats was similar.

Amino Acids↗